共查询到20条相似文献,搜索用时 156 毫秒
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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。 相似文献
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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。 相似文献
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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。 相似文献
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明胶分子量与黏度的关系 总被引:2,自引:1,他引:1
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。 相似文献
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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。 相似文献
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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。 相似文献
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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 相似文献
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《Journal of the European Ceramic Society》2017,37(5):1879-1889
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. 相似文献
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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。 相似文献
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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。 相似文献
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F. Yu. Sharikov Yu. V. Sharikov V. D. Lunev 《Theoretical Foundations of Chemical Engineering》2017,51(2):224-231
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. 相似文献
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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. 相似文献