AN ABSTRACT OF THE THESIS OF
Cheney L. Vidrine for the degree of Master of Science in Wood Science presented on
June 19, 2008.
Title: Copper Compounds for Durable Composites: Effects on Material Properties.
Abstract approved:
_____________________________________________________________________
Jeffery J. Morrell
Frederick A. Kamke
The effects of incorporation of selected biocides on physical and mechanical
properties of aspen strandboard were assessed using five copper-based preservatives
or zinc borate at three retention levels. Tebuconazole or 4,5-dichloro-2-N-octyl-4isothiazolin-3-one (DCOI) were added as co-biocides to selective copper-based
treatments. Mold box tests showed that only panels treated with DCOI provided
significant protection against mold growth, and DCOI with a copper-based
preservative provided the best protection. Exposure to brown or white rot fungi in a
laboratory soil block test showed that all preservatives except micronized copper
hydroxide or DCOI alone reduced weight losses below 10 %. The other three copperbased preservatives performed well independently. The addition of DCOI or
tebuconazole markedly improved mold resistance.
No reductions in bending strength or stiffness were associated with biocide
addition. Internal bond strengths in panels treated with the liquid copper-based
preservative were significantly lower than the untreated controls. Preservative
addition was associated with increased thickness swelling compared to the untreated
controls, but this effect was slight. Some treated panels also experienced slight
increases in the rate of linear expansion, but the values all were well below the
maximum accepted thickness swelling value. Some preservatives were slightly prone
to chemical leaching, but two copper-based biocides were highly resistant. The results
indicate that the three copper-based preservative systems increased resistance to decay
fungi without adversely affecting mechanical or physical properties. Further field
studies to assess resistance to fungal and insect attack are underway.
© Copyright by Cheney L. Vidrine
June 19, 2008
All Rights Reserved
Copper Compounds for Durable Composites: Effects on Material Properties
by
Cheney L. Vidrine
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Presented June 19, 2008
Commencement June 2009
Master of Science thesis of Cheney L. Vidrine presented on June 19, 2008.
APPROVED:
_____________________________________________________________________
Co-Major Professor, representing Wood Science
_____________________________________________________________________
Co-Major Professor, representing Wood Science
_____________________________________________________________________
Head of the Department of Wood Science and Engineering
_____________________________________________________________________
Dean of the Graduate School
I understand that my thesis will become part of the permanent collection of Oregon
State University libraries. My signature below authorizes release of my thesis to any
reader upon request.
_____________________________________________________________________
Cheney L. Vidrine, Author
ACKNOWLEDGEMENTS
The author expresses sincere appreciation to the following people and
organizations for their assistance towards the completion of this thesis. This work
would never have been completed without the undying support of Dr. Jeffery J.
Morrell throughout the entirety of the thesis process. Dr. Fredrick A. Kamke endowed
the author with knowledge and training in the manufacturing of strand-composite
panels. Camille Freitag provided time, patience and a wealth of knowledge for the
author to complete the biological testing. Mental and mechanical support was kindly
bestowed by Milo Clausen. Dr. Alan Preston, Dr. Lehong Jin and Christoph
Schauwecker of Viance LLC (Charlotte, NC) provided materials, expertise and
limitless support for the project. Connie Love provided expertise and assistance with
a variety of tasks during the experimental phase of the work. In all stages of the
project, Amanda J. Benton provided endless assistance, perspective and support.
Louisiana-Pacific’s Newberry, MI siding plant kindly donated all of the aspen
strands used in the study. Resin was provided by Georgia Pacific Chemicals LLC
(Albany, OR). Wax was supplied by Hexion Specialty Chemicals Inc (Springfield,
OR). Zinc borate was graciously donated by Rio Tinto Minerals (Edgewood, CO).
The support of these organizations was vital to the completion of this work.
The author would also like to thank Dr. Jeffery Stone and Dr. Claire
Montgomery for their willingness to serve on my graduate committee.
TABLE OF CONTENTS
Page
Chapter 1 -- Introduction................................................................................................ 1
Background ............................................................................................................ 1
Objectives............................................................................................................... 2
Chapter 2 – Literature Review ....................................................................................... 3
Use of Composites ................................................................................................. 3
Oriented Strandboard ............................................................................................. 4
Composite Durability ............................................................................................. 4
Mold of Composites............................................................................................... 5
Mold Growth .................................................................................................. 5
Health Issues .................................................................................................. 7
Fungal Decay of Composites ................................................................................. 8
Brown Rot Fungi ............................................................................................ 9
White Rot Fungi ............................................................................................. 9
Soft Rot Fungi .............................................................................................. 10
Building Practices That Encourage Decay........................................................... 10
Treatment Methods of Wood Composites ........................................................... 12
Naturally Durable Wood Substrates............................................................. 13
Recycled Treated Wood Substrates.............................................................. 14
Pre-Treatment of Wood Substrates .............................................................. 15
Post-Treatment of Wood Substrates............................................................. 16
In-Process Treating of Wood Substrates...................................................... 17
Preservatives for Treatment of Strand-Composite Panels ................................... 18
TABLE OF CONTENTS (continued)
Page
Copper-Based Preservatives......................................................................... 19
Chlorothalonil............................................................................................... 20
Didecyl Dimethyl Ammonium Chloride (DDAC)....................................... 21
Bifenthrin ..................................................................................................... 21
Isothiazolone ................................................................................................ 22
Triazoles ....................................................................................................... 22
Borates.......................................................................................................... 23
Acetylation ................................................................................................... 24
Isocyanates ................................................................................................... 25
Chapter 3 – The effects of novel copper-based preservative technologies on the
resistance of aspen strandboards to biological degradation. ............................ 26
Abstract ................................................................................................................ 26
Introduction .......................................................................................................... 27
Materials and Methods ......................................................................................... 30
Panel Fabrication.......................................................................................... 30
Retention Analysis ....................................................................................... 33
Soil Block Test ............................................................................................. 34
Mold Box Test.............................................................................................. 35
Statistical Analysis ....................................................................................... 36
Results and Discussion......................................................................................... 36
Retention Analysis ....................................................................................... 36
Soil Block Test ............................................................................................. 38
Mold Box Test.............................................................................................. 43
TABLE OF CONTENTS (continued)
Page
Additional Research ............................................................................................. 47
Conclusions .......................................................................................................... 48
References ............................................................................................................ 49
Chapter 4 – The effects of novel copper-based preservative technologies on the
mechanical and physical properties of aspen strandboard. .............................. 53
Abstract ................................................................................................................ 53
Introduction .......................................................................................................... 53
Materials and Methods ......................................................................................... 56
Panel Fabrication.......................................................................................... 56
Static Bending .............................................................................................. 59
Internal Bond Strength ................................................................................. 59
Permanent Thickness Swell ......................................................................... 60
Hygroscopicity ............................................................................................. 60
Resistance to Leaching................................................................................. 61
Statistical Analysis ....................................................................................... 62
Results and Discussion......................................................................................... 62
Static Bending .............................................................................................. 62
Internal Bond Strength ................................................................................. 65
Permanent Thickness Swelling .................................................................... 67
Hygroscopicity ............................................................................................. 75
Resistance to Leaching................................................................................. 79
Conclusions .......................................................................................................... 80
References ............................................................................................................ 81
TABLE OF CONTENTS (continued)
Page
Chapter 5 – General Conclusions................................................................................. 84
Bibliography................................................................................................................. 86
Appendices................................................................................................................... 96
Appendix A – Statistical Output .......................................................................... 96
LIST OF FIGURES
Figure
Page
1. Cutting pattern used to produce test specimens ....................................................... 33
2. Weight losses of strandboard blocks subjected to various treatments and exposed to
Gloeophyllum trabeum in a soil block test................................................................... 40
3. Weight losses of strandboard blocks subjected to various treatments and exposed to
Postia placenta in a soil block test............................................................................... 41
4. Weight losses of strandboard blocks subjected to various treatments and exposed to
Trametes versicolor in a soil block test ....................................................................... 42
5. Surface mold growth on CC1 or CC2 and tebuconazole treated strandboard in an
AWPA E24 mold box test............................................................................................ 45
6. Surface mold growth on strandboards treated with DCOI alone or as a co-biocide
with two copper complexes.......................................................................................... 46
7. Cutting pattern used to produce test specimens ....................................................... 58
8. Determination of specific gravity............................................................................. 59
9. Modulus of elasticity of treated and untreated strandboards ................................... 65
10. Internal bond strength of treated and untreated strandboards ................................ 66
11. Thickness swelling of treated and untreated strandboards after 2 hours of water
submersion ................................................................................................................... 69
12. Thickness swelling of treated and untreated strandboards after 24 hours of water
submersion ................................................................................................................... 70
13. Moisture contents of untreated and treated strandboards after 2 hours submersion
...................................................................................................................................... 73
14. Moisture contents of untreated and treated strandboards after 24 hours submersion
...................................................................................................................................... 74
15. Moisture contents of treated and untreated strandboards conditioned at 30°C and
30% RH conditioning room environments .................................................................. 77
16. Moisture contents of treated and untreated strandboards conditioned at 30°C and
90% RH conditioning room environments .................................................................. 78
LIST OF FIGURES (Continued)
Figure
Page
17. Linear expansion with change in moisture content of treated and untreated
strandboards conditioned at 30°C and 30% RH, then 30°C and 90% RH................... 79
LIST OF TABLES
Table
Page
1. Preservative treatments assessed.............................................................................. 31
2. Visual scale to rate the extent of mold growth......................................................... 35
3. Chemical retentions of aspen strandboards treated with various preservatives...... 37
4. Wood weight losses of aspen strandboard blocks subjected to various treatments
and exposed to decay fungi in a soil block test............................................................ 39
5. Effects of various treatments on mold resistance of strandboards in an AWPA E24
mold box test. ............................................................................................................... 44
6. Preservative treatments assessed.............................................................................. 57
7. Effects of the addition of preservatives on mechanical properties of strandboards. 63
8. Thickness swelling of treated and untreated strandboards after 2 or 24 hours of
submersion ................................................................................................................... 68
9. Moisture contents of treated and untreated strandboards submerged in water for 0, 2
or 24 hours ................................................................................................................... 72
10. Moisture contents and linear changes in treated and untreated strandboards
conditioned under two different temperature/relative humidity regimes..................... 76
11. Resistance of treated strandboards to chemical leaching after 14 days in an AWPA
E10 leaching test .......................................................................................................... 80
CHAPTER 1 -- INTRODUCTION
Background
Wood is the primary building material used in North America. Concerns
regarding excessive harvesting of old- and second-growth forests have led to an
increased use of wood-based composites that utilize small diameter logs and
processing waste that would otherwise be discarded. Oriented strandboard (OSB) is
composed of various sized strands that have been oriented in a specific direction and
pressed to a desired thickness and density. The small size of the strands allows the use
of small, inexpensive logs that reduce panel cost compared to plywood. Although
OSB can tolerate brief periods of wetting during construction, it is designed to be a
dry-use product. Wood products are susceptible to mold, decay or insect attack when
exposed to high moisture environments for prolonged periods. Due to the geometry of
the product and the species composition, OSB is generally considered to be more
susceptible to decay than softwood plywood.
In response to rising energy costs, a number of building practices have been
implemented to seal homes in order to limit the escape of warm or cold air. These
practices reduce the interior/exterior air exchange and can trap moisture from both
interior and exterior sources. The accumulation of moisture within wall cavities can
lead to mold and decay.
The continued use of wood-based composites in moisture-prone applications is
adding to the growing perception that wood is a non-durable material. Increasing the
ability of wood-based building materials to tolerate short term wetting would yield
1
2
more durable buildings, and the production of decay-resistant wood composite panels
is one possible solution.
Objectives
The objectives of this project were:
•
•
•
Determine the effectiveness of various copper-based preservative
technologies incorporated into the furnish of strandboard
Evaluate the efficacy of two organic biocides in combination with these
copper-based preservatives
Determine the effects of incorporating various copper-based
preservatives on physical and mechanical properties of strandboard
panels
3
CHAPTER 2 – LITERATURE REVIEW
Use of Composites
Merriam-Webster (1993) defines a composite as “a solid material which is
composed of two or more substrates having different physical characteristics and in
which each substrate retains its identity while contributing desirable properties to the
whole.” A wood-composite is a manufactured solid material in which solid wood,
strands, veneers or fibers are permanently connected to each other or another material
by means of mechanical fasteners and/or adhesives. The goal is to combine desirable
characteristics of each component to create a new material with characteristics that are
superior to the original substrates in terms of mechanical properties, homogeneity,
dimensions, durability, price or aesthetic values. Many composites also distribute
defects inherent to the material, such as knots, more evenly, thereby producing
materials with much better performance predictability. This homogeneity can also
have the added benefit of reducing the tendency to shrink, warp and bow (Laks &
Palardy, 1990a). Composites can also be used to optimize material utilization. For
example, higher quality material can be used where higher stress concentrations are
likely to occur, while lower quality material can be used in neutral axes. Wood-based
composites are also able to use small substrates, eliminating the requirement for large
timbers. This allows for the utilization of small diameter logs and processing waste
(i.e. trimmings, chips and fines), which helps to increase the efficiency of material use
and reduces the need for tree harvesting. There is a multitude of commercially
available composite materials, each with its own attributes.
4
Oriented Strandboard
Composite panels are used in both structural and non-structural applications,
and are composed of veneers, strands, fiber or particles. Plywood and oriented
strandboard (OSB) are currently the two most widely used materials for structural
applications. Plywood consists of laminated veneers, while OSB is composed of
various sized strands that have been oriented in a specific direction, combined with
resin and pressed to a desired thickness and density. Plywood was the only structural
wood panel available until the advent of OSB in the late 1970’s. OSB products
surpassed North American plywood production in 2000 (SBA, 2008).
The main advantage of OSB over softwood plywood is cost. Because of the
small size of the strands that make up OSB, expensive “peeler” logs used to
manufacture plywood are unnecessary, and smaller, lower quality species of wood,
such as aspen (Populus tremuloides), can be employed. The lower cost of the material
in OSB greatly reduces the final cost per panel compared to plywood. The resource
impact of OSB is also lower than that of plywood because it alleviates pressure to use
large logs from slow-growing species, such as Douglas-fir (Pseudotsuga menziesii)
(Laks & Palardy, 1990a).
Composite Durability
Although wood and wood-based composite sheathing panels can tolerate brief
periods of wetting during construction, they are designed to remain dry while in
service. Exposing these products to high relative humidities or liquid water for
5
prolonged periods sharply increases the chances of mold, stain or decay (Fogel &
Lloyd, 2002; Morris et al., 1999). Softwood plywood panels tend to be more resistant
to decay and mold attack than OSB (Laks, 1999; Laks et al., 2002). Even though OSB
and strand-composite products are made from decay susceptible species, they are
increasingly being used in applications that subject them to conditions suitable for
insect and fungal attack (Jeihooni et al., 1993; Morrell, 2002; Morris, 1995; Morris et
al., 1999).
The higher susceptibility of OSB to decay reflects both the geometry of the
product and the species composition. OSB is composed of small strands that have
been pressed together. This process results in numerous void spaces that act as
pathways for moisture and organisms to enter the panel. The increased water
accessibility results in more rapid swelling of individual strands, which opens gaps
that allow better access for the fungi (Anderson, 1972; Chung et al., 1999). The
higher nitrogen content of aspen also favors stain and mold fungi, and these organisms
can increase wood permeability and lead to a tendency for OSB to sorb even more
water (Morris et al., 1999). The lower intrinsic decay resistance of poplar compared to
softwood species also reflects the lower lignin content (Laks, 2002).
Mold of Composites
Mold Growth
Mold and decay fungi require an ample supply of oxygen, adequate
temperature range, liquid water and the availability of nutrients for growth. Because
6
these conditions are almost exactly the same as those necessary for human existence,
it is not surprising that fungi are common in wood framed housing.
Molds are fungi whose visible damage is largely confined to the surface of a
substrate, although they grow more deeply into the material. Mold occurs primarily in
the sapwood, where low molecular weight carbohydrates, proteins, lipids and other
compounds stored in xylem parenchyma cells are readily available (Laks, 2002).
Discoloration of the wood is due to the development of pigmented spores on the
surface, although shallow discoloration may also occur within the wood (Scheffer &
Cowling, 1966). The hyphae of mold fungi grow though the pits in the wood cells and
this damage renders the wood more permeable. The more permeable wood wets faster
and may therefore be more susceptible to fungal decay. Of the approximately 250,000
species of fungi, only a small percentage are classified as mold fungi, and all molds
are members of the Ascomycota. Unfinished aspen OSB often develops a dark
discoloration due to the fungus Alternaria when used in exterior applications, athough
other common molds such as Epicoccum, Aureobasidium, Penicillium, Paecilomyces,
Trichoderma, and Diplodia are often isolated from moldy panels (Schmidt, 1993).
Although humid air does not have enough water vapor to wet wood adequately
to support the growth of decay fungi, some researchers have found it to be adequate
for mold growth (Clausen & Yang, 2007). Others suggest that condensation of water
onto wood surfaces, not high relative humidity (RH), is necessary for mold growth
(Morrell, 2002). The amount of available water, which is usually expressed as water
activity or as RH, is the most important factor for growth (Nielsen et al., 2004). Wang
7
(1993) found that RH also plays an important role in the rate of mold growth.
Growth is most rapid at temperatures between 15-25ºC when RH exceeds 90%.
Health Issues
A major concern regarding the growth of mold in homes and office buildings is
the fear that spores produced by these fungi induce sinus and respiratory problems. A
number of molds commonly found in buildings produce mycotoxins that may lead to
adverse health effects in some individuals (Nielsen et al., 2004). The majority of the
molds found in buildings are species of Cladosporium, Penicillium, Alternaria,
Fusarium, Trichoderma,and Stachybotrys. All of these genera contain species capable
of producing of mycotoxins (Clausen & Yang, 2004). Members of the genera
Cladosporium, Penicillium, and Alternaria can cause chronic sinus infections,
respiratory infections and induce asthma attacks (Fogel & Lloyd, 2002). Aspergillus,
another common mold genus, contains two species considered to be pathogenic to
humans (Clausen & Yang, 2004).
In the 1990’s, outbreaks of pulmonary humosiderosis (bleeding lung disease)
killed approximately 70 children. The outbreaks were, at first, linked to the toxic
mold Stachybotrys atra, and were attributed to have resulted from inadequate home
ventilation and humidity controls (Jacobs et al., 1999).
The initial concerns regarding the exposure to mycotoxins such as those
produced by Stachybotrys have not held up to scientific scrutiny, although some
sensitive individuals may be prone to asthmatic attacks due to mold exposure (CDC,
2000; IOM, 2004). Despite these findings, mold is no longer an acceptable blemish on
8
most consumer-related wood products and there is a continuing need for methods to
produce mold resistant materials.
Fungal Decay of Composites
Wood decay fungi are specialized heterotrophic fungi, usually basidiomycetes
along with some ascomycetes, which obtain most of their nutrients from the
decomposition of wood holocellulose. Some of these fungi also have the ability to
utilize lignin. The requirements for growth of decay fungi are the same as those for
molds. Most decay fungi prefer temperatures between 15 and 45ºC. Although
atmospheric oxygen is required for growth, most wood-inhabiting fungi will prosper at
relatively low oxygen levels. Energy and metabolites are obtained from wood cell
wall components. An ample amount of water is also required for the decay process.
Water acts as a reactant for cell wall hydrolysis, a diffusion medium for degradative
enzymes and solublized wood components, a medium for important life systems and
as a swelling agent of the wood substrate (Zabel & Morrell, 1992). Most fungi that
degrade wood require a wood moisture content (MC) above the fiber saturation point
(FSP). The FSP is the level at which no more water can be bound to the cell wall, and
any additional water accumulates as liquid and vapor within the lumen. The FSP for
most wood species is between 27 and 30% MC. Although MCs above the FSP are
required for initial growth, fungi can continue to grow at MCs as low as 20% once the
wood substrate has been colonized (Morrell, 2002).
Decay fungi can be separated into three distinct decay types based upon their
mechanisms of decay and the different cell wall constituents they degrade. Brown and
9
soft rot fungi tend to preferentially degrade the carbohydrate fraction, while white rot
fungi can degrade all three components. Although brown rots and whites rots can be
found concurrently on all wood species, brown rots preferentially decay softwoods
while white rots prefer hardwoods (Schmidt, 1993).
Brown Rot Fungi
Brown rot fungi preferentially attack the carbohydrate portion of the cell wall.
The brown residue left after degradation, hence the name “brown rot,” consists of
partially demethylated lignin. These fungi rapidly and severely depolymerize the
crystalline cellulose in the early stages of attack at relatively low weight losses.
Brown-rot degradation of cellulose appears to involve two mechanisms, oxidation and
hydrolysis, that might be either sequential or concurrent. These reactions appear to be
intertwined, with oxidation most likely accomplished by a non-enzymatic mechanism,
and hydrolysis catalyzed by a complex of enzymes (Highley et al., 1994).
White Rot Fungi
White rots degrade all components of the cell wall. The whitened appearance
of white-rotted wood is due to the removal of the brown colored lignin and oxidative
bleaching reactions that occur during the decay process. Initially, some white rot
fungi preferentially degrade the lignin portion of the cell wall. Because these fungi
require carbohydrates as an energy source, which lignin cannot provide, the cellulose
and hemicellulose portions of the cell wall are simultaneously degraded, but at a
slower rate. The breakdown of lignin primarily occurs through a series of exzymatic
10
oxidative reactions. As with brown rot fungi, hemicellulose and cellulose are first
disrupted by oxidative reactions that make the substrates more accessible to enzymatic
degradation. Hydrolysis is accomplished by enzymes that break cellulose and
hemicellulose into glucose and other simple sugars that can be absorbed and
metabolized by the fungi (Eaton & Hale, 1993; Zabel & Morrell, 1992).
