Study On New Curing Agents Of High-performance Phthalonitrile Resins

Phthalonitrile resins were a class of phthalonitrile-terminated thermosetting resins. They had excellent comprehensive performance and could be used for matrices of composite materials, coatings, adhesives and so on, so they would have broad application prospects in aerospace, ships, electronics, machinery and other high-tech fields. In this article, new curing agents of phthalonitrile resins were explored. On the one hand, ZnCl2was supported on carriers to obtain a series of supported ZnCl2, then the feasibility and effectiveness of supported ZnCl2to cure phthalonitrile resins were systematically researched; On the other hand, ammonium molybdate tetrahydrate-urea (AMTU) was explored as a new curing agent of phthalonitrile resins, meanwhile the feasibility and effectiveness of AMTU to cure phthalonitrile resins were systematically studied.TiCl4and Ce (NO3)3were precipitated and calcined at high temperature to obtain porous TiO2, CeO2and TiO2-CeO2. The methanol solution of ZnCl2was used to impregnate TiO2, CeO2, TiO2-CeO2and silica gel with200-300mesh to gain a series of curing agents including ZnCl2/Ti02, ZnCl2/CeO2, ZnCl2/TiO2-CeO2, ZnCl2/silica gel. Phthalonitrile-terminated poly(phthalazinone ether nitrile)(PPEN-Ph) were cured at250℃for2h,280℃for2h,300℃for8h with supported ZnCl2and ZnCl2as curing agents. FTIR spectras and TGA curves were used to study the structures and heat resistance of cured PPEN-Phs, respectively. DSC was used to study the curing reaction kinetics. Producing aryl-s-triazine structures in cured PPEN-Phs was demonstrated by the FTIR spectra. According to TGA curves, the initial decomposition temperature (Ti) of cured PPEN-Ph with ZnCl2was lower than those with supported ZnCl2; Compared with ZnCl1,T5%of cured PPEN-Phs with supported ZnCl2were improved about9-15℃and the carbon residue at800℃(Cy800) increased about0.5-1.7%. The curing reaction kinetics of both ZnCl2/TiO2-CeO2and ZnCl2were studied. On the basis of results, the curing temperature of ZnCl2/TiO2-CeO2was lower about43℃than that of ZnCl2, but the apparent activation energy (Ea) of ZnCl2/TiO2-CeO2was higher than that of ZnCl2.PPEN-Phs were cured at250℃for2h,280℃for2h and300℃for8h with AMTU,4,4’-diaminodiphenyl sulfone (DDS), ZnCl2as a curing agent, respectively. Cured PPEN-Phs were characterized by the same methods as described above. Producing aryl-s-triazine structures in cured PPEN-Phs were demonstrated by the FTIR spectra. On the basis of TGA curves, T, of cured PPEN-Ph with DDS was higher than those with AMTU and ZnCl2; Ti of cured PPEN-Ph with ZnCl2was approximately equal to that with AMTU; Td5%of cured PPEN-Ph with ZnCl2(488℃) and AMTU (487℃) were higher than that with DDS (483℃); Cy8oo of cured PPEN-Ph with DDS was highest and up to79%, but Cy800of cured PPEN-Ph with AMTU was lowest and attained75%. According to the results of DSC and Ea, the curing temperature of maximum peak with AMTU was lowest, followed by the DDS, and the highest was ZnCl2. Ea of DDS was lowest, followed by AMTU, and the highest was ZnCl2.