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.
Gang TANG Haohao JIANG Lijuan CHEN Hao ZHANG Chunlin LIU Zijian ZHOU
. Preparation of glass fiber reinforced polyamide 6/yttrium hypophosphite composites and their flame retardant properties[J]. The Chinese Journal of Process Engineering, 2018
, 18(6)
: 1340
-1346
.
DOI: 10.12034/j.issn.1009-606X.218104
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