Soft Rot Fungi
The term soft rot is used to describe ascomycetes that attack the outer surface
of wood in relatively wet environments. There are two distinct methods by which soft
rot fungi attack wood cell walls. Cavity formation, or Type I, is characterized by the
degradation of the S2 layer within the cell wall. Cellulases and phenol oxidase
enzymes degrade cellulose and lignin, respectively, and are secreted from fine
microhyphae growing parallel to the wood cell microfibrils. This decay mechanism
creates diamond-shaped cavities that continue in stepwise start-stop chains that are
unique to soft-rotted wood. Type II soft rot is described as a general erosion of wood
cell walls, beginning from the S3-lumen interface and attacking outward. Type I and
Type II soft rot can occur independently, within the same piece of wood or by the
same fungus within the same piece of wood (Goodell et al., 2008). Because soft rot
fungi are usually found to degrade wood products in wet environments, like telephone
poles or fence posts, they are generally not considered a threat to wood composite
panels.
Building Practices That Encourage Decay
11
Rising energy costs in North America have encouraged an array of building
practices designed to conserve energy by sealing homes to limit the escape of warm or
cold air. Unfortunately, reducing the interior/exterior air exchange can also trap
moisture from many interior sources within the building. (Anderson, 1972; Barnes &
Amburgey, 1993; Cassens, 1978; Laks, 1999; Laks et al., 2002; Merrill & TenWolde,
1989; Morrell, 2002; Schmidt, 1993). One of the most common and problematic of
these practices is to wrap buildings with a weather-resistant barrier. These plastic-like
membranes are wrapped over the sheathing and under the exterior siding to prevent
the intrusion of air and moisture. Although building wraps accomplish this task, they
also prevent the escape of moisture generated from within the building. The
accumulation of moisture within wall cavities can lead to mold and decay (Barnes &
Amburgey, 1993; Schmidt, 1993; Yang et al., 2007).
The more efficiently new buildings reduce heat transfer, the greater the
potential for moisture condensation to occur (Anderson, 1972; Merrill & TenWolde,
1989). In cold climates, condensation occurs when the colder outside wall surface
cools the warm, moist indoor air as it contacts the inside wall surface. Excess
condensation within wall cavities, though not clearly linked to wood decay (Burch et
al., 1979; Burch & Treado, 1978; Sherwood, 1983; Tsongas, 1980, 1986), can provide
in ideal environment for mold growth (Fogel & Lloyd, 2002; Morrell, 2002). The
opposite effect occurs in air-conditioned houses in warm climates when moist air on
the outside condenses on colder, air-conditioned interior surfaces.
12
Concerns about the cost of building materials also led to architectural design
changes in many wood structures that inadvertently promoted the possibility of
exterior moisture intrusion. Decreases in the size of roof overhangs reduced material
costs, but also increased the probability that wetting of siding will occur (Scheffer &
Moses, 1993). Inadequate site drainage, water leaks, poor insulation, relatively flat
roof pitches, improper ventilation, and indoor pluming all contribute to increased
indoor moisture accumulation (Barnes & Amburgey, 1993; Clausen & Yang, 2004;
Morrell, 2002; Morris, 1997). Poor execution of building features compounds the
issues associated with new design features and energy efficient sealed homes (Laks,
1999; Morrell, 2002). All of these factors, coupled with the increased use of less
durable sheathing and an increasingly litigious society, have resulted in a substantial
rise in moisture-related building issues.
Treatment Methods of Wood Composites
The continued use of wood-based composites in moisture-prone applications is
adding to the growing perception that wood is a non-durable material. Increasing the
ability of wood building materials to tolerate short term wetting would yield more
durable buildings, and the use of decay resistant wood composite panels is one
possible solution (Yang et al., 2007).
Contemporary composites must be both effective and environmentally
acceptable. Murphy et al. (1993) summarized the criteria for an acceptable
preservative treatment process for wood composites:
13
•
•
•
•
•
•
•
Efficacy – The preservative should be effective against decay fungi
and wood degrading insects.
Environment – The treatment operation and product should have
acceptable environmental characteristics.
Mechanical properties – The treatment should have no negative impacts
on mechanical properties.
Physical properties – Interference with physical properties, such as
EMC and dimensional stability, should be minimal.
Appearance – Unless it is desired for identification purposes, the
treatment should not change the appearance of the wood.
Speed and Flexibility – The treatment process should be as rapid as
possible and be able to produce as much product to meet orders in short
notice.
Verification and compliance with standards – The treated material
should be easily analyzed for quality control.
Other considerations when designing a preservative treatment are the product
life cycle, compatibility and adaptability with current processes, resin and additive
systems, stability and consistency of the preservative, and product durability and
characteristics (Ross et al., 2003; Wu, 2004). Theoretically, achieving uniform
biocide distribution in wood-based composites should be easier to attain than in solid
wood products (Barnes & Amburgey, 1993). Durable wood composites can be
produced through the use of wood species with high natural durability, incorporating
recycled treated wood, pre-process preservative treatments of the wood, post-process
preservative treatments and in-process preservative treatments (Gardner et al., 2003).
Treatment methods are dependent upon the final product.
Naturally Durable Wood Substrates
The use of naturally durable wood species as the primary strand type produces
a synthetic chemical-free, decay resistant wood composite panel, and this approach
14
has been commercialized to a limited extent (Gardner et al., 2003). The heartwood
of certain tree species contains fungal and insect resistant extractives (Hawley et al.,
1924). The heartwood of naturally durable species like western redcedar could be
used as furnish for particleboard, OSB and other composite panels (Yang et al., 2007).
Important issues, such as availability of raw materials, effects of extractives on
bonding, variable heartwood decay resistance and possible effects of heat on durability
must be addressed (Gardner et al., 2003).
Recycled Treated Wood Substrates
One other method for fabricating durable strand composite panels is to use
recycled treated wood as the raw material. Chromated copper arsenate (CCA) was the
most widely used preservative treatment of wood for residential applications from the
1970’s until 2004. Large volumes of CCA treated lumber will continue to come out of
service over the next few decades. Instead of disposing of this material in landfills,
where it may take decades or more to degrade, it may be possible to turn this wood
into strands that can be used as OSB furnish (Gardner et al., 2003; Laks & Palardy,
1993; Li et al., 2004; Mengeloglu & Gardner, 2000; Zhang et al., 1997). There are a
number of issues that must be addressed before commercialization of this process.
Bonding problems can arise due to the presence of insoluble metal deposits that inhibit
adhesion between the wood and the resin (Gardner et al., 2003; Vick et al., 1996).
Worker safety and environmental problems may also arise due to the potential for
arsenic releases during processing of composite panels made from treated wood
(Smith & Shiau, 1998). Furthermore, a large portion of CCA treated members only
15
contain a shell of protection surrounding an untreated core. As a result, furnish
prepared from such material would contain mixtures of heavily treated, lightly treated
and untreated particles. This variability makes it difficult to ensure that a targeted
amount of preservative is present in the resulting composite panel (Laks & Palardy,
1993).
Pre-Treatment of Wood Substrates
It is also possible to produce wood composite products using wood substrates
that have been treated prior to pressing (Gardner et al., 2003; Morrell, 2002). Strands,
veneers or solid wood members can be treated by dipping, soaking or spraying
chemical onto the materials. The wood is then dried and processed into a finished
panel. This approach can be used with any type of wood composite, although it has
some issues. As with recycled treated wood for wood composites, bonding of treated
wood can pose a challenge. Pre-treating the substrate also requires an extra drying
step, which is energy intensive and less efficient. Finally, any chemicals used must be
safe to handle, create no hazardous waste and not negatively affect final panel
properties.
An alternative to chemical treatments is the pre-treatment of strands using
various heating processes that alter the wood chemistry to reduce moisture uptake and,
potentially, fungal attack. The effects of heat treatment on solid wood properties are
well understood (Seborg et al., 1953; Stamm, 1956; Tjeerdsma et al., 1998), and the
process can reduce fungal decay in low moisture environments. Heat pre-treatment of
strands does not appear to be effective against mold or brown-rot fungi (Kartal, 2007).
16
Heat treatment of strands also dramatically reduces the mechanical properties of the
resulting OSB (Paul et al., 2006). For these reasons, heat treatment appears to be
unacceptable for protecting wood-based composite panels from decay.
Post-Treatment of Wood Substrates
Some wood composites can be treated after production using conventional
treatment methods (Gardner et al., 2003; Laks & Palardy, 1990a; Morrell, 2002; Wu,
2004) such as spraying, immersion or pressure treatment. The envelope of protection
created by the spray and immersion treatments are designed to provide short term
resistance to decay, mold and water intrusion during transportation and building
construction (Ross et al., 2003; Wu, 2004). The advantages of these treatments include
low cost and relative ease of application. Pressure treatment of wood composites is
generally limited to glued laminated wood (glue-lams), laminated veneer lumber
(LVL) and plywood. Pressure treatment of glue-lams often only provides an envelope
of protection which can be breached if the post-treated product is cut, notched or
drilled (Gardner et al., 2003). Other wood composites, including strand or fiber
composites, often experience unacceptable, permanent deformation during pressure
treatment with water-based preservatives (Laks, 1999; Morrell, 2002). Deformation
results in permanent thickness swelling, strength reduction and an increase in surface
roughness of the panel (Wu, 2004). As a result, pressure treating is not considered to
be a suitable method for protecting many of these wood-based composites.
The vapor boron process, whereby trimethylborate diffuses into pressed panels
under a vacuum and reacts with water to produce boronic acid and methanol, could be
17
a non-swelling method of post-process treating durable panels (Morrell, 2002).
Methanol can be recovered at the end of the process and used to produce new
trimethylborate. The treatment does not interfere with the adhesive when used in
composite panels, and has only slight negative effects on mechanical properties.
Because the treatment is applied to the final product, there are no issues related to the
disposal of treated off-cuts (Murphy & Dickinson, 1997; Murphy et al., 1993; Murphy
& Turner, 1989). The limiting factors with this process are the treatment cost, the
difficulty recovering the methanol within the wood and the inability of boric acid to
fix to wood. As a result, vapor boron is only suitable to environments not subjected to
wetting and would not be ideal for most durable wood composite panels.
Supercritical fluids may also be used as carriers for impregnating biocides into
composites (Morrell, 2002). Supercritical fluids are solvents that diffuse through
wood like gasses but can have solvating properties like liquids (Gardner et al., 2003).
Supercritical fluids have been found to have no negative impacts on mechanical
properties of various wood-based composites, and the process results in excellent
preservative distribution (Acda et al., 1996). The biggest disadvantage of
commercializing supercritical fluid treatment is the high capital cost of the highpressure treatment facility.
In-Process Treating of Wood Substrates
One of the more effective methods for treating strand and fiber composites is
to incorporate the biocide into the furnish prior to pressing. Uniform distribution of
the preservative within the product can provide much better protection than “shell”
18
treatment (Laks & Palardy, 1992). Finished products can also can be machined at
any point without losing resistance to biological attack because the entire panel is
uniformly treated (Gardner et al., 2003; Laks & Palardy, 1993). Factors that affect the
suitability of a preservative for in process treatments include preservative thermal
stability, the diffusivity of the chemical during consolidation, the presence of
emulsifiers in the preservative formulation, preservative availability in powder or
liquid form, adhesive interactions and wood species (Laks & Palardy, 1992). Five
attributes of an ideal in-process treatment system include (Laks & Palardy, 1993):
•
•
•
•
•
Preservative remains stable during pressing
No interference of the preservative with adhesive bond formation
Biocide relatively immobile within the product during service
Strength properties of the panel not negatively affected by the
preservative
Limited volatility of the biocide, especially during processing
There are a number of methods for applying preservative to OSB. An
additional sprayhead or blender system may be used to treat the strands before or after
drying. Chemical can also be mixed with the adhesive or wax before application to
strands in the blender, liquid preservative can be sprayed onto the strands, or a
powdered chemical can be mixed into the blender. Powdered preservatives can also
be metered onto dried strands just before they are placed in the blender, where the
powder would be mixed with the strands (Laks & Palardy, 1990b). Of all these
methods, preservative addition to the adhesive or wax is probably the most convenient
for the manufacturer (Laks & Palardy, 1992).
Preservatives for Treatment of Strand-Composite Panels
19
There are a number of preservatives that may be suitable for composite
panels. Each has advantages and disadvantages in terms of cost, safety, ease of
handling and efficacy.
Copper-Based Preservatives
Waterborne copper-based preservatives, such as chromated copper arsenate
(CCA) have long dominated the treated sawn dimensional lumber and plywood
markets. Since the 2004 withdrawal of CCA from residential building applications,
new generation, arsenic free, copper-based preservatives have been used to treat both
lumber and plywood. These preservatives have been shown to protect waferboards
against fugal attack, but the added steps of dip-treating and drying the strands prior to
blending make manufacturing uneconomical (Boggio & Gertjejansen, 1982). These
chemicals also affect bonding and reduce mechanical properties of the panels
(Goroyias & Hale, 2000; Hall et al., 1982).
Other copper preservatives, such as copper naphthenate, ammoniacal copper
complexes or copper carbonate in powdered forms have shown good efficacy when
included in wood composite panels (Kirkpatrick & Barnes, 2006b). Kirkpatrick and
Barnes (2006a) continued research by Schmidt (1991) and found that powdered
copper naphthenate could be added to the furnish of aspen strandboards without
significant negative effects on mechanical and physical properties. Copper
ammonium carbonate (CAC) was found to be effective and was used as an pre-process
preservative for OSB produced by Potlatch Corporation (Preston et al., 2003). The
added steps during strand pre-treatment before blending made the CAC treatment
20
uneconomical. Goroyias and Hale (2000) added a copper carbonate hydroxidebased preservative, with boric acid, tebuconazole, and an aliphatic amine derivative as
co-biocides, at various points during the manufacturing of strandboard. They found
that the preservative reduced mechanical properties when sprayed in-line with resin
application and pressed at 210°C.
Copper based biocides appear to have a strong potential as wood composite
panel preservatives if formulation and application methods can be optimized.
Preferably, a powdered copper complex would be added to the strands prior to resin
application and pressed using a standard press schedule.
Chlorothalonil
Chlorothalonil has been used as a mildewcide in paint and as a fungicide and
termiticide in agricultural and industrial applications. Chlorothalonil is often
combined with methylene bis-thiocyanate in the anti-sapstain market (Freeman,
2008). The chemical is also an effective preservative in solid wood (Woods & Klaver,
1992; Woods et al., 1995). However, Laks et al. (1992) found that chlorothalonil
produced very little reduction in weight losses of solid wood by brown or white rot,
even at high loadings. Micales-Glaeser (2004) found only moderate effectiveness
against mold on pine and aspen blocks, while Laks et al. (1992) determined that high
loading levels or in combination with other biocides gave effective protection to
lumber products. This molecule is exceptionally difficult to solubilize, and some of
the poor performance observed in previous tests may reflect formulation issues.
21
Didecyl Dimethyl Ammonium Chloride (DDAC)
Didecyl dimethyl ammonium chloride (DDAC) is a quaternary ammonium
compound that is broadly effective against fungi, colorless, has low toxicity to nontarget organisms, has limited volatility and dissolves easily in organic and aqueous
solvents. DDAC has been found to effectively prevent decay in laboratory tests, but
has produced variable protection in above ground field tests (Yu & Ruddick, 1995). It
is the most common quaternary ammonium compound used as a co-biocide in
ammoniacal copper quat (ACQ), and is also commonly used with 3-iodo-2-propynyl
butyl carbamate (IPBC) as an anti-sapstain preservative. Solid wood treated with
DDAC alone provides very little protection against mold fungi, but greatly reduces
mold growth when combined with chlorothalonil (Micales-Glaeser et al., 2004).
Although DDAC does not interfere with bonding properties when used with phenol
formaldehyde adhesives (Vick et al., 1990), the chemical has a tendency to leach inservice (Nicholas et al., 1991; Ruddick & Sam, 1982), which is probably reflected in
the poor decay resistance results. The low efficacy against mold fungi and the
tendency to leach in-service makes DDAC a poor candidate for a composite panel
preservative.
Bifenthrin
Bifenthrin is a low-toxicity insecticide that has proven to be very effective
against termites at low loadings. It is chemically stable, compatible with fungicides,
has a high vapor pressure and is soluble in a range of solvents (Rustenburg, 1995;
Shires et al., 1996). Norton and Stephens (2007) showed that this insecticide could be
22
successfully added into multiple adhesive systems for use in composite panels.
Although widely used in Australia as an effective preservative when combined with a
supplemental fungicide, this chemical is not currently used for wood treatment in the
US. Bifenthrin has the potential to be a co-biocide for insect protection of wood-based
composite panels.
Isothiazolone
Isothiazolone (DCOI) is a broad-spectrum fungicidal preservative that is
effective at low levels against decay fungi in both laboratory and field tests (Leightley
& Nicholas, 1990; Nicholas et al., 1984). Williams and Lewis (1989) found that
DCOI reduced mold growth on Scots pine (Pinus sylvestris) lumber. Wood pressuretreated with isothiazolone produced no harmful combustion products when burned,
which indicates that isothiazolone treated wood can be safely incinerated for disposal
(Yu, 1997). Isothiazolone is a water insoluble preservative that is delivered into
wood using an oil-in-water micro-emulsion that results in a uniform distribution of
nanometer-sized droplets that provide consistent treatment throughout the wood
product (Yu & Leightley, 1992). These formulations exhibit minimum leaching losses
while providing good anti-fungal efficacy (Hegarty et al., 1997). These favorable
attributes make isothiazolone a potential candidate for composite panel protection.
Triazoles
Triazoles are a class of compounds that contain a five-membered ring of two
carbon atoms and three nitrogen atoms. Azole-based fungicides are widely used in a
23
range of agricultural and pharmaceutical applications. These biocides inhibit fungal
ergosterol biosynthesis, and their highly specific mechanism of action gives them low
mammalian toxicity. Azaconazole provided good protection against fungal decay,
was leach resistant and did not affect mechanical properties of waferboard when added
as a dry powder to the furnish with PF resin (Schmidt & Gertjejansen, 1988). Jeihooni
et al (1994) found that azaconazole did not affect panel properties and still provided
protection against a brown rot fungus. Aspen OSB treated with tebuconazole using
supercritical carbon dioxide was less resistant to decay in an above ground field test
than similarly treated plywood (Morrell et al., 2005). While there is little data on the
efficacy of triazoles in composites, there is a wealth of data on solid wood. Clausen
and Yang (2003; 2005; 2007) found that thiabendazole and voriconazole completely
inhibited mold growth of dip-treated southern pine. Tolley et al. (1998) found that
tebuconazole and propiconazole provided moderate protection against mold, but
protection was improved when the chemicals were combined. In other tests,
tebuconazole treated wood experienced weight losses below 10% when exposed to
brown or white rot fungi (Laks & Palardy, 1992). The combination of very low
mammalian toxicity, little effect on wood composite properties and excellent decay
resistance makes tebuconazole a candidate for further research in composite panels.
Borates
Borates have a number of appealing benefits as wood preservatives, including
good efficacy against fungi and insects, fire retardancy, ease of application into the
board furnish, low cost, low mammalian toxicity and low environmental impact.
24
Borates do not have a significant vapor pressure and will not degrade under press
conditions (Laks & Palardy, 1990b). However, borates have a few disadvantages that
limit them as an ideal wood composite panel preservative.
Biologically-effective treatment levels of sodium borate and boric acid react
with phenol formaldehyde (PF) resin to prevent good adhesion between wood
substrates, resulting in boards with unacceptably low mechanical properties. It is
believed that the resin cures prior to strand consolidation due to the reaction of boron
ions with the functional methylol groups on the resin molecules (Lee et al., 2001).
The interference problem can be reduced by using pMDI resin instead of PF resin, but
this has other negative effects including higher panel production costs (Laks et al.,
1988; Laks & Palardy, 1993). A number of borate treatments, including disodium
octaborate tetrahydrate (DOT) and anyhydrous borax, are extremely water-soluble and
their propensity to leach in-service makes them unsuited to exterior exposures
(Gardner et al., 2003). As an alternative, zinc borate (ZB) is a relatively waterinsoluble alternative that is currently used in exterior applications with low to
moderate leaching hazards (Laks, 1999; Manning & Laks, 1996). This chemical has
sufficient solubility to produce protective boron levels in water within the wood cell,
but is not so soluble that it will completely migrate from the wood. In addition, ZB
has less interaction with resin and does not adversely affect bonding like other borates.
Acetylation
Chemicals such as acetic anhydride can react with hydroxyls in the wood to
limit moisture uptake and thereby increase the dimensional stability of wood and limit
25
wood decay (Rowell et al., 1997). Phenolic or isocyanates resins can be used to
acetylate OSB strands prior to blending. Gardner et al. (2003) and Okino et al. (2004)
found a reduction in mechanical properties due to reduced penetration of the adhesive
into the modified cell wall. Kumar and Morrell (1993), on the other hand, found that
the use of thioacetic acid instead of the more common acetic anhydride produced
increases in internal bond strength, maximum bending load and tensile strength.
Weight gains of the acetylating agent must be upwards of 17% to provide sufficient
biological protection. This unavoidably high weight gain, coupled with bonding
issues due to reduced adhesive penetration, make acetylation a poor candidate for a
treatment of price-sensitive commodity composite panels like OSB.
Isocyanates
Chemical modification of strands using an isocyanate polymer system prior to
blending can improve resistance to biological attack and the dimensional properties of
OSB. The modifying agent reacts with cell wall hydroxyl groups to form crosslinkages that reduce hygroscopicity. Wood modification is attractive because there are
no residual toxic materials in the wood. The major drawbacks that eliminate
isocyanates as an acceptable preservative for wood composite panels are associated
with the large uptakes required to produce protection and the cost of treatment (Wu,
2004).
26
CHAPTER 3 – THE EFFECTS OF NOVEL COPPER-BASED
PRESERVATIVE TECHNOLOGIES ON THE RESISTANCE OF ASPEN
STRANDBOARDS TO BIOLOGICAL DEGRADATION.
