Preparation And Properties Of Bismaleimide/diallylbisphenol A Resin Modified By Polythioetherimide

Advanced polymeric composite, which has many advantages such as high strength rate, high modulus rate, high temperature resistance and corrosion resistance, has been widely used in aerospace, mechanical and electronics information industries. Bismaleimide(BMI), as a common matrix resin of advanced polymeric composite, has attracted widespread attention due to their excellent properties, such as heat resistance, radiation resistance and processability. However, brittleness and poor processing characteristics limit its application. Diallyl bisphenol A(BA) can improve BMI resin toughness effectively, but reduces its heat resistance. In order to remedy this defect, Polythioetherimide(PTEI), with high flexibility sulfide, which is of good compatibility with the matrix, is used to modify BMI/BA resin system. The research targets and pilot program of this project are determined based upon literature search, and the research works are carried out as follows.Based on the synthesis of PTEI and modification of BMI/BA resin, the effect of the addition of PTEI on mechanical properties, heat resistance, dielectric properties and microstructure morphology were studied. The results showed that the addition of PTEI can significantly improve the mechanical property of BMI/BA resin. By using 5wt% PTEI, impact strength increased 69.6% and bending strength increased 49.7% compared with untreated BMI/BA resin. SEM results showed that the addition of PTEI led to “sea-land” phase structure which can improve the toughness of the material. According to thermal analysis, the addition of PTEI resin significantly increased storage modulus and loss modulus. Furthermore, the addition of PTEI resin improved the carbon residue rate. By using 5wt% PTEI, the carbon residue rate increased 2.8%. However, the glass transition temperature and the initial decomposition temperature reduced 10 oC and 13 oC compared to the BMI/BA resin. Dielectric analysis showed that PTEI/BMI/BA resin had lower dielectric constant and dielectric loss compared to BMI/BA resin.In order to solve the above problem, amino-polythioetherimide(PTEI-N) was synthesized and used to modify BMI/BA resin. The impact of the addition of PTEI-N of mechanical properties, heat resistance, dielectric properties and microstructure morphology were studuied, and the impact of the amino group on two different modified systems was discussed. The results showed that the addition of PTEI-N can significantly improve the mechanical property of BMI/BA resin. By using 5wt% PTEI-N, impact strength increased 75.6% and bending strength increased 73.5% compared with BMI/BA resin. The results showed that the fracture surface of the modified systems displayed tough fracture features, markedly different from that of the unmodified BMI/BA resin system. Thermal analysis showed that the addition of PTEI-N not only improved storage modulus and loss modulus of the resin, but also increased the glass transition temperature of the resin and carbon residue rate. By using 5wt% PTEI-N, the glass transition temperature of the resin increased 30 oC and the carbon residue rate increased 1.5%, and the initial decomposition temperature was unchanged compared with BMI/BA resin. Dielectric analysis results showed that the addition of PTEI-N can make resin has lower dielectric constant and dielectric loss compared with BMI/BA resin and PTEI/BMI/BA resin.