PHASE-BEHAVIOR AND PROPERTIES OF POLY(METHYL-METHACRYLATE) POLY(VINYL-ACETATE) BLENDS PREPARED VIA IN-SITU POLYMERIZATION

Polymer blends composed of poly(methyl methacrylate) (PMMA) and poly(v inyl acetate) (PVAc) were prepared via radical-initiated polymerizatio n of methyl methacrylate ( MMA) in the presence of PVAc, Differential scanning calorimetry and dynamic mechanical analysis were employed to investigate the miscibility and phase behavior of the blends. The PMMA /PVAc blends of in situ polymerization were found to be phase separate d and exhibited a two-phase structure, although some chain transferrin g reaction between the components occurred. The phase separation resul ted from the solvent effect of MMA during the in situ polymerization, which was confirmed by the investigation of phase behavior based on so lution cast blending. Solubility analysis of the polymerized blends in dicated that some chain transferring reaction between the components o ccurred during the polymerization. An abrupt increase in gel content f rom 21.2 to 72.4 wt % was observed when the inclusion of PVAc increase d from 30 to 40 wt %, and the gel component consisted of the component polymers as shown by infrared spectroscopy studies. The thermogravime tric analysis study indicated that the inclusion of a small amount of PVAc gives rise to a marked stabilization effect on the thermal stabil ity. The PMMA/PVAc blends exhibited increased notched impact propertie s with the inclusion of 5 wt % PVAc. (C) 1998 John Wiley & Sons, Inc.