Synthesis and characterization of siliconized epoxy-1, 3-bis(maleimido)benzene intercrosslinked matrix materials

Intercrosslinked network of siliconized epoxy-1,3-bis(maleimido)benzene mat rix systems have been developed. The siliconization of epoxy resin was carr ied out by using various percentages of (5-15%) hydroxyl-terminated polydim ethylsiloxane (HTPDMS) with gamma -aminopropyltriethoxysilane (gamma -APS) as crosslinking agent and dibutyltindilaurate as catalyst. The siliconized epoxy systems were further modified with various percentages of (5-15%) 1,3 -bis(maleimido)benzene (BMI) and cured by using diaminodiphenylmethane (DDM ). The neat resin castings prepared were characterized for their mechanical properties. Mechanical studies indicate that the introduction of siloxane into epoxy resin improves the toughness of epoxy resin with reduction in th e values of stress-strain properties whereas, incorporation of bismaleimide into epoxy resin improves stress-strain properties with lowering of toughn ess. However, the introduction of both siloxane and bismaleimide into epoxy resin influences the mechanical properties according to their percentage c ontent. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of heat distortion temperature were also carried out to assess the thermal behavior of the matrix samples. DSC thermogram of th e BMI modified epoxy systems show unimodel reaction exotherms. The glass tr ansition temperature (T-g), thermal degradation temperature and heat distor tion temperature of the cured BMI modified epoxy and siliconized epoxy syst ems increase with increasing BMI content and this may be due to the homopol ymerization of BMI rather than Michael addition reaction. The morphology of the BMI modified epoxy and siliconized epoxy systems were also studied by scanning electron microscopy. (C) 2001 Elsevier Science Ltd. All rights res erved.