The Modification Of Glass Fiber Reinforced Benzoxazine Resin Composites At Cryogenic Temperature

In this paper,a novel kind of composite laminate was modified by using the glass fiber cloth as enhancosome and adopting different modifiers to modify benzoxazine resin as matrix.The scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FTIR),thermo gravimetric analysis(TGA)and differential scanning calorimetry(DSC)were used to investigate the properties of the composites.The infrared analysis showed that with the addition of propylene oxide copolymer glycol and polyether sulphone,the flexible polyether chain could be introduced into the rigid network structure of benzoxazine resin.The SEM analysis of composite section morphology indicated that the addition of propylene oxide copolymer glycol and polyether sulphone can not only enhance bonding ability between the resin matrix and glass fiber,but also increase the toughness of resin matrix.The mechanical properties of the composites were studied at the temperatures of 25 ? and-70 ?,respectively.The results indicated that the mechanical properties of the composites are optimized when the amount of propylene oxide copolymer glycol is 20 wt%.At 25 ?,the tensile strength of the composites increased by 13.8%the flexural strength increased by 12.2%,the flexural modulus increased by 17.6%and the interlaminar shear strength increased by 27.9%.At-70 ?,the tensile strength of the composites increased by 14.6%,the flexural strength increased by 44.2%the flexural modulus increased by 22.9%,and the interlaminar shear strength increased by 32.1%.With the modifier of polyether sulfone,the mechanical properties of the composites are optimized when the amount of polyether sulphone is 15 wt%.At 25 ?,the tensile strength of the composites is improved by 10.2%,the flexural strength increased by 13.4%,the tlexural modulus increased by 34.7%and interlaminar shear strength increased by 32.9%;At-70 ?.the tensile strength of composite material increased by 11%,the bending strength increased by 43.6%,the bending modulus increased by 35.1%and the interlaminar shear strength increased by 33.1%.The thermo gravimetric analysis showed that the thermal stability of the resin matrix did not change significantly when the propylene oxide copolymer glycol and the polyether sulphone were used as the modifier.The differential scanning calorimetry analysis showed that when the propylene oxide copolymer glycol was added as the modifier,when the addition amount of propylene oxide copolymer glycol was 20 wt%,the Tg of resin matrix depressed by 11?.When the polyether sulphone was used as the modifier,when the amount of the polyether sulphone was 15 wt%,the Tg increased by 7 ?.