超高分子量聚乙烯分子量测试方法研究进展

聚合物材料的性能与其分子量及其分布有较强的相关性,对分子量及其分布准确测量具有重要意义。文章介绍了基于分析化学的端基分析法,基于热力学原理的沸点上升法/冰点下降法、渗透压法,基于物理性能的光散射法,基于机械性价的黏度法、流变法等分子量测试方法的研究进展。通过对比不同测试方法的特点,为超高分子量聚乙烯分子量及其分布的测试提供技术支撑。流变法、GPC法和检测联用技术有望成为PE-UHMW分子量测试方法研究重点。     

流变法在氟塑料分子量及其分布测试中的应用

本文基于实验和现有文献资料,从基本原理、关键难点和应用实例三个方面对熔体零切黏度法和动态模量法测试聚合物分子量及其分布进行综合性的介绍,重点关注了二者在氟塑料分子量及其分布测试中的应用。     

流变学方法研究共聚甲醛分子量及其分布

针对聚甲醛(POM)分子量及其分布测试较为困难的情况,采用旋转平板流变仪对不同牌号的市售共聚POM树脂的流变性能进行了测试,利用复合黏度和角频率的关系曲线得到了零切黏度,然后利用零切黏度与重均分子量的关系式得到了不同牌号POM的分子量,同时利用Vinogradov模型和Carreau-Yasuda模型得到了其分子量分布曲线,并与凝胶渗透色谱(GPC)测试结果进行了对比。结果表明,采用流变学的方法可以快速、准确地测试POM树脂的分子量及其分布,其结果与GPC测试结果相差不大。另外,流变学法测试结果初步表明,零切黏度大的POM树脂的重均分子量较大,熔体流动速率较小的POM树脂的分子量分布较宽。     

一种快速测定多聚羟基烷酸分子量的方法

以氯仿作溶剂，用黏度法测定了多聚羟基烷酸的分子量．摸索了检测的最佳温度与溶液浓度．比较了黏度外推法与黏度单点法测验结果，建立了黏度法测定多聚羟基烷酸平均分子量的操作方法。该法具有溶剂毒性小、溶解性好、准确度高和操作简便等优点．适用于生产过程和成品检验中的多聚羟基烷酸分子量的测定。     

黏度法测定高聚物分子量实验的改进

物理化学实验中"黏度法测定高聚物的分子量"实验所用的聚乙烯醇和消泡剂正丁醇对人体有害。现拟测定不同温度、不同浓度壳聚糖的分子量代替测定聚乙烯醇的分子量,探讨并得出黏度法测定高聚物摩尔质量的优化方法。与测定聚乙烯醇分子量实验对比,得到更准确的实验结果,使实验易做、重现性好。采用Orgin8.0绘图工具处理实验数据,结果更加客观准确。     

超高分子量聚乙烯分子量及分子量分布的测定

超高分子量聚乙烯UHMWPE的分子量和分子量分布直接影响其加工性能和机械性能,然而传统的凝胶色谱法(GPC)存在一定的局限性,粘均分子量难以全面反映UHMWPE的结构特点。为了开发出一种精度高、重复性好的UHMWPE分子量和分子量分布测试方法,本研究在常规高温GPC设备的基础上,基于溶液流动分级机理,选取了合适凝胶孔径的凝胶色谱柱,改善了普通GPC测试结果分子量分布偏宽的问题。并通过对UHMWPE/三氯苯溶解方法的深入研究,解决了普通GPC测试结果重复性差的问题。对UHMWPE新产品的研发和后期的加工有着重要的实际意义。     

全自动黏度仪SVM 3000在润滑油黏度测定中的应用

考察全自动黏度仪SVM 3000在润滑油黏度测定中的应用,并与现行黏度测试标准方法(GB/T 265—1988)即毛细管黏度计法进行对比分析。结果表明,SVM 3000自动黏度仪的重复性和再现性均在标准方法允许的误差范围内,测试结果均符合国标GB/T 265—1988相关规定。     

双毛细管黏度测试法的应用

介绍了双毛细管黏度法对聚酯特性黏度的测试。通过测试结果分析,认为双毛细管黏度法,具有较好的准确性、分析快速、连续性强、重现性好、安全环保的特点。     

明胶分子量与黏度的关系

明胶的分子量测定对控制生产过程及产品性能具有重大的意义。本实验中采用凝胶色谱(GPC)测定明胶的重均分子量和数均分子量,同时使用乌氏黏度计和勃氏黏度计测定相应样品浓度分别为0.6%和6.67%的水溶液的黏度(记为[η]0.6%和η6.67%),并对分子量与黏度之间的相关性进行了研究,得出了明胶黏度与分子量之间的近似线性关系。     

黏度法测定聚乙二醇分子量实验方法改进

针对"多点法"两曲线外推繁琐耗时,对传统的乌氏黏度计测定聚乙二醇(PEG)黏均分子量实验方法进行了方法和加料顺序的改进。基于"一点法"近似公式,在温度25℃下恒温,改变稀释溶液顺序,使常规6 h的物理化学学生实验缩短为2 h,其所得的特性黏度值相对误差在±5%范围内,测得PEG黏均分子量为5.9500×10~4与标签吻合。改进后的实验步骤方便快捷,结果满意。     

