Thermodynamische Stabilität makromolekularer Kristalle
Thermodynamische Stabilität makromolekularer Kristalle
复制标题
大分子晶体的热力学稳定性
DOI：
10.1007/bf01337766
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发表时间：
1960
期刊：
影响因子：
--
通讯作者：
E. Fischer
中科院分区：
文献类型：
--
作者：
A. Peterlin;E. Fischer
链状晶体的自由能密度包含两项相反的符号，这取决于垂直于轴的晶体表面之间的大分子直线段中的链元的数目。表面能有一个正项，随着n的减小而减小。周期晶格场的振幅Φ与链在轴上的平移相反，产生负项。由于任意链的四个一阶邻居的非相干纵向热振动，fieldΦ被抹去了。它的振幅随高氮的增加而减小，从而产生随氮的增加而增加的自由能密度。由于表面能和晶格场在n内变化的相反符号，自由能密度在有限处显示最小值，对应于热力学稳定的晶体厚度。随着温度的升高和相邻链间相互作用的降低，sn的增加与实验数据在定性上完全一致。
The density of free energy of a chain crystal contains two terms of opposed sign dependent on the numberN of chain elements in the straight section of the macromolecules between the surfaces of the crystal perpendicular to thec-axis. The surface energy contributes a positive term decreasing withN. The amplitude Φ of the periodic lattice field opposing the chain translation in thec-axis yields the negative term. Due to the incoherent longitudinal thermal vibration of the four first-order neighbours of any chain the fieldΦ is smeared out. Its amplitude decreases the more the higherN and hence yields an increase in free energy density with increasingN. As a consequence of the opposite sign of surface energy and lattice field changes withN the free energy density shows a minimum at finiteN corresponding to the thermodynamically stable crystal thickness. With increasing temperature and lower interaction between adjacent chainsN increases in perfect qualitative agreement with experimental data.