The crystallization morphology and melting behavior of polymer crystals in nano-sized domains

The crystallization morphology and the melting behavior of the phase-separating poly(?-caprolactone) (PCL) and poly(ethylene oxide) (PEO) blends were studied using atomic force microscopy. Two blends consisting of PCL and PEO with weight ratios of 10/90 and 90/10 were prepared to form the isolated spherical domains by the phase-separating process. The results show that the melting temperatures of the PCL and PEO lamellae in the confined domains increased as the lamellar length increased, and the melting behavior of the PCL and PEO lamellae in the matrix and confined domains was also studied.     

Twisting orientation and the role of transient states in polymer crystallization

A possible connection is suggested and explored between non-planer crystal habits in banded polymer spherulites and disordered chain folding in polymers crystallized relatively rapidly from the melt. It is proposed that, when lateral growth faces and fold surfaces are not orthogonal (because chain stems are tilted with respect to the lamellar normal), different degrees of disorder develop at opposite fold surfaces. Resulting differences in surface stress give rise to bending moments, but these are likely to be of transient existence. It is shown that, on this basis, an appealingly simple rationale can be developed to account for the complex and hitherto puzzling observations of Bassett and Hodge on polyethylene spherulites, including S-bending and non-uniform axial twisting in lamellae, and also an empirical correlation between these deformations. Much depends, however, upon interactions between interleaved crystals and upon relaxation of bending moments. Existing evidence in support of the rationale is outlined. Implications with respect to polymers other than polyethylene, and to kinetics of crystallization in general, are discussed briefly. Calculations concerning axial twisting under the influence of surface stresses suggest that the twisted crystals incorporate twist boundaries, possibly formed by aggregation of dislocations generated during the growth of what must initially be relatively disordered crystals. The ‘chiral’ factor determining handedness of twisting in a given crystal is the direction in which chain stems tilt with respect to the lamellar normal.     

CFRPA1010等速降温结晶动力学的研究

将等温Ａｖｒａｍｉ方程推广应用于等速降温的非等温结晶过程，用ＤＳＣ法研究了ＣＦＲＰＡ１０１０的等速降温结晶行为和结晶动力学。结果表明，用此方法得到的动力学参数与文献报导的等温法结果有良好的一致性；ＣＦＲＰＡ１０１０中的ＣＦ使基体的结晶温度明显提高，使结晶峰呈不对称形态，结晶温度范围变窄。其结晶行为和动力学参数ｎ、ｋ、ｔ１／２等结果显示，ＣＦ具有诱导基体结晶作用，影响了ＰＡ１０１０结晶的成核和生长机     

t EducationArt EducationArt Education

d Motion Picture TechnologyAdvanced Motion Picture TechnologyAdvanced Motion Picture TechnologyAdvanced Motion Picture TechnologyAdvanced Motion Picture TechnologyAdvanced Motion Picture TechnologyAdvanced Motion Picture TechnologyAdvanced Motion Picture TechnologyAdvanced Motion Picture Techno使PET降解严重；对苯酚钠甲酸钠能够提高T_c达17．75℃且对PET相对分子质量影响很小；对苯二甲酸二钠成核作用最差,低于滑石粉。此外,成核剂的成核能力越强,PET双熔融峰中的低温峰顶温度就越高。     

DESIGN OF BATCH DISTILLATION COLUMNS FOR BINARY MIXTURES

In this note analytical equations are presented that describe the separation obtained for binary batch distillation. Formulas are obtained for both the constant distillate composition and constant reflux methods of operation. The results are strictly for distillation with an infinite number of stages ( corresponding to minimum reflux) however, it is shown that the equations derived closely describe the operation with a small finite number of stages.     

As—Te硫系膜的光学性质及其热致变化

利用真空射频溅射法制得了非晶态As-Te硫系薄膜。借助于XRD法研究了该系统薄膜的热致析晶,并与相应的块状样品作了比较。薄膜在热处理前后的光学折射率和消光系数分别进行了测定,分析了它们与薄膜组成、结构以及析出晶相的关系。另外还对薄膜随温度的变化过程进行了研究,指出了造成反射率发生变化的主要原因以及它们所对应的温度区域,对该系统薄膜在光盘方面的应用作了预言。     

Design and operation of multiproduct and multipurpose batch chemical plants. — An analysis of problem structure

The general structure of batch processing problems is reviewed. A classification scheme is presented which analyses the specification of the system components, -comprising product requirements, specification of process tasks and available equipment items, followed by consideration of constraints on system structure, problem definition and solution methods. A hierarchy of model types for batch units is proposed for use in different problem situations. Examples of the use of the scheme are provided by the classification and comparison of selected publications on batch processing and the scheme is also used to draw attention to potential areas for further work. Brief remarks are added on problem size and computational experience in different areas of batch processing.     

High voltage electron microscope irradiation and observations in metallic glasses

High voltage electron microscope (hvem) has been extensively used to produce radiation damage and to study the characteristics of defects so produced in crystalline solids. To understand the defect production in metallic glasses and to evaluate the influence of such defects on physical properties like crystallisation temperature etc., high voltage microscopy and subsequentin situ heating and observation has been extremely useful technique. This paper gives a qualitative overview of such work performed in metallic glasses. In particular results obtained on a nickel based metallic glass using ahvem and an electron accelerator are presented. The advantages and limitations ofhvem irradiation are highlighted.     

On the triple melting behaviour of poly(ethylene succinate)

The morphology of melt-crystallized poly(ethylene succinate) (PES) was investigated by optical microscopy and scanning electron microscopy, and the melting behaviour of PES was studied by differential scanning calorimetry (DSC). At low crystallization temperature imperfect crystals were formed which could melt and recrystallize during the DSC scan. Triple melting peaks were observed, and the melting behaviour was strongly dependent on crystallization time and scan rate. It was observed that crystallization at high temperature perfected the crystals (dominant and subsidiary lamellae in the spherulitic structure). Increasing the scan rate reduced the chance for reorganization. However, at high crystallization temperature two melting peaks were observed. The material formed was much more perfect, so that the melting process was not dominated by recrystallization. Accordingly, the cause of dual melting is the existence of two kinds of crystal perfection.     

聚丙烯共混物的形态结构与性能研究进展

从聚丙烯与其共混组分的相容性和结晶性的角度出发，综述１９９２年国内关于聚丙烯共混物的形态结构研究及形态结构与聚丙烯共混材料性能的关系。