New epoxy resins. II. The preparation, characterization, and curing of epoxy resins and their copolymers

TLDR

Polymers with high aromaticity or cyclic ring structures in the backbone typically exhibit high heat and flame resistance. The authors synthesized five glycidyl‑ether epoxy resins from bisphenol A and related aromatic monomers and cured them with trimethoxyboroxine and diaminodiphenylsulfone to study structure–property relationships. The cured resins displayed increasing char yield and glass‑transition temperature with aromaticity, with TGETA expected to have the highest Tg, and incorporating DGEBF, DGEFX, DGEA, or TGETA into a DGEBA system raised char yield, Tg, and oxygen index proportionally.

Abstract

Abstract A polymer having high aromaticity and/or cyclic ring structures in the chain backbone usually gives high heat resistance and flame resistance. Five glycidyl ether‐type epoxy resins are prepared from bisphenol A (DGEBA), 9,9‐bis(4‐hydroxyphenyl)fluorene (DGEBF), 3,6‐dihydroxyspiro‐[fluorene‐9,9′‐xanthane] (DGEFX), 10,10‐bis(4‐hydroxyphenyl) anthrone (DGEA), and 9,9,10,10‐tetrakis(4‐hydroxyphenyl)anthracene (TGETA) in order to study structure–thermal stability–flame resistance property relationships. In this study, trimethoxyboroxine (TMB) and diaminodiphenylsulfone (DDS) are employed as the curing agents. The char yield at 700°C under a nitrogen atmosphere and the glass transition temperature ( T g ) for the uncured resins decrease according to the sequence TGETA > DGEFX > DGEA > DGEBF > DGEBA. The Tg values for these cured epoxy resins are DGEBA < DGEBF < DGEFX < DGEA. A T g for the TGETA is not obtainable but would be expected to be the highest. The char yields at 700°C of these cured epoxy resins have the same trend as the uncured resins. DGEBF, DGEFX, DGEA, and TGETA added to the DGEBA system show increases in the char yield, T g , and oxygen index with increasing concentration of these novel epoxy resins.