Effect of methylmethacrylate‐butadiene‐styrene modifier level on the viscoelastic beta process in poly(vinyl chloride)

Abstract

AbstractViscoelastic measurements were made on test specimens cut from plaques made from milled, compression molded blends of poly(vinyl chloride) (PVC) and methylmethacrylate‐butadiene‐styrene modifier (MBS). The experimental frequency range was from 0.0159 to 79.6 Hz. and the temperature range was from −140 to 20°C. The MBS modifier level studied was 8.26, 10.71, and 13.04 weight percent. This experimental range covers the beta relaxation process of PVC and the alpha relaxation process of the rubbery regions of the modifier. The complex compliance was represented in terms of a function originally proposed by Havriliak and Negami to represent the dielectric relaxation processes in polymers. The parameters of this expression as well as their dependence on temperature were determined by the multi‐response statistical techniques developed by Havriliak and Watts. Addition of MBS modifier to PVC appears to enhance the already present beta relaxation process in PVC. In addition the temperature dependence of the relaxation time has been increased so that the process is faster at room temperature. The α and β parameters of the relaxation function have changed so that the process is narrower at room temperature. There is no significant viscoelastic evidence supporting a second phase. This observation suggests significant impedance matching of the two phases which may be an important criteria for impact modification. Similarity of the two processes suggests a possible mechanism for the PVC beta process.