Innovative utilization of starch in biodegradable and antimicrobial materials
University of New Brunswick
As one of the most abundant naturally occurring polysaccharides in the world, starch and its derivatives have been extensively used in various applications, such as food and pharmaceutical industries. The current thesis work mainly focuses on the utilization of starch in the preparation of starch/biodegradable polyester blends and as antimicrobial agent carrier in the antimicrobial packaging materials. In the first part of the study, starch was melt blended with the biodegradable polyester, poly(butylene adipate-co-terephthalate) (PBA T) for the preparation of a low cost biodegradable composite material. In order to improve the mechanical properties of the composites, starch and PBA T were compounded in the presence of compatibilizers and modified PBA T. The tensile strength, elongation at break and starch dispersion of the resulting composites were enhanced compared to the original PBAT/starch blends. In the second part of the study, a non-leaching antimicrobial film based on linear low density polyethylene (LLDPE) as packaging material was prepared using starch as the antimicrobial agent carrier. The antimicrobial activity and the non-leaching effect of the resultant films were assessed and confirmed through shaking flask test and ring diffusion test, respectively. In the third section, a non-leaching antimicrobial biodegradable PBA T packaging material in the presence of antimicrobial thermoplastic starch (ATPS) and coupling agent were prepared. The results from antimicrobial test suggested that the prepared film was able to deactivate E. Coli within a short time at a relatively low dosage. The water washing and ring diffusion tests further demonstrated the non-leaching effect of the antimicrobial agent. In the fourth part of this dissertation, the biodegradation behavior and antimicrobial property of the novel antimicrobial PBA T films before and after a three-month soil burial test was investigated. The weight retention data indicated that both PBA T and starch were still able to degrade in the presence of antimicrobial agent, yet the biodegradation rate was retarded. The film samples containing coupling agent presented growth inhibition against E.Coli over 99% after the three-month biodegradation test due to better PHGH retention.