Abstract
A bismaleimide (BMI)/diallylbisphenol A (DABPA) resin was modified with a multifunctional thiol containing long chain aliphatic unit. To investigate the relationship of the curing reaction and properties of cured BMI/DABPA resin modified with multifunctional thiol, the time course of the functional groups during the curing reaction process was analyzed using Fourier-transform infrared (FTIR) analysis. Despite the decreased crosslink density with increasing multifunctional thiol concentration, the glass transition temperature and fracture toughness of the cured resin was increased. These results is considered as follows; (1) the flexibility of cured BMI/DABPA resin is increased by introducing the long chain aliphatic unit, resulting in improved toughness, (2) The reaction of the maleimide group and the thiol group occurs besides the reaction of the maleimide group and the allyl group, as a result, degree of the reaction with maleimide group was increased. And the curing reaction is progressing further by introducing the long chain aliphatic unit than that for the unmodified resin, because the reduction of the molecular mobility of the cured network in the BMI/DABPA resin modified with multifunctional thiol is small as compared with that of the unmodified resin. Therefore, the segmental motion of the network structure is less likely to occur, as a result, the glass transition temperature is increased.
