Abstract:
Wood plastic composites (WPCs) have been popular day by day in Bangladesh
as well as in the whole world and have characteristics similar or close to
commercial wood. In this research work, different types of soft wood reinforced
polypropylene (PP) composites were prepared by injection moulding technique.
To prepared improved sawdust-PP composites by chemical treatment, an
innovative, clean, cheap and effective yet simple technology with different
procedures was introduced in this work to demonstrate the suitability of wood
plastic composites’ techniques for developing countries. The effects of
treatments on the physico-mechanical properties of composites were studied.
Untreated raw sawdust was modified by sodium hydroxide and the effect of
alkali treated sawdust reinforced PP composites was studied comparing with the
raw sawdust-PP composites. FT-IR spectroscopic analyses were done for
chemical treatment and results showed the evidence of positive reactions. The
effects of fiber content on the physico-mechanical properties of composites were
studied by preparing the composites with different percentage of fiber loading
(from 20 wt.% to 35 wt.%) for each type of composites. Mechanical properties;
tensile strength, tensile modulus, elongation at break, flexural strength, flexural
modulus and hardness were measured for both alkali treated sawdust-PP
composites and raw sawdust-PP composites. Improved mechanical properties
were obtained for most of the treated sawdust-PP composites over untreated
raw sawdust-PP composites.
Thermal analysis was done with the fractured part of the composite specimens
and increased thermal stability was found for alkali treated sawdust-PP
composites compared to that of raw sawdust-PP composites.
Scanning Electron Microscopy (SEM) and water absorption test were done to
study the physical properties of both types of composites. SEM was taken to
investigate the interfacial adhesion and bonding between the sawdust and PP
matrix from various chemical treatments. Improved interfacial interactions were
found for treated composites than untreated composites.
Water absorption tests were carried out of all composites to investigate the
effect of chemical treatment on the moisture absorption characteristics of
hydrophilic sawdust in sawdust-PP composites which has direct effect on the
dimensional stability of the composites. Reduced water absorption was found for
alkali treated sawdust-PP composites. All the findings are reported in details in
this thesis.