Abstract
Mold and decay resistance of aspen strandboards treated with various copperbased preservative systems were evaluated in laboratory tests. Five copper-based
chemicals or zinc borate were blended into the furnish at three retention levels.
Tebuconazole or 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one (DCOI) were added as
co-biocides to selective copper-based treatments. All retention levels were well below
targets. Panels were inoculated with four common molds and subjected to high
temperature and humidity for eight weeks, according to AWPA Standard E24. Most
panels experienced extensive mold growth, but panels treated with DCOI had marked
resistance to attack. The two combinations of copper-based preservatives and DCOI
also performed well. Panels were also assessed for decay resistance in a laboratory
soil block test against the brown rot fungi Gloeophyllum trabeum or Postia placenta,
or the white rot fungus, Trametes versicolor, according to AWPA Standard E10. All
preservatives reduced weight losses caused by G. trabeum or T. versicolor below 10
%, except for micronized copper hydroxide or DCOI alone. The four other copperbased preservatives performed well independently and with the addition of DCOI or
tebuconazole. The results suggest that incorporating combinations of copper-based
preservative systems with organic co-biocides improved decay and mold resistance of
aspen oriented strandboard.
27
Introduction
Oriented strandboard (OSB) is a composite sheathing panel product composed
of various sized strands that have been mixed with resin, oriented in a specific
direction and pressed to a desired thickness and density. OSB is a high quality
product that effectively utilizes lower quality species of wood. The inexpensive raw
material costs are passed on to the consumer as a low cost product. The resource
impact of OSB is also lower than that of plywood, the traditional sheathing panel
product, due to the tree species used (Laks & Palardy, 1990a).
Although wood and wood-based composite sheathing panels can tolerate brief
periods of wetting during construction, they are designed to remain dry while in
service. Exposing these products to high relative humidities or liquid water for
prolonged periods sharply increases the chances of mold, stain or decay (Fogel &
Lloyd, 2002; Morris et al., 1999). Softwood plywood panels tend to be more resistant
to decay and mold than OSB (Laks, 1999; Laks et al., 2002). Even though OSB and
strand-composite products are made from decay susceptible species, they are
increasingly being used in applications that subject them to conditions suitable for
insect and fungal attack (Jeihooni et al., 1993; Morrell, 2002; Morris, 1995; Morris et
al., 1999). In response to rising energy costs, a number of building practices have
been implemented to seal homes to limit the escape of warm or cold air. These
practices reduce the interior/exterior air exchange, which can trap moisture from both
interior and exterior sources (Anderson, 1972; Barnes & Amburgey, 1993; Cassens,
1978; Laks, 1999; Laks et al., 2002; Merrill & TenWolde, 1989; Morrell, 2002;
28
Schmidt, 1993). Accumulation of moisture within wall cavities can lead to mold
and decay (Barnes & Amburgey, 1993; Schmidt, 1993; Yang et al., 2007).
A variety of methods can be used to protect composite panels from biological
attack (Gardner et al., 2003). In-process treatments appear to be among the best
treatment methods. Uniform preservative distribution within the product produces
much better protection than “shell” treatments provided by post-treatment processes,
while pre-treating the substrate requires an extra drying step that is energy intensive
and costly (Laks & Palardy, 1992).
There are a number of preservatives that may be suitable for composite panels.
Each has advantages and disadvantages in terms of cost, safety, ease of handling and
efficacy. Organic biocides are increasingly used as wood preservatives because of
their low toxicity to non-target organisms and rising consumer concerns about the use
of heavy metals. Triazoles are a class of organic fungicides that are widely used in
agriculture, and are increasingly employed as co-biocides in wood preservatives.
These systems provide adequate protection against decay fungi, moderate protection
against surface mold, and little interference with mechanical or physical properties of
OSB (Schmidt & Gertjejansen, 1988; Tolley et al., 1998). Isothiazolone is a broad
spectrum fungicide that has been found to reduce mold growth (Williams & Lewis,
1989) and to be effective against decay fungi in both laboratory and field tests
(Leightley & Nicholas, 1990).
Borates have a number of appealing benefits as wood preservatives, including
good efficacy against fungi and insects, fire retardancy, ease of application into the
29
board furnish, low cost, low mammalian toxicity and low environmental impact
(Laks & Palardy, 1990b). However, borates have a few disadvantages that limit them
as composite panel preservatives. Biologically-effective treatment levels of sodium
borate and boric acid react with phenol formaldehyde (PF) resin to prevent good
adhesion between wood substrates, resulting in boards with unacceptably low
mechanical properties. A number of borate treatments, including disodium octaborate
tetrahydrate (DOT) and anyhydrous borax, are extremely water-soluble and therefore
have a propensity to leach in-service (Gardner et al., 2003). As a result, these products
are not recommended for ground-contact. As an alternative, zinc borate (ZnB) is a
relatively water-insoluble alternative that is currently used in coated exterior
applications with low to moderate leaching hazards (Laks, 1999; Manning & Laks,
1996). Various physical or chemical modifications have also been assessed for OSB
protection, including acetylation, isocyanates, supercritical fluids and heat treatment
(Acda et al., 1996; Kumar & Morrell, 1993; Murphy & Turner, 1989; Paul et al.,
2006). None of these treatments are currently practical due to unacceptable weight
gains, efficiency issues and/or cost.
The use of copper preservatives, such as copper naphthenate, ammoniacal
copper complexes or copper carbonate in powdered forms have shown good efficacy
when included in wood-based composites (Kirkpatrick & Barnes, 2006b). Kirkpatrick
and Barnes (2006a) continued research by Schmidt (1991) and found that powdered
copper naphthenate could be added to the furnish of aspen strandboards without any
significant effects on mechanical and physical properties. Copper ammonium
30
carbonate (CAC) was found to be effective and was used as a pre-process
preservative for OSB produced by Potlatch Corporation (Preston et al., 2003). The
added pre-treatment steps of the strands before blending make CAC treatment
economically infeasible. Goroyias and Hale (2000) added a copper carbonate
hydroxide-based preservative, with boric acid, tebuconazole, and an aliphatic amine
derivative as co-biocides, at various points during the manufacturing of strandboards.
They found that the preservative reduced mechanical properties when sprayed in-line
with the resin and pressed at 210°C. Copper based biocides appear to have a strong
potential as a composite panel preservative if formulation and application methods can
be optimized. Preferably, a powdered copper complex would be added to the strands
prior to resin application and pressed in a standard press schedule.
The objective of this research was to evaluate the effects of incorporating
various copper-based preservatives into the furnish, with or without organic cobiocides, on the resistance to mold and decay of aspen strandboards.
Materials and Methods
Panel Fabrication
Commercially manufactured aspen strands obtained from Louisiana-Pacific
(Newberry, MN) were dried in a commercial laundry dryer to approximately 3%
moisture content (MC) and stored in plastic bags until use.
Preservatives were acquired from Viance, Inc (Charlotte, NC) and Rio Tinto
Minerals, Inc (Edgewood, CO). Seven chemicals were incorporated individually or in
combination into board furnishes at various target concentrations (Table 1) and
31
compared to untreated negative controls and zinc borate treated positive controls.
Each treatment group was replicated on six panels.
Table 1. Preservative treatments assessed for their ability to improve strandboard
panel durability
Treatment
Untreated control
Zinc Borate
Copper Ammonium Acetate Complex (liquid)
Copper Diammine Acetate
Copper Diammine Carbonate
Micronized Copper
Basic Copper Carbonate
Copper Diammine Acetate / Tebuconazole
Isothiazolone
Isothiazolone / Cu Diammine Acetate
Isothiazolone / Cu Ammonium Acetate (liquid)
Untreated control
Abbreviation
Control
Loading (wt/wt %) Matt MC (%) Manufacturer
0
7.4
0.585
7.4
Rio Tinto
ZB
0.878
7.4
Minerals
1.17
7.3
0.25
10.2
CC 1
0.50
13.1
Viance
0.75
16.0
0.25
7.4
CC 2
0.50
7.3
Viance
0.75
7.3
0.25
7.4
CC 3
0.50
7.3
Viance
0.75
7.3
0.25
7.4
MCOH
0.50
7.3
Viance
0.75
7.3
0.25
7.4
BCC
0.50
7.4
Viance
0.75
7.3
0.5 / 0.01
7.3
CC 2 / azole
0.5 / 0.02
7.3
Viance
0.5 / 0.04
7.3
0.05
6.7
DCOI
0.05 / 0.5
6.6
Viance
DCOI / CC 2
0.05 / 0.5
12.4
DCOI / CC 1
0
5.7
Control (400 seconds)
Due to the size of the blender (6 ft diameter, 3 ft depth), each furnish batch was
capable of producing three panels (strands, preservative, wax and resin). The strands
were added first, and then dry salts of treatment chemical were sprinkled over the
mixture. The preservative and the strands were then blended for five minutes at 16
revolutions per minute. A touch-up paint spray gun attached to the inside of the
blender was used to spray the liquid copper complex onto the tumbling strands. DCOI
(4,5-dichloro-2-N-octyl-4-isothiazolin-3-one) was added to the wax emulsion.
32
A wax emulsion with 58% solids content (Hexion Specialty Chemicals;
Springfield, OR) was sprayed onto the tumbling strands at a loading of 1.0% wt/wt
using the touch-up paint spray gun. OSB face-resin with 48% solids content (GeorgiaPacific; Albany, OR) was then applied to the strands at a loading of 3.5% wt/wt
through a spinning disk atomizer at 6000 rpm during blending.
A 560mm square forming box was placed on top of a steel caul plate and
blended strands were distributed in the box. No attempt was made to orient the
strands. The forming box was removed and a second caul plate was placed atop the
formed mat. The mat and caul plates were then placed in the hot press.
The hot press, with upper and lower platens set at 200º C, pressed the mat to a
target thickness of 11 mm for 200 seconds. Because of the difficulties in producing
acceptable boards using DCOI, press time was increased to 400 seconds. A second
untreated control group was also pressed for the extended time. The press was then
vented by opening at a rate of 0.002 cm/second for 60 seconds to produce finished
boards that were approximately 12.7 mm thick and had a density of approximately 577
kg/m³.
Approximately 90 mm was trimmed from each edge of the board using a table
saw. Specimens were then cut from the panels for biological and mechanical tests
(Figure 1).
33
Figure 1. Cutting pattern used to produce test specimens from treated and untreated
strandboard panels
Retention Analysis
The six leached blocks from each treatment were ground to pass a 30 mesh
screen and combined for preservative analysis. The level of each preservative
component in the wood was determined using the appropriate analytical method:
Copper was determined by X-ray spectroscopy according to AWPA Standard A9
(AWPA, 2006e). ZB treated wood was extracted by nitric acid digestion (AWPA,
2006f), and analyzed by Inductively Coupled Plasma Emission Spectrometry (ICP)
following AWPA Standard A21 (AWPA, 2006g). DCOI and tebuconazole were
extracted in methanol; the resulting extracts were analyzed by High Performance
34
Liquid Chromatography (HPLC) with UV detection, according to AWPA Standard
A30 or Standard A28, respectively (AWPA, 2006h, 2006i).
Soil Block Test
The American Wood Protection Association (AWPA) Standard E10-06 soil
block test is a relatively rapid laboratory method for determining the decay resistance
of preservative treated wood-based material (AWPA, 2006a). Three 19 mm by 19 mm
blocks were cut from each panel, labeled, oven-dried at 103º C and weighed.
Ponderosa pine sapwood cubes (19mm) were included as comparator controls. The
blocks were submerged in deionized water for 15 minutes to increase MC, and
sterilized by exposure to 2.5 mrad of ionizing radiation from a cobalt 60 source.
Decay chambers were prepared by filling 480 ml glass jars halfway with
potting soil, adding 20 ml of water, and placing western hemlock (for brown rot fungi)
or alder (for white rot fungi) feeder strips on top of the soil. Caps were loosely
screwed on and the jars were autoclaved for 45 minutes at 125º C.
After cooling, the feeder strips were inoculated with 2 to 3 mm diameter malt
agar disks cut from the actively growing edges of cultures of the test fungus. Two
brown rot fungi, Gloeophyllum trabeum (Pers.ex. Fr.) Murr. (Isolate # Madison 617)
and Postia placenta (Fr.) M. Larsen et Lombard (Isolate Madison 698), and one white
rot fungus, Trametes versicolor (L. ex Fr.) Pilát (Isolate # FP-101664-Sp) were
evaluated. The jars were loosely capped to allow air exchange, and incubated until the
feeder strips were thoroughly covered by the mycelium. Two sterilized blocks from a
given treatment were then placed on the feeder strip within the jars. The jars were
35
incubated at 28º C for 12 or 16 weeks for the brown or white rot fungi, respectively.
Each treatment variable was evaluated on six blocks per test fungus.
After incubation, the jars were removed from the chamber, brushed free of
mycelium, weighed, oven dried at 103º C and weighed again. Percent weight loss of
the blocks was used as a measure of decay resistance.
Mold Box Test
The AWPA Standard E24-06 mold box test is a relatively rapid method for
determining the resistance of wood-based material surfaces to mold fungi (AWPA,
2006b). Samples (75 mm by 100 mm) were cut from each board. A small hole was
drilled in one corner to allow for the attachment of a wire hanger. The samples were
sprayed with an inoculum solution containing the following common molds:
Aureobasidium pullulans (d. By.) Arnaud, Aspergillus niger v. Tiegh., Penicillium
citrinum Thom and Alternaria alternata (Fr.) Keissl. The samples were suspended
above moist soil, which was in a tray above water, in the sealed mold box. The
interior of the mold box was maintained at 25º C and the room was maintained at 20º
C, thus resulting in an elevated relative humidity and the potential for condensation.
Table 2. Visual scale to rate the extent of mold growth on treated and untreated
strandboard panels.
Rating
0
1
2
3
4
5
Description
No mold growth
Mold covering up to 10% of surfaces
Mold covering between 10% and 30% of surfaces
Mold covering between 30% and 70% of surfaces
Mold on greater than 70% of surfaces
Mold on 100% of surfaces
36
The samples were incubated for 8 weeks, and were inspected every two
weeks by individually removing samples and visually assessing each for degree of
discoloration on a scale (Table 2).
Statistical Analysis
Differences between treatments and the control groups were assessed using a
Completely Randomized Design analysis of variance using SAS 9.1 (SAS Institute, α
= 0.05). Tukey’s Honestly Significant Difference multiple comparison test was used
to determine differences between treatment means to minimize Type I errors, that is to
conclude something was different when it was actually the same. Duncan’s Multiple
Range Test was used prior to the Tukey’s Studentized Range Test for multiple
comparisons to harmonize the mean cell size when there were unequal replications.
Results and Discussion
Retention Analysis
Target retentions were not met for any preservative treatments (Table 3).
Panels treated with CC 1 alone had the best retention because it was sprayed onto the
strands during blending, but retention levels were still 27 to 35% below target levels.
CC 2, CC 3 and BCC treated panels were 53 to 71% below target retentions.
Insufficient preservative adherence to the strands, even after the addition of wax and
resin, was one cause for the low retentions because they were added to the blender as
solid copper-compounds. MCOH were up to 89% retention below the target level,
indicating a major incompatibility of the preservative formulation with this application
37
method. DCOI was added to the wax, and was assumed to have good distribution
onto the strands with minimal loss. The lower retentions may have been due to
degradation of the biocide due to exposure to high temperatures in the press.
Table 3. Chemical retentions of aspen strandboards treated with various preservatives
Treatment
Strandboard Control
Abbreviation
Control
Zinc Borate
ZB
Copper Ammonium Acetate Complex (liquid) CC 1
Copper Diammine Acetate Complex
CC 2
Copper Diammine Carbonate Complex
CC 3
Micronized Copper
MCOH
Basic Copper Carbonate
BCC
Cu Diamine Acetate / Tebuconazole
CC 2 / azole
Target Retention Actual Retention
a
(wt/wt %)
(wt/wt %)
0.585
0.878
1.17
0.25
0.50
0.75
0.25
0.50
0.75
0.25
0.50
0.75
0.25
0.50
0.75
0.25
0.50
0.75
0.5 / 0.01
0.5 / 0.02
0.5 / 0.04
0.05
0.05 / 0.5
0.05 / 0.5
0.861
1.218
1.881
0.183
0.332
0.486
0.088
0.146
0.292
0.095
0.226
0.353
0.039
0.055
0.115
0.095
0.168
0.238
0.189 / 0.006
0.217 / 0.012
0.235 / 0.024
0.024
0.025 / 0.164
0.027 / 0.375
Isothiazolone
DCOI
Isothiazolone / Cu Diammine Acetate
DCOI / CC 2
Isothiazolone / Cu Ammonium Acetate (liquid) DCOI / CC 1
Strandboard Control (400 seconds)
Control (400 seconds)
a
Values represent the combination of six treatment blocks analyzed by appropriate method.
38
Soil Block Test
Weight losses for both sets of untreated strandboards exposed to G. trabeum
were greater than 50%, indicating that conditions were suitable for aggressive fungal
attack, and that the extra press time alone had no effect on decay resistance (Table 4).
All chemical treatments reduced weight losses to below 10%, except panels
treated with DCOI alone, micronized copper hydroxide (MCOH), and the lowest
treatment levels of copper diammine acetate (CC 2) and basic copper carbonate (BCC)
(Figure 2). The DCOI levels employed were extremely low and were not intended to
provide protection against fungal decay. The poor performance of the particulate
copper was surprising, although it may be due to extremely low copper retentions.
This system was an experimental formulation and is not directly comparable to the
micronized copper systems currently in commercial use. Panels treated with
combinations of DCOI and the liquid copper ammonium acetate complex (CC 1)
performed the best against G. trabeum, with average weight losses below 1%. Panels
treated with CC 1 alone experienced similar weight losses, suggesting that DCOI was
not needed for decay resistance.
Table 4. Wood weight losses of aspen strandboard blocks subjected to various treatments and exposed to decay fungi in a soil
block test
Retention
(wt/wt %)
a
Wood Weight Loss (%)
G. trabeum
P. placenta
T. versicolor
Treatment
55.6
(4.4)
a,b
18.6
(27.5)
b
52.8
(12.0)
b,c
Control
0.585
6.2
(9.6)
e,f
1.0
(0.1)
b
2.6
(2.1)
e
ZB
0.878
1.9
(0.6)
e,f
1.2
(0.1)
b
1.5
(0.2)
e
1.17
1.4
(0.1)
f
1.2
(0.2)
b
1.4
(0.1)
e
0.25
4.4
(0.7)
e,f
1.1
(0.2)
b
3.3
(0.3)
e
CC 1
0.50
3.2
(1.0)
e,f
1.3
(0.1)
b
2.2
(0.4)
e
0.75
2.4
(0.7)
e,f
16.4
(23.1)
b
2.2
(0.3)
e
0.25
12.2
(5.6)
e,f
0.8
(0.2)
b
13.3
(2.7)
e
CC 2
0.50
3.8
(1.3)
e,f
25.3
(23.9)
a,b
6.0
(2.2)
e
0.75
2.7
(1.0)
e,f
1.0
(0.1)
b
2.6
(0.7)
e
0.25
9.4
(2.3)
e,f
16.9
(24.7)
b
7.9
(1.7)
e
CC 3
0.50
2.8
(0.7)
e,f
15.4
(22.8)
b
3.7
(1.3)
e
0.75
1.9
(0.4)
e,f
0.9
(0.1)
b
3.4
(0.8)
e
0.25
46.0
(16.9)
b
21.2
(31.4)
b
29.4
(12.8)
d
MCOH
0.50
29.6
(14.2)
c,d
0.8
(0.1)
b
33.0
(12.7)
d
0.75
41.8
(23.1)
b,c
34.6
(27.1)
a,b
41.2
(23.3)
c,d
0.25
17.4
(3.7)
d,e
0.8
(0.1)
b
8.6
(1.7)
e
BCC
0.50
3.3
(1.3)
e,f
15.7
(23.2)
b
3.7
(0.9)
e
0.75
2.0
(0.8)
e,f
0.8
(0.1)
b
2.9
(0.6)
e
0.5 / 0.01
2.7
(0.6)
e,f
0.8
(0.1)
b
4.7
(1.2)
e
CC 2 / azole
0.5 / 0.02
2.0
(0.3)
e,f
1.1
(0.1)
b
3.2
(0.4)
e
0.5 / 0.04
1.6
(0.3)
e,f
12.1
(5.7)
b
3.6
(1.6)
e
0.05
62.4
(7.0)
a
25.1
(33.7)
a,b
58.6
(5.3)
a,b
DCOI
0.05 / 0.5
2.3
(0.7)
e,f
35.4
(27.4)
a,b
4.4
(1.8)
e
DCOI / CC 2
0.05 / 0.5
0.8
(0.2)
f
17.9
(26.7)
b
1.2
(0.4)
e
DCOI / CC 1
53.5
(12.3)
a,b
27.4
(31.9)
a,b
67.8
(11.7)
a
Control (400 seconds)
68.4
(2.1)
a
63.0
(1.0)
a
28.4
(5.1)
d
Pine Control
a
Values represent means of 6 blocks per treatment, while figures in parentheses represent one standard deviation. Isothiazolone,
Waferboard Controls at 400 seconds and Pine Controls represent means of 5, 5, and 6 blocks, respectively. Values followed by a common
letter are not signifantly different using Tukey's Studentized Range test that was harmonized using Duncan's Multiple Range Test.
39
40
Weight Loss - G. trabeum
70
60
Weight loss (%)
50
40
30
20
10
O
I
CO CC
I/ 2
C
on C C
tr o
1
l
pi (40
ne
0)
co
nt
ro
l
O
D
C
D
C
C
2
I/
/a
D
C
le
zo
C
BC
M
C
O
H
3
C
C
C
C
2
1
C
C
ZB
C
on
tr o
l
0
Figure 2. Weight losses of strandboard blocks subjected to various treatments and
exposed to Gloeophyllum trabeum in a soil block test. Values represent means of 6
replicates, while error bars represent one standard deviation about the mean.
