Kinetics and mechanism of the thermal reaction between tert‐butyl perbenzoate and n‐alkanes: A model system for the crosslinking of polyethylene
Kinetics and mechanism of the thermal reaction between tert‐butyl perbenzoate and n‐alkanes: A model system for the crosslinking of polyethylene
复制标题
过苯甲酸叔丁酯与正烷烃之间热反应的动力学和机理：聚乙烯交联的模型系统
DOI：
10.1002/pol.1976.170140616
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
H. Oosterwijk
中科院分区：
文献类型：
--
作者：
J. D. V. Drumpt;H. Oosterwijk
在尽可能接近聚乙烯实际交联过程的条件下，研究了过苯甲酸叔丁酯与正构烷烃之间的热反应。产品分析允许描述90-95%的过氧化物片段的命运。发现约50-60%的在夺氢后形成的底物自由基联合收割机并产生交联，而约30%显示出交联，从而导致底物不饱和。这两个竞争反应占所产生的底物自由基的85-90%。该模型系统提供了一个简单方便的方法比较过氧化物的交联效率，这些数据报告为一些商业过氧化物。为了便于外推的结果在液体烷烃固体聚乙烯（PE），底物的粘度和温度对过氧化物的分解速率，产品分布，和交联效率的影响进行了研究。在正构烷烃中，过氧化物的分解遵循一级动力学，Arrhenius活化能为32.9 ± 0.5 kcal/mole。此外，在模型系统的动力学进行了比较，从流变仪（扭矩与时间）测量未填充的PE和乙烯-丙烯-双环戊二烯三元乙丙橡胶（EPDM）的固化计算。过氧化物分解速率和总活化能只有微小的差异。
The thermal reaction between tert-butyl perbenzoate and n-alkanes has been studied under conditions as close as possible to those during actual crosslinking of polyethylene. Product analysis allowed a description of the fate of 90–95% of the peroxide fragments. Approximately 50–60% of the substrate radicals, formed upon hydrogen abstraction, were found to combine and give crosslinks, whereas about 30% showed disproportionation, thus leading to substrate unsaturation. The two competing reactions account for 85–90% of the generated substrate radicals. The model system provides a simple and convenient method for comparing the crosslink efficiencies of peroxides; these data are reported for some commercial peroxides. In order to facilitate an extrapolation of the results in liquid alkanes towards solid polyethylene (PE), the influence of substrate viscosity and temperature on the peroxide decomposition rate, product distribution, and crosslink efficiency was studied. In n-alkanes peroxide decomposition follows first-order kinetics well, with an Arrhenius activation energy of 32.9 ± 0.5 kcal/mole. In addition, the kinetics in the model system are compared with those calculated from Rheometer (torque vs. time) measurements on the curing of unfilled PE and ethylene-propylene-dicyclopentadiene terpolymer (EPDM). Only minor differences in peroxide decomposition rate and overall activation energy were found.