The study of water transport in polylactide and polylactide derivatives

Abstract

Bio-based polymers have numerous potential advantages over traditional polymers. Polylactide (PLA) is a biodegradable and environmentally friendly polyester that is made from renewable sources. However, the moisture barrier properties in PLA are still poorly understood. That is one of the major problems preventing PLA from being competitive with petroleum-based polymers in food packaging applications.The objective of this research is to study water transport properties in PLA with the final goal to improve its moisture barrier properties. This dissertation reported water sorption and permeation in commercial and modified polylactide (PLA) with detailed mechanisms and characterization studies. Modified PLA or PLA’s derivatives were prepared by varying aliphatic content with different end groups, copolymerization, and polymer blending with composite particles. Water sorption in PLA was studied via the quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) technique. Theoretical models were applied to compare with experimental results. Water barrier properties in PLA are improved by varying aliphatic content with different hydrophobic end groups and fabricating nanocomposites but not by graft copolymerization with rubbery backbone materials. This dissertation significantly contributes to a complete understanding of different factors that can affect moisture transport properties in PLA, which provides a guideline in designing a material with optimal barrier properties by applying a certain combination of factors.%%%%Ph.D., Chemical Engineering – Drexel University, 2012