Composites of poly(propylene carbonate) (PPC) reinforced with micrometric and nanometric calcium carbonate particles were prepared via melt mixing followed by compression molding. The morphology and mechanical and thermal behaviors of the composites were investigated. Static tensile tests showed that the tensile strength, stiffness, and ductility of the composites tended to increase with increasing contents of micrometric calcium carbonate particles. This improvement in the tensile properties was attributed to good interfacial adhesion between the fillers and matrix, as evidenced by scanning electron microscopy examination. However, because of the agglomeration of calcium carbonate nanoparticles during blending, those composites with nanoparticles exhibited the lowest tensile strength. Thermogravimetric measurements revealed that the incorporation of calcium carbonate into PPC resulted in a slight improvement in its thermooxidative stability.

ABSTRACT:Composites of unplasticized poly(vinyl chloride) (PVC) blended with bamboo flour and pine flour, respectively, were prepared in a batch mixer followed by compression molding. The effects of wood flour fillers on the morphology, static mechanical properties, and thermal properties of the composites were investigated. Compared with neat PVC resin, the introduction of both bamboo flour and pine flour significantly improved the stiffness of the composites, while decreasing the tensile strength to some extent. Tensile tests showed that pine flour-filled composites exhibited better mechanical properties than those filled with bamboo flour with the same particle size at the same loading level. Scanning electron microscopic examination revealed good dispersion and alignment tendency of short pine fiber within the composites at a lower loading level. Moreover, experimental results indicated that both bamboo flour and pine flour additions showed no obviously adverse effect on the thermal stabilities of these composites. Based on the comprehensive properties, these composites meet the need of woodlike material for use as wood structures.

Biodegradable composites of poly(propylene carbonate) (PPC) reinforced with unmodified cornstarch were compounded in a batch mixer followed by compression molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, as well as thermal properties of PPC/starch composites, were investigated. Tensile tests showed that incorporation of starch improves the stiffness and tensile strength of composites significantly. Scanning electron microscopic examination revealed the existence of good interfacial adhesion between the fillers and PPC matrix. Moreover, experimental results indicated that the starch addition leads to a significant improvement in the thermal stability of the composites. This paper demonstrates that the incorporation of low‐cost and biodegradable cornstarch into PPC provided a practical way to produce completely biodegradable and cost‐competitive composites with good mechanical properties. Polym. Eng. Sci. 44:2134–2140, 2004. © 2004 Society of Plastics Engineers.