Influence of temperature dependence on the structural characteristics of polyoxymethylene/poly(lactic acid) blends by injection molding

Abstract

Abstract In this research, different strategies to modify the structure of polymer blends were investigated with the objective of adjusting the composition of polyoxymethylene (POM) and poly(lactic acid) (PLA) under typical processing conditions. POM shows a good balance of mechanical and thermal properties. However, this polymer is obtained from petrochemical sources, and in some markets, environmentally friendly materials are important. Blending POM with PLA preserves the advantages of POM while ensuring the bio-based content of PLA. POM/PLA blends were prepared by an injection molding process with various injection speeds of 10, 50, 100, and 1000 mm/s to ensure high ductility. Mechanical property analysis showed that the PLA content and processing temperatures are highly effective in modifying the stiffness of POM/PLA blends. The effect of crystallization on POM/PLA blends was assessed by varying the annealing time. High-magnification scanning electron microscopy images revealed that the gaps between fibrillar regions represent the growth direction of the PLA phase before it was removed. This was evidence for the effect of PLA on the crystallization of POM. The crystal size and crystalline volume also affected the structural characteristics of POM/PLA blends.