The depolymerization of polymethylene and polyethylene
The depolymerization of polymethylene and polyethylene
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DOI：
10.1021/ja01642a017
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发表时间：
1954-07
影响因子：
15
通讯作者：
L. A. Wall;S. L. Madorsky;D. W. Brown;S. Straus;R. Simha
中科院分区：
文献类型：
--
作者：
L. A. Wall;S. L. Madorsky;D. W. Brown;S. Straus;R. Simha
研究了聚亚甲基的解聚速率和分子量变化，并对所得挥发性产物进行了质谱分析。将结果与商业和辐射交联聚乙烯的结果进行比较。交联对解聚速率影响不大。线性聚亚甲基的行为接近理论预测的可忽略的去传播和显着的转移。如果发生单一类型的分子间转移，则动力学相当于随机聚合，并在此基础上分析实验结果。该速率表现出作为转化率函数的特征最大值，这在聚乙烯中不存在，但通过理论预测。这些差异可能与聚乙烯的支化结构有关。目前对长支链和短支链数量的估计导致初始速率比线性聚合物增加不超过五倍。这些估计并不能解释聚乙烯没有最高比率的原因。这似乎需要更多的长分支或更长的短分支。
Depolymerization rates and molecular weight changes of polymethylene have been studied and mass spectrometric analyses of the volatile products obtained. The results are compared with those for commercial and radiation cross-linked polyethylene. Cross linking has little effect on the rate of depolymerization. The behavior of linear polymethylene approaches that predicted by theory for negligible depropagation and pronounced transfer. Provided a single type of intermolecular transfer occurs, the kinetics becomes then equivalent to a random polymerization and the experimental results are analyzed on this basis. The rate exhibitis a characteristic maximum as a function of conversion, which is absent in polyethylene but is predicted by theory. The differences are presumably connected with the branched structure of polyethylene. Current estimates of the amount of long and short branches lead to an increase of the initial rate over that of the linear polymer by a factor not exceeding five. These estimates do not explain the absence of a maximum rate for polyethylene. This seems to require more long branches or longer short branches.