Cyanate Modified Epoxy Composite

In this dissertation preparation and curing of Bisphenol A Dicyanate (BACY) were studied and it was used in modification of Low brominated epoxy resin (LBE), bisphenol A diglycidyl ether epoxy resin (BA) and novolac epoxy resin (NE). Further more, their curing characteristics were studied.Bisphenol A Dicyanate monomer was prepared by two steps, which were preparation of cyanogen bromide and preparation of BACY by cyanogen bromide. In the preparation of cyanogen bromide, the influence of reaction temperature and reactant ratio on product was studied. The results indicate that the highest yield (86.7%) was achieved under 5 C and 1.1:1.0 (potassium cyanide / bromine). In the preparation of BACY, the influence of reaction temperature , amount of cyanogen bromide and introduction speed of triethyl amine on product purity and yield. The study show that high yield BACY can be obtained under 0-5 C and excess of cyanogen bromide about 50%. At the same time, slow dropping of triethylamine and fast stirring are also crucial. BACY was characterized by 1H NMR and FT-IR. The curing reaction of BACY was studied by DSC, and difference of activation energy among different calculation method calculated from isothermal DSC data and difference of activation energy calculated from dynamic DSC and isothermal DSC data.The co-curing behavior of LBE/ BACY ratio catalyzed by copper acetylacetone ( Cu(AcAc)2 ), reaction mechanism and structure of co-curing product were studied by DSC and FT-IR, along with effect of different LBE/ BACY ratio, amount of curing agent on curing temperature and glass transition temperature of co-curing product. The study show that reaction mechanism (WLBE: WBACY=1:1) can be described as following: the first is cyclotrimerization ofBACY, then isocyanurate and oxazolidione are formed in turn by reaction of partial trimer with BACY epoxy group. Simultaneously BACY react with epoxy group to form oxazoline and oxazolidione directly. The results revealed that different ratio of LBE/ BACY has no significant impact on Tg of product in the range of 3/5 to 7/5.,curing temperature relate to content of system, which curing temperature lower with decrease of LBE and addition of Cu(AcAc)2. Prolonged time is favored to completion of reaction, lead to increasement of Tg.Thermal weight loss and decomposition dynamics of co-curing product of three kind of epoxy resin with BACY were studied by dynamic TGA. The results indicate that sample with higher content of epoxy resin has higher extension starting temperature and lower char yield at 600 C. Co-curing products of LBE/BACY exhibit lower extension starting temperature and termination temperature compared with other co-curing system, Co-curing products of NE/BACY exhibit higher char yield compared with other co-curing system.The performance of laminate composed of modified LBE, B A and ME were studied under different ratio of epoxy resin to BACY and category and amount of curing agent used. The results revealed that decreasement of BACY and addition of curing agent lead to serious deterioration of Tg and dielectric performance, although curing agent are favored to co-curing reaction. LBE/BACY (W/W=1/1) exhibit best dielectric performance, NE/BACY(W/W=1A) exhibits highest Tg (205 C) and integrative performance among three kind of complex system.