埃洛石-二氧化锆改性聚磷腈橡胶基复合材料高温烧蚀行为和原位陶瓷化反应

Ablative behavior and in-situ ceramization mechanism of poly(diaryloxyphosphazene)rubber matrix compositesm odified with Halloysite-ZrO_(2) under high temperature

聚磷腈橡胶(PDPP)具有优异的阻燃性、热稳定性和高残炭率,是一种潜在的制备耐烧蚀绝热层的橡胶基体。为提高PDPP复合材料的耐烧蚀性,以埃洛石(HAL)和二氧化锆(ZrO_(2))为陶瓷化填料制备了HAL-ZrO_(2)-PDPP基复合材料,研究了这种混合陶瓷化体系对复合材料力学性能、热稳定性和烧蚀性能的影响。结果表明,HAL和ZrO_(2)陶瓷化填料对PDPP复合材料的拉伸力学性能和热稳定性无明显影响;含5 phr HAL和15 phr ZrO_(2)的PDPP复合材料拉伸强度为4.57 MPa,断裂伸长率为104.4%,经氧乙炔烧蚀后的线烧蚀率为0.060 mm/s,相较于单独使用HAL和ZrO_(2)分别提高了43.4%和33.2%。XPD和XPS结果表明,PDPP橡胶基体热解后的残炭分别与SiO_(2)和ZrO_(2)发生了生成SiC和ZrC的原位陶瓷化反应。在烧蚀过程中,低熔点陶瓷化填料熔融将基体热解形成的炭层与高熔点陶瓷粘结,使之成为含陶瓷-玻璃-热解炭复相结构的致密且具有一定强度的类陶瓷层,对提高复合材料的耐烧蚀性有积极作用。

Poly(diaryloxyphosphazene) rubber is a potential matrix for the preparation of thermal insulation materials due to its excellent flame retardant,thermal stability and high carbon residue rate.In order to improve the ablative resistance of poly(diaryloxyphosphazene) rubber composites,HAL-ZrO_(2) poly(diaryloxyphosphazene) rubber matrix composites were prepared by using Halloysite(HAL) and ZrO_(2) as ceramic fillers.The effects of the mixed ceramicizable system on the mechanical properties,thermal stability and ablative properties of the composites were studied.The results show that HAL and ZrO_(2) have no effect on the tensile mechanical properties and thermal stability of PDPP composites.The tensile strength of PDPP composites with 5 phr HAL and 15 phr ZrO_(2) mixed ceramic system is 4.57 MPa and the elongation at break is 104.4%,and the linear ablation rate of the composites after oxyacetylyne ablation is 0.060 mm/s,which is 43.4% and 33.2% higher than that of HAL and ZrO_(2) alone.XRD and XPS show that the residual carbon after pyrolysis of the rubber matrix has in situ ceramic reaction with SiO_(2) and ZrO_(2) to form SiC and ZrC,respectively.During the ablation process,the low melting point ceramic filler bonded the carbon layer formed by the pyrolysis of the matrix with the high melting point ceramics,making it become a dense and strong ceramic-like layer containing the ceramic-glass-pyrolysis carbon composite structure,which plays a positive role in improving the ablation resistance of the composites.