Novel Mn-Schiff Base-graphite Oxide Hybrids And Their High Performance Cyanate Ester Resins

Cyanate ester(CE) resin, as “the most competitive resin of high performance structural and functional materials in the 21 st century”, has extremely outstanding comprehensive performances, including high heat resistance, extremely low dielectric constant and loss, good adhesive property, low moisture absorption rate and shrinkage,etc., and thus showing great potential in aerospace, electronics, packaging and other fields, etc. However, like others heat resistant thermosets, CE resin also has high curing temperature and big brittleness. Available techniques do not simultaneously overcome the two bottlenecks. Therefore the investigation on toughening and reducing curing temperature of CE resin is still a big challenge.In this thesis, by virtue of the hybrid concept, we made the transition metal ion(Mn)which had an excellent catalytic effect for CE load on GO by coordination, prepared a new multifunctional modifier — manganese Schiff base graphene oxide(MSG) for the first time, then explored the influence of MSG for the catalytic performance and crosslinking density of CE. Results showed that MSG had an obvious coordination catalytic effect for CE. When adding 1wt% MSG, the curing exothermic peak of CE was decreased by 135 oC, and MSG shortened the time of CE curing reaction. Then the addition of MSG could also improve the curing degree of CE resin.We prepared the MSG/CE modified resins through melting polymerization, and systematically studied the influence of MSG for the curing process, dielectric properties,mechanical properties(including toughness and rigidity) and the thermal performance of CE. The research results showed that MSG had a good dispersion in CE. Compared with the traditional GO/CE resin, the performances of toughness, rigidity and heat resistant of MSG/CE resins had been obvious improved. Specifically, compared with CE, the maximums of impact strength, flexural strength and flexural modulus are 1.7, 1.25 and1.66 times of CE’s values. At same time, the Tdi of MSG/CE reins was also improved by10 oC. It was attributed to that MSG not only showed the effect of physical junction in the resin matrix as rigid particles, but also improved the crosslinking density of CE for its effective catalysis. So MSG played a dual role of strengthening and tougheningIn order to further enhance the mechanical properties of CE resins, we introduced hyperbranched polysiloxane(PHSi) into the structure of MSG, prepared synthesized manganese-Schiff base-hyperbranched polysiloxane-GO hybrid(MSSiG), prepared the MSSiG/CE resins, and studied the influence of MSSiG for the performances of catalysis and toughening. Results showed that when the content of MSSiG was 1wt%, the curing exothermic peak of CE was decreased by 138.7 o C, which was lowered by 5 oC,compared with the same proportion of MSG/CE resin. Moreover, under the same curing condition, CE monomer in MSSiG/CE resin had a higher conversion. When the content of MSSiG was 0.75wt%, the impact strength and flexural strength of modified resins were respectively 1.85 and 1.74 times of CE values. Compared with MSG/CE resin,MSSiG/CE resin could achieve a better toughing effect with a fewer content of MSSiG.