Curing Behavior, Thermal, and Mechanical Properties of Epoxy Resins Cured With a Novel Liquid Crystalline Dicarboxylic Acid Curing Agent

摘要

A novel di-carboxyiic acid curing agent (DACA) was successfully synthesized and cured with three different epoxy resins: glycidyl end-capped poly(bisphenol-A-co-epichlorohydrin) (pDGEBA, M_n = 377),N,N-diglycidyl-4-glycidyloxyaniline (TGAP), and 4,4'-methylenebis(N,N-diglycidylaniline) (TGDDM). The cured epoxy exhibited excellent thermal stability, which was indicated by high initial degradation temperature (T_(id)) and char yield. The T_(id) values of cured epoxy were in the range of 327-338 C, and the char yields increased with increasing epoxy functionality. The char yields of cured DACA/ pDGEPA, DACA/TGAP, and DACA/TGDDM samples were 21.1, 60.4, and 66.9%, respectively. In addition, the cured epoxy samples also showed low coefficients of thermal expansion and high storage moduli (E), which were around 60 ppm/ C and 2800 MPa, respectively. The failure surfaces were ductile and rough, so the cured epoxy samples are expected to have high fracture toughness and impact strength.