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首页> 美国卫生研究院文献>International Journal of Molecular Sciences >Study on Thermal Decomposition Behaviors of Terpolymers of Carbon Dioxide, Propylene Oxide, and Cyclohexene Oxide
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Study on Thermal Decomposition Behaviors of Terpolymers of Carbon Dioxide, Propylene Oxide, and Cyclohexene Oxide

机译：二氧化碳，环氧丙烷和环己烯氧化物三元共聚物的热分解行为研究

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The terpolymerization of carbon dioxide (CO2), propylene oxide (PO), and cyclohexene oxide (CHO) were performed by both random polymerization and block polymerization to synthesize the random poly (propylene cyclohexene carbonate) (PPCHC), di-block polymers of poly (propylene carbonate–cyclohexyl carbonate) (PPC-PCHC), and tri-block polymers of poly (cyclohexyl carbonate–propylene carbonate–cyclohexyl carbonate) (PCHC-PPC-PCHC). The kinetics of the thermal degradation of the terpolymers was investigated by the multiple heating rate method (Kissinger-Akahira-Sunose (KAS) method), the single heating rate method (Coats-Redfern method), and the Isoconversional kinetic analysis method proposed by Vyazovkin with the data from thermogravimetric analysis under dynamic conditions. The values of ln k vs. T−1 for the thermal decomposition of four polymers demonstrate the thermal stability of PPC and PPC-PCHC are poorer than PPCHC and PCHC-PPC-PCHC. In addition, for PPCHC and PCHC-PPC-PCHC, there is an intersection between the two rate constant lines, which means that, for thermal stability of PPCHC, it is more stable than PCHC-PPC-PCHC at the temperature less than 309 °C and less stable when the decomposed temperature is more than 309 °C. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis/infrared spectrometry (TG/FTIR) techniques were applied to investigate the thermal degradation behavior of the polymers. The results showed that unzipping was the main degradation mechanism of all polymers so the final pyrolysates were cyclic propylene carbonate and cyclic cyclohexene carbonate. For the block copolymers, the main chain scission reaction first occurs at PC-PC linkages initiating an unzipping reaction of PPC chain and then, at CHC–CHC linkages, initiating an unzipping reaction of the PCHC chain. That is why the T−5% of di-block and tri-block polymers were not much higher than that of PPC while two maximum decomposition temperatures were observed for both the block copolymer and the second one were much higher than that of PPC. For PPCHC, the random arranged bulky cyclohexane groups in the polymer chain can effectively suppress the backbiting process and retard the unzipping reaction. Thus, it exhibited much higher T−5% than that of PPC and block copolymers.
机译：通过无规聚合和嵌段聚合进行二氧化碳（CO2），环氧丙烷（PO）和环氧环己烯（CHO）的三元聚合反应，以合成无规聚碳酸丙烯环己酯（PPCHC），聚二嵌段聚合物（碳酸亚丙酯-碳酸环己酯）（PPC-PCHC）和聚（碳酸环己酯-碳酸亚丙酯-碳酸环己基酯）（PCHC-PPC-PCHC）的三嵌段聚合物。通过多重加热速率方法（Kissinger-Akahira-Sunose（KAS）方法），单一加热速率方法（Coats-Redfern方法）和Vyazovkin提出的同转化动力学分析方法，研究了三元共聚物的热降解动力学。动态条件下的热重分析数据。四种聚合物热分解的ln k对T -1 值表明，PPC和PPC-PCHC的热稳定性比PPCHC和PCHC-PPC-PCHC差。另外，对于PPCHC和PCHC-PPC-PCHC，两条速率常数线之间有一个交点，这意味着，对于PPCHC的热稳定性，它在低于309°C的温度下比PCHC-PPC-PCHC更稳定。当分解温度高于309°C时，C不稳定。热解-气相色谱/质谱（Py-GC / MS）和热重分析/红外光谱（TG / FTIR）技术用于研究聚合物的热降解行为。结果表明，解压缩是所有聚合物的主要降解机理，因此最终的热解产物为环状碳酸亚丙酯和环状碳酸环己烯。对于嵌段共聚物，主链断裂反应首先发生在PC-PC链上，引发PPC链的解链反应，然后发生在CHC-CHC链上，引发PCHC链的解链反应。这就是为什么二嵌段和三嵌段聚合物的T-5％不会比PPC高很多的原因，而嵌段共聚物和第二种共聚物的两个最高分解温度都比PPC高得多。对于PPCHC，聚合物链中无规排列的大体积环己烷基团可有效抑制回位过程并延缓解链反应。因此，它表现出比PPC和嵌段共聚物更高的T-5％。

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