不同粒径的PP粉的相对分子质量及其分布、结晶性能和力学性能

采用差示扫描量热仪和凝胶渗透色谱仪研究了PP粉粒径大小对其相对分子质量及分布、结晶行为和力学性能的影响。结果表明,粒径大小对PP粉的相对分子质量及分布、结晶温度、结晶速率、成核能力、力学性能等均有明显的影响。随着粒径的减小,PP粉的数均相对分子质量下降,相对分子质量分布变宽,熔体流动速率逐渐增大;结晶温度和结晶起始温度升高,成核能力增加,起始结晶速率增大,晶粒更加细化均匀;但其拉伸强度和缺口冲击强度有不同程度的下降。     

相对分子质量及其分布对成核聚丙烯性能的影响

通过加入过氧化二异丙苯（DCP）来改变聚丙烯（PP）的相对分子质量及其分布，研究了成核PP相对分子质量及其分布对其性能的影响。结果表明：加入DCP后。成核PP的相对分子质量降低、分布变窄，促使PP结晶速度进一步提高，晶体尺寸进一步减小。成核PP中的β晶型消失。当成核剂TM-3和降解剂DCP的含量分别为0．4％和0．05％时。成核PP的透明性最好。随成核PP的相对分子质量降低、分布变窄，成核PP的力学性能略微下降。     

过氧化物对PP纤维料性能影响对比

采用化学降解法，探究了过氧化物对聚丙烯(PP)纤维料性能的影响。选取2种不同的过氧化物(过氧化物A和过氧化物B),对比其对PP纤维料熔体流动速率(MFR)、力学性能、熔融、结晶、相对分子质量分布、气味等的影响。结果表明：随着过氧化物质量分数的增加，MFR明显增大，明确了改进PP纤维料性能的最佳固体过氧化物添加量。相同有效浓度下，过氧化物A与过氧化物B的相对分子质量分布、气味、30 min内热稳定性能表现相当。过氧化物A的质量分数在0.13%～0.17%时PP纤维料力学性能改善较佳。     

相对分子质量调节剂在PP熔体微分静电纺丝中的纤维细化作用

利用自制熔体微分静电纺丝装置,添加相对分子质量调节剂CR76,进行聚丙烯(PP)熔体微分静电纺丝,讨论了CR76含量及纺丝温度对PP熔体黏度及纤维直径的影响。结果表明:在200~280℃加工温度下,添加质量分数2%~10%CR76的PP熔体黏度降低到纯PP的25%以下;提高CR76含量与纺丝温度有助于PP纤维直径细化;添加质量分数10%CR76,纺丝温度280℃,制备的PP纤维直径大都小于1μm,平均直径可达970 nm。     

相对分子质量对等规聚丙烯性能的影响

选取了6个相对分子质量不同的等规聚丙烯(i PP),研究了相对分子质量对i PP特性黏数和熔体流动速率的影响,并探讨了相对分子质量对i PP力学性能的影响规律。结果表明:i PP的特性黏数和熔体流动速率分别与重均分子量成0.78,-3.84次方关系,特性黏数与熔体流动速率成-0.200次方关系。随着i PP相对分子质量的减小,其弯曲强度、弯曲模量和拉伸强度先增大后减小,而断裂拉伸应变和悬臂梁缺口冲击强度单调递减。     

宽相对分子质量分布聚丙烯技术进展

介绍了相对分子质量分布对聚丙烯(PP)性能的影响以及加宽相对分子质量分布在PP新产品开发中的作用。通过改变聚合工艺或采用新型催化剂加宽PP的相对分子质量来克服普通PP刚性差、热变形温度低、熔体强度差的缺点，提高PP的性能，拓宽了PP应用领域。     

等规聚丙烯在静态条件下的结晶行为北大核心

采用热台偏光显微镜研究了等规聚丙烯(i PP)结晶形态随时间的变化。通过控制目标结晶温度,比较了不同结晶温度条件下,成核速率、球晶生长速率随时间的变化以及温度对结晶完成时间的影响,并讨论了相对分子质量对结晶速率的影响。结果表明:等温结晶时,晶核数目和球晶直径都与时间呈良好的线性关系;成核速率与球晶生长速率均随温度的升高而逐渐降低;结晶完成时间实际上是球晶生长速率的反映,随温度的升高而增加;相对分子质量对i PP结晶速率的影响程度具有明显的温度依赖性,温度较低时,影响不明显,随着温度的升高,影响逐渐增大,并且成核时间和结晶完成时间均随着相对分子质量的增加而增加。     

等规聚丙烯在静态条件下的结晶行为

采用热台偏光显微镜研究了等规聚丙烯(i PP)结晶形态随时间的变化。通过控制目标结晶温度,比较了不同结晶温度条件下,成核速率、球晶生长速率随时间的变化以及温度对结晶完成时间的影响,并讨论了相对分子质量对结晶速率的影响。结果表明:等温结晶时,晶核数目和球晶直径都与时间呈良好的线性关系;成核速率与球晶生长速率均随温度的升高而逐渐降低;结晶完成时间实际上是球晶生长速率的反映,随温度的升高而增加;相对分子质量对i PP结晶速率的影响程度具有明显的温度依赖性,温度较低时,影响不明显,随着温度的升高,影响逐渐增大,并且成核时间和结晶完成时间均随着相对分子质量的增加而增加。     

双峰PE树脂的结构与性能

研究了国产催化剂和进口催化剂分别生产的同一牌号双峰聚乙烯树脂的结晶性能和流变行为,表征了其相对分子质量及其分布.2种树脂的力学性能差异可归结为其相对分子质量及其分布和结晶性能的不同:国产催化剂生产的树脂要达到同进口催化剂生产的树脂一样的流变行为,模头温度必须达到200℃以上.     

熔喷专用聚丙烯树脂的研发和性能表征

以均聚聚丙烯(PP)为基础树脂,采用可控降解法生产了具有超高流动性的熔喷专用PP树脂RP1200,并通过了工业化应用试验。采用流变仪、凝胶渗透色谱仪、偏光显微镜及差示扫描量热仪对RP1200和进口同类树脂进行了对比研究。结果表明:RP1200与进口PP试样在相对分子质量及其分布、流变性能、微观结晶形态等方面较接近,但在结晶和熔融性能方面有较明显的差别;RP1200的结晶峰温度显著高于进口试样,且结晶峰较窄,即结晶速率更快;RP1200的熔融峰温度与进口试样较接近,但熔融峰较进口试样稍宽,说明其结晶完善程度的差异较大。在工业化应用中,RP1200的使用性能与进口PP树脂类似。     

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。     

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.     

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.     

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。     

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.     

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.