Mechanical, physical, thermal and biodegradability studies of low density polyethylenethermoplastic sago starch kenaf core flour biocomposites
Loading...
Date
2015-09-01
Authors
Norshahida Sarifuddi
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Environmental problems associated with the use of typical plastics or so called synthetic polymers have direct to the utilization of biodegradable polymer and natural fiber for producing a degradable composite. The efforts currently are underway in producing such composites with the use of thermoplastic sago starch (TPSS) and kenaf core fillers (KCF) in the low density polyethylene (LDPE). In this work, the effect of blend ratio, treatment of natural filler and hybridization with inorganic mineral fillers on the mechanical, physical, thermal and biodegradability properties of composites were studied. Firstly, the LDPE/TPSS/KCF composites containing 0-40 wt. % of TPSS and 0-40 phr KCF were prepared by using melt-blended mixing and compression molding method. The addition of 10 wt. % of TPSS as well as 10 phr KCF had resulted the highest tensile strength. Chemical similarity of TPSS and KCF formed hydrogen bonding as shown in IR spectra and such interaction indicated better interfacial adhesion detected by SEM morphology. As such, the addition of both TPSS and KCF showed an improvement in thermal and has boosted up the water absorption percentages due to their hydrophilic nature. The deteriorating impact of composites due to exposure to natural weathering can be seen with the collapse of overall tensile properties upon addition of TPSS and KCF. The IR spectra is further confirming the photo-degradation occurred with the appearance of carbonyl (C=O) peaks. Likewise, tensile properties, FTIR, SEM and weight loss
of soil burial samples also proved the degradation activities over a predetermined time. Next, the effects of graft copolymerization of methyl methacrylate (MMA) onto KCF as well as their loading on the composites were examined. Grafted KCF is found to be a promising reinforcement to augment the tensile strength, particularly at 10 phr loading and this is evidenced by the adhesion of matrices onto the filler surface in SEM morphology. This is further confirmed by FTIR results whereby grafted KCF formed ester carbonyl groups which are assumed to provide linkage between filler and matrix.Subsequently, the tensile properties of composites with grafted KCF are somehow slightly retained upon exposure to weathering. However, they are still susceptible to degradation due to the presence of monomer and it is verified by FTIR, SEM and weight loss. Lastly, the influences of inorganic mineral filler (halloysite clay) incorporation into the composites at various loadings (3-15 phr) were evaluated. Addition of filler raised the tensile strength up to 12 phr loading. When the filler is loaded beyond 12 phr, the strength tended to decline. Correspondingly, the composites became thermally stable upon inclusion of this silicate fillers. Upon weathering, composite samples with halloysite results a progressive decay in tensile properties compared to the control samples. Similar tendency was obtained from soil burial samples. The severity of deterioration upon degradation was confirmed by the formation of the larger pores and cracks as well as greater weight loss.