Synthesis of two novolac type epoxy resin curing agents and their application

摘要

Two novolac resins were synthesized by the reaction between bisphenol A and benzaldehyde (bis-BENR) or bisphenol A and p-hydroxybenzaldehyde (bis-PHNR). Fourier Transform Infrared Spectroscopy (FTIR) and nuclear magnetic resonance (NMR) were applied to characterize the molecular structure of bis-BENR (or bis-PHNR). Then the two novolac resins were used as curing agent for bisphenol A type epoxy resin (DGEBA). The curing reaction and curing kinetics were studied by Dynamic FTIR and Differential Scanning Calorimetry (DSC). Dynamic FTIR showed that the two novolac resins reacted with epoxy resins and formed a crosslinking network structure. DSC results show that the optimum mass ratio between DGEBA and bis-BENR (or bis-PHNR) was 7:3, under which the curing reaction processed completely. The mechanical properties and sulfide resistance of DGEBA/bis-BENR (or bis-PHNR) system were also investigated. The results showed that when the mass ratio between DGEBA and bis-BENR (or bis-PHNR) was 7:3, the curing coatings had optimum mechanical properties and sulfide resistance.