Diffusion and Morphology of Polymer

在过去的两年中(2000-2001)，我们在薄膜中进行了聚合物晶体生长的实验，取得了以下结果。1)聚合物晶体生长速率与过冷度(ΔT)的关系不依赖于晶体的形态和膜厚：G与EXP(-K/TΔT)成正比。2)晶片厚度由结晶温度决定，而与形态和膜厚无关。3)在生长面宽度有限的晶体生长中，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预测的结果不一致。2002年，我们分别研究了聚(1，4-反式丁二烯)晶体中的热粗化和聚丁烯-1晶体中的动力学粗化，结果1)在聚合物结晶中普遍成立。我们通过观察聚偏氟乙烯晶体和聚对苯硫醚晶体的径向球晶生长速度证实了结果3)。在此基础上，我们提出了一种新的聚合物结晶模型；在该模型中，聚合物链段在附着到晶面之前，由于熵的损失而经历了激活的自由能垒。我们还通过应力-应变曲线和X射线测量观察了交联型聚异戊二烯橡胶的结晶过程，研究了扩散对聚合物结晶的影响；热力学分析可以很好地再现结晶速率与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.