Influence of PEG on Mechanical Properties and Biodegradability of Composites Based on PLA and Starch

Biodegradable composites based on polylactide (PLA) and starch are obtained via solid‐phase mixing under conditions of shear deformation. The mechanical properties and biodegradability of composites under action of mold fungi as well as during exposure in soil are investigated. Using the scanning electron microscopy, the comparative study of the morphology of the initial samples and samples after biodegradation is carried out and the formation of structural defects resulting in sample destruction followed by fragmentation is revealed. The influence of PEG on mechanical properties and biodegradation process of the composites is shown. The analysis of composites by FTIR spectroscopy allows the estimation of the change in the PLA crystallinity and morphology of the film composites during the biodegradation in soil. The appearance of starch on the surface of films after exposure in soil enables a mechanism of biodegradation to be proposed. Under shear deformation, biodegradeable binary composites of polyactide (PLA) with starch, as well as ternary composites with polyethylene glycol (PEG) are produced. The apparent differences in structure of the samples after exposure in soil and to the action of fungi are shown. The weight loss of ternary composite is 50%. The mechanisms of sample destruction after exposure in soil and to the action of fungi are discussed.