ポリエチレンの熱分解と分子量変化が及ぼす燃焼性

摘要

高分子材料はこれまで本来的に可燃性であるとされてきた為，5%から60%程度添加剤を加え難燃性をもたせてきた．本報では，ポリエチレン（PE）の高分子のマトリックス構造の変化における燃焼性を解析した．重量平均分子量76，000以上のPEは一次的な分解で溶融し，下に落下していく間に二次的な分解が起こり燃焼していると考えられる．一方，重量平均分子量35，000のPEは着火することなく溶融し，Fに落下し続けた．したがって，本実験方法において垂崖平均分子最が35，000のPEは着火もせず燃焼が継続しないことが明らかになった．しかし，分子量の違いによる垂最減少挙動に違いは見られず，また，TGによって同様に熱履歴を与えた後の試料の分子量分布は，同熱分解率では同分子量にピークが計測された．分子量が異なる場合でも，PEはランダムに分解し，分解生成物の構造は類似のものであると推定された．%The combustion of polyethylene (PE) was studied from the point of view of their molecular weight by the UL combustion test, which has been widely applied to evaluate the fire retardancy of polymeric materials. The PEs whose molecular weights were above 76,000g/mol burnt out but the PE with a molecular weight of 35,000 g/mol did not burn after the ignition by a butane burner during the UL combustion test. The weight loss rates of both kinds of PE during the combustion procedure were the same although the combustions were quite different. The PEs with a molecular weights above 76,000 burnt out. However, we consider that rather than burning by direct combustion, the PE first melted and the melted specimen decomposed during its dropping and burning. Moreover, the molecular weight of the low molar mass PE, which dripped during the UL combustion test, did not change during burning. These results suggest PE can be used as non-flammable material.