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研究动态硫化EPDM/PP热塑性弹性体相态结构及其力学行为。结果表明:动态硫化EPDM/PP共混物相态是EPDM橡胶以颗粒状分布在PP连续相中,这种相态结构一般不随橡塑比的变化而改变,但EPDM橡胶颗粒的形态变化显著。动态硫化EPDM/PP共混物,在橡塑比小于25/75,共混物具有类似橡胶应力-应变特征。 相似文献
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聚丙烯/顺丁橡胶动态硫化法增韧 总被引:3,自引:0,他引:3
用简单共混和动态硫化共混两种不同工艺制取PP/BR共混物,分别测定了两种共混物在室温和低温下的冲击强度,用扫描电镜(SEM),动态粘弹谱(DDV)和偏光显微镜等手段对共混物进行了分析。结果表明,动态硫化共混法,可以减小PP球晶尺寸,增加PP球晶分布的均匀性,有效地改善共混物的形态结构,增加两相的相容性;提高共混物的冲击强度,特别是低温下的冲击强度。研究工作为用动态硫化法进一步提高顺丁橡胶(BR)增韧PP的效果提供了实验依据。 相似文献
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动态硫化EPDM/PP热塑性弹性体的流变性能 总被引:6,自引:0,他引:6
研究了共混工艺条件,橡塑比,橡胶相交联速率及交联密度,PP的熔体流动指数对EPDM/PP共混物流变性能的影响。结果表明,当降低EPDM含量,减小EPDM相粒径时,共混物的流动性增强。共混物发生熔体破裂是由于EPDM和PP相在挤出后两相大分子的弛豫行为不同所致。提高PP含量,降低了EPDM相粒径,同时EPDM分散相具有适宜的交联密度时,可以得到挤出表面光滑的共混物。 相似文献
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聚丙烯/三元乙现橡胶共混体系的研究 总被引:2,自引:0,他引:2
研究了三元乙丙橡胶(EPDM)对聚丙烯(PP)结晶行为的影响以及PP/EPDM共混物的形态与性能的关系。EPDM对PP的熔点、结晶温度无明显影响,PP/EPDM共混物的结晶度随EPDM组份含量的增加而降低,适量的EPDM可使PP的晶体尺寸减小,晶胞参数与组份比无关。当EPDM用量为30% ̄40%时,共混物的冲击强度迅速提高。 相似文献
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动态硫化PP/EPDM性能对共混工艺的依赖及其机理研究 总被引:13,自引:0,他引:13
本文通过对一步法和母料法两种共混工艺制备的动态硫化PP/EPDM力学性能、拉伸形变特性,熔体流动行为,交联程度和微观结构等的表征和分析,研究了动态硫化PP/EPDM性能对共混工艺的依赖及其作用机理。结果显示,在保证有效地提高材料加工流动性的前提下,母料法能有效地抑制动态硫化中PP的降解,提高EPDM的交联程度,粒度均匀性和分散均匀性,从而强化材料的增韧效果以及其它力学性能,并提高材料性能的均匀性。 相似文献
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研究了橡胶型乙烯醋酸乙烯酯共聚物(EVM)/NBR共混比、硫黄和叔丁基酚醛树脂(2402树脂)硫化体系对共混物性能的影响,并对比了动态硫化和静态硫化共混物在性能上的差异。试验结果表明,EVM/NBR共混比显著影响共混物的力学性能,而采用NBR预先动态硫化的方法后,共混物胶料的挤出口型膨胀率明显减小,老化性能得到改善,同时减弱了硫黄和2402树脂等硫化体系对EVM硫化的影响,使多种硫化体系可以共存于共混物中。DSC分析表明EVM/NBR动态硫化共混物只有一个玻璃化温度,且介于EVM和NBR之间,说明EVM和NBR具有良好的相容性。 相似文献
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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。 相似文献
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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. 相似文献
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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. 相似文献
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《国际聚合物材料杂志》2012,61(1-4):113-122
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. 相似文献
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G. R. Hamed 《The Journal of Adhesion》1983,16(1):31-39
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. 相似文献
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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. 相似文献
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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. 相似文献