同步辐射小角X射线散射研究PAN原丝制备过程中孔结构的演变

采用同步辐射小角X射线散射研究了PAN原丝制备过程中纤维孔结构的演变。结果表明,在水洗工艺中,纤维孔隙较多、较大,孔径分布较宽,近似圆形;在热水牵伸工艺中,纤维孔隙仍较多、较大,孔径分布较宽,近似椭圆形,长轴约17 nm~21 nm,短轴约4 nm~11 nm;在干燥致密化工艺中,孔隙急剧减少、减小,孔径分布较窄,沿纤维轴向约7 nm~9nm,垂直纤维轴向约2 nm;经过蒸汽牵伸,孔隙又增多、增大,孔径分布变宽,孔隙沿纤维轴向被牵伸得很长,近似梭形;但是随后的松弛热定型又使孔隙减小,孔径分布变窄。

Pore Structure Evolution in PAN Fibers During Preparation by Synchrotron Radiation Small Angle X-Ray Scattering

The pore structure changes of the PAN fibers were characterized by synchrotron radiation small angle X-ray scattering.It is found that the pores in fibers formed during washing are rich and large,having a quasi-spherical shape and a wide size distribution.The stretching of fibers in hot water elongates the pores,leading to an ellipsoidal shape with 17 nm～21 nm in long axis and 4 nm～11 nm in short axis.The drying of fibers leads to a decrease in size and amount of pores,7 nm～9 nm along the axis and ≈2nm perpendicular to the axis,and a narrow pore size distribution.The steam stretching of fibers increases the amount of pores and elongates significantly the pores along the fiber axis.The heat treatment of fibers makes the pore size smaller and the pore size distribution narrower.