Polymerization Of Maleimide With Functional Group And Its Use In Epoxy Resin

N-substituted maleimides are one kind of thermal improver which are developed recently. When copolymerized with common vinyl monomers, the resulting copolymers contain five-member planar rings in the chain, which hinder the rotation of the imides residues around the backbone chain of the macromolecules, resulting in a greater structural stiffness and a higher thermal stabilityThe monomers N- (p-hydroxyphenyl) maleimide and N- (p-carboxyphenyl) maleimide were prepared from maleid anhydride and the correspongding amine using acetic anhydride as dehydrator, sodium acetate as catalyst. The obtained monomers were characterized by FT-IR and H NMR methods.The copolymerizations of N-substituted maleimides with styrene were studied with toluene as solvent, azobisisobutyronitrile (AIBN) as initiator. The effects of polymerization time, polymerization temperature and monomer mixture composition on copolymerization of N- (p-hydroxyphenyl) maleimide with styrene were investigated. The compositions of the two monomers in copolymers were close to 1:1 even at a high monomer conversion of about 60%, and did not change as the N- (p-hydroxyphenyl) maleimide feed mole fraction varied from 10% to 90%. The obtained teactivity ratios of the two monomers r_HPM=0.038, r_st=0.067, resulting that the copolymerization of N- (p-hydroxyphenyl) maleimide with styrene were alternating one.O-cresol formaldehyde epoxy resins were cured with the obtained copolymers 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).DSC studies showed that the apparent reaction activation energy of O-cresol formaldehyde epoxy resin with copolymer of N- (p-hydroxyphenyl) maleimide with styrene calculated from Kissinger's and Ozawa's models were 60.18 KJ/mol and 65.53 KJ/mol. The results of TGA showed that the cured thermal properties of maleimides were superior to PMDA and NA. The results also showed that the thermal properties of o-cresol formaldehyde epoxy resin were improved greatly because of introduction of the ring of maleimides on the epoxy resin and enhancement of crosslink density through reaction of double bond at high temperature.The studies showed that the copolymers of N-substituted maleimides are excellent curing agents for o-cresol formaldehyde epoxy resin and have good applications in the future.