ISPITIVANJE TOPLINSKIH SVOJSTAVA LAMINIRANIH TKANINA
INVESTIGATION OF THE THERMAL PROPERTIES OF LAMINATED
MATERIALS
Goran Majstorović1, Dubravko Rogale2, Snježana Firšt Rogale2
Weltex, Čačak, Serbija
Faculty of Textile technology, University of Zagreb, Croatia
REZIME
U ovom radu biti će prikazani rezultati mjerenja toplinskog otpora prolasku topline laminiranih tkanina. U tu svrhe
koristio se novi originalni patentirani mjerni sustav za određivanje statičkih i dinamičkih toplinskih svojstava tekstilnih
plošnih proizvoda, kompozita i odjeće. Spomenuti originalni i patentirani mjeriteljski sustav razvijen je, instaliran i
umjeren u Laboratoriju za procesne parametre u Zavodu za odjevnu tehnologiju Tekstilno-tehnološkog fakulteta
Sveučilišta u Zagrebu, a temeljno mu je obilježje, uz originalnost, tehnički cjelovita povezanost, točnost i usklađenost
ispitnih parametara.
Ključne reči: laminirane tkanine, toplinska svojstva, toplinski otpor, vruća ploča
SUMMARY
This paper looks at the results of measurement of thermal resistance by testing laminated materials. In this case, new
original patented system of measurement was used to determine static and dynamic thermal properties of fabric surfaces,
composition and clothes. As we mentioned before, this patented system of measurement was developed, installed and
calibrated in Laboratory for process parameters in Department of clothing technology Faculty of Textile technology of
the University of Zagreb. Its fundamental feature is technically complete connectivity, so as originality and accuracy and
compatibility of tested parameters.
Key words: laminated materials, thermal properties, hot plate
1. LAMINATED MATERIALS
Laminates are multilayered constructions that can be completely made from textile fabrics or, on the other hand in
combination with non-textile layers. During the manufacture of protective clothing from this materials we should respect
functionality of design that should suit requirements of wearing, usage and comfort. Protective clothing made from twolayer and three-layer laminated textile fabrics, mostly waterproof and windproof on the outside but in the same time vapor
for sweat and creates an atmosphere of warmth in humid and windy weather. When it comes to two-layer laminates, one
(top) layer is mostly a waterproof fabric and down layer is membrane. In three-layer laminate fabrics membrane is
between two outer layers. Membrane has a function not to leak rain, snow, humidity and wind through inside layers of a
garment, but in the same time to insure the high leak of water heat from the inside of garment to the outside. By this water
heat (sweat) is leaving without disturb with favorable microclimate and 2.5 times bigger ability to preserve the body
temperature.
Nowdays the wide range of clothing with functional membranes can be found, and among them there are different types
of the fiber composition of, work mechanisms, and quality, for example: Gore-tex, Sympatex, Windstopper, Polartec etc.
[1]. One of the most significant membranes is Gore-tex membrane. It is a hydrophobic membrane based on
polytetrafluoroethylene. Its pores are 20.000 times smaller than a rain drop, but in the same time 700 times bigger than a
molecule of water heat. This exceptional properties result high-quality characteristics of clothing made from Gore-tex
laminates, Fig. 1 [2].
Figure 1 Gore-tex membrana
To ensure the water tightness of clothing made of laminated material it is necessary to combine ultrasound method and
thermal methods that use conduction and convection effect, while stitching seams, so as to apply electromagnetic fields
of high frequency [3].
2. MEASURING SYSTEM FOR DETERMINATION OF STATIC AND DYNAMIC THERMAL PROPERTIES
OF COMPOSITE AND CLOTHING
Measuring System for Determination of Static and Dynamic Thermal Properties of Composite and Clothing enabled the
process of measuring and calculating the thermal properties of composites or clothing to repeat automatically in a same
way with a certain number of repetitions and in defined time interval.
The measuring system consists of a hot plate for testing thermal properties of fabric surfaces, thermal mannequin for
testing thermal properties of clothing and corresponding software [4, 5]. Hot plate, Fig. 2 and thermal mannequin are
placed in air chamber where the parameters of ambient air are set up and also to achieve standard values of test. The
measurements of thermal properties of the composite values and the clothes can be performed, as opposed to other systems
in the same environmental conditions according to ISO 15831. To determine the thermal properties of composites and
clothing, air temperature is set to a certain temperature and specific humidity. Speed of air produced by the ventilation
system of the air chamber can be adjusted in a range 0-1 ± 0, 05 m/s [6]. A temperature controller based on the data of
temperature sensors must maintain a temperature of measurement surface (ts) within the limits ± 0, 1 oC. The electrical
power required for maintaining the temperature of the measuring surface where the measuring sample is situated (H), is
led to measuring system and it is measured within ± 1 % of the total range. In the study of the measurement results
obtained by measuring the thermal resistance with the device described in this paper we can notice that results constantly
depend on work of measuring equipment and good reproducibility.
