聚丙烯腈基碳纤维的制备工艺过程和纤维结构研究

采用丙烯腈(AN)与丙烯酸(AA)自由基溶液共聚合,以偶氮二异丁腈(AIBN)为引发剂,在二甲基亚砜(DMSO)中合成了聚丙烯腈纺丝溶液,经湿法纺丝制得聚丙烯腈(PAN)原丝,经过热稳定化和炭化得到聚丙烯腈基碳纤维,拉伸强度达到3.2GPa,杨氏模量为236GPa.采用扫描、透射电镜对纤维的结构进行表征.     

聚丙烯腈基碳纤维的制备工艺过程和纤维结构研究

采用丙烯腈（AN）与丙烯酸（AA）自由基溶液共聚合,以偶氮二异丁腈（AIBN）为引发剂,在二甲基亚砜（DMSO）中合成了聚丙烯腈纺丝溶液,经湿法纺丝制得聚丙烯腈（PAN）原丝、经过热稳定化和炭化得到聚丙烯腈基碳纤维,拉伸强度达到3．2GPa,杨氏模量为236GPa。采用扫描,透射电镜对纤维的结构进行表征。     

聚丙烯腈基碳纤维生产工艺特性研究

以丙烯酸 (AA)为第二共聚单体与丙烯腈 (AN)进行溶液聚合 ,偶氮二异丁腈(AIBN)为引发剂 ,二甲基亚砜 (DMSO)作为溶剂合成聚丙烯腈 (PAN)原丝纺丝溶液。研究了单体浓度、引发剂的用量等对聚合反应的影响。探讨了聚丙烯腈原丝及其预氧丝、碳纤维制备的工艺过程 ,对纤维的结构和性能进行了 SEM和 TEM分析     

偶氮二氰基戊酸引发丙烯腈溶液聚合的研究

以含有羧基(—COOH)官能团的偶氮二氰基戊酸(ACVA)为引发剂,二甲基亚砜为溶剂,采用均相溶液聚合制备丙烯腈均聚物(PAN);研究了单体浓度和反应时间对聚合反应的影响,并对PAN的结构和性能进行了表征。结果表明:ACVA引发的丙烯腈聚合反应基本遵循自由基聚合的一般规律;与偶氮二异丁腈(AIBN)相比,采用ACVA引发制得的PAN接触角约下降7°,亲水性能略微提高,环化反应的起始温度和放热峰温度分别下降了约32℃和10℃,热稳定化放热过程中集中放热现象得到一定程度的缓和。     

AIBN对P(AN-co-IA)共聚物性能影响的研究

主要研究了丙烯腈(AN)与衣康酸(LA)发生共聚反应时,不同偶氮二异丁腈(AIBN)引发剂用量对聚合产物的分子质量、分子立构及热性能的影响。研究结果表明:丙烯腈聚合产物的分子链构型符合无规聚合的概率论分布规律,但聚合物分子中全同立构体的比例随AIBN加入量的增大而增加;通过研究聚合物在氮气氛围中的热降解,发现共聚物在受热分解时热量的变化随引发剂用量的增加而趋于平缓。     

丙烯腈共聚合溶液动力黏度影响因素研究

聚丙烯腈原丝(PANF)是由原料丙烯腈(AN)与丙烯酸甲酯(MA)、甲叉丁二酸(IA)在引发剂偶氮二异丁腈(AIBN)作用下,通过自由基聚合生成聚丙烯腈(PAN)/二甲基亚砜(DMSO)溶液(也称为原液),再经过纺丝加工而成。借助旋转黏度计,研究了引发剂浓度、原液温度、w(总固)等因素对动力黏度的影响。研究认为:PAN溶液的动力黏度与引发剂浓度成反比,与原液温度成反比,与w(总固)成正比。通过动力黏度的调整,纺丝机头的压力控制在(0.7~1.4)MPa,压力值控制在±0.05MPa以内,可以实现良好的可纺性。     

