The effect of alkalization and fibre alignment on the mechanical and thermal properties of kenaf and hemp
bast fibre composites: Part 1 – polyester resin matrix
Sharifah H. Aziz and Martin P. AnsellCorresponding Author Contact Information, E-mail The Corresponding Author
Department of Engineering and Applied Science, University of Bath, Bath BA2 7AY, UK
Abstract
Long and random hemp and kenaf fibres were used in the as-received condition and alkalized with a 0.06 M
NaOH solution. They were combined with polyester resin and hot-pressed to form natural fibre composites.
The mechanical properties of the composites were measured to observe the effect of fibre alignment and
alkalization. A general trend was observed whereby alkalized and long fibre composites gave higher flexural
modulus and flexural strength compared with composites made from as-received fibres. Alkalized long kenaf–
polyester composites possessed superior mechanical properties to alkalized long hemp–polyester composites.
For the hemp–polyester composites a high flexural modulus and a high flexural strength are associated with a
low work of fracture. Scanning electron microscopy micrographs of the treated hemp and kenaf fibres showed
the absence of surface impurities which were present on the untreated fibres. Apparent density measurements
on hemp and kenaf fibres did not show a significant change after alkalization with 0.06 M NaOH. Wide
endothermic peaks present in differential thermal analysis thermograms for all of the composites indicated the
presence of moisture which leads to inferior mechanical properties. Dynamic mechanical thermal analysis
carried out on the polyester matrix composites showed that the alkalized fibre composites have higher E′
values corresponding to higher flexural moduli. Any correlation between fibre surface treatment and the work
of fracture and tanδ of composites is less clear.
Author Keywords: A. Polymer matrix composites; B. Mechanical properties; B. Thermal properties; Dynamic
mechanical analysis; D. Scanning electron microscopy
Composites Science and Technology
Volume 64, Issue 9, July 2004, Pages 1219-1230
Injection Molding of Postconsumer Wood–Plastic Composites II: Mechanical Properties
R. Gosselin
Department of Chemical Engineering, CERSIM Université Laval, Quebec City, Canada, G1K 7P4
D. Rodrigue
Department of Chemical Engineering, CERSIM Université Laval, Quebec City, Canada, G1K 7P4Denis.Rodrigue@gch.ulaval.ca
B. Riedl
Department of Wood Sciences, CERSIM, Université Laval Quebec City, Canada, G1K 7P4
ABSTRACT: In the first part of this study, fiber-reinforced microcellular foams were produced via injection
molding to study their morphological properties as a function of mold temperature as well as wood, blowing
agent, and coupling agent concentrations. Yellow birch wood fibers are added to a recycled postconsumer
HDPE/PP matrix (85: 15 ratio) in proportions ranging from 0 to 40 wt% and then foamed with a chemical
blowing agent. Maleic-anhydride-polypropylene copolymer (MAPP) is also used as a coupling agent in
proportions ranging from 0 to 10 wt% of wood content. In this second part, the mechanical properties in
flexion, torsion, and traction are presented.
Key Words: injection molding , composite, foam , mechanical properties , MAPP
Journal of Thermoplastic Composite Materials, Vol. 19, No. 6, 659-669 (2006)
Characterisation of melt-processed poly(ethylene terephthalate)/synthetic mica nanocomposite sheet and
its biaxial deformation behaviour
Soon, Kok H; Harkin-Jones, Eileen; Rajeev, Rajvihar S; Menary, Gary; McNally, Tony; Martin, Peter J; Armstrong, Cecil
Abstract
BACKGROUND: Poly(ethylene terephthalate) (PET) is widely used in the packaging industry. In order to enhance
the mechanical and barrier properties, nanoscale fillers are added to PET matrices to form nanocomposites. In
the work reported here, a melt-processed PET/synthetic mica nanocomposite sheet was characterised to
determine the effect of the incorporation of synthetic mica on the sheet properties and also to see if these
properties are an indicator of subsequent performance under high-speed, high-temperature biaxial
deformation, typical of processes such as stretch blow moulding.
