Holdsworth Alistair F, Horrocks A Richard, Kandola Baljinder K
Institute for Materials Research and Innovation, University of Bolton, Deane Road, Bolton, Greater Manchester BL3 6HQ, UK.
Now at School of Chemical Engineering and Analytical Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Polymers (Basel). 2020 Jul 13;12(7):1543. doi: 10.3390/polym12071543.
While environmental concerns have caused polymeric brominated primary flame retardants (PolyBrFRs) to be effective replacement monomeric species, few alternatives for antimony trioxide (ATO) have been developed beyond the zinc stannates (ZnSs). Previous research, which explored the interactions of aluminium (AlW), tin (II) (SnW) and zinc (ZnW) tungstates with several phosphorus-containing flame retardants in polyamide 6.6 (PA66), is extended to two PolyBrFRs: brominated polystyrene (BrPS), and poly(pentabromobenzyl acrylate) (BrPBz). On assessing the effect of each tungstate on the thermal degradation and flammability in combination with each PolyBrFR using TGA, UL94, LOI, cone calorimetry and TGA-FTIR, only ZnW and SnW showed significant increases in LOI (>26 vol.%). Both ZnW-BrPS- and ZnW-BrPBz-containing formulations yielded average UL94 ratings ≥ V-2 and TGA char residues (corrected for metals content at 500 °C) in air > 15 wt.%. BrPS-containing samples, especially those containing ZnW and SnW, generated peak heat release rates approximately 50% lower than the equivalent BrPBz samples. These reductions did not correlate with respective increases in LOI, suggesting that tungstate-PolyBrFR combinations influence pre-ignition differently to post-ignition behaviour. Calculated synergistic effectivities indicate that ZnW functions as a synergist in both pre- and post-ignition stages, especially with BrPS. TGA-FTIR and char analyses showed that, in addition to the vapour-phase activity normally associated with PolyBrFRs, condensed-phase processes occurred, especially for the ZnW-PolyBrFR combinations. Additionally, ZnW demonstrated significant smoke-suppressing properties comparable with zinc stannate (ZnS).
虽然环境问题使得聚合溴化 primary 阻燃剂（PolyBrFRs）成为有效的替代单体物种，但除了锡酸锌（ZnSs）之外，几乎没有开发出三氧化二锑（ATO）的其他替代品。先前的研究探索了钨酸铝（AlW）、钨酸锡（II）（SnW）和钨酸锌（ZnW）与聚酰胺6.6（PA66）中几种含磷阻燃剂的相互作用，现在将其扩展到两种PolyBrFRs：溴化聚苯乙烯（BrPS）和聚（五溴苄基丙烯酸酯）（BrPBz）。使用热重分析（TGA）、UL94、极限氧指数（LOI）、锥形量热法和TGA-傅里叶变换红外光谱（TGA-FTIR）评估每种钨酸盐与每种PolyBrFR组合对热降解和可燃性的影响时，只有ZnW和SnW的LOI有显著提高（>26体积%）。含ZnW-BrPS和含ZnW-BrPBz的配方平均UL94等级≥V-2，且在空气中500℃时的TGA残炭（校正金属含量后）>15 wt.%。含BrPS的样品，尤其是那些含ZnW和SnW的样品，其峰值热释放速率比等效的含BrPBz样品低约50%。这些降低与LOI的相应增加不相关，这表明钨酸盐-PolyBrFR组合对点火前行为和点火后行为的影响不同。计算得到的协同效应表明，ZnW在点火前和点火后阶段均起协同作用，尤其是与BrPS组合时。TGA-FTIR和残炭分析表明，除了通常与PolyBrFRs相关的气相活性外，还发生了凝聚相过程，尤其是对于ZnW-PolyBrFR组合。此外，ZnW表现出与锡酸锌（ZnS）相当的显著抑烟性能。
