A study of the crystallinity index of polypropylene fibres

Crystallinity measurements were carried out with the help of X-ray diffraction, differential scanning calorimetry (DSC) and density measurements. The results of this study provide a better understanding of the morphology and complex thermal behaviour of polypropylene fibres. Crystallinity studies show that the crystallinity of PP fibres when measured by X-ray and DSC methods as a function of draw-ratios increases with increasing draw-ratios while the crystallinity of the same samples as derived by density measurements shows an inverse trend. These discrepancies are accounted for by the formation of microvoids within the polypropylene fibres due to drawing. In the DSC scan two endothermic peaks were found to occur in some of the samples. This is explained by the presence of two morphological forms i. e. lamellar and fibrillar morphology in the same sample. The crystallinity values obtained from different methods are correlated with mechanical properties, such as tenacity and elongations.Dedicated to Prof. Dr. H. Janeschitz-Kriegl, a pioneer of Polymer Physics in Austria, in honour of his sixtieth birthday.     

旋转光纤对二阶偏振模色散的影响

论述了单模光纤生产过程中旋转光纤对二阶偏振模色散的影响. 从理论上指出虽然旋转光纤 有助于减小一阶偏振模色散，但是同时会使二阶偏振模色散增大，这对10 Gb/s以上速率的 光纤通信系统是个重要的问题. 关键词： 二阶偏振模色散 旋转光纤 动态方程     

Analysis of Optical Equalization in WDM System

ＡｎａｌｙｓｉｓｏｆＯｐｔｉｃａｌＥｑｕａｌｉｚａｔｉｏｎｉｎＷＤＭＳｙｓｔｅｍＳＵＮＪｉａｎＧＵＷａｎｙｉＬＩＧｕｏｒｕｉＸＵＤａｘｉｏｎｇ（ＢｅｉｊｉｎｇＵｎｉｖ．ｏｆＰｏｓｔｓ＆Ｔｅｌｅｃｏｍ．，ＢｅｉｊｉｎｇＰ．Ｏ．Ｂｏｘ１２８，Ｃｈｉｎａ...     

直读光谱法快速测定无锡薄钢板铬层镀铬量

本文提出了直读光谱仪测定无锡薄钢板铬层铬量的新方法。通过选用基体元素的内标元素，引入Ｉｄ／Ｉ０×１００％来判断原板痕量铬对实验结果的影响程度，选择合适条件，解决了薄板易击穿，确保不同铬量无锡薄板的内标元素光强直稳定性等技术关键，采用比色法制作一套不同镀铬量的标准无镀锡薄板，绘制校准曲线，方法精度ＲＳＤ小于３．０％，准确度为１５０±５ｍｇ／ｍ＾２与经典方法比较该法操作简单，分析速度快。     

Complex monodromy and the topology of real algebraic sets

A relation between the Euler characteristics of the Milnorfibres of a real analytic function is derived from a simple identity involvingcomplex monodromy and complex conjugation. A corollary is the result of Costeand Kurdyka that the Euler characteristic of the local link of an irreduciblealgebraic subset of a real algebraic set is generically constant modulo 4. Asimilar relation for iterated Milnor fibres of ordered sets of functions isused to define topological invariants of ordered collections of algebraicsubsets.     

Use of ISO Guides 25, 30, 31, 34, 35, and 9001 in re-engineering Bethlehem Steel Corporation's analytical chemistry reference materials program

 Many certified reference materials are needed to calibrate and control analytical measurement processes in integrated steel works. It is beyond the scope and capacity of most national laboratories to supply all of these needs. Yet, the demand for these materials is steadily increasing as more steel producers update their quality systems in preparation for ISO 9000 registration and/or ISO Guide 25 laboratory accreditation assessments. This paper describes how the Bethlehem Steel Corporation updated its reference materials program to meet its internal needs and offers a model for use by others in improving their programs. Received: 22 April 1998 · Accepted: 12 May 1998     

赤霉素在钼蓝法测定砷,磷,硅中的应用——连续测定钢铁中的砷,磷,硅

将植物生长刺激素赤霉素引入光度分析作新显色剂，研究了赤霉素将砷、磷、硅杂多酸还原成相应杂多蓝的显色反应。在０８４、１２０、２１６ｍｏｌ／ＬＨＣｌ介质中，赤霉素能分别将砷、磷、硅杂多酸还原成相应的杂多蓝，其最大吸收波长分别为８３５、８２０和８１０ｎｍ，表观摩尔吸光系数分别为２６４×１０４、２５４×１０４和３５１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１。线性范围分别为０～２４ｍｇ／Ｌ、０～１ｍｇ／Ｌ和０～０８ｍｇ／Ｌ。该法应用于钢铁中砷、磷、硅的连续测定，结果令人满意。     

Al-4.5Cu和Mullite增强Al-4.5Cu复合材料时效析出行为的DSC研究

用差示扫描量热法（DSC）对Al-4.5Cu合金和莫来石（Mullite)短纤维增强Al-4.5Cu复合材料的时效析出行为进行了研究；结果表明Al-4.5Cu合金和Mullite增强Al-4.5Cu复合材料固溶淬火试样的DSC扫描曲线存在较大不同，溶质原子富集区（GP）形成和溶解的信息在基体合金的DSC曲线上清晰可见，但在复合材料的DSC曲线上则很难确认，表明纤维推延或抑制了GP区的形成；中间沉淀析出相θ″和θ′的析出过程由于纤维的引入而得到明显加快，峰值温度降低，活化能减小，时效析出过程加快；但是，扫描参数选择不当时，容易对析出相的析出过程产生错误判断，应引起重视。     

Nanoindentation of regenerated cellulose fibres

Nanoindentation was performed on cross sections of regenerated cellulose fibres with different structure and properties. Same as in single-fibre tensile tests, the elastic modulus of lyocell was higher than the elastic modulus of viscose. However, in spite of its tensile strength being twice as high as viscose, the hardness of lyocell was 15% lower than viscose. The overall degree of orientation of cellulose chains being higher in lyocell than in viscose, it is proposed that reduced lateral bonding in lyocell is the reason for the low hardness measured by nanoindentation compared to viscose.     

Nafion聚合物涂层碳纤维微电极微分脉冲伏安法测定咖啡因的研究

咖啡因属生物碱,是中枢神经兴奋药物之一~[1]。目前,咖啡因的常用测定方法有紫外分光光度法~[2]和高效液相色谱法~[3]等.电化学测定方法已有报道~[4～6],但尚未见到利用Nafion聚合物涂层碳纤维微电极的伏安测定方法.本文提出了一种简单易行的碳纤维微电极及其Nafion聚合物涂层的制造方法.得到了利用该电极微分脉冲伏安法测定咖啡因的最佳体系为