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用DSC以5℃/min的升温速度从室温到280℃对聚丙烯腈原丝(PAN)进行模拟预氧化实验,并研究了以一定的牵伸倍数在180~275℃度范围内的实际预氧化过程中250~275℃的样品的XRD图谱。借助XRD分析,考察了PAN原丝模拟预氧化和实际预氧化过程中从线性结构向环状结构转变的环化机理。利用群子统计理论探讨了PAN在预氧化过程中成环和成线的竞争关系,并求出了在250~275℃内反应活化能。结果表明随着预氧化的温度增加,模拟预氧化和实际预氧化的环化程度均增加;在一定的预牵伸条件下,实际预氧化的反应活化能(49.942KJ/mol)要比模拟与氧化的活化能(84.072KJ/mol)小。
Poly (acrylic acid) PAN filaments (PAN) were pre-oxidized by DSC at room temperature to 280 ℃ with a heating rate of 5 ℃ / min. The experimental results showed that PAN with a certain draw ratio of 180 ~ 275 ℃ XRD patterns of samples at 250-275 ° C during oxidation. By means of XRD analysis, the cyclization mechanism of transition from linear structure to cyclic structure in simulated and pre-oxidized PAN filaments was investigated. Based on the theory of subgroup statistics, the competitive relationship between ring formation and formation of the PAN in the preoxidation process was discussed. The activation energy of reaction at 250-275 ℃ was obtained. The results show that with the increase of pre-oxidation temperature, the degree of cyclization of simulated pre-oxidation and actual pre-oxidation both increase. Under certain pre-draw conditions, the actual activation energy of pre-oxidation (49.942 KJ / mol) The activation energy of oxidation (84.072KJ / mol) is small.