The melt elasticity of polymer blends: Polystyrene/poly(methyl methacrylate)

Abstract

Samples of general-purpose polystyrene and poly(methyl methacrylate) were melt blended in a special mixer–extruder over the complete range of compositions from 100% polystyrene to 100% poly(methyl methacrylate). The blends were characterized for their melt rheological characteristics in a melt elasticity tester which measured their stress–strain behavior and strain recovery characteristics as a function of time. In addition, the blends were processed through a laboratory fiber spinning apparatus wherein the spinline tension was measured. Large maxima in the amount of recoverable strain, in the time for the strain recovery to finish, and in the melt tension were observed at a weight percent composition of 40% polystyrene and 60% poly(methyl methacrylate). The melt stress-strain curves showed double yield points at certain compositions. The results are discussed in terms of a model consisting of two interpenetrating continuous phases.