Synthesis Of Different Degree Of Bisphthalonitrile Resin Prepolymerization And Effect On Properties Of Its Composites

Resin matrix composites have been applied as the high-performance materials due to their light weight,high strength and high modulus.As the structural materials,the resin matrices dominate the overall performance of the high-performance composites.Thus,carrying out the controlling study on the overall properties of the resin matrices would play an important role during the designing and fabrication of the high-performance composites.Based on this,phthalonitrile-based resins were selected and two kinds of phthalonitrile monomers were designed and prepared with molecular-designing.Then,the aromatic diamine was selected as the catalyst and various pre-polymerization degrees of the phthalonitrile pre-polymers were prepared via solution reactions.Finally,glass fibers were applied as the reinforcement,the phthalonitrile-based fiber-reinforced composites were fabricated via hot-press molding technology.Then,the flexural properties,the interfacial adhesion properties and the thermal stabilities of the various composites were studied and discussed,to reveal the effects of the prepolymer degrees on the overall properties of the phthalonitrile-based composites.The detailed studies are as follows:(1)Two kinds of diphenol were used and two phthalonitrile monomers were prepared via substitution reactions.The FTIR and DSC were applied to study the molecular structures and the curing behaviors.Then,the aromatic diamines were used as the catalyst to prepare the phthalonitrile pre-polymers with various pre-polymer degrees.Their structures and melting viscosity were characterized with FTIR and dynamic rotation rheology.The effects of the pre-polymer degrees on the curing behaviors and the viscosity were studied and discussed.(2)The DSC and dynamic rheology characteristics were performed to investigate the curing behaviors and the polymerization processes of the various phthalonitrile pre-polymers.The curing behaviors and the curing processes of the pre-polymers were studied to reveal the effects of the pre-polymer degree on the polymerizationactivity and polymerization rates of the phthalonitrile-based resins.Based on this,the molding processes of the phthalonitrile-based resin were confirmed.(3)Glass fibers were used as the reinforcement to fabricate the fiber-reinforced phthalonitrile-based matrix composites via hot-press molding technology.The variousphthalonitrile –based composites with various pre-polymer degrees were prepared and their flexural strength,interfacial properties and thermal stabilities were thoroughly studied to reveal the effects of the pre-polymer degree on the overall properties of the phthalonitrile-based composites.It can be expected that through the studies of this work,new research directions and novel preparation methods would be promoted on the designing and fabrication of the phthalonitrile-based composites.