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New epoxy resins. I. The stability of epoxy–trialkoxyboroxines triaryloxyboroxine system
Author(s) -
Chen C. S.,
Bulkin B. J.,
Pearce E. M.
Publication year - 1982
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/app.1982.070270407
Subject(s) - epoxy , diglycidyl ether , materials science , glass transition , polymer chemistry , curing (chemistry) , char , thermal stability , thermosetting polymer , polymerization , polymer , composite material , bisphenol a , chemistry , organic chemistry , pyrolysis
A polymer with high aromaticity and/or cyclic ring structures chain backbone usually has high heat, thermal, and flame resistance. Two diglycidyl ethers of bisphenols were prepared from 4,4′ isopropylidenediphenol (DGEBA) and 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) for evaluation. Four boroxines—trimethoxyboroxine (TMB), triethoxyboroxine (TEB), triisopropoxyboroxine (TIPB) and triphenoxyboroxine (TPB)—were used as the curing agents. DGEBA and DGEBF cured with various boroxines indicate that the trend for their respective glass transition temperature ( T g 's), degradation temperatures ( T d 's), and gel fractions are TMB‐cured epoxy ≈ TEB‐cured epoxy < TIPB cured epoxy < TPB cured epoxy. The DGEBF system usually has a higher T g , T d , gel fraction, oxygen index (OI), and char yield than the related DGEBA system. DGEBF/DGEBA (80/20 mol ratio) shows a synergistic effect in regard to char formation. This effect exists not only in the copolymer system but also in blended homopolymers of the separately cured resins. A modified mechanism for the polymerization of phenyl glycidyl ether (PGE) with TMB has been proposed.