均四甲苯基中间相沥青纤维不熔化行为的研究

STABILIZATION OF MESOPHASE PITCH FIBERS FROM DURENE METHYLENE-BRIDGED OLIGOMERS

由均四甲苯出发，通过甲醛／Ｈ＋交联及进一步热处理合成了低软化点（２６０℃）、高Ｈ／Ｃ原子比（０．８６）、富含甲基基团、分子结构呈完全渺位缩合构型的中间相沥青。研究了该中间相沥青纤维的不熔化行为，发现它呈现出与一般石油系或煤焦油系中间相沥青的不同氧化行为，虽然具有较高的氧化反应性（在１５０℃开始与氧反应），但要实现纤维的完全不熔化却需较多量的氧与之交联。以０．２℃·ｍｉｎ－１（１７０℃～２６０℃）的升温速率升到２６０℃，恒温１８０ｍｉｎ得到的不熔化纤维的氧含量达１７．６％，其炭纤维强度可达２１００ＭＰａ。沥青呈现高氧化反应性的原因在于体系中含有较多量的甲基、亚甲基及孤立芳氢，它们引发了氧化反应的快速；中间相沥青的渺位缩合构型分子及小芳香核片的存在是不熔化过程需要多量氧的原因。

A novel mesophase pitch with lower softening point (260℃), higher H/C atomic ratio (0.86), abundant methyl and some amount of naphthenic groups and kata type polyaromatic molecular skeleton was prepared from Durene by sym trioxane/H + cross linkage and further heat treatment. In this paper, the stabilization of Durene based mesophase pitch fiber was studied by TG,infusibility variations and elemental analysis. It was found that the mesophase pitch fiber exhibits different oxidation behaviours in comparison with mesophase pitch fibers from petroleum pitch, coal tar pitch and naphthalene based pitch synthesized by HF/BF 3. The Du based mesophase pitch fiber not only exhibits higher reactivity with oxygen,but also needs more oxygen uptake to make it infusible.It is an interesting characteristic for the synthetic mesophase pitch, which may be attributed to the structural features of mesophase pitch. Abundant methyls, naphthenic groups and isolated aromatic C H groups present in the molecules promote the chemical reactivity with oxygen, while the slightly low aromaticity and condensation degree of component molecules make it need more oxygen cross linkage between molecules.