Study On Modification Of Cyanate Ester Resin

Cyanate ester resin (CE) is a new type of thermosetting resins. It can maintain stable in the broad frequency range of temperature, and has low dielectric constant and dielectric loss. It also has good heat resistance and technical properties, which qualify cyanate ester resin for high-performance resin matrix of composite materials. But its toughness and modulus remains to be enhanced. The aim of this paper is to find a new type of cured cyanate resin system, which has good mechanical properties, chemical properties, hot-resistance properties and good dieletronic properties; at the same time, it is hoped to find a new method and explaination theory of cure cyanate resin.The experiment was performed on the basis of the previous studies on toughened epoxy modified isocyanates, in which the ratio of CE and EP (epoxy resin) is 7 : 3 (mass ratio, the same below). By adding a third component of bisphenol A to the system is used to lower curing temperature, and improve its performance. The influence of different amount of bisphenol A on physical properties, curing mechanism, curing process, hygrothermal performance of modified resin system is studied.The methods of testing cured system, such as DSC,FTIR,GPC, are also studied. It is shown that with the enhance of the BPA ,the tensile properties increased; while the impact properties increased at first, later decreased. It is found that the addition of bisphenol A can change the curing mechanism and decrease the curing temperature obviously. On the base of analysis of DSC, FTIR, GPC and other methods, the cured mechanism of EP/CE/BPA is proposed: The-C-O-C-bands are formed in the EP/CE cured resin system when the bisphenol A is added, and the interpenetrated network is also formed between the bisphenol A and EP/CE cured resin system, therefore the toughness of cured system is increased. The moisture absorption of the EP/CE cured systems are also found to increase with increase of bisphenol A. When CE : EP : BPA is 7 : 3 : 0．75 (mass fraction), the tensile strength could be raised by 27．3 %, and the impact strength also increased by 34．7 %, while the moisture absorption decreased to 1．2 %.