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Structure development via reaction‐induced phase separation in tetrafunctional epoxy/polysulfone blends
Author(s) -
Yoon Taesung,
Kim Bong Sup,
Lee Doo Sung
Publication year - 1997
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19971219)66:12<2233::aid-app4>3.0.co;2-h
Subject(s) - polysulfone , epoxy , materials science , phase (matter) , composite material , chemical engineering , chemistry , organic chemistry , polymer , engineering
For the cure process of tetrafunctional epoxy resin/polysulfone(EP/PSF) blends, we investigated the effect of cure temperature and blend composition on the phase separation behavior by light scattering and the structure development during cure by an optical microscope. The EP/PSF blend without the curing agent was shown to exhibit an LCST‐type phase behavior (LCST = 241°C). At the early stage of curing, the EP/PSF blend was homogeneous at the cure temperature. As the cure reaction proceeded, the blend was thrust into a two‐phase regime by the LCST depression caused by the increase in a molecular weight of the epoxy‐rich phase, and the phase separation took place via a spinodal decomposition (SD) or nucleation and growth (NG) mode, depending on the blend composition and the cure temperature. When cured isothermally at 220°C, the blend exhibited a sea‐island morphology formed via the NG mode below 5 wt % PSF content, while the SD mode prevailed above 20 wt % PSF content. At the intermediate composition range, combined morphology with both sea‐island and cocontinuous structure was observed. On the other hand, by lowering the cure temperature and/or increasing the content of PSF component, a two‐phase structure with a shorter periodic distance was obtained. It seems that the rate of the phase separation is considerable reduced, while that of the cure reaction is not as much. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2233–2242, 1997