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采用三元催化剂(Y(Cl3COO)3-ZnEt2-glycerin)催化二氧化碳与氧化环己烯共聚反应,制备了高分子量二氧化碳与氧化环己烯共聚物(PCHC).8 h内催化剂平均活性达到11.8 kg polymer/mol Zn,PCHC主链上碳酸酯单元含量大于95%,数均分子量达到7.0×104.研究了PCHC的玻璃化转变温度和分子量的关系,当PCHC的数均分子量(Mn)低于8.5×104时,玻璃化转变温度(Tg)随Mn增加而升高;Mn高于8.5×104时,Tg对Mn的依赖性不大.当PCHC的分子量充分高时,其玻璃化转变温度可以达到120℃,PCHC的自由体积特征常数K=1.91×105.研究了聚合物分子量对其热稳定性的影响,结果表明提高分子量有利于提高PCHC的热分解温度.通过实施聚合反应和后处理,三元催化剂转化为相应的金属氧化物(主要为氧化锌)残留在聚合物中,采用Kissinger方法得到纯PCHC(除去金属氧化物)的热分解表观活化能约为199.9 kJ/mol,含金属氧化物(Zn含量4400×10-6)PCHC的热分解表观活化能下降为143.9 kJ/mol.因此氧化锌能够促进PCHC的热降解,减少PCHC中氧化锌的含量有利于改善PCHC的耐热性能.
The high molecular weight carbon dioxide and cyclohexene oxide copolymer (PCHC) were prepared by the copolymerization of carbon dioxide and cyclohexene oxide using a three-way catalyst (Y (Cl3COO) 3-ZnEt2-glycerin) .The average catalyst activity reached 11.8 kg polymer / mol Zn, the content of carbonate units in PCHC backbone is more than 95% and the number average molecular weight is 7.0 × 104. The relationship between the glass transition temperature and the molecular weight of PCHC has been studied. When the number average molecular weight (PC) of PCHC is less than 8.5 × 104, the glass transition temperature (Tg) increases with the increase of Mn, and the dependence of Tg on Mn is not obvious when the Mn is higher than 8.5 × 104. When the molecular weight of PCHC is sufficiently high, the glass transition temperature can reach The free-volume characteristic constant of PCHC at 120 ℃ was 1.91 × 105. The effect of polymer molecular weight on its thermal stability was studied.The results showed that increasing the molecular weight was beneficial to increase the thermal decomposition temperature of PCHC.Through the polymerization reaction and the post-treatment, The metathesis catalyst is converted to the corresponding metal oxide (mainly zinc oxide) remaining in the polymer. The apparent thermal activation energy of pure PCHC (excluding metal oxide) obtained by Kissinger method is about 199.9 kJ / mol, Material (Zn content of 4400 × 10-6) PC The apparent activation energy of HC decreases to 143.9 kJ / mol. Therefore, zinc oxide can promote the thermal degradation of PCHC and reduce the content of zinc oxide in PCHC, which is in favor of improving the heat resistance of PCHC.