Compatibilization by homopolymer: significant improvements in the modulus and tensile strength of PPC/PMMA blends by the addition of a small amount of PVAc.

Poly(propylene carbonate) (PPC), a polymer produced from CO2, has been melt-mixed with 30 wt % poly(methyl methacrylate) (PMMA) with the aim of enhancing the physical properties of PPC for practical use but keeping a relatively high CO2 fixing rate in the compound. The observation of a coarse phase structure with a large PMMA domain size and a large size distribution in the blend indicates the immiscibility between PPC and PMMA. The addition of a small amount of poly(vinyl acetate) (PVAc) not only shifts the glass transition temperatures (T(g)'s) of both PPC and PMMA markedly but also significantly increases the modulus and tensile strength of the blend. The prepared compound with 5 per hundred parts of resin PVAc shows a 26 times higher elastic modulus and an approximately 3.8 times higher tensile strength than pure PPC at room temperature. The morphological investigation indicates that the incorporation to PVAC not only induces the finer dispersion of PMMA in the PPC matrix but also results in the phase transformation from a sea-island to a co-continuous structure.