| 双官能团引发剂引发甲基丙烯酸甲酯的聚合速率 |
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| 引用本文： | 吴建一,盛维琛,单国荣,黄志明,翁志学. 双官能团引发剂引发甲基丙烯酸甲酯的聚合速率[J]. 化工学报, 2005, 56(2): 358-362 |
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| 作者姓名： | 吴建一 盛维琛 单国荣 黄志明 翁志学 |
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| 作者单位： | 浙江大学聚合反应工程国家重点实验室， 浙江 杭州 310027;嘉兴学院化工系， 浙江 嘉兴 314000 |
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| 摘 要： | 研究了双官能团引发剂2,5-双(2-乙基己酰过氧化)-2,5-二甲基己烷（TX-141）引发甲基丙烯酸甲酯（MMA）的自由基聚合动力学，考察了引发剂浓度、聚合温度对聚合动力学的影响.结果表明：该体系的聚合活化能为91 kJ•mol-1左右，计算得到TX-141引发剂的分解活化能为140 kJ•mol-1左右，与实验值接近;TX-141引发剂的反应级数约为0.72，说明MMA聚合终止基元反应中单基和双基终止并存.同时与相似半衰期的过氧化二苯甲酰（BPO）比较，发现当TX-141引发剂浓度为BPO的1/2时，两者在各个聚合温度下的聚合动力学曲线几乎相同;但相对分子质量有明显增加，随聚合转化率增加，TX-141与BPO引发的聚合物数均分子量之比从1.2变化到1.33;由TX-141引发的聚合物低转化率时DSC曲线出现放热峰，而高转化率以及BPO引发的聚合物则没有.说明双官能团引发剂TX-141引发聚合时，在低转化率下TX-141引发剂的2个过氧键没有全部断裂，随聚合进行，断裂程度加深.
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| 关 键 词： | 动力学 双官能团引发剂 甲基丙烯酸甲酯 |
| 文章编号： | 0438-1157(2005)02-0358-05 |
| 收稿时间： | 2003-11-09 |
| 修稿时间： | 2004-2-16 |
Kinetics of methyl methacrylate polymerization initiated by bifunctional initiator |
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| WU Jianyi,SHENG Weichen,Shan Guorong,Huang Zhiming,Weng Zhixue. Kinetics of methyl methacrylate polymerization initiated by bifunctional initiator[J]. Journal of Chemical Industry and Engineering(China), 2005, 56(2): 358-362 |
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| Authors: | WU Jianyi SHENG Weichen Shan Guorong Huang Zhiming Weng Zhixue |
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| Abstract: | Bifunctional initiators with two labile groups (e.g. peroxides or azo groups) are frequently used in the polymer industry for the synthesis of vinyl polymers and resin curing. In general, there are two types of bifunctional initiators: one is symmetrical bifunctional initiators containing two labile groups of equal structure, the other is unsymmetrical bifunctional initiators containing two labile groups of unequal structure. One of the potential advantages of using bifunctional initiators is that high polymer molecular mass and high polymerization rate can be obtained simultaneously by controlling the initiator decomposition rate through optimal reaction temperature programming. For free radical polymerization of methyl methacrylate (MMA) with monofunctional initiators, the kinetics is reasonably well understood in both low and high monomer conversion regimes. However, the presence of an additional labile group in bifunctional initiators makes the polymerization kinetics very complicated. This is because labile groups such as peroxides become redistributed repeatedly in the growing and inactive polymers and they are engaged in further initiation, propagation, chain transfer and termination reactions during the course of polymerization. The effects of temperature and initiator concentration on the kinetics of MMA bulk polymerization initiated by 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxide) hexane (TX-141) were investigated.The energy of activation of MMA bulk polymerization initiated by TX-141 was about 91 kJ•mol-1, and that of TX-141 decomposition was about 140 kJ•mol-1, which was more close to the experimental data.The reaction order of TX-141 concentration was about 0.72,because there was mono- and bi-molecule termination. The kinetic comparison initiated by TX-141 and benzoyl peroxide (BPO) with the same half life period showed that the kinetics was the same when the concentration of TX-141 was half of that of BPO.But, the number-average molecular mass ratio of that initiated by TX-141 to that by BPO was from 1.2 to 1.33 increasing with the conversion.There was an exothermal peak in the DSC curve of polymer initiated by TX-141 at low conversion, but there was no peak at high conversion and no peak was observed for the polymer initiated by BPO.It was shown that the two functional groups of bifunctional initiator decomposed at different times during the polymerization process. |
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| Keywords: | kinetics bifunctional initiator methyl methacrylate |
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