Innovative utilization of starch in biodegradable and antimicrobial materials
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Date
2014
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University of New Brunswick
Abstract
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.