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Blends of epoxy/anhydride thermosets with a high‐molar‐mass poly(methyl methacrylate)
Author(s) -
Galante M J,
Oyanguren P A,
Andromaque K,
Frontini P M,
Williams R J J
Publication year - 1999
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199908)48:8<642::aid-pi207>3.0.co;2-b
Subject(s) - thermosetting polymer , materials science , epoxy , molar mass , diglycidyl ether , methyl methacrylate , polymer chemistry , bisphenol a , composite material , differential scanning calorimetry , polymer , monomer , physics , thermodynamics
Poly(methyl methacrylate) (PMMA, M n = 232 000) was used to modify a stoichiometric epoxy (diglycidyl ether of bisphenol A; DGEBA)–anhydride (methyl tetrahydrophthalic anhydride; MTHPA) thermoset. PMMA concentrations in the range 3–7 wt% led to morphologies consisting of a continuous PMMA‐rich region that appeared rough and striated in scanning electron micrographs and large domains of the thermoset exhibiting a dispersion of PMMA‐rich particles in the micrometre range. These morphologies are the result of the critical point location, estimated at 2.1 wt% PMMA as a result of the high molar mass of the additive. A 5 wt% PMMA led to an increase of the stress intensity factor K IC from 0.65 MPa m 1/2 , for the neat thermoset, to 0.94 MPa m 1/2 . However, T g was reduced from 117 °C for the neat thermoset to about 105 °C for the PMMA‐modified material. The T g decrease is ascribed to the differential segregation of both monomers to the PMMA‐rich phase. No influence of PMMA addition on the cure kinetics was observed. An upper critical solution temperature was observed, meaning that cloud‐point conversions increased with cure temperature. Phase separation took place before gelation in the temperature range investigated in this study. © 1999 Society of Chemical Industry