Rheological characterization of styrene acrylonitrile copolymers

The relationship between copolymer composition, molecular weight distributi on, and rheological properties of random styrene acrylonitrile copolymers s ynthesized by radical polymerization in bulk was investigated. From differe ntial scanning calorimetry analysis, glass transition temperature was obtai ned and increases with the acrylonitrile content. The knowledge of the glas s transition is a key factor to compare the different copolymers in an iso- free volume condition for melt rheology. Owing to time temperature superpos ition, a large frequencies window ranging from the terminal zone until the glassy plateau can be obtained. Thus, the mechanical spectroscopy was used to estimate the rubbery plateau modulus and the Newtonian viscosity. (C) 20 00 John Wiley & Sons, Inc.