New Bismaleimide Resin Toughened By In-situ Ring-opening Polymer Of Cyclic Butylene Terephthalate Oligomer

Blending or copolymerizing with high performance thermoplastic polymer(HTP) is proved to be one important toughening method for thermosetting resin(TSR), which can improve the toughness while maintaining the heat resistance. However, HTPs usually have poor solubility, high melting point and less reactive groups, so it is difficult to get good processing feature with TSR. Therefore, how to get significant toughening effect while maintaining good processing feature and outstanding thermal resistance is still a great challenge for development of HTP/TSR system.In this thesis, cyclic butylene terephthalate oligomer(CBT) is chosen as the modifier,which will occur the ring-opening polymerization with the presence of initiators. However,the commonly used initiators are organic tin compounds(such as dihydroxy butyl tin chloride(BCD) and tin naphthenic), they cannot be directly used in toughening thermally resistant TS resins due to three main problems. In the thesis, a new type of organotin initiator(HSi Sn) with high efficiency was synthesized and fully characterized, the influences of HSi Sn on the ring-open polymer of CBT(c PBT) and the curing of cyanate ester(CE) were discussed, the initiating and catalytic abilities were discussed. In addition,as the initiator HSi Sn was added into bismaleimide/diallyl bisphenol A resin(BD), and a series of HSi Sn/CBT-BD resins were prepared. The ring-opening polymerization was discussed during the prepolymerization of the resin. The structure and properties of modified resins were systematically studied and compared with those of BCD/CBT-BD.HSi Sn/CBT and HSi Sn/CE resins were prepared, the initiating and catalytic ability were systemically discussed, and the influences of HSi Sn on the ring-open polymer(c PBT)and CE resin were investigated. Results show that HSi Sn has appropriate initiating ability,which keeps the crystal structure of c PBT and effectively reduces the crystallinity of the c PBT at the same time; HSi Sn introduces a large number of active aminos to c PBT, and theintroduction of Si-O-Si improves the thermal stability of c PBT; HSi Sn is a mild catalyst for the HSi Sn/CE resin, and the cured HSi Sn/CE resin has a uniform structure and high char yield.In addition, a series of HSi Sn/CBT-BD resins were prepared. The ring-opening polymerization was discussed during the prepolymerization of the resin. Compared with BCD/CBT-BD and BD resins, the influence of initiators(BCD and HSi Sn) on the structure and performances, including phase structure, mechanical properties, thermal properties,dielectric properties and water resistance were discussed. Results show that HSi Sn/CBT-BD resins have excellent compatibility, all resins have homogenous phase and no phase separation appears; with small loadings of CBT, HSi Sn/CBT-BD resins have remarkably improved mechanical properties compared to BCD/CBT-BD and BD resins;moreover, HSi Sn/CBT-BD resins have excellent heat resistance, the addition of CBT does not decrease the thermal properties, while BCD/CBT-BD resins decrease obviously;however, the glass transition temperature of HSi Sn/CBT-BD resins decreases; in addition,HSi Sn/CBT-BD resins maintain the excellent flame retardancy, the heat release rate is lower than that of BCD/CBT-BD resin which is close to that of BD resin.