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Pure Appl. Chem., Vol. 70, No. 8, pp.1547-1566, 1998

MACROMOLECULAR DIVISION

STRUCTURE AND PROPERTIES OF COMMERCIAL POLYMERS*

Rheological and Mechanical Properties of
Poly (-Methylstyrene-co-Arcrylonitrile) / Poly (Methyl Methacrylate) Blends in Miscible and Phase Separated Regimes of Various Morphologies

I. CHARACTERIZATION OF CONSTITUENTS, BLEND PREPARATION, AND OVERVIEW ON BLEND MORPHOLOGY

(Technical Report)

H. M. Laun

Synopsis: For a collaborative blend study the components P MSAN (Mw = 82 000, 30% acrylonitrile) and PMMA (Mw = 88 000, 5% methylacrylate) were selected to have a similar melt viscosity and elasticity at 210 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 C. The P MSAN/PMMA blends show LCST behaviour. Transparent samples were prepared by melt mixing and subsequent squeezing at temperatures _ 160 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 MSAN rich samples have higher cloud point temperatures than their PMMA rich counterparts. RuO4-stained ultrathin sections of optically transparent blends containing 40% P MSAN show a distinct microheterogeneity due to ¸ 10 nm PMMA rich spheres. 65 hours annealing at 150 C yields 0.1 µm spheres whereas a co-continuous structure is found after 22 h at 170 C. Temperatures _ 200 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.


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