通过红外光谱(FT-IR)、X射线衍射(XRD)和力学性能等测试手段研究了不同丝束PAN纤维预氧化过程中化学结构、晶体结构和力学性能的变化。结果表明:大丝束有蓄热现象,预氧化前期,由于PAN纤维的导热性差,大丝束温度上升慢,表现为75K预氧化纤维的环化程度低于50K;预氧化后期,化学反应开始加速时,对于大丝束来说,化学反应释放的热量难以及时释放到环境中去,从而热量聚集在纤维束内部,大丝束的环化程度较大。并且,大丝束预氧化纤维中间部分和边缘部分结构上有差异,中间部分的环化程度高于边缘部分。PAN纤维的非晶区在预氧化初期分子链结构重组并向有序化转变,之后化学反应加速使晶区破坏,晶粒尺寸呈先增大后减小的趋势。
The changes of chemical structure,crystal structure and mechanical properties of PAN fibers with different tows during pre-oxidation were studied by infrared spectrum (FT-IR),X-ray diffraction (XRD) and mechanical properties tests.The results showed that the large tow had heat storage phenomenon.In the early stage of pre-oxidation,the temperature of the large tow rose slowly due to the poor thermal conductivity of the PAN fibers,and the cyclization degree of the 75K pre-oxidized fiber was lower than 50K.In the later stage of pre-oxidation,when the chemical reaction began to accelerate,the heat caused by the chemical reaction was difficult to be released into the environment in time for the large tow,so that the heat accumulated in the interior of the fiber bundle,and the cyclization degree of the large tow was relatively higher.Moreover,there were structural differences between the middle part and the edge part of the pre-oxidized large tow fibers,and the cyclization degree of the middle part was higher than that of the edge part.At the initial stage of pre-oxidation,the molecular chain structure of the amorphous region of PAN fiber was reorganized and changed to order.After that,as the chemical reaction accelerated,the crystal regions were destroyed,and the grain size increased first and then decreased.
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基金资助
吉林省重大科技专项(YDZJ202203CGZH025);吉林省碳纤维产业创新中心项目(2022C002)
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