Electroinsulating And Fire Retardant Properties Of Glass Fiber-reinforced Resin Composites Used In High-speed Train

With the development of high-speed train, the security of materials used in high-speed train is more and more important. Glass fiber-reinforced resin composites (GFR), with excellent electroinsulating property and excellent fire retardant property when fire-retardandes had been added in, are the perfect materiales for the insulating and fireproof components of high-speed train.This paper studied the effects of resin and glass fiber, preparation process and technological parameter, service condition, environmental aging, fire-retardand on the electroinsulating property of GFR. The results show that the dielectric strength of GFR. made by VIMP process was higher than that of the GFR made by hand layup and bag moulding process. The dielectric strength of GFR quickly decreased at the initial stages of environmental test. For the hygrothermal aging, salt fog andultraviolet (UV) irradiation testes, the decreasing velocities of the dielectric strength were 0.39 KV/(mm·d), 0.56 KV/(mm·d) and 0.43 KV/(mm·d), respectively. The descent velocity of the dielectric strength of GFR was the greatest, 0.14 KV/(mm·℃),when the measuring temperature was at the glass-transition temperature of the resin matix. The dielectric strength of the resin and glass fiber-reinforced resin composites was reduced by the tensile stress. The equation for expressing the relationship between dielectric strength and tensile stress in resin, was proposed and experimentally proved. When tensile stress was 40% of the tensile strength of resin matix, the dielectric strength of the resin had reduced by 14.98%. While for the composites, the interface of the fiber and resin played a dominant role in affecting dielectric strength of composites, and there was no negative exponential equation between dielectric strength and tensile stress. When longitudinal and transverse tensile stress were 50% of the longitudinal and transverse tensile strength of unique direction glass fiber reinforced composites, the dielectric strength reduced by 19.86% and 12.59%, respectively. Fire retardand, such as ATH(AlOH₃) and DMMP(Dimethyl Methyl Phosphonate), could enhance the electroinsulating properties of resin matix and composites. For the ratio of DMMP less than 10 phr, the dielectric strength of resin matix and composites could be increased by DMMP . When the ratio was 5 phr, the dielectric strength of resin matix and composites was the maximum , 19.95 KV/mm and 8.80 KV/mm, respectively. For the ratio of ATH at 80 phr, the dielectric strength of resin matix and composites still could be increased by ATH . When the ratio was 60 phr, the dielectric strength of resin matix and composites was the maximum , 28.85 KV/mm and 9.25 KV/mm, respectively. A kind of bicomponent fire retardant formulation resin with excellent mechanical and fire retardant properties, which could be used for the vacuum infusion molding process (VIMP), had been developed. Effects of measuring temperature and environmental aging on dielectric strength of bicomponent fire retardand resin composites were studied. The bicomponent fire retardant formulation resin was made up of 9001-I-1 unsaturated polyester, ATH and DMMP . When the ratios of ATH and DMMP were respectively 80 phr and 15 phr, the tensile strength, tensile modulus, flexural strength and modulus of the glass fiber-reinforced resin composites made by bicomponent fire retardant formulation resin were 584.35 MPa, 304.39 GPa, 425.44 MPa and 213.51 GPa, respectively. And the OI of the composites was 61.9%, which exceeded the first degree of National fire retardant standard(45%).