Rheological and mechanical properties of poly(alpha-methylstyrene-co-acrylonitrile)/poly(methyl methacrylate) blends in miscible and phase separated regimes of various morphologies - I. Characterization of constituents, blend preparation, and overvie

摘要

For a collaborative blend study the components P alpha MSAN (M-w = 82 000, 30% acrylonitrile) and PMMA (M-w = 88 000, 5% methylacrylate) were selected to have a similar melt viscosity and elasticity at 210 degrees C. Their dynamic moduli are identical in the investigated frequency domain except for a constant factor of 0.61 in the relaxation times. Only a small difference of the WLF temperature shift factors is found between 150 and 230 degrees C. The P alpha MSAN/PMMA blends show LCST behaviour. Transparent samples were prepared by melt mixing and subsequent squeezing at temperatures less than or equal to 160 degrees C. Annealing yields phase separated specimens with various morphologies. This enables to study the influence of phase structure on rheological and mechanical properties for a constant composition. The P alpha MSAN rich samples have higher cloud point temperatures than their PMMA rich counterparts. RuO4-stained ultrathin sections of optically transparent blends containing 40% P alpha MSAN show a distinct microheterogeneity due to approximate to 10 nm PMMA rich spheres. 65 hours annealing at 150 degrees C yields 0.1 mu m spheres whereas a co-continuous structure is found after 22 h at 170 degrees C. Temperatures greater than or equal to 200 degrees C initiate rapid phase separation with a co-continuous structure being formed for the 40/60 and 60/40 blends whereas the 15/85 and 85/15 blends show droplet morphologies. This paper describes the properties of the constituents, reviews the limits of miscibility, and gives an outline of the whole project. [References: 8]