Thermal, Rheological and Mechanical Properties of Biodegradable Poly(propylene carbonate)/Epoxidized Soybean Oil Blends

Biodegradable poly(propylene carbonate) (PPC)/epoxidized soybean oil (ESO) blends with different component ratios were prepared by melt blending to improve the performance of PPC. The phase morphology, thermal properties, rheological properties and mechanical properties of the blends were investigated in detail. SEM examination revealed good interfacial adhesion between PPC matrix and ESO. According to DSC and DMA, as the content of ESO increased, the glass transition temperature of the PPC component increased, indicating that there was a strong interfacial interaction between the PPC matrix and ESO. The interfacial interaction may be caused by ring-opening reaction between the hydroxyl end groups of PPC and the epoxy groups of ESO, which restricted the chain movement of PPC matrix. The disappearance of the epoxy groups in FTIR indicated that the interfacial interaction between the two phases was due to the ring-opening reaction between PPC and ESO. With the addition of ESO, the thermal stabilities were enhanced. With the increasing ESO content, the modulus gradually decreased. However, the strength at yield, the strength at break and the elongation at break were increased for the PPC/ESO blends, suggesting that the enhancement of the strength and toughness of PPC was achieved by the incorporation of ESO. The rheological measurement revealed that the complex viscosity, storage modulus and loss modulus of PPC were increased with the increasing ESO content at low frequency, which indicated that the addition of ESO enhanced the melt strength of PPC instead of plasticizing PPC.