水洗条件对聚丙烯腈碳纤维及其原丝性能的影响

对二甲基亚砜法(DMSO)生产聚丙烯腈(PAN)碳纤维原丝的水洗温度、时间、方式等进行探讨,进而对水洗工艺进行优化和改善。实验结果表明,控制单束12k PAN原丝水洗水用量在400~500 L/h,水洗温度在45℃,水洗时间在30~40 min,通过在水洗槽中增加拍打辊及V型隔板,可以实现丝束内DMSO残留质量分数≤0.07%。     

聚丙烯腈原丝新型水洗工艺的研究

采用浸渍水洗结合涌泉式水洗的新型水洗技术,研究了水洗流量、水洗时间及水洗温度对水洗效果的影响。结果表明:温度控制在60℃,浸涌式水洗水涌量3m3/h,水洗30min,使得纤维中二甲基亚砜(DMSO)残留量≤3.2×10-4,新型水洗效率高,达到了降低原丝表面所含溶剂的目的,提高了原丝的质量。     

聚丙烯腈碳纤维原丝水洗控制方法研究

通过对聚丙烯腈碳纤维原丝二甲基亚砜(DMSO)残留量、 膨润度、 碳纤维强度等数据进行分析,并比较其生产过程中拍打式水洗不同的张力条件,得出拍打式水洗过程中需要适宜的张力,张力过大不但会造成亚砜残留量过高,还会对生产过程产生影响,而适宜的张力可以提高水洗效果以及原丝取向度,进而提高碳纤维的强度.     

聚丙烯腈基碳纤维纺丝过程中的取向性研究

以聚丙烯腈(PAN)为原料,二甲基亚砜(DMSO)为溶剂,通过干喷湿纺工艺制备PAN基碳纤维原丝,采用X射线衍射仪对纺丝过程中不同工艺阶段纤维微晶进行测试,研究PAN纤维在纺丝过程中密度和微观结构的变化.结果表明,在纺丝过程中PAN纤维通过凝固浴、水洗、沸水牵伸、致密化、蒸汽牵伸和热定型工艺,纤维的密度增大、线密度逐步...     

二甲基亚砜法与硝酸法生产聚丙烯腈原丝的优劣比较

从溶剂性质、原丝结构性能以及所制备的碳纤维性能等方面,对二甲基亚砜（DMSO）法与硝酸（HNO3）法生产的两种原丝进行比较,找出并分析两种溶剂生产的聚丙烯腈（PAN）原丝在密度及结构均一性等方面的区别。研究表明,DMSO法PAN原丝具有强度高、取向度高等优点,DMSO法更有利于提高碳纤维用PAN原丝质量。     

聚丙烯腈原丝超声波水洗工艺

将超声波技术应用到聚丙烯(PAN)原丝的水洗工艺中,研究了超声波功率、水洗温度、水洗时间对PAN原丝中残留二甲基亚砜(DMSO)含量的影响。结果表明,超声波功率为200 W,洗涤温度50℃,洗涤时间10 min,洗涤后的PAN原丝中的DMSO含量大幅降低,且超声波水洗PAN原丝的洗涤效果比普通水洗好。     

影响碳纤维用聚丙烯腈原丝水洗效果因素的探讨

水洗是碳纤维用聚丙烯腈（PAN）原丝生产过程中的重要环节,其效果好坏将直接影响碳纤维强度的高低。实验结果表明：在选择共聚单体组分时,要充分考虑共聚单体时聚合物亲水性的影响,有利于提高水洗效果;聚合物相对分子质量过高,会影响水洗效果;纺丝液中总固含量过大会增加水洗难度;采用梯度水温,外加浸洗与喷淋相结合方式对碳纤维用PAN原丝的洗涤效果较好,水的用量不会太大;对PAN纤维多段牵伸后水洗效果较好。     

干湿法制备异形PAN原丝及其力学性能的研究

对二甲基亚砜(DMSO)干湿法制备三角形截面聚丙烯腈(PAN)基碳纤维原丝的截面形成因素进行了研究,并比较了不同条件下纤维的性能。结果表明:在干湿法纺制三角形截面PAN基碳纤维原丝过程中,凝固浴条件对PAN纤维的截面影响非常明显,同时凝固浴条件和拉伸条件对纤维的力学性能也有非常显著的影响。     

聚丙烯腈原丝中二甲基亚砜残留对碳纤维性能的影响

通过对水洗条件的改变,考察了PAN原丝中溶剂二甲基亚砜残留量对碳纤维性能的影响。在原丝中溶剂残留量较高的情况下,碳纤维的密度和强度大幅下降,同时原丝的截面形状和表面形态遭到破坏,影响了碳纤维的性能。     

DMSO法PAN原丝湿法纺丝工艺研究

通过实验对二甲基亚砜（DMSO）法聚丙烯腈（PAN）原丝的纤维凝固成形、水洗、牵伸、干燥定型条等湿法纺丝工艺对纤维性能的影响进行了研究,实验结果表明：增大喷丝板孔径,有利于提高原丝的取向度和干燥收缩率;调节凝固浴质量分数和温度,可生产出综合性能较好的原丝;提高水洗温度有利于制得性能好的原丝;热水、沸水和蒸汽3级牵伸工艺...     

