Bisphenol A-based benzoxazine (BOZ) was blended with cyanate ester (CE) to improve the properties of cyanate resin. The effects of the content of BOZ on the mechanical property and dielectric property of the blends have been investigated. The results show that a suitable addition of BOZ can enhance the impact strength and flexural strength as well as reduce the dielectric constant and the dielectric loss of CE. The mechanical properties are significantly improved when the content of BOZ is 10 wt%, and the dynamic mechanical analysis reveals that the cross-link density of the blend is lower than pure CE. Scanning electron microscopy analysis shows distinct characteristics of ductile fracture of the blends. In addition, the dielectric constant and the dielectric loss of modified system decreases, compared with the curing CE. The optimal addition amount of BOZ resin is 15 wt% for the dielectric properties. The blend of a suitable addition of BOZ still remains a good thermal resistance. All these changes in properties are closely correlated to the copolymerization between BOZ and CE.
Grafting of hyperbranched cyclotriphosphazene polymer (HBP) onto reduced graphene oxide (HBP-RGO) surface was achieved by the repeated reactions between the chlorine groups of hexachlorocyclotriphosphazene and the amino groups of hexamethylenediamine. FTIR and XPS analyses showed that hyperbranched cyclophosphazene-grafted graphene had been successfully prepared. AFM results showed that HBP-RGO had a dendritic structure as designed. TGA analysis indicated that HBP-RGO had good thermal stability. The dispersion showed that HBP-RGO is amphiphilic.
A novel reactive phosphorus-containing flame retardant was synthesized and used to modify bismaleimide resin. According to investigations, the modified bismaleimide resin has good mechanical properties, thermal stability and flame retardancy.
Poly(p-phenylene benzobisoxazole) (PBO) fibers were activated by the horseradish peroxidases (HRP) and then treated by 3-Glycidoxypropyltrimethoxysilane (KH-560) to improve the wettability and the interfacial adhesion between PBO fibers and cyanate ester matrix. The chemical compositions of PBO fibers were characterized and analyzed by FTIR and XPS. Surface morphologies of PBO fibers were examined by SEM. The wettability of PBO fibers was evaluated by the dynamic contact angle analysis test. The mechanical properties were evaluated by tensile strength and interfacial shear strength, respectively. The results demonstrated that hydroxyl groups and epoxy groups were introduced onto the surface of PBO fibers during the treatments. These treatments can effectively improve the wettability and adhesion of PBO fibers. The surface free energy of PBO fibers was increased from 31.1 mN/m to 55.2 mN/m, and the interfacial adhesion between PBO fiber and cyanate ester resin was improved to 10.77 MPa. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40204.
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