丙烯腈/溴乙烯共聚纤维稳定化过程的特点

本文采用红外光谱分析、X 射线衍射分析、差示扫描量热分析、热机械分析、热重分析等实验手段,研究了丙烯腈(AN)/溴乙烯(VBr)共聚纤维在加热过程中环结构的形成、环化反应的特点、环化活化能的大小及 VBr 含量对环化的影响。结果表明共聚组分 VBr 对环化时氰基的聚合(oligome-rization)有着强烈的引发作用,使环化活化能下降,以致在比较低的温度下就能进行环化反应。在DSC 图谱上,于环化放热主峰前呈现一个很宽的峰肩部分,放热范围变宽。放热过程趋于缓和。因此 AN/VBr 共聚纤维非常适合于作为碳纤维原丝。此外共聚组分 VBr 的含量对纤维的放热特性、环化度和环化序列长度都有显著影响。研究表明 VBr 含量在6%左右较为合适。含量过高,稳定化处理时纤维的环化度和环化序列长度反而有所下降。

THE CHARACTERISTICS OF AN/VBr COPOLYMER FIBERS DURING STABILIZATION

In this paper the formation of cyclized struoture during heat treatmeut and thecharacteristic of cyclized process as well as the magnitude of activation energy forcyclization of the acrylonitrile(AN)/vinyl bromide(VBr)copolymer fibers wereinvestigated by means of infra-red spectra,X-ray diffraction,differential scanningcalorimetry,thermomechanical analysis and thermogravimetry.The effect of VBrcontent on cyclization was also discussed.The results indicated that the copolymercomposition VBr strongly affects the initiation of the CN oligomerization.Theactivation energy for cyclization of AN/VBr copolymer fiber is lower than that ofPAN fiber,hence permining the cyclization reaction to proceed at lower tempera-ture.Before the main exothermic peak,there appears a shoulder on the DSCthermogram.The heat release is spread over a broad range of temperature.Thereforeit is very suitable that AN/VBr copolymer fibers are used as carbon fiber precursor.The VBr content in AN/VBr copolymer markedly affects the exothemic characteristicof fiber,the cyclization degree and the length of the cyclized sequences.The opti-mum appears to be roughly 6%(w%)VBr in the copolymer.Too great amount ofVBr leads to a decrease of cyclization degree and of length of the cyclized sequences.