Curing Reaction Of O-cresol Formaldehyde Epoxy Resin With Maleimide As Cure Agent

In this article, developing trends of heat-resistant modification of epoxy resin and researchs of functional curing agent were summarized. Advance and synthesis of maleimides and applications of polyimide in epoxy resins in recent years were reviewd in details. Then, the research subject on the sythesis of novel hydroxyl-containig maleimide and carboxyl-containing maleimide and the curing reaction of o-cresol formaldehyde epoxy resin with maleimides as curing agent were put forword to improve the thermal properties of the cured resin.1. Two novel hydroxyl-containig maleimide (HPM) and carboxyl-containing maleimide (p-CPMI) were obtained through two-step method and were then polymerized with styrene . Their structures were characterized with Fourier transform infrared spectroscopy(FT-IR) , nuclear magnetic resonance spectroscopy (NMR).2. O-cresol formaldehyde epoxy resin were cured with HPM, p-CPMI and their copolymers with styrene as curing agent. The curing reaction characters such as curing kinetics were examined by differential scanning calorimetry (DSC) and thermal properties of cured resin were examined by DSC and thermaogravimetric analysis (TGA). The solvent's choosen, the influence of the curing agent(HPM)'s proportion on thermal properties of cured resin, different cured thermal properties of the monomer(HPM) and its polymers were studied especially in order to speculate the curing mechanism of HPM on o-cresol formaldehyde epoxy resin. The cured thermal properties of HPM and p-CPMI were compared with the typical curing agents such as PMDA,NA anhydride or DDS . .DSC studies showed that the apparent reaction activation energy of O-cresol formaldehyde epoxy resin with HPM calculated from Kissinger's and Ozawa's models were 60.97 KJ/mol and 65.53 KJ/mol. The results of TG, DTG showed that the cured thermal properties of maleimides were superior to PMDA and NA. and the thermal properties when the monomer HPM as curing agent were more excellent than when its polymers as curing agent. Its curing mechanism was probably that hydroxyl or carboxyl of maleimides had opened the epoxy rings at low temperature and double carbon bonds of maleimide were polymerized at high temperature simultanetly.3. When maleimides as curing agent, the thermal properties of o-cresol formaldehyde epoxy resin were improved greatly because of introduction of the ring ofmaleimide on the epoxy resin and enhancement of crosslink density through reaction of double bond at high temperature . The studies showed that HPM and p-CPMI are excellent curing agents for o-cresol formaldehyde epoxy resin and have good applications in the future.