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Toughness Behaviour of Vinylester/Epoxy Thermosets with Interpenetrating Network Structure
Author(s) -
KargerKocsis József,
Gryshchuk Oleg
Publication year - 2004
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200451328
Subject(s) - thermosetting polymer , materials science , epoxy , interpenetrating polymer network , dynamic mechanical analysis , toughness , composite material , fracture toughness , curing (chemistry) , diamine , scanning electron microscope , polymer , polymer chemistry
Vinylester/epoxy‐based (VE/EP) thermosets of interpenetrating network (IPN) structure were produced by using a VE resin (bismethacryloxy derivative of a bisphenol‐A type EP resin) and EP resins of aliphatic (Al‐EP) and cycloaliphatic (Cal‐EP) nature. Curing of the EP resins occurred either by an aliphatic (Al‐Am) or a cycloaliphatic (Cal‐Am) diamine compound. Dynamic mechanical thermal analysis (DMTA) and atomic force microscopy (AFM) suggested the presence of an interpenetrating network (IPN) in the resulting thermosets. AFM scans taken on the ion‐etched surface of EP showed a featureless homogeneous structure. On the other hand, VE exhibited a two‐phase microgel, whereas VE/EP a two‐phase interpenetrating network (IPN) structure. Toughness was characterised by parameters of the linear elastic fracture mechanics, viz. fracture toughness (K c ) and fracture energy (G c ). Unexpected high K c and G c data were found for the systems containing cyclohexylene units in the EP network. This was attributed to beneficial effects of the conformational changes along the cyclohexylene linkages (chair/boat). The failure mode of the VE/EP thermoset combinations was studied by scanning electron microscopy (SEM) and discussed.