Study On The Heat Resistant Property Of SiC/organosilicon Modified Phenolic Resin Composite

Phenolic resins(PF)are the pioneer industrialized and synthetical resins, which have been widely used in many fields due to their excellent flame resistance, insulativity, adhesivity and thermal stablity. Pure phenolic resins are commonly used in200℃for a long time, when heated to more than300℃,which will degrade quickly and possibly destroy the performance. Especially when phenolic resins used as ablation matrix materials, a higher carbon residue is needed in high temperature, so they should be modified to improve heat resistance, meeting in application requirements of high temperature fields. This paper studied phenolic resins modified by phenyltriethoxysilane(PTES) and SiC, both are mainly to improve the heat resistance, and to be used as heat resistant materials matrix.In this paper, we prepared and characterized phenyltriethoxysilane modified phenolic resin. We prepared phenyltriethoxysilane hydrolysis in certain conditions, and then they participated in the synthesis of phenolic resin reaction. The results showed that free phenol a little rose, the content of solid and carbon residue amount and thermal stability were remarkably improved when PTES modified phenolic resin. The results of Fourier transform infrared spectroscopy (FT-IR) proved that chemical reaction occurred between phenyltriethoxysilane hydrolysis and PF matrix. Thermo gravimetric analysis (TGA) test showed that the weight of20%PTES can greatly improve the thermo stability of PF, especially elevated the initial decomposition temperature to386℃, nearly40℃increased, and in800℃residual carbon was62.9%, a8.4%increase compared to common phenolic resin. And synchronous thermal analysis(TG-DSC-DTG) showed20%PTES modified phenolic had a higher weightlessness peak temperature in400~600℃, absorption and exothermic peak were moving toward a higher temperature, which proved the thermal stability of the resin improved.We also prepared and characterized nano SiC modified20%PTES/PF in this paper. The surface of SiC was treated by coupling agent KH-550, which can improve the interface compatibility between SiC particles and phenolic resin matrix.SEM analysis of the fracture surface of the SiC modified PTES/PF indicated that the SiC were uniformly dispersed in the PF matrix, with diameters ranging from200-300nm, but there still particles reunion. Thermo gravimetric analysis showed that when the content of SiC was3%,6%,9%,12%, the carbon residue in800℃were increased by2.2%,4.2%,5.3%and7.1%compared to PTES/PF. When the content of SiC was6%, tensile strength increased2.1MPa, impact strength increased0.48kJ/m2,but the amount of SiC more than6%, enhance did not play a significant role.