RESULTS: The incorporation of synthetic mica was found to enhance the modulus, particularly above the glass
transition temperature, and barrier properties of the extruded sheet and it significantly altered the
deformation behaviour of PET under biaxial deformation. The plastic flow of PET during biaxial deformation
was found to diminish for the nanocomposites, and strain hardening occurred earlier.
CONCLUSION: The modulus and barrier properties of PET were enhanced by the incorporation of synthetic
mica. Clay loading also altered the biaxial deformation behaviour of PET. Copyright © 2009 Society of Chemical
Industry
Keywords: PET nanocomposites; mechanical properties; biaxial stretching; barrier properties
Polymer International, Volume 58, Number 10, October 2009 , pp. 1134-1141(8)
The effect of fibre and coupling agent content on the mechanical properties of hemp/polypropylene
composites
Mechraoui, A.1; Riedl, B.2; Rodrigue, D.1
Abstract
Composites made from hemp and polypropylene were prepared in order to determine the effect of fibre and
coupling agent content on their mechanical properties. The samples were prepared by compression molding
after an initial melt blending and homogenization step in an internal batch mixer. Different fibre contents (0,
10, 20 and 30 wt%) and sizes (355 and 500 μm) were used with two coupling agents: maleic anhydride
polypropylene (MAPP) pellets and wax. For each case, MAPP concentrations between 0 and 7 wt% (fibre basis)
were added to determine the optimum amount maximizing mechanical properties. The fractured surfaces of
these composites were investigated by scanning electron microscopic technique (SEM) to investigate the
fibre/matrix interfacial bonding. The mechanical properties of the composites were characterized in tensile,
torsion, and flexion and the results showed that coupling agent addition has a positive effect on all moduli with
an optimum content ranging between 2 and 4 wt%. It was also found that the coupling agent wax was more
effective that the pellets.
Keywords: POLYPROPYLENE; HEMP; MAPP; MECHANICAL PROPERTIES
Composite Interfaces, Volume 14, Numbers 7-9, 2007 , pp. 837-848(12)
The effect of basecoat pigmentation on mechanical properties of an automotive basecoat/clearcoat system
during weathering
H. Yaria, S. Moradiana, Corresponding Author Contact Information, E-mail The Corresponding Author, B. Ramazanzadea, A. Kashania and N. Tahmasebib
aPolymer and Color Engineering Department, Amirkabir University of Technology, PO Box 15875-4413, Tehran, Iran
bColor Engineering group, Azad University of Mahshahr, Postal Code 63519, Bander-e-Mahshahr, Khoozestan, Iran
Abstract
The aim of this study is to elucidate the effect of basecoat pigmentation on mechanical aspects of an
automotive basecoat/clearcoat (BC/CC) system during artificial weathering exposures. A silver basecoat as the
most reflective and a black basecoat as the most absorptive basecoat were selected. These two extreme
behaviored basecoats were chosen with hopes that other basecoats would behave somewhere between the
silver and the black extremes. The structural and mechanical properties of the coatings were investigated after
various weathering exposure times (0, 150, 300, 450, 600 h). Dynamic mechanical thermal analysis (DMTA) was
carried out to study variations in structure and basic characteristics of the system such as cross-linking density
and Tg during weathering. In order to investigate variations in mechanical properties of the system, nano
indentation, nano scratch, and tensile tests were also utilized.
It was found that although both silver and black systems experienced post-curing reactions (dominant at earlier
stages of weathering) and degradation reactions (dominant at later stages of weathering), but basecoat
pigmentation affected the post-curing and degradation reaction rates of the BC/CC system, leading to
variations in mechanical properties. It was concluded that post-curing occurred to a greater extent in the black
pigmented system whilst in the silver pigmented system weathering degradation was much more sever.
Keywords: Weathering; Mechanical properties; Automotive coating; Nano-indentation
Polymer Degradation and Stability
Volume 94, Issue 8, August 2009, Pages 1281-1289