Study On Modified Epoxy Resin Prepreg And Composites

Epoxy resin has been widely used in the field of composites, because of its excellent mechanical properties, electrical insulation properties, corrosion resistance, adhesion properties and processing properties. However, the shortage of heat resistance limited the application of advanced technology fields. In this paper, aiming at the shortage of epoxy resin (E-51), it modified by cyanate ester resin and potassium titanate whisker, the heat resistance and mechanical properties of composites discussed and got the best effect.Firstly, the micronized dicyandiamide was selected as curing agent, epoxy prepreg and composites were prepared. The best amount of curing agent by infrared analysis, the effect of temperature on the gel time, the glass transition temperature and mechanical properties of composites were tested. When the dicyandiamide content is 7%(weight), the gel time is 23min at 120℃. The glass transition temperature of the composite is 165.9℃. Tensile strength, tensile modulus and elongation at break of the composite is 361.22 MPa,9.04 GPa and 4.27%, respectively. The flexural strength and flexural modulus are 550.42 MPa and 17.57 GPa.Secondly, epoxy resin (E-51) was modified with bisphenol A dicyanate, the glass transition temperature, tensile properties, flexural properties and moisture absorption of composites were tested. The results show that the glass transition temperature of the composites significantly improved with the incorporation of cyanate ester resin. When the mass ratio of epoxy/cyanate ester is 50/50, the glass transition temperature of the composite is 215.6℃. Compared to unmodified epoxy composite, it increased by 49.7℃. But the tensile and flexural properties of the composites were decreased by 19.09% and 12.05%. The water absorption of composites significantly decreased with the corporation of cyanate ester, when the mass ratio of epoxy/cyanate ester is 70/30, the water absorption of the composite is the lowest.Finally, potassium titanate whiskers were treated with silane coupling agent (KH-550) and modified with cyanate ester/epoxy, the heat resistance and mechanical properties of composites were discussed. We can draw the conclusion, the interface compatibility of resin and whiskers increased after potassium titanate whiskers were treated by KH-550. When adding whiskers to the composites, the thermal decomposition temperature and char yield of composites increased, tensile strength and flexural strength increased first and then decreased. SEM analysis showed that whiskers and resin matrix have a good compatibility with the proper amount of potassium titanate whiskers. When the mass content of potassium titanate whiskers increased, the dispersion of whiskers are poor in the resin, agglomerate easily, this results in the decrease of the mechanical properties of the composites.