含氮酚醛微球阻燃有机硅橡胶及其作用机制

Nitrogen-Enriched Phenolic Microspheres as Flame Retardant for Organic Silicone Rubber and Its Mechanism

以三聚氰胺、间苯二酚和甲醛为原料,采用水热法制备出一种单分散的含氮酚醛微球,将其作为填料加入甲基苯基硅橡胶,研究了所制硅橡胶材料的拉伸性能、阻燃性能及高温稳定性。锥形量热仪与极限氧指数试验结果表明,含氮酚醛微球的加入能够显著提高硅橡胶的阻燃性,使热释放速率峰值从220kW/m^(2)降至125kW/m^(2),极限氧指数从21.11%升至28.83%,表现出含氮酚醛微球优异的阻燃功能。进一步通过热重-红外联用、热裂解-气质联用、形貌分析等表明,含氮酚醛微球通过在气相中释放三聚氰胺、氨气等气体,以及在固相中维持硅橡胶体积和形状的方式提高了硅橡胶的阻燃性。拉伸试验、高温炭化试验及扫描电镜分析表明,含氮酚醛微球与硅橡胶的相容性较好,能够显著将硅橡胶的拉伸强度从0.24MPa提升至0.74MPa,同时维持其断裂伸长率在110%左右,并能增加炭化后产品的结构完整性,在耐烧蚀硅橡胶防热涂层中具有一定的应用潜力。

Monodisperse nitrogen-enriched phenolic microspheres were synthesized by hydrothermal method using melamine,resorcinol and formaldehyde as raw material,and used as filler for methyl phenyl silicone rubber.The tensile properties,flame retardant properties and high temperature stability of the silicone rubbers were studied.The results of cone calorimetry and limiting oxygen index(LOI)tests show that the addition of nitrogen-enriched phenolic microspheres(40 phr)significantly improves the flame retardant of silicone rubbers.The peak heat release rate is reduced from 220 kW/m^(2) to 125 kW/m^(2) and the LOI is improved from 21.11%to 28.83%,indicating the excellent flame retardant function of nitrogen-enriched microspheres.Thermogravimetric-infrared,pyrolysis gas chromatography mass/spectrometry and morphology analysis indicate that the nitrogen-enriched phenolic microspheres improve the flame retardancy of silicone rubbers by releasing melamine and ammonia in gas phase and maintaining the volume and shape of silicone rubber in solid phase.The tensile test,high temperature carbonization test and SEM reveal that nitrogen-enriched phenolic microspheres have the good compatibility with silicone rubber,improve the tensile strength of the rubber from 0.24 MPa to 0.74 MPa while maintaining its elongation at break at 110%,and increase the structural integrity of the product after carbonization,so have certain potential applications in ablative silicone rubber heat resistance coating.