氢氧化铝包覆改性聚磷酸铵及其在阻燃聚丙烯中的应用研究

针对聚磷酸铵(APP)有一定的水溶解性和阻燃效率不高等问题, 提出了采用氢氧化铝(ATH)包覆改性APP的方法。X射线荧光光谱(XRF)和扫描电镜(SEM)分析结果显示, 在APP颗粒表面实现了ATH的包覆改性。测试表明, ATH包覆改性后的APP溶解度明显下降, 比表面大幅增加。将改性后的APP与双季戊四醇(DPER)复配, 作为膨胀阻燃剂添加到PP中, 阻燃PP的燃烧性能测试结果表明: 阻燃剂总添加量为25%时, 包覆ATH的APP使阻燃PP 3.2 mm样条的垂直燃烧级别从V-1提高到V-0, 氧指数(LOI)从26.6%增加到31.8%, 热释放速率峰值(PHRR)从475 kW/m²下降至308 kW/m², 下降了约35%。对阻燃PP的燃烧残炭研究说明, APP经ATH包覆改性后, 促进了阻燃PP在燃烧时形成更加完整均匀的炭层, 因而改善了阻燃性能。

Preparation of Ammonium Polyphosphate Coated with Aluminium Hydroxide and Its Application in Polypropylene as Flame Retardant

A new surface-modification method was adopted to decrease water solubility and enhance flame retradancy of ammonium polyphosphate (APP) by means of coating with aluminium hydroxide (ATH). The data of X-Ray Fluorescence Spectrometer (XRF) and scanning electron microscope (SEM) demonstrated that ATH was deposited on the surface of APP particles, and lower water resistance and rougher surface were verified. Furthermore, the modified APP was applied with dipentaerythritol (DPER) to prepare flame retarded polypropylene (FR-PP). The combustion behaviors of FR-PP were studied by limiting oxygen index (LOI), UL 94 vertical burning and cone calorimeter tests. Results show that loading of the coated APP has improved flame retardancy of FR-PP composites remarkably. Compared with unmodified APP, PP/DPER/coated APP can pass V-0 in UL 94 test, LOI value increases from 26.6% to 31.8%, and the peak heat release rate (PHRR) decreases from 475 kW/m² to 308 kW/m². Finally, study on char residues of FR-PP composites indicates that APP coated with ATH makes char layer more complete and more compact, which contributes to the improvement of flame retardancy.