Weight losses from panels treated with tebuconazole and CC 2 were less than
3%. This was a slight improvement over CC 2 alone at the medium target retention,
but the differences were not statistically significant. Increased tebuconazole
retentions appeared to be associated with reduced weight losses, but these differences
were not statistically significant. It is likely that the added fungicide had only a
minimal effect because of the protection already afforded by the copper compound.
Zinc borate (ZB) performed as well as the copper compounds with a maximum weight
loss of 6.2% for the lowest target retention, illustrating the excellent performance of
this system.
41
Weight losses of untreated and treated OSB blocks exposed to P. placenta
were extremely variable, and there were no statistically significant differences
between any treatment groups (Table 4). Pine control blocks experienced 63% weight
loss, which validated the test and reflected the preference of brown rot fungi for
softwoods.
Weight Loss - P. Placenta
70
60
Weight loss (%)
50
40
30
20
10
O
I
CO CC
I/ 2
C
on C C
tr o
1
l
pi (40
ne
0)
co
nt
ro
l
O
D
C
D
C
C
2
I/
/a
D
C
le
zo
C
BC
M
C
O
H
3
C
C
C
C
2
1
C
C
ZB
C
on
tr o
l
0
Figure 3. Weight losses of strandboard blocks subjected to various treatments and
exposed to Postia placenta in a soil block test. Values represent means of 6 replicates,
while error bars represent one standard deviation about the mean.
All copper-based treatments experienced mean weight losses above 10% in at least
one of the three treatment levels, and there appeared to be no dose response for any
treatment chemical (Figure 3). The decay of panels treated with copper-based
preservatives by P. placenta probably reflects the well-known tolerance of this fungus
to copper biocides.
42
Treated and untreated blocks exposed to T. versicolor experienced weight
losses similar to those exposed to G. trabeum, indicating that conditions were suitable
for aggressive fungal attack (Table 4, Figure 4). Weight losses exceeding 50% were
found on both untreated strandboard control groups. Pine controls had a mean weight
loss of 38%, reflecting the preference of white rot fungi for hardwoods. ZB performed
exceptionally well against T. versicolor at all three levels tested.
Weight Loss - T. versicolor
70
60
Weight loss (%)
50
40
30
20
10
O
I
CO CC
I/ 2
C
on C C
tr o
1
l
pi (40
ne
0)
co
nt
ro
l
O
D
C
D
C
C
2
I/
/a
D
C
le
zo
C
BC
C
O
H
3
C
C
C
C
2
1
ZB
C
C
M
C
on
tr o
l
0
Figure 4. Weight losses of strandboard blocks subjected to various treatments and
exposed to Trametes versicolor in a soil block test. Values represent means of 6
replicates, while error bars represent one standard deviation about the mean.
All three copper complexes performed well against T. versicolor. Panels
treated with CC 1 had the best efficacy overall, with the lowest treatment level
resulting in only 3.3% weight loss. This may be a reflection of the increased retention
of the liquid preservative compared to the other treatments. The medium target
43
retention of CC 2 had a mean weight loss of 6%, and performance was slightly
improved by the addition of tebuconazole. As with the brown rot fungi, MCOH
performed poorly against the white rot fungus with no evidence of a dose response
effect. In this case, the highest target retention experienced the greatest amount of
weight loss, although the differences were not statistically significant. Low retention
levels, as noted earlier, probably played a role in the poor performance of this system.
Panels treated with combinations of DCOI and CC1 or CC 2 performed as well
as panels treated only with these copper complexes at the same target retention levels.
DCOI was added at extremely low levels as a mold inhibitor and its failure to improve
performance of copper compounds at this level is not surprising.
Mold Box Test
Very few treatments had any effect on mold resistance of strandboards (Table
5). ZB, CC 2, CC 3, MCOH and basic copper carbonate at all treatment levels
received ratings of at least 3, representing between 30 and 70% surface coverage, after
2 weeks in the mold box. These treatments all received ratings of at least 4, or greater
than 70% coverage, by week 3. CC 1 appeared to reduce mold growth after 2 weeks,
especially at the highest retention level (Figure 5), possibly because the liquid
preservative was more evenly distributed over the strand surfaces. The highest
retention level of CC 1 had a rating of 4.2 after 4 weeks, indicating that this compound
no longer protected against mold growth. While copper compounds are widely used
Table 5. Effects of various treatments on mold resistance of strandboards in an AWPA E24 mold box test
a
Mold Rating
b
Week 8
Treatment
Week 2
Week 3
Week 4
Week 6
3.7 (0.6) a,b,c,d 3.7 (1.0) a,b,c 4.3 (0.8) a,b,c 4.7 (0.5)
a
Strandboard Control
0.585
3.3 (0.6) a,b,c,d,e 4.0 (0.0) a,b 4.3 (0.5) a,b,c 5.0 (0.0)
a
ZB
0.878
3.7 (0.6) a,b,c,d 4.2 (0.4) a,b 4.2 (0.4) a,b,c 4.8 (0.4)
a
1.17
3.7 (0.6) a,b,c,d 4.0 (0.0) a,b 4.5 (0.5) a,b 4.8 (0.4)
a
0.25
3.0 (1.0) a,b,c,d,e 4.3 (0.5)
a
4.5 (0.5) a,b 4.8 (0.4)
a
CC 1
0.50
3.0 (1.7) a,b,c,d,e 4.5 (0.5)
a
4.8 (0.4)
a
5.0 (0.0)
a
0.75
1.7 (1.2)
d,e
3.8 (0.8) a,b 4.2 (0.4) a,b,c 5.0 (0.0)
a
0.25
4.3 (0.6)
a,b
4.8 (0.4)
a
4.7 (0.5) a,b 5.0 (0.0)
a
CC 2
0.50
4.3 (0.6)
a,b
4.7 (0.5)
a
4.8 (0.4)
a
5.0 (0.0)
a
0.75
5.0 (0.0)
a
4.5 (0.5)
a
4.8 (0.4)
a
4.8 (0.4)
a
0.25
4.3 (0.6)
a,b
4.5 (0.5)
a
4.7 (0.5) a,b 5.0 (0.0)
a
CC 3
0.50
3.7 (0.6) a,b,c,d 4.2 (0.4) a,b 4.8 (0.4)
a
5.0 (0.0)
a
0.75
4.3 (0.6)
a,b
4.5 (0.5)
a
4.8 (0.4)
a
5.0 (0.0)
a
0.25
3.7 (0.6) a,b,c,d 4.2 (0.4) a,b 4.3 (0.5) a,b,c 4.5 (0.5) a,b
MCOH
0.50
4.3 (0.6)
a,b
4.5 (0.5)
a
4.5 (0.5) a,b 4.7 (0.5)
a
0.75
4.3 (0.6)
a,b
4.5 (0.5)
a
4.5 (0.5) a,b 4.8 (0.4)
a
0.25
4.0 (0.0) a,b,c 4.2 (0.4) a,b 4.2 (0.4) a,b,c 4.7 (0.5)
a
BCC
0.50
4.0 (0.0) a,b,c 4.3 (0.5)
a
4.5 (0.5) a,b 4.7 (0.5)
a
0.75
4.0 (0.0) a,b,c 4.5 (0.5)
a
4.3 (0.5) a,b,c 5.0 (0.0)
a
0.5 / 0.01 4.3 (0.6)
a,b
4.5 (0.5)
a
4.5 (0.5) a,b 5.0 (0.0)
a
CC 2 / azole
0.5 / 0.02 3.0 (1.0) a,b,c,d,e 4.2 (0.4) a,b 4.5 (0.5) a,b 4.8 (0.4)
a
0.5 / 0.04 2.0 (0.0) c,d,e 4.0 (0.0) a,b 4.0 (0.0) a,b,c 4.8 (0.4)
a
0.05
2.5 (0.8) b,c,d,e 3.0 (1.1) b,c 3.7 (0.5) b,c,d 4.3 (0.5) a,b 4.7 (0.5) a,b
DCOI
0.05 / 0.5 1.5 (0.5)
e
2.5 (0.5) c,d 3.3 (0.5) c,d 3.8 (0.4) b,c 4.2 (0.4) b,c
DCOI / CC 2
0.05 / 0.5 1.3 (0.8)
e
1.7 (0.8)
d
2.8 (0.8)
d
3.3 (0.5)
c
3.7 (0.5)
c
DCOI / CC 1
3.8 (0.4) a,b,c 4.2 (0.4) a,b 4.7 (0.5) a,b 4.8 (0.4)
a
5.0 (0.0)
a
Strandboard Control (400 seconds)
a
Mold was visually assessed for the degree of discoloration on a scale from 0 to 5, where 0 denoted no discoloration. Values represent means of 6 blocks
per treatment, while figures in parentheses represent one standard deviation. Values followed by a common letter are not signifantly different using a
Tukey's Studentized Range test that was harmonized using Duncan's Multiple Range Test.
Retention
(wt/wt %)
b
The first test was discontinued after 6 weeks because all treatments had failed. The second test was evalutated for the full 8 weeks.
44
45
in heavy duty wood treatments, they are prone to surface mold growth on prolonged
wet storage. This performance attribute appears to extend to copper in panel products.
Boards treated with CC 2 and supplemented with tebuconazole appeared to
experience reduced mold growth at 2 weeks, but all had experienced substantial mold
growth by week 3 (Figure 5). These data showed that tebuconazole performed poorly
as a moldicide, but this might be due to insufficient target loading levels or actual
retentions less than half the target levels. Clausen and Yang (2005) found that the
0.043 wt/wt % of voriconazole, which shows more efficacy against mold than
tebuconazole, was needed to inhibit mold growth on unseasoned southern pine. This
suggests that 0.024 wt/wt % tebuconazole was inadequate in this application (Table 3).
Mold Resistance
5
Rating (0-5)
4
3
2
Control
CC 1 (7500ppm Cu)
1
CC 2 (5000ppm Cu) / azole (400ppm)
0
0
1
2
3
4
5
6
Week
Figure 5. Surface mold growth on CC1 or CC2 and tebuconazole treated strandboard
in an AWPA E24 mold box test. Values represent means of 6 replicates.
46
Mold growth was much lower on panels containing DCOI alone or with
copper compounds throughout the 8 week test (Figure 6). Boards treated with DCOI
alone had a rating of 2.5 after two weeks, although this was not significantly different
from the controls (400 seconds). DCOI also showed good efficacy against mold
growth as a co-biocide. Addition of DCOI to panels with CC 1 and CC 2 resulted in
ratings below 4, even after 6 weeks of exposure. Actual DCOI retentions were half of
the target levels (Table 3), suggesting that resistance to mold growth would have been
improved had target levels been met. DCOI is subject to degradation at high pHs
(Morrell, 2004), but the two copper complexes did not appear to completely diminish
moldicidal efficacy.
Mold Resistance
5
Rating (0-5)
4
3
2
Control
DCOI
DCOI / CC 2
DCOI / CC 1
Control (400)
1
0
0
1
2
3
4
5
6
7
8
Week
Figure 6. Surface mold growth on strandboards treated with DCOI alone or as a cobiocide with two copper complexes. Values represent means of 6 replicates.
47
Additional Research
The ability of a preservative system to adequately protect a wood product is
dependent upon the system’s efficacy against attack by multiple biological organisms
in a specified intended use. The laboratory soil block test is a relatively rapid method
for evaluating decay resistance, but it uses unrealistic conditions for degradation of
most wood products. In the worst case scenario, OSB would be exposed in an exterior
above-ground environment. To test the efficacy of the treated and untreated
strandboard panels in exterior above-ground application, samples were exposed using
AWPA Standard E18-06 ground proximity field test (AWPA, 2006c). Two 50 mm by
125 mm samples were cut from each board and labeled with metal identification tags.
The samples were shipped to Hilo, HI where they were exposed in a ground proximity
test. Squares of 100 mm thick concrete masonry blocks were placed directly in
contact with the ground. The cinder blocks allowed moisture to wick from the soil to
the samples, but did not allow direct soil/wood contact. The sample blocks were
placed on top of the concrete blocks and the assembly was covered with a shade cloth
that allowed rain to pass through, but prevented exposure to direct sunlight. The
assembly resulted in a high moisture regime that created an extreme above ground
decay environment. The samples will be visually evaluated on an annual basis for
soundness on a scale from 0 to 10, where 0 denotes failure and 10 denotes no sign of
degradation.
There is also a need to evaluate the resistance of the treated panels to termite
damage. A termite field test was initiated using an adaptation of AWPA Standard E9-
48
06 field test for the evaluation of wood preservatives used in non-soil contact
(AWPA, 2006d). Two 50 mm by 125 mm samples were cut from each board and
labeled with plastic identification tags. The samples were sent to Hilo, HI, where they
were placed horizontally on 100 mm high concrete masonry blocks, which are placed
directly in contact with the ground above a known Formosan termite (Coptotermes
formosanus) colony. Wood stakes were driven into the ground within the array to
provide an upward pathway for foraging termite workers. Untreated pine sapwood
sticks (19 mm by 19 mm at various lengths) were placed between rows of samples so
that termites could attack untreated wood to reach the test samples. The assembly was
covered with a plywood box that prevented overhead wetting. The samples will be
visually evaluated at six month intervals for soundness on a subjective scale from 0 to
10, where 0 denotes failure due to termite attack and 10 denotes no attack.
Conclusions
Retentions levels for all treatments were significantly below targets. Nearly all
preservative treatment systems except MCOH or DCOI alone were effective against
brown or white rot fungi. Panels treated with CC 2, CC 3 or BCC experienced
unacceptable weight losses at the lowest target retentions. Panels treated with CC 2
and tebuconazole did not perform differently from those with the copper complex
alone. Panels treated with CC 1 and DCOI appeared to provide the most protection,
but this could not be confirmed due the low replication. Very few of the preservative
systems had any effect on surface mold growth on the panels. Panels treated with CC
1 or CC 2 with the highest retention of tebuconazole initially limited mold growth, but
49
were nearly completely covered after three weeks. DCOI significantly improved
resistance to mold growth compared to untreated panels. The combination of DCOI
with CC 1 or CC 2 provided the best protection against mold. Copper-based
preservatives in conjunction with DCOI appeared to provide the best protection for
aspen OSB.
References
Acda, M.N., Morrell, J.J., & Levien, K.L. (1996). Decay resistance of composites
following supercritical fluid impregnation with tebuconazole. Material und
Organismen, 30(4), 293-300.
Anderson, L.O. (1972). Condensation problems: Their prevention and solution. In
U.S. Forest Products Laboratory. U.S.D.A Forest Service Research Paper (Vol.
FPL 132, pp. 36 ): Madison, WI
AWPA. (2006a). E10-06. Standard method of testing wood preservatives by
laboratory soil-block cultures. In AWPA Book of Standards. Granbury, TX.
AWPA. (2006b). E24-06. Standard method of evaluating the resistance of wood
product surfaces to mold growth. In AWPA Book of Standards. Granbury, TX.
AWPA. (2006c). E18-06. Standard field test for evalutaion of wood preservatives
intended for use category 3B applications exposed, out of ground contact,
uncoated ground proximity decay method. In AWPA Book of Standards.
Granbury, TX.
AWPA. (2006d). E9-06. Standard field test for the evaluation of wood preservatives to
be used in non-soil contact. In AWPA Book of Standards. Granbury, TX.
AWPA. (2006e). A9-01. Standard method for analyzsis of treated wood and treating
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AWPA. (2006h). A30-00. Standard method for the determination of 4,5 Dichloro-2N-octyl-4-isothiazolin-3-one (RH-287) in wood by high performance liquid
chromatography (HPLC). In AWPA Book of Standards. Grandbury, TX.
AWPA. (2006i). A28-05. Standard method for determinination of propiconazole and
tebuconazole in wood, in waterborne formulations and in treating solutions by
HPLC. In AWPA Book of Standards: Grandbury, TX.
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unseasoned pine. International Biodeterioration & Biodegradation, 55, 99-102.
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53
CHAPTER 4 – THE EFFECTS OF NOVEL COPPER-BASED
PRESERVATIVE TECHNOLOGIES ON THE MECHANICAL AND
PHYSICAL PROPERTIES OF ASPEN STRANDBOARD.
Abstract
The effects of biocide addition on mechanical and physical properties of aspen
strandboards was investigated. Five copper-based chemicals or zinc borate were
examined alone or with tebuconazole or 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one
(DCOI) as co-biocides. Bending properties, internal bond strength, thickness swelling
and hygroscopic properties were determined according to ASTM Standard D-1037.
Resistance to chemical leaching was assessed using AWPA Standard E10. Biocide
addition produced no reductions in bending strength or stiffness. Internal bond
strength was lower in panels treated with the liquid copper-based preservative. Slight
increases in thickness swelling and hygroscopic linear change were associated with the
addition of nearly all preservatives. Two copper-based preservatives were highly
resistant to leaching. The results suggest that biocide addition had no significant
negative effects on the properties of aspen strandboards.
Introduction
The use of oriented strandboard (OSB) in the North American structural panel
market has continually risen since its advent in the 1970’s (SBA, 2008). OSB is
composed of various sized strands that are oriented in a specific direction and pressed
to a desired thickness and density. The relatively small strand dimensions permits the
54
utilization of low quality, low cost raw material that results in a high quality, low
cost product. The geometry of the strands within OSB also makes the material more
likely to sorb water. These sorption characteristics, coupled with the low durability of
the wood species used produces a panel that is more susceptible to decay and mold
attack than softwood plywood (Laks, 1999, 2002). OSB is designed as a dry-use
product, although it can tolerate brief periods of wetting during construction (Morris et
al., 1999). OSB is increasingly used in applications that subject it to conditions
conductive to insect and fungal attack (Morrell, 2002; Morris, 1995). A number of
building practices implemented in response to rising energy costs attempt to seal
homes in order to limit the escape of warm or cold air. These practices reduce air
exchange and can trap moisture from both interior and exterior sources (Anderson,
1972; Barnes & Amburgey, 1993; Cassens, 1978; Merrill & TenWolde, 1989). The
prolonged accrual of moisture within wall cavities creates conditions conducive to
mold, decay and insect attack (Barnes & Amburgey, 1993; Schmidt, 1993; Yang et al.,
2007). Preservation technologies can be employed to protect wood from biological
attack.
Durable wood composites can be produced through the use of wood species
with high natural durability, incorporating recycled treated wood, pre-process
preservative treatments of the wood, post-process preservative treatments and inprocess preservative treatments (Gardner et al., 2003). The particular treatment
methods employed are dependent upon the final product. In-process treatments appear
to be the best treatment method for OSB. The equal distribution of the preservative
55
within the product can offer much better protection than “shell” treatments provided
by post-treatments (Laks & Palardy, 1992). Pre-treating the substrate also requires an
extra drying step that is energy intensive and less efficient. According to Murphy et
al. (1993), the criteria for an acceptable preservative treatment process for wood
composites are:
•
•
•
•
•
•
•
Efficacy – The preservative should be effective against decay fungi and
wood degrading insects.
Environment - The treatment operation and product should have
acceptable environmental characteristics.
Mechanical properties – The treatment should have no negative impacts
on mechanical properties.
Physical properties – Interference with physical properties, such as
EMC and dimensional stability, should be minimal.
Appearance – Unless it is desired for identification purposes, the
treatment should not change the appearance of the wood.
Speed and Flexibility – The treatment process should be as rapid as
possible and be able to produce as much product to meet orders in short
notice.
Verification and compliance with standards – The treated material
should be easily analyzed for quality control.
Two of the main limiting factors for the use of some preservative systems in
strand-composite panels are their effects on mechanical and physical characteristics.
Vick et al. (1990) found that various waterborne systems were incompatible with
phenol-formaldehyde adhesives, including ammoniacal zinc arsenate, copper
naphthenate, copper octoate, zinc naphthenate, and all borate preservatives tested.
Borates have a number of appealing benefits as wood preservatives, and are currently
the only biocides used to produce durable OSB panels. However, borates have a few
disadvantages that limit their use in composite panels. Biologically-effective
treatment levels of sodium borate and boric acid react with phenol formaldehyde (PF)
56
resin to prevent sufficient adhesion between wood substrates, resulting in boards
with unacceptably low mechanical and physical properties (Laks et al., 1988; Laks &
Palardy, 1993). Copper-based biocides may be useful for incorporation into OSB
furnish, but there is little data on the effects of these materials on panel properties.
The objective of this research was to determine the effects of incorporating
various copper-based preservatives into the furnish on mechanical and physical
properties of aspen strandboard.
Materials and Methods
Panel Fabrication
Commercially manufactured aspen strands obtained from Louisiana-Pacific
(Newberry, MN) were dried in a commercial laundry dryer to approximately 3%
moisture content (MC) and stored in plastic bags until use.
Preservatives were acquired from Viance, Inc (Charlotte, NC) and Rio Tinto
Minerals, Inc (Edgewood, CO). Seven chemicals were incorporated individually or in
combination into board furnishes at various concentrations (Table 6) and their
performance was compared to untreated negative controls and zinc borate treated
positive controls. Each treatment group was replicated on six panels.
Due to the size of the blender, the furnish was prepared in quantities sufficient
to produce three panels per batch (strands, preservative, wax and resin). The strands
were added first, and then dry salts of the treatment chemical were sprinkled over the
mixture. The preservative and the strands were then blended for five minutes at 16
revolutions per minute. A touch-up paint spray gun attached to the inside of the
57
blender was used to spray the liquid copper complex onto the tumbling strands.
4,5-dichloro-2-N-octyl-4-isothiazolin-3-one (DCOI) was added to the wax emulsion.
