The effect of novel reactive compatibilizer on mechanical properties and thermal stability of PLA/starch blend

Poly (lactic acid) (PLA) is a biodegradable polymer, but its applications are limited by its high cost. Blending granular corn starch with PLA reduces the cost, but usually the blends have poor strength. In this study, a 50/40 (w/w) mixture of PLA and dried corn starch with 10% PEG400 as plasticizer was blended thermally in a twin-screw extruder with dimeric TDI as reactive compatibilizer. Additionally pure PLA and PLA/starch blend without reactive compatibilizer were also prepared for comparison. Mechanical test, TG and Rheology test were performed to characterize the mechanical and thermal properties, and the results showed that blends with reactive compatibilizer had enhanced mechanical properties and thermal stability. According to FTIR and DMA test, the reason that enhanced properties of PLA/starch blend could be explained by the in situ formation of a block copolymer, which increased the adhesion between PLA and starch granule. In addition the -OH located on the plasticizer could also react with the compatibilizer, that arrest plasticizer move out from polymer matrix.