数据库技术在提高工程设计质量中的应用

针对自控专业工程项目设计文件在编制过程中出现的质量问题进行深入分析,根据分析结果引入数据库技术并且采用软件编程的手段对设计过程中的各个环节进行优化,不仅提高了设计文件的质量,同时也提高了设计文件的准确率与设计的工作效率。     

浅谈钛材换热器的管板焊接

在氧化性、中性及含氯离子的介质中,钛的耐腐蚀性能均优于普通不锈钢和铝等。但钛材的焊接性能不好,焊接时极易产生氧化、氮化和脆化等缺陷。根据钛材的焊接特性,在焊接过程中有针对性地采取合理的保护措施,制定合适的焊接工艺,严格把好各个施工环节质量关,就能保证钛材的焊接质量。     

白首乌保健含片的研制

研制了具有增强免疫力等保健功能的白首乌含片。首先确定最佳醇提浓度;其次采用L9 (34 )正交实验设计,以白首乌中C21甾苷相对含量和出膏率为评价指标,优化醇提工艺;最后优选各种辅料,确定含片处方。结果表明最佳提取条件为95%乙醇8倍量,提取3次,每次2h。研制了符合药典相关质量要求,口感良好的白首乌含片。     

The role of process parameters in determining wall thickness distribution in plug‐assisted thermoforming

This article describes the results of a comprehensive investigation to determine the link between process parameters and observed wall thickness output for the plug‐assisted thermoforming process. The overall objective of the work was to systematically investigate the process parameters that may be adjusted during production to control the wall thickness distribution of parts manufactured by plug‐assisted thermoforming. The parameters investigated were the sheet temperature, plug temperature, plug speed, plug displacement, plug shape, and air pressure. As well as quantifying the effects of each parameter on the wall thickness distribution, a further aim of the work was to improve the understanding of the physical mechanisms of deformation of the sheet during the different stages of the process. The process parameters shown to have the greatest effect on experimentally determined wall thickness distribution were the plug displacement, sheet temperature, plug temperature, and plug shape. It is proposed that during the plug‐assisted thermoforming of polystyrene the temperature dependent friction between the plug and sheet surface was the most important factor in determining product wall thickness distribution, whereas heat transfer was shown to play a less important role. POLYM. ENG. SCI., 50:1923–1934, 2010. © 2010 Society of Plastics Engineers     

Microstructure characterisation of ceramics via 2D and 3D X-ray refraction techniques

3D imaging techniques are very fashionable nowadays, and allow enormous progress in understanding ceramic microstructure, its evolution, and its link to mechanical, thermal, and transport properties. In this feature article, we report the use of a powerful, yet not so wide-spread, set of X-ray techniques based on refraction effects. X-ray refraction allows determining internal specific surface (surface per unit volume) in a non-destructive fashion, position and orientation sensitive, and with a nanometric detectability. While the techniques are limited by the X-ray absorption of the material under investigation, we demonstrate showcases of ceramics and composite materials, where understanding of process parameter influence or simply of microstructural parameters could be achieved in a way unrivalled even by high-resolution techniques such as electron microscopy or computed tomography.     

浅谈水泥窑协同处置危险废物生产控制

水泥窑协同处置危险废物流程及环节控制,通过对各环节控制分析提出操作要点。做好安全防控,避免各环节引发安全风险发生。做到无害化、减量化、资源化处理。     

PP气相流化床反应器平均停留时间的计算

介绍了聚丙烯流化床反应器流化特性和卸料过程;提出了利用其料位测量机理计算平均停留时间的方法,并将实际计算结果与理论值进行了比较。     

高海拔地区新型干法窑的操作

烧成是水泥生产中最重要的环节，在烧成过程中，可以通过正确的操作手段来稳定系统的热工制度，可以通过各操作参数和窑内情况判断工况优劣，可以结合化验室的各种检测数据来对系统进行调整，可最终达到优质高产低耗和长期安全生产的目的。     

Modeling and optimizing the process of modifying chlorine-containing epoxy resins using butanediol

The results of an investigation of the modification kinetics of chlorine-containing epoxy resins by 1,4-butanediol in the presence of alkali catalyst have been considered. Experimental investigations have been carried out using a Setaram C80 calorimeter of heat flow in combination with analytical methods for determining initial and final functional groups. The link between conversion and the heat effect was set. A two-phase kinetic model of the modification process was proposed. The parameters of the proposed model have been determined from the condition of minimum disagreement between the experimental and calculated data using nonlinear programming methods in order to find the minimum. The task of finding the optimal temperature profile has been set and solved. A scheme of process control for maintaining the optimal temperature has been proposed.     

Temperature selective condensation of tyre pyrolysis oils to maximise the recovery of single ring aromatic compounds

Scrap tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a condenser system maintained at separately controlled temperature to determine the yield and composition of the condensed oil. The main objective was to maximise the selective condensation of single ring aromatic compounds which are of known higher commercial value. In addition, the molecular weight range of the condensed oils was also determined. The influence of condenser packing material was also examined. The results showed that the type of packing material within each condenser was also examined and found to be important in determining the yield and composition of the condensed oil. Similarly, condenser temperatures determined the yield and also composition of the oils. Maximum concentrations of single ring aromatic compounds in relation to the selective condensation process showed significant increases in the concentration of certain compounds could be achieved in the condensed oils collected in each condenser.