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[塑料] 塑料阻燃性深度总结(三)--阻燃作用机理

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发表于 2013-10-20 10:22:19 | 显示全部楼层 |阅读模式
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本帖最后由 846082533 于 2015-12-31 14:59 编辑 <br /><br />
1.3 阻燃
1.3.1 一般阻燃作用机理
12Although flame retardants may differ from one another in terms of chemical structure, certain general mechanisms of action are applicable to various classes of flame retardants. The first line of separation normally distinguishes gas-phase-active and condensed-phase-active flame retardants. Gas-phase-active
flame retardants act primarily through scavenging free radicals responsible for the branching of radical chain reactions in the flame. This is the chemical mechanism of action in the gas phase. Other flame retardants generate large amounts of noncombustible gases, which dilute flammable gases, sometimes dissociate endothermically, and decrease the temperature by absorbing heat. This slows combustion and may eventually result in extinguishment of the flame. This is the physical mechanism of action in the gas phase.
尽管各种阻燃剂的化学结构不同,但通用的作用机理是可适用于多种阻燃剂的。通常根据作用机理,可将其分为气相作用阻燃剂凝聚相作用阻燃剂两大类。气相作用阻燃剂主要通过捕捉燃烧的链支化反应所需的活性自由基发挥作用,这是其化学作用的机理。另一类阻燃剂可产生大量的不可燃气体以稀释可燃气体,有时也可以通过吸热来降低材料表面温度。这有效降低了材料的可燃性,也可致其自熄。这是阻燃剂于气相中的物理作用机理
13Condensed-phase mechanisms of action are more numerous than the gas-phase mechanisms. Charring, discussed briefly above, is the most common condensed-phase mode of action. Again, charring could be promoted either by chemical interaction of the flame retardant and the polymer or by physical retention of the
polymer in the condensed phase. Charring could also be promoted by catalysis or oxidative dehydrogenation.
凝聚相作用机理比气相作用机理更为常见。前面简要讨论过的成炭是最为常见的凝聚相作用机理。提高材料的成炭性有多种途径:聚合物和阻燃剂的反应型成炭、聚合物在凝聚相滞留成炭或氧化脱氢成炭。
14Some flame retardants show almost exclusively a physical mode of action. Examples are aluminum hydroxide and magnesium hydroxide. On the other hand, there is no single flame retardant that will operate exclusively through a chemical mode of action. Chemical mechanisms are always accompanied by one or several physical mechanisms, most commonly endothermic dissociation or dilution of fuel. Combinations of several mechanisms can often be synergistic.
有些阻燃剂几乎是通过单一的物理作用机理阻燃的,例如氢氧化铝(ATH)和氢氧化镁(MH.然而,没有一种阻燃剂是通过单一的化学作用机理而阻燃的。化学作用机理通常伴随一种或多种物理机理(如分解导致的吸收热量或稀释可燃气体)发挥阻燃作用。多种阻燃机理配合发挥作用,称之为协效阻燃。


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