利用TG-FTIR联用技术对Kevlar纤维的热解过程的分析

现代工业应用与技术领域要求材料具有良好的机械性质与热学性质，Kevlar纤维做为近年来材料领域研究的热点纤维材料，具有高强度、耐高温等良好的性能。纤维材料的性质依赖于自身的结构和组成，热分解过程对于研究材料的结构和热学性质有着十分重要的意义。热红联用技术做为一种新型的联用技术，既能定量又能定性地进行分析，在研究材料的热分解过程中具有明显的优势。由于Kevlar纤维的热分解过程在文献中少有报道，本文首次利用TG-FTIR联用技术对Kevlar纤维在室温到800 ℃的热解过程进行分析，得到了Kevlar纤维热解过程的详细步骤及各个步骤的反应产物。结果表明，Kevlar纤维的热解经历了3个阶段，分别为100～240，240～420，420～800 ℃。在500 ℃之前Kevlar纤维失重很缓慢，第三个阶段是纤维的主要失重阶段，最终固体的残留质量为56.21%。红外光谱数据表明，Kevlar纤维热解过程先释放出游离水，随后发生脱水反应和解聚反应，使纤维分子链断裂。最后纤维碎片进一步反应生成小分子气体，水、氨气、一氧化碳、二氧化碳为主要产物。其中水的析出量逐渐增大;氨气的析出量保持基本一致;一氧化碳仅在515～630 ℃产生，随后即氧化生成二氧化碳;二氧化碳的析出量经历了一个由于一氧化碳转化而产生的增长后，又下降到一定值保持稳定。

Research on Pyrolysis Process of Kevlar Fibers with Thermogravimetric Analysis coupled and Fourier Transform Infrared Spectroscopy

Modern industrial application and technologies require materials with superior mechanical and thermal properties. Kevlar fibers have been known as fibrous materials with good properties of high strength and high decomposition temperature which have become a hot research field in recent years.The properties of fibrous materials depend on their structures and compo-sitions.Thermal decomposition processing of the materials is of great significance for their structures and thermal properties.As a new technique,thermogravimetric (TG)analysis coupled with Fourier transform infrared spectroscopy(FTIR),are able to an-alyze materials not only qualitatively but also quantitatively.This method has obvious advantages in researching the thermal de-composition of many materials.However,the thermal decomposition processing of Kevlar fibers is rarely reported in the litera-ture,therefore,we firstly studied the pyrolysis behavior of Kevlar fibers with thermogravimetric analysis coupled with Fourier transform infrared spectroscopy at the temperature of 30~800 ℃.We not only obtained the processing of the Kevlar fibers'ther-mal decomposition with great details but also the products of every stage.Experimental results exhibited that the decomposition of Kevlar fibers has experienced three stages:100~240,240~420 and 420~800 ℃.The weight loss of Kevlar fibers was quite slow before 500 ℃.The third stage was the main stage of the decomposition,and the amount of residue finally reached to a mass percent of 56.21%.FTIR analysis illustrated that free water released from Kevlar fibers at the first stage,followed by the dehy-dration and depolymerization which made polymer chains short.Finally the fiber fragments further reacted and produced the ga-ses of small molecular mass,and the main products were water,ammonia,carbon monoxide and carbon dioxide.Generation rate of water was increased;the emission of ammonia was at the same rate;carbon monoxide was only produced at the temperature of 515~630 ℃,then turned into carbon dioxide.The release of carbon dioxide was on rise because of the conversion process of car-bon monoxide,and then dropped to a certain value.