Processability, property, and morphology of biodegradable blends of poly(propylene carbonate) and poly(ethylene-co-vinyl alcohol)

Biodegradable blends of poly(propylene carbonate) (PPC) and poly(ethylene-co-vinyl alcohol) (EVOH) were melt compounded in a batch mixer followed by compression molding. The processability, mechanical properties, thermal behavior, and morphologies of the blends were investigated with torque rheometer, Fourier transform infrared spectroscopy, tensile tests, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Torque rheometry indicated good interfacial miscibility between PPC and EVOH phases, and then fourier transform infrared spectroscopy spectra demonstrated that a certain extent of hydrogen-bonding interactions between PPC and EVOH matrix in the blends. A study of the mechanical properties and thermal behavior showed that the EVOH incorporation can significantly enhance the tensile strength, thermal stability, and crystallinity of the blends. Moreover, dynamic mechanical analysis and differential scanning calorimetry both revealed that PPC and EVOH were compatible to some extent. Further, scanning electron microscopic examination also revealed the good interfacial adhesion between EVOH and PPC phases.