Study On The Curing Reaction And Performance Of The Blends Of Bismaleimide And Novolac Cyanate Resins

Cyanate ester resin is a kind of high performance thermosetting resin and developed after the epoxy resin, bismaleimide and polyimide resin. In the1980s,it realized industrialized production, and bisphenol A cyanate ester resin and dicyclopentadiene cyanate ester resin are the mature type of cyanate at present. It has many excellent properties, such as good mechanical properties, dielectric performance, water resistance, heat resistance, antiablative performance and so on, and are widely used in printed circuit board, high performance wave transmission and structural composites materials of aircrafts. Novolac cyanate ester is developed after bisphenol A cyanate ester. because of its unique structure, the cured resin has higher glass transition temperature, as high as400℃,but the large rigid groups density in the cured resin caused its toughness very poor, so it is needed to be modified. The research at home and abroad about modification of bisphenol A cyanate ester has been many, but the modified research about novolac cyanate is little. In this paper, we selected bismaleimide to modify the novolac cyanate.The structure of the resin decided the performance and the curing mechanism of the resin greatly affected it structure. In this paper, we study the curing mechanism, curing reaction kinetics and curing process about the blends of novolac cyanate resin and bismaleimide resin. Through FIIR and DSC techniques, we can get a conclusion that novolac cyanate resin and bismaleimide resin exit a copolymerization reaction, generating a pyrimidine and pydidine structure. when PT:BMI is6:4(for quality),the reaction between them fully happened. The apparent activation energy of the system is80.96KJ/mol, the frequency factor is4.00x107S-1, reaction order is0.927. Combined with the main functional groups conversion and the reaction rate, we finally determined the curing process of the modification system,120℃/1h+160℃/2h+215℃/2h+300/2h.This paper also study the performance of the modified resin system and its composite material. The results indicate that the manufacturability of the modified resin system is very good and the its reaction is excellent. The modulus of the cured resin is reduced, toughness is improved, heat resistance decrease, but still remain at350℃or so, antiablative performance is excellent, dielectric constant and dielectric loss angle tangent keep a low value in a wide temperature and frequency range.SEM analysis shows that the bonding of the resin and fiber is good.