水溶性偶氮引发剂AIBA引发AN-MA-IA水相沉淀共聚合的研究

以含有亲水基团的偶氮二异丁脒盐酸盐（AIBA）为引发剂,以丙烯腈（AN）、丙烯酸甲酯（MA）和衣康酸（IA）为单体,β-巯基乙醇（β-ME）为分子量调节剂,采用水相沉淀聚合法制备了不同分子量的AN-MA-IA共聚物,研究了AIBA浓度、单体浓度和β-ME浓度对聚合过程的影响。根据AIBA分解半衰期和单体竞聚规律确定了聚合温度70℃和pH=4.7为较优反应条件。结果表明,AIBA浓度是影响聚合转化率的决定因素,通过调整AIBA浓度可以得到分子量60000~500000的PAN共聚物,较高的AIBA浓度会由于聚合场所的改变而造成分子量分散度小幅上升;浓度在0.2%（质量）以内时,分子量调节剂β-ME可以调控PAN共聚物的分子量,并使其分布变窄。     

丙烯腈/β-衣康酸单甲酯共聚物制备及性能的研究

以丙烯腈和β-衣康酸单甲酯为共聚单体,偶氮二异丁腈为引发剂,使用自由基溶液聚合的方法在二甲基亚砜体系中制备丙烯腈共聚物。测试聚合体系的转化率、牛顿黏度和黏均分子质量,采用DSC分析了丙烯腈/β-衣康酸单甲酯共聚物的热性能,并测试了其原丝的力学性能。研究结果表明:丙烯腈/β-衣康酸单甲酯共聚物的黏均分子质量达到了1.28×105,β-衣康酸单甲酯有效降低了共聚物的放热起始温度,纺制出的原丝强度高达8.8 cN/dtex,性能稳定。     

AMPS氨化对四元聚丙烯腈原丝结构和性能的影响

利用氨水对2-丙烯酰胺-2-甲基丙磺酸(AMPS)的磺酸基进行氨化改性以制备氨化AMPS,采用丙烯腈、丙烯酸甲酯、衣康酸和氨化AMPS为聚合单体,以偶氮二异丁腈为引发剂,在溶剂二甲基亚砜中经溶液共聚合成了四元聚丙烯腈(PAN)纺丝液,并通过湿法纺丝纺制了碳纤维前驱体四元PAN原丝,分析了AMPS的氨化率对原丝结构和性能的影响。结果表明,AMPS氨化改性后成功将亲水基团NH_4~+引入到四元PAN原丝中;AMPS氨化率为0%～40%时,随着氨化率的增加,纺丝液中共聚物的接触角逐渐减小,原丝的孔隙率先下降后上升,拉伸性能先增大后减小;AMPS氨化率为30%时,原丝的孔隙率最小、拉伸性能最好、截面形貌近似为圆形,其热反应起始温度有所降低、放热峰变宽,最终制得的原丝孔隙率为12.3%,拉伸强度、拉伸弹性模量和断裂伸长率分别为7.5,123.2c N/dtex和15.2%,由此制备的碳纤维拉伸强度、拉伸弹性模量和断裂伸长率达到了4 321MPa,211GPa和2.9%,分别较未氨化时提高了12.4%,6.6%和7.4%。     

丙烯腈共聚物的热性能与膜结构研究

以丙烯腈和衣康酸为共聚单体,偶氮二异丁腈为引发剂,使用自由基溶液聚合的方法在二甲基亚砜体系中制备聚丙烯腈树脂。采用氧化改性的方法将衣康酸氨化为衣康酸铵,与丙烯腈进行共聚反应。借助DSC、SEM等测试方法研究了氨化改性对共聚物的热性能及聚合物膜结构的影响。结果表明：共聚单体可以在较低温度下以离子机理引发氰基发生低聚反应,导致梯形环化结构的形成,有效降低放热起始温度。而衣康酸铵中的氨基可作为环化反应的催化剂,促进聚丙烯腈在预氧化过程中形成均匀的环化梯形结构。且铵盐具有亲水性,使纤维内部缺陷更容易弥合。     

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.     

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.     

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.