凝固过程聚丙烯腈(PAN)初生纤维在径向上各点的双扩散程度不同,可能会造成PAN纤维在径向上致密结构的差异。首先采用光密度法测定PAN初生纤维径向的致密结构及其差异性的可行性和影响因素,在此基础上采用光密度法研究了凝固浴温度对PAN初生纤维致密性结构差异的影响。结果表明:对于PAN初生纤维,采用纤维切片厚度为4μm、调整入射光强使背景灰度为140时进行PAN初生纤维光密度的测定;保持凝固浴浓度恒定不变,凝固浴温度从25℃升高到65℃会导致PAN初生纤维的灰度降低、光密度值增大、纤维径向皮部与芯部的光密度差值增大,这表明随着凝固浴温度的升高,纤维的致密性降低、径向致密结构差异增大。光密度法可以用来定量表征PAN纤维的径向结构及其差异。
The different degrees of double diffusion in the radial direction of polyacrylonitrile (PAN) nascent fibers during coagulation process may cause difference in the radial dense structure of PAN fibers.In this paper,the feasibility and influencing factors of optical density method for measuring the radial dense structure and difference of PAN nascent fibers were studied.On this basis,the influence of coagulation bath temperature on the dense structure differences of PAN nascent fibers was studied by optical density method.The results showed that the optical density of PAN nascent fibers was measured by adjusting the incident light intensity to make the background grayscale as 140 and the thickness of fiber slice to 4 μm for PAN nascent fibers.Keeping the concentration of the coagulation bath constant,with the increase of coagulating bath temperature from 25℃ to 65℃,the gray scale of PAN nascent fiber decreased,the optical density value increased,and the optical density difference between the radial cortex and core of the fiber increased.The results showed that with the increase of coagulation bath temperature,the fiber density decreases and the difference of radial density structure increased.Optical density method could be used to quantitatively characterize the radial structure of PAN fibers and their differences.
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基金资助
国家自然科学基金(U22B20142)
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