FLAMMABILITY OF POLYACRYLONITRILE AND ITS COPOLYMERS .2. THERMAL-BEHAVIOR AND MECHANISM OF DEGRADATION
FLAMMABILITY OF POLYACRYLONITRILE AND ITS COPOLYMERS .2. THERMAL-BEHAVIOR AND MECHANISM OF DEGRADATION
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DOI：
10.1002/pi.1994.210330310
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发表时间：
1994-03-01
影响因子：
3.2
通讯作者：
HALL, ME
中科院分区：
文献类型：
--
作者：
HORROCKS, AR;ZHANG, J;HALL, ME
用热分析（DSC， TGA和DTG）研究了不同升温速率（10-100 K min-1）和空气和氮气条件下均聚聚丙烯腈和含醋酸乙烯酯或丙烯酸甲酯共聚单体的成纤维共聚物。在250-350°c、350-550°c和550°c以上的温度范围内观察到三个明确的热解阶段。每个阶段都涉及挥发和循环或成炭反应之间的竞争，这取决于加热速率和氧气的存在与否。在碳纤维生产过程中，丙烯酸前驱体在250-350℃的温度范围内，只有在低加热速率下才会发生环化。在高加热速率下，挥发占主导地位，这解释了为什么丙烯酸聚合物在快速加热时具有高可燃性。对全热解机理进行了半定量分析，讨论了共聚单体的作用。这使得对这些聚合物的潜在燃烧行为有了更全面的了解。
Homopolymeric polyacrylonitrile and fibre-forming copolymers containing either vinyl acetate or methyl acrylate comonomer have been studied by thermal analysis (DSC, TGA and DTG) at various heating rates (10-100 K min-1) and under air and nitrogen. Three well-defined pyrolysis stages have been observed which occur over the temperature ranges 250-350-degrees-C, 350-550-degrees-C and above 550-degrees-C. Each stage involves a competition between volatilisation and cyclisation or char-forming reactions which depends on heating rate and the presence or absence of oxygen.The well-established dominance of cyclisation in the 250-350-degrees-C temperature range obtained during carbon fibre production from acrylic precursors occurs only at low heating rates. At high heating rates, volatilisation dominates and this explains why acrylic polymers have high flammabilities when heating rapidly.The full pyrolysis mechanism has been semi-quantitatively analysed and the role that comonomers play discussed. This has enabled a fuller understanding of the potential burning behaviour of these polymers to be developed.