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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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