Table 6. Preservative treatments assessed for their ability to improve OSB panel
durability
Treatment
Untreated control
Zinc Borate
Copper Ammonium Acetate Complex (liquid)
Copper Diammine Acetate
Copper Diammine Carbonate
Micronized Copper
Basic Copper Carbonate
Copper Diammine Acetate / Tebuconazole
Isothiazolone
Isothiazolone / Cu Diammine Acetate
Isothiazolone / Cu Ammonium Acetate (liquid)
Untreated control
Abbreviation
Control
Loading (wt/wt %) Matt MC (%) Manufacturer
0
7.4
0.585
7.4
Rio Tinto
ZB
0.878
7.4
Minerals
1.17
7.3
0.25
10.2
CC 1
0.50
13.1
Viance
0.75
16.0
0.25
7.4
CC 2
0.50
7.3
Viance
0.75
7.3
0.25
7.4
CC 3
0.50
7.3
Viance
0.75
7.3
0.25
7.4
MCOH
0.50
7.3
Viance
0.75
7.3
0.25
7.4
BCC
0.50
7.4
Viance
0.75
7.3
0.5 / 0.01
7.3
CC 2 / azole
0.5 / 0.02
7.3
Viance
0.5 / 0.04
7.3
0.05
6.7
DCOI
0.05 / 0.5
6.6
Viance
DCOI / CC 2
0.05 / 0.5
12.4
DCOI / CC 1
0
5.7
Control (400 seconds)
A wax emulsion with 58% solids content (Hexion Specialty Chemicals;
Springfield, OR) was sprayed onto the tumbling strands using the touch-up paint spray
gun at a loading of 1.0% wt/wt. OSB face-resin with 48% solid content (GeorgiaPacific; Albany, OR) was then applied to the strands at a loading of 3.5% wt/wt
through a spinning disk atomizer at 6000 rpm during blending.
A 560mm square forming box was placed on top of a steel caul plate and
blended strands were distributed in the box. No attempt was made to orient the
58
strands. The forming box was removed and a second caul plate was placed atop the
formed mat. The mat and caul plates were then placed in the hot press.
The hot press, with upper and lower platens set at 200º C, pressed the mat to a
target thickness of 11 mm for 200 seconds. Because of the difficulties in producing
acceptable boards using DCOI, press time was increased to 400 seconds for panels
containing this chemical. A second untreated control group was also pressed for the
extended time. The press was then vented by opening at a rate of 0.002 cm/second for
60 seconds to produce finished boards that were approximately 12.7 mm thick and had
a density of approximately 577 kg/m³.
Approximately 90 mm were trimmed from each edge of the board using a table
saw. Biological and mechanical test specimens were cut from the panels (Figure 7).
Figure 7. Cutting pattern used to produce test specimens from treated and untreated
OSB panels
59
Static Bending
Static bending was assessed using American Society for Testing Materials
(ASTM) Standard D-1037 (ASTM, 1999). A 76 mm by 362 mm sample was cut from
each panel and conditioned to constant weight at 20º C and 65% relative humidity.
The samples were placed in a universal testing machine that applied a constant centerloaded force to samples at a speed of 6.24 mm/minute to failure. The resulting loaddeflection data were collected and used to calculate modulus of rupture (MOR) and
modulus of elasticity (MOE). The samples were weighed after testing, oven-dried and
reweighed to determine the MC at the time of the test. Twenty-five mm squares cut
from one end of the sample were used to determine specific gravity (Figure 8) by
measuring volume and then oven-drying and weighing the blocks.
specific gravity, Gm =
(W d / Vm)
pw
Where:
W d = Oven-dry weight of wood
Vm = volume at moisture content M
pw = density of water
Figure 8. Determination of specific gravity
Internal Bond Strength
Internal bond strength was determined according to ASTM Standard D-1037
(ASTM, 1999). A 50 mm square sample was cut from each board, conditioned to
constant weight at 20º C and 65% relative humidity and weighed. Both surfaces were
glued to aluminum alloy loading blocks designed to hold the blocks securely in the
testing apparatus as a tensile force was applied at a speed of 1 mm/minute until failure.
60
After testing, the blocks were oven dried and weighed to determine moisture
content. The peak stress at failure and the peak force in kPa were used to assess the
effects of treatment on internal bond strength.
Permanent Thickness Swell
ASTM Standard D-1037 for water absorption and thickness swelling, Method
A (ASTM, 1999) was used to determine the water absorption characteristics of the
boards. Samples (152 mm by 152 mm) were cut from each board and conditioned to
constant weight at 20º C and 65% relative humidity prior to testing. The weight,
thickness and volume of each sample were measured, and then each sample was
submerged horizontally in water for 2 hours. The samples were removed, allowed to
dry for 10 minutes, and wiped free of excess water. The weight, thickness and volume
were again measured before re-submerging the samples for another 22 hours. Weight,
thickness and volume measurements were made after 24 hours of immersion, and the
samples were oven dried at 103° C to determine MC at the various stages of testing.
The amount of water absorbed, expressed as moisture content at each time
interval, and thickness swelling, expressed as the percent of original thickness, were
used to assess the effects of each treatment on panel stability.
Hygroscopicity
Panel hygroscopicity was determined using a modification of ASTM Standard
D-1037 for linear variation with change in moisture content (ASTM, 1999). A 76 mm
by 280 mm sample was cut from each board and conditioned to constant weight at 30º
61
C and 30% relative humidity. Each sample was weighed and the length was
measured. The boards were conditioned to constant weight at 32º C and 90% relative
humidity and then re-measured. The samples were then oven-dried at 103º C,
weighed and re-measured. Moisture content and linear change following exposure to
each environmental condition were used to assess the effects of treatment on
hygroscopicity.
Resistance to Leaching
AWPA Standard E10 was used to assess the resistance of each chemical to
leaching (ASTM, 1999). Test blocks (19 mm by 19 mm) were cut from each board,
oven-dried and weighed in collective treatment groups prior to testing. Six samples
from each treatment group were placed into a 500 ml beaker, held down by weights in
300 ml of water and placed into a desiccator. A vacuum was applied to the desiccator
(13.3 kPa or less) for 30 minutes. The vacuum was then broken and the weights were
removed. Leachate water was removed after 6, 24, 48 and then at 24-hour intervals
thereafter for a total of 14 days and replaced with an equal amount of fresh deionized
water. The blocks were then oven-dried and weighed.
The six leached blocks from each treatment were ground to pass a 30 mesh
screen and combined for preservative analysis. The level of each preservative
component in the wood was determined using the appropriate analytical method:
Copper was determined by X-ray spectroscopy according to AWPA Standard A9
(AWPA, 2006e). ZB treated wood was extracted by nitric acid digestion (AWPA,
2006f), and analyzed by Inductively Coupled Plasma Emission Spectrometry (ICP)
62
following AWPA Standard A21 (AWPA, 2006g). DCOI and tebuconazole were
extracted in methanol; the resulting extracts were analyzed by High Performance
Liquid Chromatography (HPLC) with UV detection, according to AWPA Standard
A30 or Standard A28, respectively (AWPA, 2006h, 2006i).
Statistical Analysis
Differences between treatments and the control groups were assessed using a
Completely Randomized Design analysis of variance using SAS 9.1 (SAS Institute, α
= 0.05). Because it was important that the comparison minimize Type I errors, (i.e. to
conclude something is different when it is actually the same), a Tukey’s Honestly
Significant Difference multiple comparison test was used to determine differences
between treatment means. Duncan’s Multiple Range Test was used prior to the
Tukey’s Studentized Range Test for multiple comparisons to harmonize the mean cell
size when there were unequal replications.
Results and Discussion
Static Bending
While there were slight differences between the bending properties of
preservative treated strandboard and untreated controls, the differences were not
statistically significant (Table 7). The inability to delineate treatment differences was
Table 7. Effects of the addition of preservatives on mechanical properties of strandboards
a
Internal Bond Strength
Flexural Property (%)
a
Specific gravity
MOE (Gpa)
Treatment
MOR (MPa)
(kPa)
0.57 (0.02) a,b,c,d,e,f
4.26 (0.5) a,b,c
24.2 (4.2) a
247 (81.0) a,b,c,d,e
Strandboard Control
0.585
0.56 (0.02) c,d,e,f
3.87 (0.3) c
22.2 (4.0) a
189 (47.3) a,b,c,d,e,f
ZB
0.878
0.58 (0.02) a,b,c,d,e,f
4.28 (0.4) a,b,c
27.0 (4.3) a
199 (46.1) a,b,c,d,e,f
1.17
0.57 (0.03) a,b,c,d,e,f
3.73 (0.5) c
22.7 (5.4) a
254 (64.7) a,b,c,d,e
0.25
0.59 (0.02) a,b,c,d,e,f
4.60 (0.3) a,b,c
23.2 (4.2) a
95 (35.1) e,f
CC 1
0.50
0.61 (0.03) a,b
4.95 (0.4) a,b,c
29.1 (2.3) a
67 (59.6) f
0.75
0.62 (0.02) a
5.18 (0.4) a,b
22.2 (9.1) a
139 (79.1) b,c,d,e,f
0.25
0.60 (0.02) a,b,c,d,e
4.79 (0.3) a,b,c
26.5 (4.0) a
225 (151.2) a,b,c,d,e,f
CC 2
0.50
0.56 (0.02) b,c,d,e,f
4.11 (0.4) a,b,c
23.2 (5.5) a
244 (61.8) a,b,c,d,e,f
0.75
0.60 (0.04) a,b,c,d,e
4.29 (1.3) a,b,c
25.4 (10.3) a
143 (46.8) b,c,d,e,f
0.25
0.60 (0.02) a,b,c,d,e,f
4.57 (0.3) a,b,c
29.8 (1.7) a
271 (104.4) a,b,c,d,e
CC 3
0.50
0.58 (0.02) a,b,c,d,e,f
4.30 (0.5) a,b,c
26.9 (4.2) a
257 (90.5) a,b,c,d,e
0.75
0.59 (0.03) a,b,c,d,e,f
4.51 (0.5) a,b,c
27.0 (4.1) a
301 (33.9) a,b,c
0.25
0.61 (0.03) a,b,c,d
4.90 (1.0) a,b,c
30.2 (5.4) a
299 (35.7) a,b,c
MCOH
0.50
0.59 (0.03) a,b,c,d,e,f
4.66 (0.4) a,b,c
30.8 (4.8) a
342 (135.8) a
0.75
0.59 (0.02) a,b,c,d,e,f
4.76 (0.6) a,b,c
27.9 (6.5) a
310 (63.9) a,b
0.25
0.61 (0.02) a,b,c
4.90 (0.4) a,b,c
31.8 (3.0) a
287 (13.9) a,b,c,d
BCC
0.50
0.58 (0.03) a,b,c,d,e,f
4.22 (0.9) a,b,c
26.4 (8.4) a
212 (108.1) a,b,c,d,e,f
0.75
0.62 (0.03) a
5.15 (0.6) a,b
31.8 (4.3) a
254 (50.4) a,b,c,d,e
0.5 / 0.01 0.61 (0.02) a,b
4.79 (0.4) a,b,c
27.3 (4.8) a
230 (84.2) a,b,c,d,e,f
CC 2 / azole
0.5 / 0.02 0.56 (0.02) c,d,e,f
4.09 (0.5) a,b,c
22.6 (3.6) a
117 (28.7) d,e,f
0.5 / 0.04 0.55 (0.02) e,f
3.96 (0.5) b,c
22.7 (3.5) a
123 (33.1) c,d,e,f
0.05
0.55 (0.02) e,f
4.14 (0.6) a,b,c
25.7 (7.1) a
242 (137.5) a,b,c,d,e,f
DCOI
0.05 / 0.5 0.56 (0.03) d,e,f
4.58 (0.4) a
27.7 (3.6) a
281 (45.2) a,b,c,d
DCOI / CC 2
0.05 / 0.5 0.60 (0.01) a,b,c,d,e,f
5.24 (0.7) a,b,c
28.7 (5.6) a
290 (164.0) a,b,c,d
DCOI / CC 1
0.55 (0.03) f
4.44 (0.8) a,b,c
28.0 (6.1) a
300 (95.4) a,b,c
Strandboard Control (400 seconds)
a
Values represent means of 6 replicates per treatment, while figures in parentheses represent one standard deviation. Means with a common letter
are not significantly different using Tukey's Studentized Range Test (α=0.05).
Retention
(wt/wt %)
a
63
64
due to high variability within treatment groups and the use of a conservative
multiple comparison tool such as Tukey’s.
Strandboards treated with the liquid copper ammonium complex (CC 1) had a
tendency to fail in shear, as opposed to tension, during testing. This type of failure
reflects poor resin curing or low density in the center of the board where the highest
shear stress concentration occurs. Insufficient resin curing was probably due to the
high moisture content of the panels produced by the liquid characteristic of the
preservative. The high moisture content of the strands increased heat transfer from the
outer strands to the internal core, but sufficient temperatures required to cure resin
might not have been reached because the water within the core prevented the
temperature from exceeding 100°C. Another explanation for poor core bonding may
be due to “wash out”, when the excessive moisture within the panel induces resin
migration away from the board center (Geimer & Christiansen, 1996). High outer
strand moisture content increased the heat exposure for resin in the outer strands,
enhancing curing in the tension layers of the panels. This effect was reflected in a
slightly higher MOE for panels treated with CC 1 alone or with DCOI (Figure 9).
65
Bending - Modulus of Elasticity
6.0
5.0
MOE (GPa)
4.0
3.0
2.0
1.0
2
C
C
D
C DC
O
O
D I/C I
C
O C
C I/ 2
on C
tro C
l( 1
40
0)
/a
zo
le
C
BC
O
H
M
C
3
C
C
2
C
C
1
C
C
C
on
tro
l
ZB
0.0
Figure 9. Modulus of elasticity of treated and untreated strandboards. Values
represent means of 6 replicates while error bars represent one standard deviation about
the mean.
Zinc borate (ZB) had no significant effect on MOR or MOE. While water
soluble borates, such as disodium octaborate tetrahydrate, decrease bending properties
due to reductions in glue-line strength (Laks et al., 1988; Lee et al., 2001), the low
water solubility of ZB limits interaction with water-containing phenolic resins, and
minimizes effects on bending properties.
Internal Bond Strength
CC 1 was the only preservative that significantly affected internal bond
strength (Table 7). Panels containing low, medium and high target retentions of CC 1
experienced 61, 73 and 44% reductions in internal bond strength, respectively. While
66
the effect was only statistically significant at the medium retention, the effects were
strikingly evident (Figure 10). Reduced internal bond strength probably reflects
reduced resin curing in the interior of the panels. Panels treated with DCOI and CC 1
did not experience reduced internal bond strength because these panels were pressed
for 400 seconds, allowing for additional resin curing.
Internal Bond Strength
500
Maximum Stress (kPa)
*
400
300
200
100
2
C
C
D
C DC
O
O
D I/C I
C
O C
C I/ 2
on C
tro C
l( 1
40
0)
/a
zo
le
C
BC
O
H
M
C
3
C
C
2
C
C
1
C
C
C
on
tro
l
ZB
0
Figure 10. Internal bond strength of treated and untreated strandboards. Values
represent means of 6 replicates while error bars represent one standard deviation about
the mean.
Previous research showed that ZB reduced internal bond strength of
waferboard (Laks & Manning, 1995), while our results showed no significant
differences between ZB treated and untreated panels. Lee et al (2001) found that the
addition of 0.9 % ZB to phenol formaldehyde (PF) resin reduced the gel time by only
1%, but gel time was greatly reduced as the addition of ZB increased. Reduced gel
67
resin gel time results in pre-curing of the resin prior to pressing, producing poor
bonding between strands.
Permanent Thickness Swelling
Most treatments failed to induce significant negative effects on thickness
swelling following a 2 hour submersion. The addition of CC 1 at the medium target
retention appeared to significantly increase swelling after 2 hours; however, the data
were extremely variable (Table 8). One batch of three panels had high swelling
values, while the other had low values (21 to 24% vs. 4.8 and 5.3%). The results
suggest that blending may have been a problem with this treatment. The most likely
cause was poor blending of the wax. The absence of effect at the lower and higher
treatment levels with this system suggests that the chemical was not the cause for
increased swelling.
Table 8. Thickness swelling of treated and untreated strandboards after 2 or 24 hours of submersion.
Thickness Swelling (%)a
2 hour submersion
24 hour submersion
Treatment
5.7 (1.2) b
15.0 (1.6) c,d,e,f
Strandboard Control
0.585
6.0 (1.1) b
17.2 (0.8) a,b,c,d,e
ZB
0.878
6.6 (0.6) b
16.7 (1.6) a,b,c,d,e,f
1.17
6.0 (1.0) b
16.7 (2.6) a,b,c,d,e,f
0.25
6.1 (0.4) b
15.2 (0.8) b,c,d,e,f
CC 1
0.50
13.9 (9.6) a
20.8 (8.3) a
0.75
6.2 (0.9) b
14.1 (1.2) c,d,e,f
0.25
8.2 (0.9) b
18.5 (1.7) a,b,c,d
CC 2
0.50
7.7 (1.2) b
17.8 (1.7) a,b,c,d
0.75
7.7 (0.9) b
17.3 (1.0) a,b,c,d,e
0.25
7.4 (0.8) b
18.4 (1.0) a,b,c,d
CC 3
0.50
7.3 (1.1) b
17.0 (1.8) a,b,c,d,e,f
0.75
7.6 (0.6) b
18.3 (0.8) a,b,c,d
0.25
8.2 (0.8) b
18.7 (1.0) a,b,c
MCOH
0.50
8.0 (0.5) b
20.2 (2.1) a,b
0.75
9.0 (2.1) b
21.3 (3.5) a
0.25
7.4 (0.9) b
18.5 (1.9) a,b,c,d
BCC
0.50
7.0 (0.5) b
17.7 (0.9) a,b,c,d
0.75
7.3 (0.7) b
19.1 (1.0) a,b,c
0.5 / 0.01
7.0 (0.9) b
17.3 (1.2) a,b,c,d,e
CC 2 / azole
0.5 / 0.02
7.0 (0.4) b
17.0 (2.8) a,b,c,d,e,f
0.5 / 0.04
7.4 (0.7) b
17.8 (1.4) a,b,c,d
0.05
6.5 (0.7) b
14.8 (2.2) c,d,e,f
DCOI
0.05 / 0.5
5.7 (0.7) b
12.6 (1.3) e,f
DCOI / CC 2
0.05 / 0.5
5.2 (0.9) b
13.6 (1.0) d,e,f
DCOI / CC 1
4.9 (0.5) b
12.0 (1.3) f
Strandboard Control (400 seconds)
a
Values expressed as a percentage of original thickness. Values represent means of 6 blocks per treatment except
micronized copper at 0.50 wt/wt% retention, which had 5. Figures in parentheses represent one standard deviation.
Means with a common letter are not significantly different using Tukey's Studentized Range Test that has been
harmonized by Duncans Multiple Range Test (α=0.05).
Retention
(wt/wt %)
68
69
Immersion for 24 hours nearly tripled the degree of swelling of the 200
second control and more than doubled the swelling for most other treatments. In
general, biocide addition did not significantly affect swelling (Table 8), although
swelling was significantly higher for panels with the medium target retention of CC 1,
as well as medium and high target retentions of micronized copper hydroxide
(MCOH).
The results indicate that addition of biocides to the furnish had a tendency to
increase swelling, but the increases were generally not statistically significant.
Thickness Swelling - 2 hours
30%
Percent Thickness Increase
*
25%
20%
15%
10%
5%
D
O CO
DC I / C I
O C
C I/C 2
on
tro C 1
l(
40
0)
/a
2
C
C
D
C
zo
le
C
BC
H
M
C
O
3
CC
C
C
2
1
CC
Co
nt
ro
l
ZB
0%
Figure 11. Thickness swelling of treated and untreated strandboards after 2 hours of
water submersion. Values represent means of 6 replicates, while error bars represent
one standard deviation about the mean.
70
Thickness Swelling - 24 hours
Percent Thickness Increase
* *
*
30%
25%
20%
15%
10%
5%
D
O CO
DC I / C I
O C
C I/C 2
on
tro C 1
l(
40
0)
/a
2
C
C
D
C
zo
le
C
BC
H
M
C
O
3
CC
C
C
2
1
CC
Co
nt
ro
l
ZB
0%
Figure 12. Thickness swelling of treated and untreated strandboards after 24 hours of
water submersion. Values represent means of 6 replicates, while error bars represent
one standard deviation about the mean.
Voluntary Product Standard PS 2-04 (NIST, 2004) has no specified maximum
amount of thickness swelling for OSB, but the Canadian Standard Association
Standard 0437 Standards on OSB and Waferboard (CSA, 1993) stipulates a maximum
swelling of 15 % for random and oriented strandboards. Except for panels treated
with the high or low retentions of CC 1, all treated panels experienced swelling above
the standard after 24 hours of submersion. The untreated controls pressed for 200
seconds had a swelling of exactly 15 %, which left no room for any excess swelling
due to the presence of preservative. This suggests that panel variables, other than the
biocidal additive, were the source for a large amount of swelling. The results indicate
71
that thickness swelling would not be a limitation to the future use of these
preservatives.
As expected, panel MCs after 2 and 24 hours submersion in water were similar
to the thickness swelling results (Table 9). Panels treated with the medium target
retention of CC 1 had much higher MCs than any other treatment. Panels with the
highest target retention of MCOH had a MC of 25.1 % after 2 hours submersion, an
increase of 22 % compared to the untreated control (Figure 13). The same treatment
group had an MC of 60.7 % after 24 hours, 34 % higher than the untreated control
(Figure 14). This increase may be due to void spaces in the panels created by the
aggregation of preservative particles.
