Diffusion and Morphology of Polymer

在过去的两年中（2000 - 2001年），我们对聚合物在薄膜中的晶体生长进行了实验，得到了以下结果：1)聚合物晶体生长速率G的过冷依赖性（ΔT）不取决于形貌和膜厚：G与exp（-K/TΔT）成正比。2)晶层厚度由结晶温度决定；厚度与形貌和薄膜厚度无关。3)对于生长面宽度有限的晶体，在晶体生长过程中，观察到最大生长速率与最小生长速率之比与标准成核理论所预测的不一致。2002年，我们分别研究了聚（1,4反式丁二烯）晶体的热粗化和聚（丁烯-1）晶体的动力学粗化，并建立了结果1)在聚合物结晶中的普遍适用。我们通过观察聚偏氟乙烯晶体和聚对苯硫醚晶体的球晶径向生长速率，证实了结果3)。在这些观察的基础上，我们提出了一个新的聚合物结晶模型；在模型中，聚合物段在粘附到晶体表面之前由于熵损失而经历了激活的自由能势垒。通过应力-应变曲线和x射线测量观察交联聚异戊二烯橡胶的结晶过程，探讨了扩散对聚合物结晶的影响；对这些数据进行热力学分析，可以很好地再现结晶速率随结晶温度的应变速率关系。

In the last two years (2000 to 2001), we performed the experiment on crystal growth of polymers in thin films to obtain the following results. 1)The super-cooling (ΔT) dependence of the growth rate G of polymer crystals does not depend on the morphology and film thickness : G is proportional to exp(-K/TΔT).2) The lamellar thickness is determined by crystallization temperature ; the thickness is independent of morphology and film thickness. 3) In the crystal growth for a crystal with a finite width of the growth surface, is observed the ratio of the maximum growth rate to the minimum one to be inconsistent with that predicted by the standard nucleation theory.In 2002, we investigated thermal roughening in poly(1, 4 trans-butadiene) crystals arid kinetic roughening in poly(butene-1) crystals respectively, and established that result 1) holds universally in polymer crystallization. We confirmed result 3)for poly(vinylidene fluoride) crystals as well as for poly(para-phenylene sulfide) by observing the radial growth rate of their spherulites. On the basis of these observations, we have proposed a new model for polymer crystallization ; in the model a polymer segment experiences an activated free energy barrier due to an entropy loss before adhesion to the crystal surface.We also investigated the effect of diffusion on polymer crystallization by observing the crystallization of cross-linked polyisoprene rubber through stress-strain curve and X-ray measurement; thermodynamic analysis of these data could reproduce well the strain rate dependence of crystallization rate depending on crystallization temperature.