Thermodynamics of polymerization of heterocyclic compounds II—The heat capacity, entropy, enthalpy and free energy of polytetrahydrofuran
Thermodynamics of polymerization of heterocyclic compounds II—The heat capacity, entropy, enthalpy and free energy of polytetrahydrofuran
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杂环化合物聚合热力学II——聚四氢呋喃的热容、熵、焓和自由能
DOI：
10.1016/0032-3861(68)90060-8
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发表时间：
1968
期刊：
影响因子：
4.6
通讯作者：
A. Tyson
中科院分区：
文献类型：
--
作者：
G. Clegg;D. R. Gee;T. P. Melia;A. Tyson
用绝热真空量热计和差示扫描量热计测量了69%结晶聚四氢呋喃样品在80° ~ 360°K范围内的热容。对80°K以下的热容值进行了估计。熵，焓和自由能值已被导出，并列出在10度。69%结晶聚合物的间隔。玻璃化转变温度、熔点和熔化热分别为185°、314° ± 1° K和2.959 ± 0.016千卡。摩尔-1。非晶聚四氢呋喃的过剩熵的温度依赖性，相对于100%的结晶样品，已被计算，并示出与理论预测吻合良好。无定形聚合物在玻璃化转变温度下的热容增加，2.7 cal. deg− 1 mole bead−1，与基于熔融空穴理论的预期一致。聚合反应的熵Δ S1 c的计算值为−14·8 ± 1·0 cal. deg− 1 mole −1，而从平衡聚合反应数据得到的结果为−9·8 ± 2·0 cal. deg− 1 mole −1。提出了支持前一值的证据。值为−5·3 ± 0·4 kcal。mole− 1是由Δ H1 c导出的。
An adiabatic, vacuum calorimeter and a differential scanning calorimeter have been used to measure the heat capacity of a 69 per cent crystalline sample of polytetrahydrofuran from 80° to 360°K. An estimate has been made of heat capacity values below 80°K. Entropy, enthalpy and free energy values have been derived and are listed at 10 deg. intervals for the 69 per cent crystalline polymer. The glass transition temperature, melting point and heat of fusion were found to be 185°, 314° ± 1° K, and 2·959 ± 0·016 kcal. mole−1. The temperature dependence of the excess entropy of amorphous polytetrahydrofuran, relative to the 100 per cent crystalline sample, has been calculated and is shown to be in good agreement with theoretical predictions. The increase in heat capacity of the amorphous polymer at the glass transition temperature, 2·7 cal. deg−1mole bead−1, is in agreement with that expected on the basis of the hole theory of melting. The entropy of polymerization, ΔS1c, has been calculated as −14·8 ± 1·0 cal. deg−1mole−1, whereas that obtained from equilibrium polymerization data is −9·8 ± 2·0 cal. deg−1mole−1. Evidence in favour of the former value is presented. A value of −5·3 ± 0·4 kcal. mole−1has been derived for ΔH1c.