超高相对分子质量聚乙烯溶液的制备

讨论了超高相对分子质量聚乙烯粉末在矿物油及矿物油与煤油的混合溶剂中的溶胀、溶解,并测定所得溶液在不同温度下的落球粘度。结果表明:聚乙烯的最佳溶胀温度随混合溶剂中煤油质量分数的增大而降低;溶液粘度随聚乙烯质量分数的升高而升高,随溶液温度的降低而升高;溶液粘流活化能随聚乙烯质量分数的升高而升高;采用混合溶剂时,溶液粘度随溶剂中煤油质量分数的升高而降低,且煤油质量分数越高,其溶液的粘流活化能越小。     

超临界CO2中合成的聚丙烯腈的相对分子质量及其分布的测定

以已知相对分子质量及其分布的聚丙烯腈宽分布共聚物为标样，采用Breeze软件，得到了有效的标定直线。根据标定直线测定了超临界CO2中合成的聚丙烯腈均聚物的相对分子量及分布。并将GPC法测得的各种平均相对分子质量结果与粘度法所测得的粘均相对分子质量做了比较。     

凝胶渗透色谱法测定聚丙烯腈的相对分子质量及其分布的研究

以纯二甲基甲酰胺(DMF)为淋洗剂用凝胶渗透色谱法(GPC法)测得的聚丙烯腈共聚物的淋洗曲线会出现分峰现象,在DMF中添加静电屏蔽剂硝酸钠后,峰的形状可以变得正常,但是无法以聚苯乙烯为标样,用高分子链的流体力学体积作为通用校正参数对GPC仪进行标定。以已知相对分子质量及其分布的聚丙烯腈宽分布样品为标样,用试凑法对CPC仪进行了准确的标定。提出了在测试条件相同的情况下,用聚苯乙烯作为标样的方法。     

纳米粒子均匀分散超高相对分子质量聚乙烯冻胶纤维的制备

将纳米粒子均匀分散于萃取荆中，在萃取阶段将其加入到超高相对分子质量聚乙烯(UHMWPE)纤维中，对其进行改性。通过表面扫描电镜(SEM)，萃取液粘度和冻胶纤维萃取除油率的测定，研究了纳米粒子在UHMWPE冻胶纤维中的分散情况及纳米粒子的加入对冻胶纤维萃取过程的影响。结果表明：在萃取过程中，纳米粒子可以扩散进入冻胶纤维中并可在冻胶纤维中达到纳米级均匀分散；纳米粒子的加入使萃取剂粘度增加，对UHMWPE冻胶纤维的萃取速率变慢。     

凝固条件对聚丙烯腈沉淀丝结构的影响

本文推荐用[(r_m/r_c)~2-1]来表征沉淀丝结构的致密性,并通过膨润度、应力-应变及扫描电镜的测定,证实了此法的可靠性,同时揭示了以DMSD为凝固浴的最佳组成。     

水解制备超高相对分子质量阴离子聚丙烯酰胺

系统研究了水解浓度，水解温度，水解时间等因素对聚丙烯酰胺水解制备阴离子聚丙烯酰胺相对分子质量的影响，并采用正交试验法确定了最佳工艺条件，通过实验得到了验证。     

超高相对分子质量丙烯腈-马来酸酐共聚物超滤膜的研究

采用超高相对分子质量的丙烯腈-马来酸酐共聚物制得平板超滤膜,并考察了预蒸发时间,共聚物浓度、铸膜液温度等工艺条件对膜结构和性能的影响。结果表明,上述诸因素对超滤膜的结构和性能有明显的影响,可通过改变上述参数在很大程度上调节膜的形态结构,从而使膜具有一系列的性能,为制造聚丙烯腈共聚物超滤膜提供参考。     

凝胶纺壳聚糖分散碳纳米管/聚丙烯腈纤维的研究

多壁碳纳米管(MWNTs)通过壳聚糖衍生物处理后与超高分子量聚丙烯腈进行复合,将得到的复合材料通过凝胶纺丝法制备出不同复合比例的MWNTs/聚丙烯腈纤维.将不同纺丝方法以及不同比例MWNTs对拉伸强度、模量、取向度、结晶结构的影响进行比较研究,同时通过电镜观察MWNTs的分散状况.结果表明:相比于湿法纺丝,通过凝胶纺丝法制备的复合纤维,MWNTs取向更好,分散更为均匀,纤维拉伸强度、模量都得到显著提高.对比未加MWNTs的对照样,在这个体系中加入质量分数为0.5%的MWNTs复合时,拉伸强度提高37%,弹性模量提高11.68%,并且声速取向度维持在相当高的水平(92.5%).     