In figure 2 you can see the hot plate developed on the Faculty of Textile technology of the University of Zagreb.
Measurement surface is visible at the top of the image, and under the ac power supply for microheater, digital interfaces
and other electronic components of system LabVIEW tt. National Instruments.
The measuring equipment consists of a measuring system and system for temperature regulation of measuring surface of
the device based on the regulation of electrical power PWM technique.
Figure 2 Hot plate for determining thermal properties of composites
Figure 3 Constituent elements of hot plate: interior with point heaters, temperature sensors and microprocessor system
The unit of measurement is a rectangular aluminum plate with a thickness of 10 mm connected to the metal block with
the heating elements, figure 3. The surface where the measurements are run (0.4 × 0.6 m) is surrounded by a protective
isolation, which prevents lateral outflow of heat from the edges of the sample. Heaters for measurement equipment, placed
below the testing surface bring warmth to measuring surface and also prevent the loss of heat on the bottom testing
surface. This rank conducts heat up only along the direction of the thickness of the sample [7]. By using hot plates thermal
insulation properties of composites are determined, that is the influence of different combinations of high-tech materials
for making clothes, impact of layered materials and conventional thermal inserts and expanding thermal inserts on the
thermal properties of clothing, already while technically designing the garments with wanted thermal properties. Figure
2 shows the interior of a prototype hot plate with point heaters, temperature sensors and a microprocessor system for
measurement and temperature regulation so as for measurement and calculation of the radiated heat. Textile creation of
size bigger than 0.4 × 0.6 m is placed on the surface of a rectangular plate which is usually heated to a constant temperature
corresponding to the temperature of the human skin (34 ° C).
It should be noted that the measuring apparatus is constructed so that the measuring board can set any temperature that
heaters, whose overall power they lead to the measuring surface is to 280 W, can provide.
Temperature of plate is measured by a digital sensor of a third generation inserted directly under the plate surface.
Elements of sensor measure temperature changes, that are achieved by heating the 32 non-inductance microheaters located
in two fields (left and right) uniformly spaced below the heated surface to ensure a uniform distribution of heat and the
temperature of whole plate. Each field of measuring plate manages a separate microcontroller system so that by work of
measuring plate constant temperature is maintained by adjusting the input electric power with modulation (PWM)
managed by two microcontrollers connected with measurement protocol via digital interface with a PC.
3. RESULTS OF MEASUREMENTS AND DISCUSSION
For the purposes of this study are tested four laminated materials produced of 100% polyester while the membrane of
polyurethane (LM-1 and LM-4) , polyester (LM-2) and polytetrafluoroethylene (LM-3). For all the tested laminated
materials were performed laboratory testing of relevant physical and chemical characteristics. Laboratory analysis of
embedded materials are made in institutions Cis Institut doo, Belgrade, (Accreditation ATS 01-057 , ISO / IEC 17025 :
2006) and Jugoinspekt Belgrade A.D. (Accreditation ATS 01-116 , ISO / IEC 17025 : 2006). Tab 1 shows the technical
characteristics of the tested laminated materials [8].
Tab. 1 An overview of the analyzed technical characteristics of laminated materials
The elements of test
The fiber composition
Surface weight
Water vapor permeability
air permeability
•
middle value
• the face on the reverse side
• to reverse the face
Resistance to the effects of water
The density of thread
• base
• weft
intertwining
The fiber composition membrane
Measuring
unit
%
g m-²
g m-2 24h-1
LM-1
LM-2
LM-3
LM-4
PES
168,9
3135,7
PES
163,9
4884,5
PES
PES
126,8
4567,9
164,4
4430,2
m³m-²min-1
m³m-²min-1
m³m-²min-1
cmH2O
0,036
0,007
0,064
1245
0,032
0,007
0,057
964
0,036
0,026
0,045
1130
0,034
0
0,068
-
thread/10 cm
thread/10 cm
380
280
380
280
420
380
100 %
twill weave
PU
twill weave
PES
ripstop
PTFE
360
260
canvas
weave
PU
Measurement of thermal resistance of laminated materials was carried out in a completely new , original and patented
metrology system installed and moderated in the Laboratory for process parameters of Office for clothing technology of
Faculty of Textile technology in accordance with ISO 15831 [ 6 ]. The hot plate is part of a measuring system for
measuring thermal properties of composites and clothing described in the chapter 2. Tab. 2 shows the results of measuring
the thermal resistance of four laminated materials. By studying the thermal resistance of laminated materials , first was
calculated the total thermal resistance of the blank surface of the hot plate together with boundary layer of air next to the
surface which amounted to 0.098547 m²KW-¹ and then the measured data on electrical power in W needed to maintain
the temperature of measurement surface, where is situated the measuring sample, and the complete thermal resistance of
sample of laminated material in m²KW-¹ and Clo units (1 Clo=0,155 m² K W -¹), Tab. 2. Measurements of thermal
resistance were carried out at a temperature of ambient air 20 °C, the surface temperature of hot plates was 34 ° C , the
air velocity of 0.4 m s -1 and relative humidity of 30% [8].
