Curing characteristics of phenolic and epoxy transition layer and properties of composites

In order to meet the requirements of structural and functional integration of composite shell of solid rocket motor，the formula，process and performance of the transition layer of the two resins were studied.The performance characteristics of the transition layer content distribution in the system of phenolic resin B30，epoxy resin TDE-85 and curing agent methylhexahydrophthalic anhydride （MHHPA） were mainly studied.The digital display rotary viscometer and digital display constant temperature water bath were used to measure the viscosity of the resin，and differential scanning calorimetry （DSC） was used for thermal analysis of the resin with gradient content.The kinetic parameters of the mechanism of multiphase reaction system were solved.The curing process and properties of the resin with transition layer were verified.The properties of the resin with transition layer were compared with those of the resin without transition layer.The results showed that：in the transition layer system，B30 and curing agent MHHPA reacted first，followed by B30 self-curing；the mechanical properties of epoxy resin TDE-85 and phenolic resin B30 met the performance requirements of structural layer and functional layer；compared with the resin without transition layer，the ablation resistance of the resin with transition layer had little change，but the bending strength increased by 67.8%，and the tensile strength increased by 56.1%；compared with the composite without transition layer，the interlaminar shear strength of the composite with transition layer increased by 94.9%，but the ablation resistance changed little.In conclusion，the transition layer can meet the structural and functional integration requirements of composite shell of solid rocket motor.