缠结对超高分子量聚丙烯腈特性粘度测定的影响

在以粘度法测定超高分子量聚丙烯腈(Ultra-High Molecular WeightPOlyacrylonitrile,以下简称UHMWPAN)分子量时发现,在溶解完全的用于测定特性粘度的UHMWPAN二甲基甲酰胺(DMF)稀溶液中,大分子链间保留着未被溶剂舒解的“天生缠结”(Inborn Entanglement),使所测特性粘度和表观分子量偏大.天生缠结是高聚物在聚合过程产生,它在稀溶液中保留的数量受到溶解和溶液处理条件等因素影响,通过机械剪切,可在无机械降解状态下完全解除大分子链间的天生缠结,得到没有缠结影响的正确特性粘度和分子量,由此确立UHMWPAN特性粘度测定方法.     

介质阻挡放电氩等离子体处理超高相对分子质量聚乙烯纤维

利用介质阻挡放电氩等离子体方法对超高分子量聚乙烯纤维进行表面处理，从而研究纤维处理前后纤维束的机械力学性能的变化、纤维束与树脂粘合性能的改善情况。通过优化的方法，找出合理的工艺参变数，为工业化应用奠定基础。     

The Chain Structure of Ultrahigh Molecular Weight Polyacrylonitrile

The chemical composition, molecular weight and its distribution, the bonding structure and the regulation of ultrahigh molecular weight polyacrylonitrile （UHMW-PAN） prepared by aqueous suspension polymerization were determined by FIIR, viscometry, GPC, ^3H-NMR and ^13CNMR. The mechanical properties of the porous hollow fiber prepared by UHMW-PAN were discussed to provide a theoretical basis for the preparation of ideal precursors of the porous hollow oxidation fiber.     

Influence of Molecular Weight of Ultra-high Molecular Weight Polyacrylonitrile on Its Rheological Behavior in Dimethylsulfoxide

Ultra-high molecular weight polyacrylonitrile (UHMW-PAN ) was prepared by aqueous suspension polymerization, and the effect of molecular weight on its rheological behaviors hi dimethylsulf oxide (DMSO) and the spinning stability were investigated. It shows that, compared with common polyacrylonitrile ( C-PAN), UHMW-PAN/DMSO solution has smaller non-Newtonian index, larger structural viscosity index, much longer maximum relaxation time, and no first-Newtonian region appears in the flow curves under the same experimental conditions. The explanations for these phenomena are given in the view of chain-entanglements. The optimal technology of preparing UHMW-PAN fibers and hollow fiber membranes could be obtained based on the rheological study.     

Enhancement of Adhesive Strength of Ultrahigh Molecular Weight Polyethylene Fibers Prepared by Polar Polymer Implantation

A new technique was proposed to enhance the adhesive strength of ultrahigh molecular weight polyethylene （UHMWPE） fibers. Polar polymer was implanted into UHMWE gel fibers during extracting process and can then be trapped on the surface of the fibers after subsequent ultra-drawing. The physical and chemical changes in the fiber structure were examined with scanning electron microscopy （SEM） and Fourier transform infrared （FTIR） spectroscopy. The mechanical and interfacial adhesion properties of UHMWPE fibers were investigated with tensile testing. The results showed that there were polar groups on the smface of pretreated UHMWPE fiber. The interracial shear strength of UHMWPE fibers with epoxy resin was greatly improved without sacrificing the excellent mechanical p~perties of fibers. After pretreated with ethylene/vinyl acetate copolymer （EVA）, the shear strength of the interface between fiber and epoxy resin increased from 1.06 to 2.49 MPa, while the integrated mechanical properties d the pretreated UHMWPE fibers were still optimal.     

高相对分子质量PAN纺丝溶液的流变性能研究

研究了高相对分子质量PAN纺丝溶液的制备工艺,讨论了影响纺丝溶液的流动曲线、非牛顿指数、结构粘度指数、孔口膨化比等的主要因素,为确定合理的PAN基碳纤维原丝生产工艺提供了科学依据.     

EFFECT OF TEMPERATURE ON THE RHEOLOGICAL BEHAVIOR OF UHMW-PAN SOLUTION

UHMW-PAN is an important polymer material used to make high strength and high modules fiber as well as hollow fiber membrane with high mechanical strength to resist the backwash process.In this paper, the effect of temperature on non-Newtonian flow index, structural viscosity index,maximum relaxation time and zero shear viscosity of the UHMW-PAN solution has been studied.The relationship between parameters and spinnability has been discussed. On the basis of above works, the suitable temperature of spinning solution by gel-spinning has been found.     

超高分子量聚乙烯磨损性能的研究

采用超高分子量聚乙烯、铸钢ZG20MnSi、Fe-05电弧熔焊、Ni60热喷焊4种材料，在HT200灰铸铁为摩擦副无润滑条件下，进行磨损试验。试验结果表明：超高分子量聚乙烯材料的磨损性能比铸钢ZG20MnSi高4.96倍；比Fe-05电弧熔焊材料磨损性能低9.8倍；比Ni60热喷焊材料磨损性能低4.5倍。从而为超高分子量聚乙烯替代金属材料在工程中的应用提供了依据。