各向同性沥青改性的中间相沥青纤维预氧化研究

Oxidative Stabilization of Precursor Fibers from Mesophase Pitch Modified with Isotropic Pitch

以各向同性沥青改性的中间相沥青为原料,经熔融纺丝、氧化及碳化处理得到沥青基碳纤维,重点研究了原丝的氧化行为.偏光显微镜研究表明,混合沥青为两相不相容共混物,中间相沥青为连续相,各向同性沥青为分散相.氧化过程中,沥青的脂肪氢和芳氢被脱除,主要生成羰基,醚键.随着氧化时间的延长,纤维中含氧量逐渐提高.当氧化时间较短时,纤维氧化不足,碳纤维芯部出现孔洞,微观组织呈现大片层结构.随着氧化程度逐渐提高,截面孔洞逐渐减小并最终消失,同时,碳纤维的强度显著提高;但是当原丝过度氧化时,碳纤维强度反而下降.

In this work,oxidation behaviors of the precursor fibers from mesophase pitch modified with isotropie pitch were studied by polarized light mieroseopy, infrared spectroscopy, elemental analysis, scanning eleetron mieroseope and mechanical testing. The blended pitch precursor exhibited a two-phase incompatible system where the mesophase pitch was the continuous phase and the isotropic pitch was the dispersed phase. During oxidative stabilization, hydrogen in aliphatie and aromatie hydrocarbons were oxidized and generated C=O and C-O-C bonds,and the oxygen content of the oxidized fibers increased with time. For incompletely oxidized fibers,the final carbon fibers had a skin-core structure or were even hollow. The optimal meehanieal properties of the carbon fibers were only obtainable when the precursor fibers were properly oxidized, and either insufficient oxidation or over-oxidation was detrimental to mechanieal properties.