Thermal and themoxidative degradation processes in poly(bisphenol a carbonate)
Thermal and themoxidative degradation processes in poly(bisphenol a carbonate)
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DOI：
10.1016/s0165-2370(02)00034-7
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发表时间：
2002-09-01
影响因子：
6
通讯作者：
Puglisi, C
中科院分区：
文献类型：
--
作者：
Montaudo, G;Carroccio, S;Puglisi, C
利用矩阵辅助激光描述电离飞行时间（MALDI-TOF）和FAB质谱技术研究了聚碳酸双酚a （PC）的热氧化分解和热氧化分解过程。PC样品在300、350、400和450度的温度下进行热降解（在惰性气氛下）加热。在300℃下获得的热解残留物的MALDI质谱显示，只有环状低聚物的丰度逐渐减少，PC样品的摩尔质量增加，这很可能是由于缩聚后的聚合反应。在350℃时，观察到发生了广泛的水解反应，产生了苯酚基团。在400°c温度下观察到以苯酚基团结尾的PC链以及端有苯基和异丙烯基的链。在加热温度为400℃的PC样品MALDI光谱中也检测到缩合芳香族化合物，如山酮类化合物，它们在450℃时成为最强烈的物质。经400℃选择性彻底氨解反应得到的热解残渣的FAB-MS谱显示，存在含有多个连续的山酮单元的化合物，这些单元经历交联过程。随着温度的升高，会产生石墨状的烧焦残渣（不溶物）。PC的热氧化降解是将样品在300℃的空气中加热30w90进行的。120. 150和180分钟产生PC摩尔质量的减少。热氧化PC样品在300℃下90和180 min的MALDI质谱显示，PC链末端有甲基酮、苯基和苯酚基团，很可能是由双酚A单元的异丙烯桥氧化降解形成的。含有联苯键的脱氢结构的存在可以解释在这些条件下产生的不溶性残留物。(C) 2002 Elsevier Science B.V.版权所有
Progress in the study of thermal and thermoxidative decomposition processes of poly(bisphenol a carbonate) (PC) was obtained by Matrix assisted laser description ionization time of flight (MALDI-TOF) and FAB mass spectroscopic techniques. PC samples were subjected to thermal degradation (under inert atmosphere) heating at 300, 350, 400 and 450 degreesC. The MALDI mass spectra of the pyrolysis residues obtained at 300 degreesC showed only a progressive reduction of the abundance of cyclic oligomers and an increase of the molar mass of the PC sample most likely due to post-condensation polymerisation reactions. At 350 degreesC the occurrence of an extensive hydrolysis reaction producing phenol groups was observed. PC chains terminated with phenol groups together with chains bearing phenyl and isopropenyl end groups were observed at 400 degreesC. Condensed aromatic compounds such as xanthones were also detected in the MALDI spectra of PC samples heated at 400 degreesC, and they became the most intense species at 450 degreesC. The FAB-MS spectrum of the pyrolysis residue obtained at 400 degreesC subjected to a selective and exhaustive aminolysis reaction showed the presence of compounds containing several consecutive xanthone units, These units undergo cross-linking processes. leading to a graphite-like charred residue (insoluble), as the temperature increases. The thermoxidative degradation of PC carried out heating the samples in air at 300 degreesC for 30, W 90. 120. 150 and 180 min produced a reduction of the PC molar mass. The MALDI mass spectra of thermally oxidised PC samples at 300 degreesC for 90 and 180 min showed the presence of PC chains terminated with methyl-ketone, phenyl and phenol groups, most likely formed by the oxidative degradation of the isopropilidene bridge of bisphenol A units. The presence of dehydrogenated structures containing biphenyl linkage may account for the insoluble residue produced in these conditions. (C) 2002 Elsevier Science B.V. All rights reserved.