The research on natural fibres polymer composites are rapidly growing due to
an increasing demand on environmentally friendly polymer products with reasonable
price. The on-going efforts are focused on the improvement in overall properties of
these composites. In this research work, linear low-density polyethylene
(LLDPE)/poly (vinyl alcohol) (PVOH) blend were utilized as polymer matrices with
a fixed composition at 60/40 (wt. %), whereas kenaf bast fiber (KNF) was used as
filler. The effect of filler loading, as well as various chemical treatments on the
natural filler towards the processing characteristic, tensile, structural, morphological,
thermal and biodegradability properties of LLDPE/PVOH/KNF composites were
explored. LLDPE/PVOH/KNF composites containing different KNF loadings (i.e. 0,
10, 20, 30 and 40 phr) were prepared by means of melt-mixing and compression
moulding. It was found that with increasing KNF loading, the processing torque,
tensile modulus, thermal stability and water absorption of composites were
increased. Nevertheless, tensile strength and elongation at break of composites were
found declined. This indicated weak interfacial adhesion between LLDPE/PVOH
matrices and KNF, as revealed by SEM studies. Natural weathering and soil burial
has affected the properties of LLDPE/PVOH/KNF composites, as displayed by the
deterioration in tensile properties, damage of exposed surfaces, and higher
percentage of weight loss. Results from FTIR spectra further confirmed the
occurrence of degradation with appearance of intense carbonyl peaks. The existence
of chemical treatments of KNF has enhanced the tensile, morphological and thermal
properties, as well as reduced the water absorption of LLDPE/PVOH/KNF
composites. The chemical treatment of KNF was further confirmed by FTIR
spectroscopy. Based on the results, it was found that addition of 3-
(trimethoxysilyl)propyl methacrylate (TMS) treated KNF into LLDPE/PVOH
matrices has increased the processing torque, tensile strength, tensile modulus,
thermal stability and reduced the water absorption of the composites. This was
evidenced by the enhanced interfacial adhesion between TMS-treated KNF and
LLDPE/PVOH matrices in SEM analysis. Addition of treated KNF with eco-friendy
coupling agent (EFCA), chromium (III) sulfate and lysine into LLDPE/PVOH
matrices were found respectively increased the processing torque, tensile properties,
thermal stability and reduced the water absorption of composites. Results from SEM
analysis revealed an improvement in the interfacial adhesion between treated KNF
and LLDPE/PVOH matrices. FTIR results also confirmed that chemical bonds were
formed between coupling agents and KNF, subsequently provide linkages between
KNF and LLDPE/PVOH matrices