Tab. 2 Thermal resistance of samples laminated materials
Conditions in which the measurement is performed:
• The temperature of the hot plate, T hp = 34 °C
• Ambient temperature, Te = 20 °C
• Air velocity, v = 0.4 m s-1
• Relative humidity, RH = 30%
• The total thermal resistance of the blank surface hot plate together with boundary layer of air next to the
surface, Rct0 = 0.098547 m ² K W-¹
Power,
The total thermal resistance of samples laminated
P
materials,
Laminated materials
Rctn
[W]
[m² KW-1]
[Clo]
LM-1
43,00
-0,0193
-0,12
LM-2
30,35
-0,0291
-0,19
LM-3
39,71
-0,0138
-0,09
LM-4
39,16
-0,0125
-0,08
For measuring samples of laminated materials are tested technical parameters. The four types of laminated material are
made of 100 % PES material. Type of laminating film divides the laminating fabrics in two groups depending on the
mode of steam leak based on hydrophilicity (three samples : LM1 , LM2 and LM4) and on the basis of hydrophobicity
(sample: LM3). Quality membranes give adequate results in terms of water vapor, which is of great importance for the
group of laminates that are studied. Results of steam leak were moving in the interval 3135-4885 g m-2 24h-1 indicating
that embedded materials in clothing systems ensure efficient exchange of sweat with the environment. The mean value
of air permeability ranged from 0,032 to 0,036 m³ m 2 min-1, which is a low value ;this indicates that there will be no
exchange of air with the environment, nor the exchange of air between the layers. The third very important feature of the
assessment is the parameter of water resistance whose value ranged from 964 to 1245 cm H2O column. Water vapor
permeable laminated material is resistant to action of atmosphere water and wind so that presents good modern material
for making the outer shell of the heating system protection and intelligent clothing. For all four measurement samples of
laminated materials LM-1 , LM-2 , LM-3 and LM-4 is a characteristic that the reduction of electric power is not found
while establishing thermodynamic equilibrium of power needed to maintain a constant surface temperature of hot plate
and radiated heat into the environment through measured material. On the contrary, the necessary electric power was
increased to maintain the thermodynamic equilibrium, and the calculation showed a negative transfer of heat resistance,
indicating that the measured material has no insulating properties but takes on the properties of heat conductivity. The
observed apparent anomaly can be explained by the fact that he polymer of membrane’s film is a few tenths and
hundredths thick and has no properties of heat insulator , but takes the attributes of a relative good thermal conductor.
Therefore, despite the fact that the membrane prevents passage of heated air through the clothes, the trapped air will be
cooled by heat transfer by conduction through the membrane, which is not considered as an insulator. In addition, the
upper side of the laminate has a different spatially distributed fibers, which have larger area. This area can transfer more
heat to the external a medium, it is because the surface that’s giving off heat increased/expanded, so the increase of energy
automatically increases. This two reasons explain how to increase the power while establishing thermodynamic
equilibrium during the measurement of thermal resistance and negative values of insulation. The influence of the
membrane to the thermal resistance is less significant (almost negligible), but it is very important for the system of a
garment when it comes to waterproof, vapor permeability and airtightness.
4. CONCLUSION
This research revealed that the quality of the membrane gives adequate results in terms of water vapor, which is of great
importance for the studied group of laminates. The results indicate that tested laminated materials, embedded in clothing
systems, ensure efficient exchange of sweat with the environment, so that are resistant to the impact of atmosphere water
and wind. It is also sure that they represent a good modern material for making the outer shell of a heating system of
protective and intelligent clothing. This noticed anomaly of increased electrical power required to maintain
thermodynamic equilibrium and negative resistance to the heat transfer can be explained by the fact that the membrane
hasn’t got properties of heat insulator but takes the attributes of relative good heat conductor. We can conclude that the
purpose of studied laminated materials is more for stability of clothing systems from the effect of wind and rain, but as
insulator.
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