硼酸锌
阻燃剂
镁
氢氧化锌
锌
硼
氢氧化物
材料科学
无机化学
吸热过程
热分解
化学工程
化学
有机化学
冶金
吸附
工程类
作者
A Genovese,Robert A. Shanks
标识
DOI:10.1016/j.polymdegradstab.2006.10.006
摘要
The mechanism of cooperative action of commercial fire retardants is interpreted as resulting from specific chemical reaction and phase changes. This investigation focuses on the thermally initiated interactions between two forms of commercially available fire retardant compounds. The fire performance of a polyolefin with a metal hydroxide fire retardant, magnesium hydroxide, can significantly reduce the heat release rate through absorption of heat during conversion to its metal oxide. Formation of water, followed by vaporisation, decreases heat and dilutes volatiles from polymer degradation. The second form of fire retardant compounds are zinc borates (2ZnO·3B2O3·3H2O and 4ZnO·B2O3·H2O), that undergo dehydration with increasing temperature. Differential thermal analysis and wide-angle X-ray spectroscopy indicated that various structural changes occurred during heating. Endothermic transitions were observed for all components, while zinc borate (2ZnO·3B2O3·3H2O) showed an exothermic crystallisation transition at relatively high temperature. The exotherm was modified by the development of a new crystalline phase, magnesium orthoborate (3MgO·B2O3) that formed on reaction with magnesium oxide (MgO) at temperatures greater than 500 °C. Formation of crystalline zinc oxide (ZnO) was also detected. From zinc borate (4ZnO·B2O3·H2O), ZnO was primarily formed. No new crystalline phases were observed in the presence of MgO over the temperature range investigated.
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