Table 9. Moisture contents of treated and untreated strandboards submerged in water for 0, 2 or 24 hours
Moisture Content (%)a
0 hour submersion 2 hour submersion 24 hour submersion
Treatment
9.2 (0.3) a,b
20.5 (1.5) b
45.2 (5.1) b,c,d,e
Strandboard Control
0.585
9.3 (0.2) a,b
21.5 (1.9) b
49.9 (2.8) a,b,c,d,e
ZB
0.878
9.1 (0.3) a,b
20.4 (1.5) b
46.7 (4.2) b,c,d,e
1.17
9.0 (0.1) b
19.6 (1.3) b
44.6 (4.1) b,c,d,e
0.25
9.2 (0.2) a,b
18.4 (1.2) b
37.4 (3.0) d,e
CC 1
0.50
9.4 (0.4) a,b
51.7 (38.3) a
69.3 (39.2) a
0.75
9.5 (0.2) a,b
17.5 (0.7) b
34.6 (2.2) e
0.25
9.4 (0.3) a,b
20.6 (1.5) b
48.7 (5.9) a,b,c,d,e
CC 2
0.50
9.1 (0.2) b
18.4 (0.6) b
39.4 (2.0) c,d,e
0.75
9.1 (0.4) a,b
18.6 (0.7) b
38.9 (4.7) d,e
0.25
9.3 (0.1) a,b
20.6 (0.6) b
48.8 (1.3) a,b,c,d,e
CC 3
0.50
9.4 (0.2) a,b
20.5 (1.4) b
45.9 (4.5) b,c,d,e
0.75
9.3 (0.1) a,b
19.6 (0.6) b
43.6 (0.9) b,c,d,e
0.25
9.3 (0.3) a,b
21.6 (1.5) b
52.6 (4.4) a,b,c,d,e
MCOH
0.50
9.2 (0.3) a,b
22.1 (2.0) b
59.9 (12.6) a,b,c
0.75
9.3 (0.2) a,b
25.1 (8.4) b
60.7 (15.3) a,b
0.25
9.3 (0.2) a,b
19.8 (0.9) b
47.1 (3.2) b,c,d,e
BCC
0.50
9.3 (0.1) a,b
20.8 (0.9) b
51.1 (3.6) a,b,c,d,e
0.75
9.2 (0.3) a,b
19.5 (1.2) b
46.7 (5.1) b,c,d,e
0.5 / 0.01
9.2 (0.2) a,b
19.0 (0.7) b
41.0 (1.7) b,c,d,e
CC 2 / azole
0.5 / 0.02
9.4 (0.1) a,b
19.2 (0.6) b
41.3 (2.5) b,c,d,e
0.5 / 0.04
9.7 (0.1) a
19.6 (0.6) b
43.0 (2.2) b,c,d,e
0.05
8.0 (0.4) c
21.7 (1.8) b
55.8 (9.0) a,b,c,d
DCOI
0.05 / 0.5
8.2 (0.3) c
18.3 (1.0) b
39.3 (2.7) c,d,e
DCOI / CC 2
0.05 / 0.5
8.1 (0.6) c
17.5 (1.3) b
38.1 (3.5) d,e
DCOI / CC 1
8.2 (0.2) c
19.1 (1.6) b
Strandboard Control (400 seconds)
a
Values expressed on an oven-dry weight basis. Values represent means of 6 blocks per treatment, while figures in
parentheses represent one standard deviation. Means with a common letter are not significantly different using Tukey's
Studentized Range Test (α=0.05).
Retention
(wt/wt %)
72
73
Moisture Content - 2 hours
*
80
Moisture Content (%)
70
60
50
40
30
20
10
2
C
CC
D
D
CO CO
I
I/
on
D
C
tr o C O C
2
l(
I
40 / C
0
C
se
1
co
nd
s)
le
/a
zo
BC
C
M
C
O
H
3
C
C
2
C
C
1
C
C
l
tr o
on
C
ZB
0
Figure 13. Moisture contents of untreated and treated strandboards after 2 hours
submersion. Values represent means of 6 replicates, while error bars represent one
standard deviation about the mean.
74
Moisture Content - 24 hours
*
80
Moisture Content (%)
70
60
50
40
30
20
10
2
C
CC
D
D
CO CO
I
I/
on
D
C
tr o C O C
2
l(
I
40 / C
0
C
se
1
co
nd
s)
le
/a
zo
BC
C
M
C
O
H
3
C
C
2
C
C
1
C
C
l
tr o
on
C
ZB
0
Figure 14. Moisture contents of untreated and treated strandboards after 24 hours
submersion. Values represent means of 6 replicates, while error bars represent one
standard deviation about the mean.
A number of the treatment groups had MCs that were lower than the untreated
controls after 2 and 24 hours, despite having greater thickness swelling values. For
panels treated with CC 1, this effect may have been due to the gradient of resin curing
through the thickness profile. Increased curing in the outer layers limited water
absorption in these strands and lowered the overall MC, while poor curing in the board
center allowed strands to absorb large amounts of water that greatly increased
thickness swelling. Moisture behavior in Copper Diammine Acetate Complex (CC 2)
amended strandboards may have been due to the alkalinity of the preservative. Mildly
alkaline treatments can alter hemicelluloses in hardwoods, causing significant
increases in cell wall swelling (Zanuttini & Marzocchi, 2003; Zanuttini et al., 1999).
75
Hygroscopicity
Preservatives incorporated into panels had little practical effect on the MC of
panels conditioned at 30°C and 30 % relative humidity (RH) (Table 10, Figure 15),
while slight MC reductions were noted when panels were conditioned at 30°C and 90
% RH (Figure 16). DCOI treated boards had the highest reductions, but these were
still only 0.8 to 1.1 % MC less than the untreated control (400 seconds) at 14.0 % MC.
None of the differences were statistically significant in comparison with the controls,
indicating that the presence of the preservative did not affect hygroscopicity.
Table 10. Moisture contents and linear changes in treated and untreated strandboards conditioned under two different
temperature/relative humidity regimes.
Retention
(wt/wt %)
a
Panel Moisture Content (%)
a
30°C / 30%RH
30°C / 90%RH
Linear Change (%)
Treatment
5.2 (0.15) b,c,d,e 14.0 (0.19) b,c,d,e,f
0.12 (0.03) b,c
Strandboard Control
0.585
5.3 (0.15) b,c,d,e 13.9 (0.08) d,e,f,g,h,i,j,k 0.12 (0.06) b,c
ZB
0.878
5.2 (0.08) b,c,d,e 14.2 (0.08) b,c
0.12 (0.02) b,c
1.17
5.1 (0.08) d,e
14.1 (0.10) b,c,d,e
0.10 (0.05) b,c
0.25
5.3 (0.10) b,c,d,e 13.6 (0.10) I,j,k,l
0.09 (0.06) c
CC 1
0.50
5.4 (0.08) a,b,c
13.7 (0.16) f,g,h,I,j,k,l
0.13 (0.04) a,b,c
0.75
5.6 (0.08) a
13.9 (0.08) c,d,e,f,g,h,I,j 0.19 (0.09) a,b,c
0.25
5.3 (0.16) b,c,d,e 13.8 (0.23) e,f,g,h,I,j,k,l
0.22 (0.13) a,b
CC 2
0.50
5.4 (0.10) a,b,c
13.8 (0.13) e,f,g,h,I,j,k
0.15 (0.03) a,b,c
0.75
5.4 (0.08) a,b
13.9 (0.12) d,e,f,g,h,i,j,k 0.16 (0.03) a,b,c
0.25
5.1 (0.10) e
13.9 (0.17) b,c,d,e,f,g,h
0.15 (0.05) a,b,c
CC 3
0.50
5.2 (0.17) b,c,d,e 13.7 (0.15) h,I,j,k,l
0.19 (0.05) a,b,c
0.75
5.3 (0.19) b,c,d,e 13.7 (0.06) g,h,I,j,k,l
0.16 (0.04) a,b,c
0.25
5.2 (0.15) b,c,d,e 13.5 (0.08) l
0.19 (0.10) a,b,c
MCOH
0.50
5.2 (0.08) c,d,e
13.8 (0.15) e,f,g,h,I,j,k
0.14 (0.03) a,b,c
0.75
5.2 (0.15) b,c,d,e 13.6 (0.12) j,k,l
0.13 (0.04) a,b,c
0.25
5.2 (0.05) c,d,e
14.1 (0.10) b,c,d
0.13 (0.05) a,b,c
BCC
0.50
5.2 (0.06) b,c,d,e 14.2 (0.13) b
0.09 (0.06) c
0.75
5.2 (0.05) c,d,e
14.0 (0.13) b,c,d,e,f,g,h
0.25 (0.06) a
0.5 / 0.01
5.1 (0.08) d,e
14.0 (0.19) b,c,d,e,f
0.14 (0.04) a,b,c
CC 2 / azole
0.5 / 0.02
5.3 (0.08) b,c,d,e 13.9 (0.15) b,c,d,e,f,g,h,i 0.14 (0.02) a,b,c
0.5 / 0.04
5.4 (0.10) b,c,d
14.0 (0.14) b,c,d,e,f,g
0.10 (0.02) b,c
0.05
4.6 (0.08) f
13.6 (0.06) I,j,k,l
0.16 (0.02) a,b,c
DCOI
0.05 / 0.5
4.6 (0.08) f
13.6 (0.14) k,l
0.09 (0.03) c
DCOI / CC 2
0.05 / 0.5
4.6 (0.08) f
14.0 (0.21) b,c,d,e,f,g,h
0.11 (0.04) b,c
DCOI / CC 1
4.5 (0.06) f
14.8 (0.18) a
0.11 (0.07) b,c
Strandboard Control (400 seconds)
a
Values represent means of 6 blocks per treatment, except Copper Diammine Carbonate Complex at 0.25 wt/wt% retention,
which had 4. Figures in parentheses represent one standard deviation. Means with a common letter are not significantly
different using Tukey's Studentized Range Test that has been harmonized by Duncans Multiple Range Test (α=0.05).
76
77
Moisture Content at 30°C & 30% RH
16
14
12
MC (%)
10
8
*
6
4
2
2
C
C
D
C DC
O
O
D I/C I
C
C
O
C I/ 2
on C
tro C
l( 1
40
0)
/a
zo
le
C
BC
O
H
M
C
3
C
C
2
C
C
1
C
C
C
on
tro
l
ZB
0
Figure 15. Moisture contents of treated and untreated strandboards conditioned at
30°C and 30% RH conditioning room environments. Values represent means of 6
replicates, while error bars represent one standard deviation about the mean.
78
Moisture Content at 30°C & 90% RH
16
*
* * *
*
* * *
14
12
MC (%)
10
8
6
4
2
2
C
C
D
C DC
O
O
D I/C I
C
C
O
C I/ 2
on C
tro C
l( 1
40
0)
/a
zo
le
C
BC
O
H
M
C
3
C
C
2
C
C
1
C
C
C
on
tro
l
ZB
0
Figure 16. Moisture contents of treated and untreated strandboards conditioned at
30°C and 90% RH conditioning room environments. Values represent means of 6
replicates, while error bars represent one standard deviation about the mean.
Linear change represented the difference in panel length after a sample was
transferred from the 30°C and 30% RH environment to an environment at 30°C and
90% RH (Table 10). Linear changes in many treatment groups were greater than the
controls, but the differences were only significant in panels treated with the highest
retention of BCC (Figure 17). The voluntary product standard PS 2-04 Performance
Standard for Wood-Based Structural Use Panels states that “The free panel linear
expansion shall be no more than 0.30% along the panel strength axis and 0.35% across
the panel strength axis” (NIST, 2004). While it was difficult to compare our nonoriented strandboards to standard OSB, the results suggest that treatment did not have
a significant negative effect on linear expansion.
79
Linear Change due to Changes in MC
Percent Increase in Length (%)
0.40
*
0.35
0.30
0.25
0.20
0.15
0.10
0.05
D
O CO
DC I / C I
O C
C I/C 2
on
tro C 1
l(
40
0)
/a
2
CC
D
C
zo
le
C
BC
H
M
CO
3
C
C
2
CC
1
CC
ZB
C
on
tro
l
0.00
Figure 17. Linear expansion with change in moisture content of treated and untreated
strandboards conditioned at 30°C and 30% RH, then 30°C and 90% RH. Values
represent means of 6 replicates, while error bars represent one standard deviation
about the mean.
Resistance to Leaching
CC 1 or CC 2 provided strong resistance to chemical leaching (Table 11). All
treatments levels of CC 1 or CC 2 alone experienced 5% or less loss of copper solids.
Chemical analysis showed an increase in copper solids due to leaching of panels
treated with CC 3 or MCOH. This increase was likely due the sampling of panels with
high variations in preservative concentration. The organic preservatives had a
tendency to leach from panels, regardless of the presence of a co-biocide. Panels
treated with tebuconazole lost between 18 and 29% of active chemical while those
80
treated with DCOI lost between 21 and 28% isothiazolone. These results differ
from previous research that found tebuconazole to be leach resistant from small solid
wood blocks treated with copper azole (Fox et al., 1994).
Resistance to leaching is a desirable preservative attribute, and is beneficial for
future development of CC 1 and CC 2 for wood-composite panel treatements.
Table 11. Resistance of treated strandboards to chemical leaching after 14 days in an
AWPA E10 leaching test.
Actual Retention (wt/wt %)
Treatment
Strandboard Control
ZB
CC 1
CC 2
CC 3
MCOH
BCC
CC 2 / azole
a
Target Retention
(wt/wt %)
Non-leached
Leached
Chemical Leached (%)
0.585
0.878
1.17
0.25
0.50
0.75
0.25
0.50
0.75
0.25
0.50
0.75
0.25
0.50
0.75
0.25
0.50
0.75
0.5 / 0.01
0.5 / 0.02
0.5 / 0.04
0.05
0.05 / 0.5
0.05 / 0.5
0.86
1.22
1.88
0.183
0.332
0.486
0.088
0.146
0.292
0.095
0.226
0.353
0.039
0.055
0.115
0.095
0.168
0.238
0.189 / 0.006
0.217 / 0.012
0.235 / 0.024
0.024
0.025 / 0.164
0.027 / 0.375
0.57
0.90
1.30
0.174
0.331
0.472
0.090
0.142
0.287
0.122
0.239
0.382
0.053
0.131
0.243
0.078
0.153
0.266
0.171 / 0.005
0.209 / 0.010
0.185 / 0.019
0.019
0.018 / 0.150
0.020 / 0.354
34
26
31
5
0
3
-2
3
2
-29
-6
-8
-36
-138
-111
18
9
-12
10 / 28
4 / 18
21 / 22
21
28 / 9
25 / 6
DCOI
DCOI / CC 2
DCOI / CC 1
Strandboard Control (400 seconds)
a
Values represent the combination of six treatment blocks analyzed by appropriate method.
Conclusions
The addition of preservatives had negligible effects on the mechanical and
physical properties of aspen strandboards. The results suggest that incorporation of
81
alkaline copper based biocides to the furnish prior to pressing represents a simple,
effective method for enhancing panel durability without adversely affecting properties.
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84
CHAPTER 5 – GENERAL CONCLUSIONS
Nearly all preservative treatment systems were effective against brown or
white rot decay fungi except all treatment levels of MCOH or DCOI alone.
Unacceptable weight losses were incurred for panels treated to the lowest retention
levels of CC 2, CC 3 and BCC. Panels treated with tebuconazole and CC 2 provided
excellent protection, but the effect of the tebuconazole on panel durability could not be
established. The best protection appeared to be achieved through the use of CC 1
combined with DCOI, although the results were not statistically better than other
effective treatments. Most preservative treatments failed to reduce the amount of
surface mold growth, except DCOI. CC 1 and DCOI provided the best mold
protection. Preservative addition had no significant negative effects on the mechanical
and physical properties of most aspen strandboards tested. Slight increases in MOE
and substantial decreases in internal bond strength were observed for panels treated
with CC 1. Increasing panel press time may alleviate this problem. Treated panels
tended to swell more than untreated controls, but the effect did not appear to be due to
of the biocidal additive. Preservative treated panels were less hygroscopic than
untreated controls when conditioned to high and low humidity environments. Linear
expansion of some treated panels increased slightly, but all were well below the
maximum acceptable thickness swelling value. Incorporation of biocides into panels
should not appreciably affect mechanical or physical properties. All three copper
complex systems were effective against decay fungi, while panels treated with CC 1
and isothiazolone offered the best protection against mold and decay fungi. Ground
85
proximity and termite field tests, are underway to more fully assess the resistance of
these materials to biological attack.
86
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96
APPENDICES
Appendix A – Statistical Output
Decay Resistance of OSB to G. trabeum
10
11:31 Monday,
April 28, 2008
The GLM Procedure
Class Level Information
Class
Levels
treatment
25 26 27
27
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Number of Observations Read
Number of Observations Used
160
158
Decay Resistance of OSB to G. trabeum
11
11:31 Monday,
April 28, 2008
The GLM Procedure
Dependent Variable: weight_loss
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
26
67268.31494
2587.24288
50.01
Error
131
6776.90867
51.73213
Corrected Total
157
74045.22361
> F
> F
Source
Source
treatment
<.0001
> F
Source
treatment
<.0001
14
R-Square
Coeff Var
Root MSE
weight_loss Mean
0.908476
47.40003
7.192505
15.17405
DF
Type I SS
Mean Square
F Value
26
67268.31494
2587.24288
50.01
DF
Type III SS
Mean Square
F Value
26
67268.31494
2587.24288
50.01
Decay Resistance of OSB to G. trabeum
11:31 Monday,
April 28, 2008
The GLM Procedure
Duncan's Multiple Range Test for weight_loss
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
Error Degrees of Freedom
Error Mean Square
0.05
131
51.73213
Pr
Pr
Pr
97
Harmonic Mean of Cell Sizes 5.806452
NOTE: Cell sizes are not equal.
Number of Means
13
14
Critical Range
10.08 10.13
2
3
4
5
6
7
8
9
10
8.35
8.79
9.08
9.29
9.46
9.60
9.71
9.80
9.89
11
12
9.96 10.02
Number of Means
15
16
17
18
19
20
21
22
23
24
25
26
27
Critical Range 10.17 10.21 10.25 10.29 10.32 10.35 10.37 10.40 10.42 10.44 10.46
10.48 10.50
Means with the same letter are not significantly different.
Duncan Grouping
B
B
B
D
D
D
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
16
A
A
A
Mean
N
treatment
68.400
4
27
62.440
5
23
C
C
C
55.633
6
1
53.500
5
26
E
E
E
45.967
6
14
41.833
6
16
F
29.617
6
15
G
G
G
G
G
17.417
6
17
12.200
6
8
9.350
6
11
6.167
6
2
4.383
6
5
3.817
6
9
3.267
6
18
3.200
6
6
2.833
6
12
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
2.683
6
20
2.683
6
10
2.433
6
7
2.333
6
24
1.983
6
19
1.967
6
21
1.933
6
13
1.867
6
3
1.633
6
22
1.350
6
4
0.817
6
25
Decay Resistance of OSB to G. trabeum
11:31 Monday,
April 28, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for weight_loss
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
98
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
131
Error Mean Square
51.73213
Critical Value of Studentized Range 5.34438
Minimum Significant Difference
15.952
Harmonic Mean of Cell Sizes
5.806452
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
A
A
A
A
A
A
68.400
4
27
62.440
5
23
55.633
6
1
53.500
5
26
45.967
6
14
41.833
6
16
29.617
6
15
B
B
B
B
B
B
B
D
D
D
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
C
C
C
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
17.417
6
17
12.200
6
8
9.350
6
11
6.167
6
2
4.383
6
5
3.817
6
9
3.267
6
18
3.200
6
6
2.833
6
12
2.683
6
20
2.683
6
10
2.433
6
7
2.333
6
24
1.983
6
19
1.967
6
21
1.933
6
13
1.867
6
3
1.633
6
22
1.350
6
4
0.817
6
25
Decay Resistance of OSB to P. placenta
10
11:48 Monday,
April 28, 2008
The GLM Procedure
Class Level Information
Class
Levels
Values
99
treatment
25 26 27
27
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Number of Observations Read
Number of Observations Used
160
158
Decay Resistance of OSB to P. placenta
11
11:48 Monday,
April 28, 2008
The GLM Procedure
Dependent Variable: weight_loss
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
26
30690.65305
1180.40973
3.65
Error
131
42396.85967
323.64015
Corrected Total
157
73087.51272
> F
> F
Source
Source
treatment
<.0001
> F
Source
treatment
<.0001
14
R-Square
Coeff Var
Root MSE
weight_loss Mean
0.419917
144.5421
17.99000
12.44620
DF
Type I SS
Mean Square
F Value
26
30690.65305
1180.40973
3.65
DF
Type III SS
Mean Square
F Value
26
30690.65305
1180.40973
3.65
Decay Resistance of OSB to P. placenta
11:48 Monday,
April 28, 2008
The GLM Procedure
Duncan's Multiple Range Test for weight_loss
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
0.05
Error Degrees of Freedom
131
Error Mean Square
323.6402
Harmonic Mean of Cell Sizes 5.806452
NOTE: Cell sizes are not equal.
Number of Means
2
3
4
5
6
7
8
9
10
11
12
13
14
Critical Range 20.89 21.98 22.71 23.25 23.67 24.00 24.28 24.52 24.73 24.90 25.06
25.20 25.33
Number of Means
15
16
17
18
19
20
21
22
23
24
25
26
27
Critical Range 25.44 25.55 25.64 25.73 25.81 25.88 25.95 26.01 26.07 26.12 26.17
26.22 26.26
Means with the same letter are not significantly different.
