聚丙烯腈基炭纤维中微孔的演变规律  

Evolution of microvoids in PAN-based carbon fibers

作　　者：李登华[1,2] 吴刚平[1] 吕春祥[1] 李永红[1] 贺福[1] 冯志海[3] 李秀涛[3] 郭玉明[3] 

机构地区：[1]中国科学院山西煤炭化学研究所中国科学院炭材料重点实验室,山西太原030001 [2]中国科学院研究生院,北京100049 [3]中国航天科技集团公司第一研究院航天材料及工艺研究所,北京100076

出　　处：《新型炭材料》2010年第1期41-47,共7页New Carbon Materials

摘　　要：利用二维小角X射线散射技术(SAXS),结合纤维孔结构解析理论及分形原理得到了炭纤维形成过程中纺丝、预氧化、低温和高温炭化等四个阶段样品的微孔结构信息。结果表明:原丝中孔隙沿纤维轴向择优取向,呈长梭状,其长轴与短轴的平均尺寸分别为24.3nm和19.2nm,长径比为1.27。遗留到预氧化阶段的原丝孔洞使得预氧化纤维出现高达1.85的长径比极大值,这可能与原丝线性结构向预氧丝耐热梯形结构转化有关。炭化阶段微孔尺寸迅速减小,长轴、短轴分别达到3.56nm和2.85nm左右,长径比也减小至1.24。分形状态研究表明:表面分形维数DS值介于2.42～2.88之间,且随工艺的进行逐渐增大,低温炭化阶段变化幅度较大,说明各级产品在微观结构上越来越复杂,亦证明低温炭化是促进炭纤维微观结构转变的重要的工艺段。Microvoids,formed in spinning,oxidation and carbonization during the preparation of PAN-based carbon fibers,were investigated by two-dimensional small angle X-ray scattering. Results indicated that microvoids in PAN fibers had a preferred elongation and orientation along the fiber axis with an average length of 24.3 nm,diameter of 19.2 nm and aspect ratio of around 1.27. The size of the microvoids remained almost unchanged during oxidation,while their aspect ratio increased to 1.85,possibly due to a crystalline transformation from a linear structure in PAN fibers to a heat-resistant ladder structure in oxidized fibers. However,the size of the microvoids decreased dramatically to about 3.56 nm in the long axis and 2.85 nm in the short axis during carbonization. The surface fractal dimension （Ds） increased in these processes from 2.42 to 2.88 and the most severe change occurred in low-temperature carbonization,indicating that surface roughness increased during processing,and carbonization was the most important process for such a transformation.

关 键 词：炭纤维 微孔 分形维数 X射线小角散射 

分 类 号：TQ342.742[化学工程—化纤工业]