以六水合氯化钇(YCl3?6H2O)和次磷酸钠(NaH2PO2)为原料，采用共沉淀法制备了一种新型稀土金属次磷酸盐—次磷酸钇(YHP)，对其进行了表征；以YHP为阻燃剂，采用熔融共混法制备了系列玻纤增强聚酰胺6(GFPA)/次磷酸钇复合材料(GFPA/YHP)，采用热重、极限氧指数(LOI)、UL-94垂直燃烧和微型量热测试研究了YHP添加量对复合材料热稳定性、阻燃性能及燃烧性能的影响. 结果表明，YHP已成功制备，其具有棒状结构，长度为20?100 ?m，宽度为5?20 ?m，热稳定性很高，降解温度T5%为410℃，最大热失重速率温度Tmax为412℃，750℃下热解的残炭率为90.8wt%. 加入YHP降低了GFPA/YHP复合材料的热分解温度，但提高了其成炭率和高温稳定性，YHP添加量为20wt%时，复合材料的热分解温度为373℃，最大热失重速率温度为414℃，700℃下热解的残炭率为50.42wt%；YHP可有效提高复合材料的阻燃性能，极限氧指数(LOI)达27.5vol%，垂直燃烧级别达UL-94 V-1级；YHP可有效降低复合材料燃烧过程的热释放速率峰值(PHRR)和总放热(THR)量，二者分别降至327 W/g和15.8 kJ/g，比GFPA分别下降了14.1%和25.4%，表明YHP有效降低了GFPA/YHP复合材料燃烧的火灾危险性.
A novel rare earth hypophosphite—yttrium hypophosphite (YHP) was synthesized by co-precipitation method using yttrium(III) chloride hexahydrate (YCl3?6H2O) and sodium hypophosphite (NaH2PO2) as raw materials, and it was characterized by XRD, FT-IR, SEM and TGA. Furthermore, YHP was used as flame retardant to prepare a series of glass fiber reinforced polyamide 6/yttrium hypophosphite composites (GFPA/YHP) by melting bending method. TG, limiting oxygen index (LOI) test, underwriters laboratories (UL) 94 (UL-94) testing and microscale combustion calorimetry (MCC) were used to investigate the effects of YHP loading on thermal stability, flame retardany and combustion properties of GFPA/YHP composites. The results showed that YHP was prepared, it presented rod-like structures with a size of 20?100 ?m in length and 5?20 ?m in width, and presented high thermal stability with degradation temperature (T5%) of 410℃, maximal mass loss rate temperature (Tmax) of 410℃ and char residue at 750℃ of 90.8wt%. The addition of YHP decreased T5% but increased char residue and thermal stability in high temperature of GFPA/YHP composites. When 20wt% YHP was loaded, GFPA/YHP20 presented T5% of 373℃ with Tmax of 414℃ and char residue at 700℃ of 50.42wt%. YHP could significantly enhance flame retardancy of the composites, GFPA/YHP20 (with 20wt% YHP) reached UL-94 V-1 rating with limiting oxygen index (LOI) of 27.5vol%. YHP could significantly decrease heat release rate (PHRR) and total heat release (THR) of GFPA/YHP composites in combustion process. PHRR and THR values of GFPA/YHP20 were decrease to 327 W/g and 15.8 kJ/g, which were reduced 14.1% and 25.1% compared with GFPA, indicating YHP could effectively reduce fire hazard of GFPA/YHP composites in combustion process.
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