自制激光小角散射仪研究高聚物球晶结构

激光小角散射技术对用于测定固态高聚物的球晶结构是一种有效和简便的测试方法。本工作应用自制激光小角散射仪测定了聚丙烯、尼龙6和聚酯薄膜中球晶半径的变化。随着结晶温度的提高,等规聚丙烯和尼龙6的球晶半径逐渐增加,但聚酯在150℃附近出现最大值。对聚丙烯纤维中的球晶形态也进行了探讨。实验表明聚丙烯纤维在熔纺成形过程中球晶内部的晶片主轴发生了偏转。     

尼龙-1010及其与聚对苯甲酰胺共混物的结晶行为

采用偏光显微镜和差示扫描量热法研究了文题内容。结果表明,尼龙-1010(Ⅰ)在150～175℃之间为球晶生长的最适宜温度。它的结晶动力学基本上符合Avrami方程,Avrami指数为2.7～3.8;结晶速率常数为10~1～10~2数量级。Ⅰ的熔融双峰是在DSC扫描过程中经历的连续熔化与再结晶过程中产生的。Ⅰ与聚对苯甲酰胺的共混物,由熔体进行结晶时都得不到完整的球晶,但结晶化温度降低。     

PCL薄膜的球晶环带结构及MWCNT对其的影响

通过溶液法制备了聚己内脂和聚己内脂/碳纳米管薄膜,研究了不同结晶温度下聚己内脂的结晶形态以及碳纳米管对聚己内酯结晶的影响.结果表明,在20～50℃较宽的温度范围内可以通过溶液结晶得到聚己内酯环带球晶,加入MWCNT使形成环带结构的温度向高温度方向拓宽.利用SEM,AFM从微观层次研究了球晶环带形成的机理.     

等规聚丙烯未拉伸单丝的结构形态

本文采用正交偏振光、小角激光散射、扫描电子显微镜,广角X光衍射、密度、双折射和切片技术,对工业用丝——IPP单丝的未拉伸丝的结构及其形态进行了广泛的研究。研究结果表明,球晶是IPP未拉伸单丝中主要的结构形式,并具有特殊的光学特性。在正交偏振光下,表征球晶特征的马尔托思黑十字图案只有在特定的位置上出现。当试样旋转360°时,黑十字共出现4次。熔体温度、挤出量、冷却介质和分子量等参数均要影响球晶的的大小。其中,冷却介质还进一步改变球晶的规整性。空气中冷却试样的消光图案不及水冷却试样清晰整齐。在球晶的结晶变体中,可以出现α晶、或是拟六方酝晶,以及两者的混合形式。同时,在IPP未拉伸单丝中,径向明显地显出结构差异,球晶尺寸,双折射等在横截面上都存在着分布。 IPP未拉伸单丝的这种结构特征,无疑要影响到它的拉伸性能和成品纤维的质量。     

聚乙烯环状条纹球晶的研究

研究了低结晶温度(过冷度>20℃),淬火介质对聚乙烯球晶形态的影响。结果表明,结晶温度在0～115℃时,可以生成环状条纹球晶,环间距随温度而异。某一温度下,淬火介质的热导率影响环状条纹球晶的形态。并就环状条纹球晶的形成机理提出见解。     

Study of Spherulite Growth Rate and Morphology of Polypropylene -based Blends by Image Processing Technology

The method for measuring the spherulite growth rate and studying the morphology of polypropylene - based blends by image processing technology is described. The main advantages of this method, as compared to existing techniques, are: better reliability; reproducibility; ease of manipulation. Such an approach provides a means of measuring the rate of spherulite growth. In this study, isotactic polypropylene (PP), polystyrene (PS)/PP, and polybutylene terephthalate (PBT)/PP have been studied. The results show that the technology of image analysis is very useful in the study of the kinetics of crystallization of polymer.     

The Microstructure of Graphite Spherulites in Cast Iron

The microstructure of graphite spherulites (G.S.) in Ce addition ductile cast iron was carried out using transmission electron microscopy (TEM) techniques. The structral characterization of the graphites is as following: there are platelets growing along the periphery as well as fan-like structure formed from platelet aggregates in the diameter section of spherulite, in which most of the platelets are with sizes ranging from several to tens nm in radial; the [001] direction of the platelets would have a tend to parallel to radial of the G. S. and meanwhile, they also a small misorientation deviated from the radial among the platelets each other. It shows that the anisotropy of graphites has been restrained by adding Ce element in cast iron and the structural characterization of the G. S. is consistent with the Double' s model of the conical helixes formed in helical growing and branching.     

半结晶性聚合物熔体冷却过程双尺度模拟

聚合物的结晶受温度及温度历史影响较大,同时发生结晶又会对聚合物材料温度场产生影响. 为了准确模拟冷却过程中温度场和结晶情况,将半结晶性聚合物熔体冷却过程及其结晶过程耦合起来分析,把宏观温度场结果作为介观模拟的输入,再把介观模拟的球晶生长情况作为宏观温度场模拟的输入,可同时得到宏观与介观二个尺度的模拟结果. 由于该耦合建立在一定的物理基础上,模拟得到的结果较为合理.