Improvement of microstructures and properties of poly(lactic acid)/poly(ε-caprolactone) blends compatibilized with polyoxymethylene

Incompatibility of poly(lactic acid)/poly(-caprolactone) (PLA/PCL) (80:20) and (70:30) blends were modified by incorporation of a small amount of polyoxymethylene (POM) (<= 3 phr). Impact of POM on microstructures and tensile property of the blends were investigated. It is found that the introduction of POM into the PLA/PCL blends significantly improves their tensile property. With increasing POM loading from zero to 3 phr, elongation at break increases from 93.2% for the PLA/PCL (70:30) sample to 334.8% for the PLA/PCL/POM (70:30:3) sample. A size reduction in PCL domains and reinforcement in interfacial adhesion with increasing POM loading are confirmed by SEM observations. The compatibilization effect of POM on PLA/PCL blends can be attributed to hydrogen bonding between methylene groups of POM and carbonyl groups of PLA and PCL. In addition, nonisothermal and isothermal crystallization behaviors of PLA/PCL/POM (70:30:x) samples were investigated by using differential scanning calorimetry and wide angle X-ray diffraction measurements. The results indicate that the crystallization dynamic of PLA matrix increases with POM loadings. It can be attributed to the fact that POM crystals have a nucleating effect on PLA. While crystallization temperature is 100 degrees C, crystallization half-time can reduce from 9.4 to 2.0 min with increasing POM loading from zero to 3 phr. (C) 2018 Wiley Periodicals, Inc.