Duncan Grouping
Mean
N
treatment
Pr
Pr
Pr
100
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
16
A
63.05
4
27
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
35.40
6
24
34.55
6
16
27.38
5
26
25.25
6
9
25.10
5
23
21.15
6
14
18.58
6
1
17.87
6
25
16.90
6
11
16.42
6
7
15.67
6
18
15.42
6
12
12.13
6
22
1.25
6
6
1.18
6
3
1.15
6
4
1.13
6
5
1.08
6
21
1.00
6
2
0.97
6
10
0.90
6
13
0.82
6
15
0.82
6
8
0.80
6
17
0.78
6
20
0.77
6
19
Decay Resistance of OSB to P. placenta
11:48 Monday,
April 28, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for weight_loss
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
131
Error Mean Square
323.6402
Critical Value of Studentized Range 5.34438
Minimum Significant Difference
39.9
Harmonic Mean of Cell Sizes
5.806452
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
63.05
4
27
101
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
A
A
A
A
A
A
A
A
A
A
35.40
6
24
34.55
6
16
27.38
5
26
25.25
6
9
25.10
5
23
21.15
6
14
18.58
6
1
17.87
6
25
16.90
6
11
16.42
6
7
15.67
6
18
15.42
6
12
12.13
6
22
1.25
6
6
1.18
6
3
1.15
6
4
1.13
6
5
1.08
6
21
1.00
6
2
0.97
6
10
0.90
6
13
0.82
6
15
0.82
6
8
0.80
6
17
0.78
6
20
0.77
6
19
Decay Resistance of OSB to T. versicolor
1
12:53 Friday,
May 23, 2008
The GLM Procedure
Class Level Information
Class
Levels
treatment
25 26 27
27
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Number of Observations Read
Number of Observations Used
160
158
Decay Resistance of OSB to T. versicolor
2
12:53 Friday,
May 23, 2008
The GLM Procedure
Dependent Variable: weight_loss
> F
Source
DF
Sum of
Squares
Mean Square
F Value
Pr
102
Model
<.0001
26
54994.76263
2115.18318
Error
131
5978.44117
45.63696
Corrected Total
157
60973.20380
> F
R-Square
Coeff Var
Root MSE
weight_loss Mean
0.901950
48.98894
6.755513
13.78987
Source
treatment
<.0001
> F
Source
treatment
<.0001
5
46.35
DF
Type I SS
Mean Square
F Value
26
54994.76263
2115.18318
46.35
DF
Type III SS
Mean Square
F Value
26
54994.76263
2115.18318
46.35
Pr
Pr
Decay Resistance of OSB to T. versicolor
12:53 Friday,
May 23, 2008
The GLM Procedure
Duncan's Multiple Range Test for weight_loss
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
0.05
Error Degrees of Freedom
131
Error Mean Square
45.63696
Harmonic Mean of Cell Sizes 5.806452
NOTE: Cell sizes are not equal.
Number of Means
2
3
4
5
6
7
8
9
10
11
12
13
14
Critical Range 7.843 8.255 8.529 8.730 8.887 9.013 9.119 9.208 9.285 9.352 9.411
9.464 9.512
Number of Means
15
16
17
18
19
20
21
22
23
24
25
26
27
Critical Range 9.554 9.593 9.629 9.661 9.691 9.718 9.743 9.767 9.789 9.809 9.828
9.846 9.862
Means with the same letter are not significantly different.
Duncan Grouping
Mean
N
treatment
A
67.840
5
26
B
B
B
58.600
5
23
52.817
6
1
C
41.150
6
16
D
D
D
D
D
33.000
6
15
29.417
6
14
28.425
4
27
E
E
E
E
E
13.317
6
8
8.550
6
17
7.883
6
11
F
F
F
103
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
7
E
E
E
E
E
E
6.017
6
9
4.650
6
20
4.433
6
24
3.717
6
18
3.667
6
12
3.583
6
22
3.417
6
13
3.333
6
5
3.150
6
21
2.900
6
19
2.633
6
10
2.617
6
2
2.233
6
6
2.167
6
7
1.533
6
3
1.433
6
4
1.200
6
25
Decay Resistance of OSB to T. versicolor
12:53 Friday,
May 23, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for weight_loss
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
131
Error Mean Square
45.63696
Critical Value of Studentized Range 5.34438
Minimum Significant Difference
14.983
Harmonic Mean of Cell Sizes
5.806452
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
Mean
A
A
A
67.840
5
26
58.600
5
23
52.817
6
1
41.150
6
16
33.000
6
15
29.417
6
14
28.425
4
27
13.317
6
8
8.550
6
17
7.883
6
11
6.017
6
9
B
B
B
D
D
D
D
D
D
D
C
C
C
E
E
E
E
E
E
E
N
treatment
104
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
28, 2008
4.650
6
20
4.433
6
24
3.717
6
18
3.667
6
12
3.583
6
22
3.417
6
13
3.333
6
5
3.150
6
21
2.900
6
19
2.633
6
10
2.617
6
2
2.233
6
6
2.167
6
7
1.533
6
3
1.433
6
4
1.200
6
25
Mold Resistance at 2 weeks
43
13:00 Monday, April
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
28, 2008
156
90
Mold Resistance at 2 weeks
44
13:00 Monday, April
The GLM Procedure
Dependent Variable: rating_1
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
99.5000000
3.9800000
8.35
Error
64
30.5000000
0.4765625
Corrected Total
89
130.0000000
> F
> F
Source
Source
treatment
<.0001
> F
Source
treatment
<.0001
R-Square
Coeff Var
Root MSE
rating_1 Mean
0.765385
20.71005
0.690335
3.333333
DF
Type I SS
Mean Square
F Value
25
99.50000000
3.98000000
8.35
DF
Type III SS
Mean Square
F Value
25
99.50000000
3.98000000
8.35
Pr
Pr
Pr
105
28, 2008
Mold Resistance at 2 weeks
47
13:00 Monday, April
The GLM Procedure
Duncan's Multiple Range Test for rating_1
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
0.05
Error Degrees of Freedom
64
Error Mean Square
0.476563
Harmonic Mean of Cell Sizes
3.25
NOTE: Cell sizes are not equal.
Number of Means
2
3
4
5
6
7
8
9
10
11
12
13
14
Critical Range 1.082 1.138 1.175 1.202 1.223 1.240 1.254 1.265 1.275 1.284 1.291
1.298 1.304
26
Number of Means
Critical Range
1.341
15
16
17
18
19
20
21
22
23
24
25
1.309 1.313 1.318 1.321 1.325 1.328 1.331 1.333 1.335 1.338 1.339
Means with the same letter are not significantly different.
Duncan Grouping
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
E
E
E
E
E
E
E
E
E
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
Mean
N
treatment
5.0000
3
10
4.3333
3
9
4.3333
3
11
4.3333
3
20
4.3333
3
13
4.3333
3
8
4.3333
3
15
4.3333
3
16
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
4.0000
3
17
4.0000
3
18
4.0000
3
19
3.8333
6
26
3.6667
3
1
3.6667
3
14
3.6667
3
3
3.6667
3
12
F
F
F
F
F
F
3.6667
3
4
3.3333
3
2
3.0000
3
5
3.0000
3
21
3.0000
3
6
2.5000
6
23
2.0000
3
22
1.6667
3
7
106
F
F
F
28, 2008
1.5000
6
24
1.3333
6
25
Mold Resistance at 2 weeks
49
13:00 Monday, April
The GLM Procedure
Tukey's Studentized Range (HSD) Test for rating_1
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
64
Error Mean Square
0.476563
Critical Value of Studentized Range 5.43738
Minimum Significant Difference
2.0821
Harmonic Mean of Cell Sizes
3.25
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Mean
N
treatment
5.0000
3
10
4.3333
3
9
4.3333
3
11
4.3333
3
20
4.3333
3
13
4.3333
3
8
4.3333
3
15
4.3333
3
16
4.0000
3
17
4.0000
3
18
4.0000
3
19
3.8333
6
26
3.6667
3
1
3.6667
3
14
3.6667
3
3
3.6667
3
12
3.6667
3
4
3.3333
3
2
3.0000
3
5
3.0000
3
21
3.0000
3
6
2.5000
6
23
2.0000
3
22
1.6667
3
7
1.5000
6
24
1.3333
6
25
107
28, 2008
Mold Resistance at 2 weeks
43
13:00 Monday, April
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
Values
26
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
28, 2008
156
90
Mold Resistance at 2 weeks
44
13:00 Monday, April
The GLM Procedure
Dependent Variable: rating_1
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
99.5000000
3.9800000
8.35
Error
64
30.5000000
0.4765625
Corrected Total
89
130.0000000
> F
> F
Source
R-Square
Coeff Var
Root MSE
rating_1 Mean
0.765385
20.71005
0.690335
3.333333
Source
treatment
<.0001
> F
Source
treatment
<.0001
28, 2008
DF
Type I SS
Mean Square
F Value
25
99.50000000
3.98000000
8.35
DF
Type III SS
Mean Square
F Value
25
99.50000000
3.98000000
8.35
Mold Resistance at 2 weeks
47
Pr
Pr
Pr
13:00 Monday, April
The GLM Procedure
Duncan's Multiple Range Test for rating_1
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
0.05
Error Degrees of Freedom
64
Error Mean Square
0.476563
Harmonic Mean of Cell Sizes
3.25
NOTE: Cell sizes are not equal.
Number of Means
2
3
4
5
6
7
8
9
10
11
12
13
14
Critical Range 1.082 1.138 1.175 1.202 1.223 1.240 1.254 1.265 1.275 1.284 1.291
1.298 1.304
26
Number of Means
Critical Range
15
16
17
18
19
20
21
22
23
24
25
1.309 1.313 1.318 1.321 1.325 1.328 1.331 1.333 1.335 1.338 1.339
108
1.341
Means with the same letter are not significantly different.
Duncan Grouping
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
E
E
E
E
E
E
E
E
E
28, 2008
49
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
Mean
N
treatment
5.0000
3
10
4.3333
3
9
4.3333
3
11
4.3333
3
20
4.3333
3
13
4.3333
3
8
4.3333
3
15
4.3333
3
16
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
4.0000
3
17
4.0000
3
18
4.0000
3
19
3.8333
6
26
F
F
F
F
F
F
F
F
F
3.6667
3
1
3.6667
3
14
3.6667
3
3
3.6667
3
12
3.6667
3
4
3.3333
3
2
3.0000
3
5
3.0000
3
21
3.0000
3
6
2.5000
6
23
2.0000
3
22
1.6667
3
7
1.5000
6
24
1.3333
6
25
Mold Resistance at 2 weeks
13:00 Monday, April
The GLM Procedure
Tukey's Studentized Range (HSD) Test for rating_1
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
64
Error Mean Square
0.476563
Critical Value of Studentized Range 5.43738
Minimum Significant Difference
2.0821
Harmonic Mean of Cell Sizes
3.25
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
109
Tukey Grouping
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
28, 2008
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Mean
N
treatment
5.0000
3
10
4.3333
3
9
4.3333
3
11
4.3333
3
20
4.3333
3
13
4.3333
3
8
4.3333
3
15
4.3333
3
16
4.0000
3
17
4.0000
3
18
4.0000
3
19
3.8333
6
26
3.6667
3
1
3.6667
3
14
3.6667
3
3
3.6667
3
12
3.6667
3
4
3.3333
3
2
3.0000
3
5
3.0000
3
21
3.0000
3
6
2.5000
6
23
2.0000
3
22
1.6667
3
7
1.5000
6
24
1.3333
6
25
Mold Resistance at 3 weeks
57
13:00 Monday, April
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
28, 2008
58
156
156
Mold Resistance at 3 weeks
13:00 Monday, April
The GLM Procedure
Dependent Variable: rating_2
> F
Source
Model
<.0001
DF
Sum of
Squares
Mean Square
F Value
25
73.3910256
2.9356410
9.35
Pr
110
> F
Error
130
40.8333333
Corrected Total
155
114.2243590
R-Square
Coeff Var
Root MSE
rating_2 Mean
0.642516
13.76850
0.560449
4.070513
Source
treatment
<.0001
> F
Source
treatment
<.0001
28, 2008
0.3141026
DF
Type I SS
Mean Square
F Value
25
73.39102564
2.93564103
9.35
DF
Type III SS
Mean Square
F Value
25
73.39102564
2.93564103
9.35
Mold Resistance at 3 weeks
61
Pr
Pr
13:00 Monday, April
The GLM Procedure
Tukey's Studentized Range (HSD) Test for rating_2
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
0.314103
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
1.2166
Means with the same letter are not significantly different.
Tukey Grouping
B
B
B
B
B
B
B
B
B
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
Mean
N
treatment
4.8333
6
8
4.6667
6
9
4.5000
6
19
4.5000
6
10
4.5000
6
13
4.5000
6
6
4.5000
6
15
4.5000
6
20
4.5000
6
11
4.5000
6
16
4.3333
6
5
4.3333
6
18
4.1667
6
17
4.1667
6
14
4.1667
6
3
4.1667
6
12
4.1667
6
21
111
B
B
B
B
B
B
B
B
B
B
B
B
B
B
A
A
A
A
A
A
A
A
A
A
A
A
D
D
D
28, 2008
C
C
C
C
C
4.1667
6
26
4.0000
6
4
4.0000
6
22
4.0000
6
2
3.8333
6
7
3.6667
6
1
3.0000
6
23
2.5000
6
24
1.6667
6
25
Mold Resistance at 4 weeks
73
13:00 Monday, April
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
28, 2008
156
156
Mold Resistance at 4 weeks
74
13:00 Monday, April
The GLM Procedure
Dependent Variable: rating_3
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
33.89743590
1.35589744
5.18
Error
130
34.00000000
0.26153846
Corrected Total
155
67.89743590
> F
> F
Source
Source
treatment
<.0001
> F
Source
treatment
<.0001
28, 2008
77
R-Square
Coeff Var
Root MSE
rating_3 Mean
0.499245
11.73231
0.511408
4.358974
DF
Type I SS
Mean Square
F Value
25
33.89743590
1.35589744
5.18
DF
Type III SS
Mean Square
F Value
25
33.89743590
1.35589744
5.18
Mold Resistance at 4 weeks
Pr
Pr
Pr
13:00 Monday, April
The GLM Procedure
Tukey's Studentized Range (HSD) Test for rating_3
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
112
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
0.261538
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
1.1101
Means with the same letter are not significantly different.
Tukey Grouping
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
28, 2008
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
D
D
D
D
D
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Mean
N
treatment
4.8333
6
9
4.8333
6
10
4.8333
6
13
4.8333
6
12
4.8333
6
6
4.6667
6
11
4.6667
6
8
4.6667
6
26
4.5000
6
15
4.5000
6
5
4.5000
6
21
4.5000
6
4
4.5000
6
18
4.5000
6
16
4.5000
6
20
4.3333
6
19
4.3333
6
1
4.3333
6
14
4.3333
6
2
4.1667
6
7
4.1667
6
3
4.1667
6
17
4.0000
6
22
3.6667
6
23
3.3333
6
24
2.8333
6
25
Mold Resistance at 6 weeks
80
13:00 Monday, April
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
28, 2008
81
Mold Resistance at 6 weeks
156
156
13:00 Monday, April
113
The GLM Procedure
Dependent Variable: rating_4
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
22.74358974
0.90974359
6.96
Error
130
17.00000000
0.13076923
Corrected Total
155
39.74358974
> F
> F
Source
Source
treatment
<.0001
> F
Source
treatment
<.0001
28, 2008
R-Square
Coeff Var
Root MSE
rating_4 Mean
0.572258
7.623347
0.361620
4.743590
DF
Type I SS
Mean Square
F Value
25
22.74358974
0.90974359
6.96
DF
Type III SS
Mean Square
F Value
25
22.74358974
0.90974359
6.96
Mold Resistance at 6 weeks
84
Pr
Pr
Pr
13:00 Monday, April
The GLM Procedure
Tukey's Studentized Range (HSD) Test for rating_4
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
0.130769
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
0.785
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
5.0000
6
9
5.0000
6
2
5.0000
6
19
5.0000
6
20
5.0000
6
13
5.0000
6
6
5.0000
6
7
5.0000
6
8
5.0000
6
11
5.0000
6
12
4.8333
6
5
4.8333
6
10
4.8333
6
21
114
B
B
B
B
B
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
4.8333
6
22
4.8333
6
3
4.8333
6
16
4.8333
6
26
4.8333
6
4
4.6667
6
1
4.6667
6
15
4.6667
6
17
4.6667
6
18
4.5000
6
14
4.3333
6
23
3.8333
6
24
3.3333
6
25
Mold Resistance at 8 weeks
1
09:42 Wednesday,
April 9, 2008
The GLM Procedure
Class Level Information
Class
Levels
treatment
4
Values
23 24 25 26
Number of Observations Read
Number of Observations Used
24
24
Mold Resistance at 8 weeks
2
09:42 Wednesday,
April 9, 2008
The GLM Procedure
Dependent Variable: rating_5
DF
Sum of
Squares
Mean Square
F Value
Model
0.0001
3
6.12500000
2.04166667
11.67
Error
20
3.50000000
0.17500000
Corrected Total
23
9.62500000
> F
> F
Source
Source
treatment
0.0001
> F
Source
treatment
0.0001
R-Square
Coeff Var
Root MSE
rating_5 Mean
0.636364
9.561829
0.418330
4.375000
DF
Type I SS
Mean Square
F Value
3
6.12500000
2.04166667
11.67
DF
Type III SS
Mean Square
F Value
3
6.12500000
2.04166667
11.67
Pr
Pr
Pr
115
Mold Resistance at 8 weeks
4
09:42 Wednesday,
April 9, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for rating_5
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
Error Degrees of Freedom
Error Mean Square
Critical Value of Studentized Range
Minimum Significant Difference
0.05
20
0.175
3.95829
0.676
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
A
A
5.0000
6
26
4.6667
6
23
C
C
C
4.1667
6
24
3.6667
6
25
B
B
B
3, 2008
Modulus of Elasticity
1
17:22 Monday, March
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
3, 2008
156
156
Modulus of Elasticity
2
17:22 Monday, March
The GLM Procedure
Dependent Variable: modulus_of_elasticity
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
25345754.97
1013830.20
3.07
Error
130
42880443.33
329849.56
Corrected Total
155
68226198.31
> F
> F
Source
R-Square
Coeff Var
Root MSE
modulus_of_elasticity Mean
0.371496
12.73405
574.3253
4510.154
Source
treatment
<.0001
> F
Source
DF
Type I SS
Mean Square
F Value
25
25345754.97
1013830.20
3.07
DF
Type III SS
Mean Square
F Value
Pr
Pr
Pr
116
treatment
<.0001
3, 2008
25
25345754.97
1013830.20
Modulus of Elasticity
5
3.07
17:22 Monday, March
The GLM Procedure
Tukey's Studentized Range (HSD) Test for modulus_of_elasticity
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
329849.6
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
1246.7
Means with the same letter are not significantly different.
Tukey Grouping
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
1
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Mean
N
treatment
5236.0
6
25
5181.5
6
7
5152.8
6
19
4945.8
6
6
4901.5
6
17
4897.5
6
14
4790.0
6
20
4786.3
6
8
4762.0
6
16
4665.0
6
15
4595.3
6
5
4580.7
6
24
4566.2
6
11
4509.7
6
13
4435.3
6
26
4298.8
6
12
4290.5
6
10
4277.8
6
3
4261.2
6
1
4223.0
6
18
4137.2
6
23
4110.8
6
9
4094.3
6
21
3960.3
6
22
3873.3
6
2
3731.0
6
4
Bending Strenth - Modulus of Rupture
14:10 Monday,
117
March 3, 2008
The GLM Procedure
Class Level Information
Class
treatment
24 25 26
Levels
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
156
156
Bending Strenth - Modulus of Rupture
2
14:10 Monday,
March 3, 2008
The GLM Procedure
Dependent Variable: modulus_of_rupture
DF
Sum of
Squares
Mean Square
F Value
Model
0.0117
25
1360079239
54403170
1.89
Error
130
3744443141
28803409
Corrected Total
155
5104522380
> F
> F
Source
R-Square
Coeff Var
Root MSE
modulus_of_rupture Mean
0.266446
20.19666
5366.881
26573.12
Source
treatment
0.0117
> F
Source
treatment
0.0117
5
DF
Type I SS
Mean Square
F Value
25
1360079239
54403170
1.89
DF
Type III SS
Mean Square
F Value
25
1360079239
54403170
1.89
Pr
Pr
Pr
Bending Strenth - Modulus of Rupture
14:10 Monday,
March 3, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for modulus_of_rupture
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
28803409
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
11650
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
A
A
A
A
31769
6
17
31759
6
19
30789
6
15
118
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
30187
6
14
29842
6
11
29077
6
6
28672
6
25
28038
6
26
27874
6
16
27696
6
24
27279
6
20
26984
6
13
26983
6
3
26924
6
12
26514
6
8
26399
6
18
25739
6
23
25355
6
10
24230
6
1
23224
6
5
23156
6
9
22742
6
22
22710
6
4
22557
6
21
22209
6
7
22197
6
2
Internal Bond Strength - Maximum Stress (kPa)
1
18:13 Monday,
March 3, 2008
The GLM Procedure
Class Level Information
Class
treatment
24 25 26
Levels
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
156
156
Internal Bond Strength - Maximum Stress (kPa)
2
18:13 Monday,
March 3, 2008
The GLM Procedure
Dependent Variable: max_stress_kPa
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
810439.392
32417.576
4.70
Error
130
897127.015
6900.977
> F
Source
Pr
119
Corrected Total
> F
155
R-Square
Coeff Var
Root MSE
max_stress_kPa Mean
0.474617
36.49722
83.07212
227.6122
Source
treatment
<.0001
> F
1707566.407
Source
treatment
<.0001
DF
Type I SS
Mean Square
F Value
25
810439.3919
32417.5757
4.70
DF
Type III SS
Mean Square
F Value
25
810439.3919
32417.5757
4.70
Pr
Pr
Internal Bond Strength - Maximum Stress (kPa)
5
18:13 Monday,
March 3, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for max_stress_kPa
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
6900.977
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
180.32
Means with the same letter are not significantly different.
