DYNAMIC-MECHANICAL BEHAVIOR OF POLY(VINYL CHLORIDE) POLY(METHYL METHACRYLATE) POLYMER BLEND

A poly(vinyl chloride) (PVC)/poly(methyl methacrylate) (PMMA) (80/20 w /w) polymer blend was studied by mechanical spectroscopy. Two relaxati ons can be distinguished: in the glassy state, a very large secondary relaxation in the range of 100 K to 325 K which results from the combi nation of secondary relaxations of PVC and PMMA; and only one main rel axation at 364 K associated to the glass rubber transition. The relaxa tion spectrum in the range of the beta relaxation has been described b y a relaxation time distribution function based upon a Gaussian functi on and a series-parallel model. The alpha relaxation was studied by me ans of a theoretical approach for the nonelastic deformation of polyme rs. We found that the miscibility of this blend appears to be a functi on of the observation scale: the PVC/PMMA blend is heterogeneous at th e scale of molecular movements involved for the beta relaxation proces s but homogeneous at the scale of the chain segments responsible for t he alpha relaxation dynamics. (C) 1996 John Wiley & Sons, Inc.