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Physical and chemical interactions and miscibility in two
binary blend system: diglycidylether of bisphenol-A (DGEBA)
with poly(methyl methacrylate) (PMMA) and DGEBA with
polycarbonate (PC), were investigated by differential scanning
calorimeter (DSC) and Fourier-transform infrared spectroscopy
(FT-IR). Both blends were miscible and homogeneous. Chemical
exchange reaction did not occure between DGEBA and PMMA.
Chemical interactions between DGEBA and PC were proven by
evidence of elevation of the glass transition temperature,
shifting of the carbonyl IR absorbance peak, and enhanced
solvent resistance of blends after heat treatment. In addition,
effects of chemical links between polymer and epoxy on phase
behavior of amine-cured epoxy/polymer blend systems were
investigated by DSC, saning electron microscopy (SEM) and
polarizing microscopy. Only a single Tg and a homogeneous
morphology were observed in cured DGEBA/PC/DDS blend, which has
been attributed to the chemical interactions between DGEBA and
PC. Since chemical reaction did not occure between DGEBA and
PMMA, two Tg's and segregated morphology were observed in the
cured DGEBA/PMMA/DDS blend. Furthermore, equilibrium phase
behavior in the blend system of PC and PMMA was investigated by
dissolving both polymer into DGEBA. Upon lowering the Tg's of
PC/PMMA blends and enhanced chain mobility by the plasticizing
epoxy, phase separation did take place with an accelerated rate
at as low as 68℃. The results suggested that the so-called
"miscibility" and "LCST" between PC and PMMA was not of a
thermodynamic nature.
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