Thermodynamic Stability of Polymer Crystals. II. Torsional Vibrations of Chain Molecules
Thermodynamic Stability of Polymer Crystals. II. Torsional Vibrations of Chain Molecules
复制标题
聚合物晶体的热力学稳定性。
DOI：
10.1063/1.1733296
复制
发表时间：
1962
影响因子：
4.4
通讯作者：
C. Reinhold
中科院分区：
文献类型：
--
作者：
A. Peterlin;E. Fischer;C. Reinhold
考虑到由于相邻链的不相干纵向振动而导致的纵向位移的链间势垒的降低，自由能密度在（001）表面之间的大分子直段中的有限数目N* 的单体单元处表现出最小值。具有N* 的晶体比具有N <$N* 的晶体更稳定。通过考虑扭转振动，可以大大提高与实验数据的一致性。从已知的两个CH_2基团之间的相互作用能出发，考虑到六个相邻聚乙烯链的影响，仅导出了晶格力场，并计算了扭转涨落幅度。当假定表面能接近40 erg/cm 2时，所得的N* 与Fischer和施密特对在不同温度下从稀二甲苯和乙酸丁酯溶液中生长的晶体的测量非常吻合。有了这个值，理论不能预测具有有限N* ab的稳定晶体。
By taking into account the decrease of interchain potential barrier for longitudinal displacement as a consequence of incoherent longitudinal vibration of adjacent chains, the free‐energy density exhibits a minimum at a finite number N* of monomer units in the straight section of the macromolecule between the (001) surfaces. Crystals with N* are thermodynamically stabler than those with N≠N*. The agreement with experimental data can be very much improved by considering torsional vibrations. Starting with the known interaction energy between two CH2 groups and considering the influence of the six adjacent polyethylene chains only the lattice force field was derived and the torsional fluctuation amplitude calculated. The resulting N* fits very well with measurements of Fischer and Schmidt on crystals grown at different temperature from dilute xylene and butyl acetate solution when the surface energy is assumed close to 40 erg/cm2. With this value the theory does not predict stable crystals with finite N* ab...