Tukey Grouping
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
F
F
F
F
F
F
F
F
F
F
F
F
Mean
N
treatment
341.82
6
15
310.22
6
16
300.78
6
13
299.72
6
26
299.18
6
14
290.15
6
25
286.95
6
17
281.47
6
24
270.53
6
11
256.62
6
12
254.40
6
19
254.40
6
4
247.05
6
1
244.23
6
9
242.32
6
23
229.97
6
20
224.55
6
8
212.12
6
18
198.73
6
3
120
E
E
E
E
E
E
E
E
E
E
E
B
B
B
B
B
D
D
D
D
D
D
D
D
D
A
C
C
C
C
C
C
C
F
F
F
F
F
F
F
F
F
F
F
F
F
189.03
6
2
142.77
6
10
138.65
6
7
123.38
6
22
116.82
6
21
95.35
6
5
66.72
6
6
Thickness Swelling at 2 Hours
1
16:50 Thursday,
March 6, 2008
The GLM Procedure
Class Level Information
Class
treatment
24 25 26
Levels
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
156
156
Thickness Swelling at 2 Hours
2
16:50 Thursday,
March 6, 2008
The GLM Procedure
Dependent Variable: swelling_2h
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
425.0056410
17.0002256
3.94
Error
130
561.4166667
4.3185897
Corrected Total
155
986.4223077
> F
> F
Source
Source
treatment
<.0001
> F
Source
treatment
<.0001
5
R-Square
Coeff Var
Root MSE
swelling_2h Mean
0.430856
28.94010
2.078122
7.180769
DF
Type I SS
Mean Square
F Value
25
425.0056410
17.0002256
3.94
DF
Type III SS
Mean Square
F Value
25
425.0056410
17.0002256
3.94
Pr
Pr
Pr
Thickness Swelling at 2 Hours
16:50 Thursday,
March 6, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for swelling_2h
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
121
Type II error rate than REGWQ.
Alpha
Error Degrees of Freedom
Error Mean Square
Critical Value of Studentized Range
Minimum Significant Difference
0.05
130
4.31859
5.31704
4.5109
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
13.850
6
6
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
9.000
6
16
8.200
6
8
8.167
6
14
8.000
6
15
7.683
6
9
7.650
6
10
7.617
6
13
7.433
6
17
7.417
6
11
7.383
6
22
7.283
6
19
7.283
6
12
7.017
6
18
6.983
6
20
6.950
6
21
6.567
6
3
6.467
6
23
6.167
6
7
6.083
6
5
6.033
6
2
5.983
6
4
5.700
6
24
5.650
6
1
5.233
6
25
4.900
6
26
Thickness Swelling at 24 Hours
1
10:56 Monday,
April 28, 2008
The GLM Procedure
Class Level Information
Class
treatment
24 25 26
Levels
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
156
122
Number of Observations Used
155
Thickness Swelling at 24 Hours
2
10:56 Monday,
April 28, 2008
The GLM Procedure
Dependent Variable: swelling_24h
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
812.430419
32.497217
6.08
Error
129
689.355000
5.343837
Corrected Total
154
1501.785419
> F
> F
Source
R-Square
Coeff Var
Root MSE
swelling_24h Mean
0.540976
13.56770
2.311674
17.03806
Source
treatment
<.0001
> F
Source
treatment
<.0001
DF
Type I SS
Mean Square
F Value
25
812.4304194
32.4972168
6.08
DF
Type III SS
Mean Square
F Value
25
812.4304194
32.4972168
6.08
Pr
Pr
Pr
Thickness Swelling at 24 Hours
5
10:56 Monday,
April 28, 2008
The GLM Procedure
Duncan's Multiple Range Test for swelling_24h
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
0.05
Error Degrees of Freedom
129
Error Mean Square
5.343837
Harmonic Mean of Cell Sizes 5.954198
NOTE: Cell sizes are not equal.
Number of Means
2
3
4
5
6
7
8
9
10
11
12
13
14
Critical Range 2.651 2.790 2.882 2.950 3.003 3.046 3.082 3.112 3.138 3.160 3.181
3.198 3.214
26
Number of Means
Critical Range
3.327
15
16
17
18
19
20
21
22
23
24
25
3.229 3.242 3.254 3.265 3.275 3.284 3.292 3.300 3.308 3.315 3.321
Means with the same letter are not significantly different.
Duncan Grouping
B
B
B
A
A
A
A
A
C
Mean
N
treatment
21.317
6
16
20.767
6
6
20.200
5
15
123
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
A
A
A
A
A
A
A
A
A
A
A
A
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
I
I
I
I
I
I
I
I
I
I
I
H
H
H
H
H
H
H
H
H
H
H
19.050
6
19
18.733
6
14
18.533
6
8
18.500
6
17
18.433
6
11
18.283
6
13
17.800
6
9
17.750
6
22
17.717
6
18
17.300
6
10
17.267
6
20
17.233
6
2
17.033
6
12
16.950
6
21
16.700
6
3
16.700
6
4
15.183
6
5
14.983
6
1
14.750
6
23
14.133
6
7
13.567
6
25
12.600
6
24
12.033
6
26
Thickness Swelling at 24 Hours
7
10:56 Monday,
April 28, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for swelling_24h
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
129
Error Mean Square
5.343837
Critical Value of Studentized Range 5.31794
Minimum Significant Difference
5.038
Harmonic Mean of Cell Sizes
5.954198
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
B
B
B
A
A
A
A
A
A
A
C
Mean
N
treatment
21.317
6
16
20.767
6
6
20.200
5
15
19.050
6
19
124
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
27, 2008
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
18.733
6
14
18.533
6
8
18.500
6
17
18.433
6
11
18.283
6
13
17.800
6
9
17.750
6
22
17.717
6
18
17.300
6
10
17.267
6
20
17.233
6
2
17.033
6
12
16.950
6
21
16.700
6
3
16.700
6
4
15.183
6
5
14.983
6
1
14.750
6
23
14.133
6
7
13.567
6
25
12.600
6
24
12.033
6
26
Moisture Content at 0 Hours
1
12:02 Tuesday, May
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
Values
26
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
27, 2008
156
156
Moisture Content at 0 Hours
2
12:02 Tuesday, May
The GLM Procedure
Dependent Variable: mc_0h
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
28.54108974
1.14164359
16.29
Error
130
9.10833333
0.07006410
Corrected Total
155
37.64942308
> F
Source
R-Square
Coeff Var
Root MSE
mc_0h Mean
0.758075
2.908135
0.264696
9.101923
Pr
125
> F
Source
treatment
<.0001
> F
Source
treatment
<.0001
27, 2008
DF
Type I SS
Mean Square
F Value
25
28.54108974
1.14164359
16.29
DF
Type III SS
Mean Square
F Value
25
28.54108974
1.14164359
16.29
Moisture Content at 0 Hours
5
Pr
Pr
12:02 Tuesday, May
The GLM Procedure
Tukey's Studentized Range (HSD) Test for mc_0h
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
0.070064
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
0.5746
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
9.6500
6
22
9.5167
6
7
9.4333
6
21
9.3833
6
12
9.3500
6
8
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
C
C
C
9.3333
6
11
9.3333
6
14
9.3167
6
6
9.3167
6
2
9.3000
6
16
9.2833
6
13
9.2833
6
18
9.2667
6
17
9.2333
6
15
9.2000
6
1
9.2000
6
19
9.1833
6
20
9.1667
6
5
9.1167
6
3
9.1000
6
10
9.0500
6
9
9.0333
6
4
8.2167
6
24
8.2167
6
26
126
C
C
C
C
27, 2008
8.1333
6
25
8.0333
6
23
Moisture Content at 2 Hours
8
12:02 Tuesday, May
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
Values
26
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
27, 2008
156
156
Moisture Content at 2 Hours
9
12:02 Tuesday, May
The GLM Procedure
Dependent Variable: mc_2h
> F
Source
Model
<.0001
> F
Sum of
Squares
Mean Square
F Value
25
6209.78494
248.39140
4.10
60.61358
Error
130
7879.76500
Corrected Total
155
14089.54994
R-Square
Coeff Var
Root MSE
mc_2h Mean
0.440737
36.75171
7.785472
21.18397
Source
treatment
<.0001
> F
DF
Source
treatment
<.0001
27, 2008
DF
Type I SS
Mean Square
F Value
25
6209.784936
248.391397
4.10
DF
Type III SS
Mean Square
F Value
25
6209.784936
248.391397
4.10
Moisture Content at 2 Hours
12
Pr
Pr
Pr
12:02 Tuesday, May
The GLM Procedure
Tukey's Studentized Range (HSD) Test for mc_2h
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
130
Error Mean Square
60.61358
Critical Value of Studentized Range 5.31704
Minimum Significant Difference
16.9
Means with the same letter are not significantly different.
Tukey Grouping
Mean
N
treatment
A
51.717
6
6
127
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
27, 2008
25.050
6
16
22.117
6
15
21.650
6
23
21.567
6
14
21.517
6
2
20.750
6
18
20.617
6
11
20.567
6
8
20.500
6
12
20.450
6
1
20.400
6
3
19.767
6
17
19.583
6
13
19.583
6
4
19.567
6
22
19.517
6
19
19.183
6
21
19.067
6
26
19.000
6
20
18.633
6
10
18.367
6
5
18.367
6
9
18.250
6
24
17.517
6
7
17.483
6
25
Moisture Content at 24 Hours
15
12:02 Tuesday, May
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
27, 2008
16
156
150
Moisture Content at 24 Hours
12:02 Tuesday, May
The GLM Procedure
Dependent Variable: mc_24h
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
24
9630.45627
401.26901
4.40
Error
125
11402.60167
91.22081
Corrected Total
149
21033.05793
> F
Source
Pr
128
> F
R-Square
Coeff Var
Root MSE
mc_24h Mean
0.457872
20.41996
9.550959
46.77267
Source
treatment
<.0001
> F
Source
treatment
<.0001
27, 2008
DF
Type I SS
Mean Square
F Value
24
9630.456267
401.269011
4.40
DF
Type III SS
Mean Square
F Value
24
9630.456267
401.269011
4.40
Moisture Content at 24 Hours
19
Pr
Pr
12:02 Tuesday, May
The GLM Procedure
Tukey's Studentized Range (HSD) Test for mc_24h
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
125
Error Mean Square
91.22081
Critical Value of Studentized Range 5.29216
Minimum Significant Difference
20.635
Means with the same letter are not significantly different.
Tukey Grouping
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Mean
N
treatment
69.283
6
6
60.683
6
16
59.883
6
15
55.833
6
23
52.550
6
14
51.133
6
18
49.883
6
2
48.800
6
11
48.717
6
8
47.050
6
17
46.717
6
3
46.667
6
19
45.867
6
12
45.167
6
1
44.550
6
4
43.617
6
13
43.033
6
22
41.300
6
21
40.983
6
20
39.367
6
9
129
E
E
E
E
E
E
E
E
E
E
13, 2008
D
D
D
D
D
D
D
D
C
C
39.267
6
24
38.900
6
10
38.117
6
25
37.350
6
5
34.600
6
7
Dry Room Moisture Content
1
15:50 Tuesday, May
The GLM Procedure
Class Level Information
Class
Levels
treatment
24 25 26
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
13, 2008
157
154
Dry Room Moisture Content
2
15:50 Tuesday, May
The GLM Procedure
Dependent Variable: dry_mc
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
12.14524892
0.48580996
41.48
Error
128
1.49916667
0.01171224
Corrected Total
153
13.64441558
> F
> F
Source
Source
treatment
<.0001
> F
Source
treatment
<.0001
13, 2008
5
R-Square
Coeff Var
Root MSE
dry_mc Mean
0.890126
2.102215
0.108223
5.148052
DF
Type I SS
Mean Square
F Value
25
12.14524892
0.48580996
41.48
DF
Type III SS
Mean Square
F Value
25
12.14524892
0.48580996
41.48
Dry Room Moisture Content
Pr
Pr
15:50 Tuesday, May
The GLM Procedure
Duncan's Multiple Range Test for dry_mc
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
Error Degrees of Freedom
Error Mean Square
Pr
0.05
128
0.011712
130
Harmonic Mean of Cell Sizes 5.886792
NOTE: Cell sizes are not equal.
Number of Means
2
3
4
5
6
7
8
9
10
11
12
13
14
Critical Range .1248 .1314 .1357 .1389 .1414 .1434 .1451 .1465 .1477 .1488 .1498
.1506 .1513
26
Number of Means
Critical Range
.1566
15
16
17
18
19
20
21
22
23
24
25
.1520 .1526 .1532 .1537 .1542 .1546 .1550 .1554 .1557 .1561 .1564
Means with the same letter are not significantly different.
Duncan Grouping
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
E
E
E
E
E
E
E
E
E
E
E
E
E
7
N
treatment
A
5.61667
6
7
B
B
B
B
B
B
B
B
B
B
B
B
B
5.41667
6
10
5.38333
6
6
5.38333
6
9
5.36667
6
22
5.33333
6
21
5.30000
6
2
5.28333
6
5
5.26667
6
13
5.26667
6
8
5.23333
6
16
5.20000
6
18
5.18333
6
1
5.18333
6
12
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
I
I
I
I
I
I
I
13, 2008
Mean
D
D
D
D
D
D
D
D
D
D
D
D
D
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
5.18333
6
3
5.18333
6
14
5.16667
6
19
5.16667
6
15
5.15000
6
17
5.13333
6
4
5.13333
6
20
5.12500
4
11
4.56667
6
25
4.56667
6
24
4.55000
6
23
4.50000
6
26
Dry Room Moisture Content
15:50 Tuesday, May
The GLM Procedure
Tukey's Studentized Range (HSD) Test for dry_mc
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
131
Alpha
0.05
Error Degrees of Freedom
128
Error Mean Square
0.011712
Critical Value of Studentized Range 5.31886
Minimum Significant Difference
0.2372
Harmonic Mean of Cell Sizes
5.886792
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
A
A
A
A
A
A
A
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
F
F
F
F
F
F
F
13, 2008
Mean
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
N
treatment
5.61667
6
7
5.41667
6
10
5.38333
6
6
5.38333
6
9
5.36667
6
22
5.33333
6
21
5.30000
6
2
5.28333
6
5
5.26667
6
13
5.26667
6
8
5.23333
6
16
5.20000
6
18
5.18333
6
1
5.18333
6
12
5.18333
6
3
5.18333
6
14
5.16667
6
19
5.16667
6
15
5.15000
6
17
5.13333
6
4
5.13333
6
20
5.12500
4
11
4.56667
6
25
4.56667
6
24
4.55000
6
23
4.50000
6
26
Wet Room Moisture Content
1
15:38 Tuesday, May
The GLM Procedure
Class Level Information
Class
treatment
24 25 26
Levels
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
157
154
132
13, 2008
Wet Room Moisture Content
2
15:38 Tuesday, May
The GLM Procedure
Dependent Variable: wet_mc
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
10.55858225
0.42234329
21.53
Error
128
2.51083333
0.01961589
Corrected Total
153
13.06941558
> F
> F
Source
R-Square
Coeff Var
Root MSE
wet_mc Mean
0.807885
1.008780
0.140057
13.88377
Source
treatment
<.0001
> F
Source
treatment
<.0001
13, 2008
DF
Type I SS
Mean Square
F Value
25
10.55858225
0.42234329
21.53
DF
Type III SS
Mean Square
F Value
25
10.55858225
0.42234329
21.53
Wet Room Moisture Content
5
Pr
Pr
Pr
15:38 Tuesday, May
The GLM Procedure
Duncan's Multiple Range Test for wet_mc
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
0.05
Error Degrees of Freedom
128
Error Mean Square
0.019616
Harmonic Mean of Cell Sizes 5.886792
NOTE: Cell sizes are not equal.
Number of Means
2
3
4
5
6
7
8
9
10
11
12
13
14
Critical Range .1615 .1700 .1756 .1798 .1830 .1856 .1878 .1896 .1912 .1926 .1938
.1949 .1959
26
Number of Means
Critical Range
.2027
15
16
17
18
19
20
21
22
23
24
25
.1967 .1975 .1983 .1989 .1995 .2001 .2006 .2011 .2015 .2020 .2024
Means with the same letter are not significantly different.
Duncan Grouping
C
C
C
C
C
C
C
E
Mean
N
treatment
A
14.76667
6
26
B
B
B
B
B
B
B
B
B
14.18333
6
18
14.16667
6
3
14.11667
6
17
14.06667
6
4
14.01667
6
1
D
D
D
133
C
C
C
C
C
C
C
C
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
13, 2008
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
B
B
B
B
D
D
D
D
D
D
D
D
D
D
D
D
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
J
J
J
J
J
J
J
J
J
J
J
J
J
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
K
K
K
K
K
K
K
K
K
K
K
K
K
14.01667
6
20
14.00000
6
22
13.98333
6
19
13.98333
6
25
13.92500
4
11
13.90000
6
21
13.86667
6
7
13.85000
6
2
13.85000
6
10
13.80000
6
9
13.80000
6
15
13.78333
6
8
13.71667
6
6
13.70000
6
13
13.68333
6
12
13.61667
6
5
13.60000
6
23
13.56667
6
16
13.55000
6
24
13.48333
6
14
Wet Room Moisture Content
7
15:38 Tuesday, May
The GLM Procedure
Tukey's Studentized Range (HSD) Test for wet_mc
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
128
Error Mean Square
0.019616
Critical Value of Studentized Range 5.31886
Minimum Significant Difference
0.307
Harmonic Mean of Cell Sizes
5.886792
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
F
F
F
F
F
F
F
C
C
C
C
C
C
C
C
C
C
C
C
C
E
E
E
E
E
E
E
E
E
Mean
N
treatment
A
14.76667
6
26
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
14.18333
6
18
14.16667
6
3
14.11667
6
17
14.06667
6
4
14.01667
6
1
14.01667
6
20
14.00000
6
22
13.98333
6
19
H
D
D
D
D
D
D
D
D
D
D
D
G
G
G
134
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
C
C
C
C
C
C
C
C
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
K
B
B
B
B
B
B
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
D
D
D
D
D
D
D
D
D
D
D
D
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
13.98333
6
25
13.92500
4
11
13.90000
6
21
13.86667
6
7
13.85000
6
2
13.85000
6
10
13.80000
6
9
13.80000
6
15
13.78333
6
8
13.71667
6
6
13.70000
6
13
13.68333
6
12
13.61667
6
5
13.60000
6
23
13.56667
6
16
13.55000
6
24
13.48333
6
14
Linear Change due to Moisture Content
1
15:44 Tuesday,
May 27, 2008
The GLM Procedure
Class Level Information
Class
treatment
24 25 26
Levels
26
Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Number of Observations Read
Number of Observations Used
157
154
Linear Change due to Moisture Content
2
15:44 Tuesday,
May 27, 2008
The GLM Procedure
Dependent Variable: change_in_length
DF
Sum of
Squares
Mean Square
F Value
Model
<.0001
25
0.23960877
0.00958435
3.15
Error
128
0.39007500
0.00304746
Corrected Total
153
0.62968377
> F
> F
Source
R-Square
Coeff Var
Root MSE
change_in_length Mean
0.380522
39.34006
0.055204
0.140325
Source
DF
Type I SS
Mean Square
F Value
treatment
25
0.23960877
0.00958435
3.15
Pr
Pr
135
<.0001
> F
Source
treatment
<.0001
DF
Type III SS
Mean Square
F Value
25
0.23960877
0.00958435
3.15
Pr
Linear Change due to Moisture Content
5
15:44 Tuesday,
May 27, 2008
The GLM Procedure
Duncan's Multiple Range Test for change_in_length
NOTE: This test controls the Type I comparisonwise error rate, not the
experimentwise error
rate.
Alpha
0.05
Error Degrees of Freedom
128
Error Mean Square
0.003047
Harmonic Mean of Cell Sizes 5.886792
NOTE: Cell sizes are not equal.
Number of Means
9
10
Critical Range
.07474
.07536
2
3
4
5
6
7
8
.06367
.06701
.06923
.07086
.07213
.07316
.07401
Number of Means
18
19
Critical Range
.07841
.07865
11
12
13
14
15
16
17
.07591
.07639
.07682
.07720
.07755
.07786
.07815
26
Number of Means
Critical Range
.07990
20
21
22
23
24
25
.07887
.07907
.07926
.07944
.07960
.07976
Means with the same letter are not significantly different.
Duncan Grouping
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
A
A
A
A
A
A
A
A
A
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Mean
N
treatment
0.24500
6
19
0.21500
6
8
0.19000
6
7
0.19000
6
14
0.18833
6
12
0.16167
6
10
0.15833
6
23
0.15500
6
13
0.15250
4
11
0.14500
6
9
0.14333
6
20
0.13833
6
15
0.13667
6
21
0.13333
6
16
0.13000
6
6
0.12833
6
17
136
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
C
C
C
C
C
C
C
0.12167
6
3
0.12000
6
2
0.11667
6
1
0.11167
6
26
0.11000
6
25
0.10000
6
22
0.09667
6
4
0.09000
6
24
0.09000
6
18
0.08500
6
5
Linear Change due to Moisture Content
7
15:44 Tuesday,
May 27, 2008
The GLM Procedure
Tukey's Studentized Range (HSD) Test for change_in_length
NOTE: This test controls the Type I experimentwise error rate, but it generally has a
higher
Type II error rate than REGWQ.
Alpha
0.05
Error Degrees of Freedom
128
Error Mean Square
0.003047
Critical Value of Studentized Range 5.31886
Minimum Significant Difference
0.121
Harmonic Mean of Cell Sizes
5.886792
NOTE: Cell sizes are not equal.
Means with the same letter are not significantly different.
Tukey Grouping
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Mean
N
treatment
0.24500
6
19
0.21500
6
8
0.19000
6
7
0.19000
6
14
0.18833
6
12
0.16167
6
10
0.15833
6
23
0.15500
6
13
0.15250
4
11
0.14500
6
9
0.14333
6
20
0.13833
6
15
0.13667
6
21
0.13333
6
16
0.13000
6
6
0.12833
6
17
0.12167
6
3
0.12000
6
2
137
B
B
B
B
B
B
B
B
B
B
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
0.11667
6
1
0.11167
6
26
0.11000
6
25
0.10000
6
22
0.09667
6
4
0.09000
6
24
0.09000
6
18
0.08500
6
5