海泡石对膨胀阻燃聚丙烯燃烧和热分解的影响

将改性后的海泡石添加到聚磷酸铵(APP)和双季戊四醇(DPER)膨胀阻燃聚丙烯(PP/IFR)体系中,采用氧指数(LOI)、热重分析(TGA)、光电子能谱(XPS)、傅里叶变换红外(FTIR)光谱、锥形量热仪(CONE)和扫描电镜(SEM)考察其对膨胀阻燃体系的催化协效作用,探讨作用机理.LOI结果表明,改性的海泡石比纳米水滑石和有机改性的蒙脱土有更好的催化协效作用.CONE数据证实,海泡石可以降低膨胀阻燃聚丙烯体系的热释放速率和总的热释放量.通过观察SEM图片发现,海泡石可以改善膨胀炭层的形貌,提高炭层的隔热隔质性能.TGA结果表明,在氮气和空气气氛下,海泡石均可以提高膨胀炭层的热稳定性,增加高温时残余物的量,其主要作用对象为APP.FTIR和XPS测试发现加热过程中海泡石可以与APP发生化学反应,形成P—O—Si键,增加了APP高温时的稳定性.

Effect of Sepiolite on the Combustion and Thermal Decomposition of Intumescent Flame Retardant Polypropylene

We added modified sepiolite to a polypropylene (PP)/ammoniumpolyphosphate (APP)/di-pentaerythritol (DPER) composite to study the effect of sepiolite on the retarding behavior of the intumescent flame retardant (IFR) PP flame. The flame retarding behavior of the PP/IFR composite was tested using the limiting oxygen index (LOI) and cone calorimeter tests (CONE). The results show that sepiolite increases the LOI value of the PP/IFR and it is more effective than other nano-fillers such as layered double hydroxides (LDH) and organic montmorillonite (OMMT). The sepiolite decreases the heat release rate (HRR) and the total heat release (THR) of the PP/IFR composite. The flame- retardant mechanism of the PP/IFR/sepiolite system is also discussed in terms of catalytic charring after analysis by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). For the binary APP/DPER mixture, sepiolite reduces the mass loss rate and increases the amount of residue at high temperature under nitrogen and air atmospheres. This has been considered to be strongly associated with the interaction between sepiolite and APP. FTIR and XPS results show that the P—O—Si bond forms at high temperature for binary mixtures of APP/sepiolite. With the addition of sepiolite to the PP/IFR, the char residue burnt is dense and homogeneous, which is important for the flame retardant performance.