乙苯,苯乙烯的生产及合成乙苯,苯乙烯催化剂的研究进展

苯乙烯是重要的石油化工原料。本文介绍了国内外苯乙烯生产的发展概况，合成乙苯，苯乙烯所用的催化剂种类，并就苯乙烯生产及催化剂的发展趋势提出了自己的观点。     

Synthesis and characterization of homopolymers and copolymers of various acrylates and acrylonitrile

Various homopolymers and copolymers of methyl acrylate, ethyl acrylate, butyl acrylate, and acrylonitrile in different feed ratios were synthesized. These were characterized by IR, ¹³C-NMR, DSC, DTA, and TGA. Spectroscopic characterization helped in differentiating copolymers of different mol ratios. Thermal analysis revealed different degradation patterns for homopolymers and copolymers. The temperature and energy changes associated with various phase transitions were dependent on the chemical composition of homo- and copolymers, as expected. © 1993 John Wiley & Sons, Inc.     

生物质气化及生物质与煤共气化技术的研发与应用

总结了生物质原料的特点及生物质单独气化的缺点;介绍了国内外生物质气化技术及生物质与煤共气化技术的研发与应用现状;分析了在此领域国内外的发展趋势与前景;概括了开展生物质与煤共气化技术研发的意义。     

Electronic structures and reactivities of monometallic and bimetallic clusters of Au and Cu

The variation of the Au 4f binding energy of Au clusters with the cluster size has been established by measuring the binding energies of clusters whose size distributions were independently determined by HREM and STM. The binding energy increases significantly when the cluster size is less than 2 nm. Au-Cu bimetallic clusters of the composition Cu₃Au have been deposited for the first time on carbon substrates. The shifts in the core level binding energies of the bimetallic clusters show the effect of alloying in the case of large clusters, but show effects of both alloying and cluster size in the case of the small clusters. The interaction of CO with Cu₃Au clusters is stronger than with a bulk Cu metal. The interaction of CO with small Cu clusters also seems to be stronger than with bulk Cu or with large Cu clusters.     

钾盐资源及钾肥供需情况分析及预测

阐述了国内外钾盐资源及钾肥生产现状,对国内外钾盐的供需形势进行了分析及预测,从资源、原材料、国际市场三方面提出了解决我国钾盐短缺的措施。     

Kinetics and Mechanism of Oxidation of Mono- and Polyacetals

Abstract

Kinetics and mechanisms of oxidation of 6 acetals by molecular oxygen and ozone in liquid phase have been studied. Reaction with molecular oxygen (70°C, 15–16 hr) leads to the formation monoethers of the corresponding glycols with 68–90% selectivity. Salts of metals and complexes with crown-ethers have increased the reaction rate significally. Ozone have reacted with acetals with formation similar products. The mechanisms of intermediate stages have been proposed.     

Comparison of the Adhesion and Cohesion of Triblock and Random Copolymers of Styrene and Butadiene

A substantially greater detachment energy is required to strip a polyethylene tereph-thalate (Mylar) film from a styrene-butadiene-styrene (SBS) triblock copolymer compared to that for peeling from a random styrene-butadiene (SBR) copolymer. This is true even though the intrinsic interaction between the Mylar and each elastomer is expected to be similar because of their virtually identical chemical composition. It is proposed that this difference in peel strength (between the SBS and SBR) is a consequence of the much higher dissipative capacity of the former elastomer. Another manifestation of this is the higher cohesive tear strength of the SBS compared to the SBR. Extents of energy dissipation within each elastomer during detachment of the Mylar adherend are consistent with the hypothesis that the average maximum stress experience before detachment is some similar fraction of each elastomer's tensile strength.     

责任和责任心的涵义与结构

责任是人应主动承担的角色义务和对其因过失所造成后果应承担的责罚.有两层涵义:一是义务;二是后果.责任心是个体自觉做好分内事务和履行道德义务的心理倾向,是个性心理品质成分中自我特征维度上的重要内容.责任心具有两个方面的涵义:一是角色分内职责;二是角色道德义务.责任心是一种通过责任认知、责任个性和责任适应的动态形式表现出来的静态品质,责任心是责任心过程结构与责任心关系结构相互制约、相互影响的统一体.     

二甲基二烯丙基氯化铵和丙烯酰胺的合成及应用

用复合引发体系(过硫酸盐-偶氮类引发剂)和脂肪胺类氧化还原体系引发,在实验室获得了单体转化率≥98%,特性粘数高于13.6 dL/g的阳离子共聚物PDA,探讨了控制聚合物分子量的影响因素.     

Wetting properties of homopolymers and copolymers of pentafluorostyrene and methylacrylate and homopolymer blends

Polypentafluorostyrene (PPFS), polymethylacrylate (PMA), and poly(pentafluorostyrene-co-methylacrylate), poly(PFS-co-MA) were prepared and the wetting characteristics of polymer blends of PPFS and PMA were compared with that of poly(PFS-co-MA) via contact angle measurements. The critical surface tension of polypentafluorostyrene was found to be 22.6 dyne/cm, which is comparable to the value reported for polytrifluoroethylene (22 dyne/cm). The critical surface tension of poly(PFS-co-MA) is not linearly related to its composition. The polymer blends of PPFS and PMA exhibit significant surface enrichment of the fluoropolymer. The harmonic-mean method¹ was employed to determine surface tensions of these polymers and many known polymers. It is found that the method produces useful surface tension data provided the contact angle values are derived from testing liquids of dissimilar polarity.