共查询到19条相似文献,搜索用时 218 毫秒
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钛系Ziegler—Natta催化剂下的丙烯α—烯烃的共聚合 总被引:3,自引:0,他引:3
研究了TiCl4/MgCl2-三乙基铝高效载体催化体系下的丙烯/癸烯-1共聚及δ-TiCl3-氯二乙基铝催化体上的丙烯/辛烯-1共聚合的基本反应规律,考察了铝钛比、温度、共聚单浓度等对共聚合的影响,对比了两种催化体系的不同,利用非均相Ziegler-Nattz催化体系下共聚合的非稳态扩散动力学的观点,解释了观察到的共聚合催化效率增加,共聚物粒子增大等实验现象。 相似文献
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单茂钛/MAO体系催化乙烯/丙烯共聚合研究:Ⅰ.乙烯/丙烯共聚物的合成及聚合 总被引:8,自引:3,他引:5
采用合成的催化剂五甲基环戊二烯基三烯丙氧基钛「Cp^*Ti(OAllyl)3」与改性甲基铝氧烷(mMAO)组成新型催化体系进行了乙烯/丙烯共聚合,考察了助催化剂(mMAO)中TMA含量、气体配比、聚合温度、助催化剂和主催化剂浓度等因素对共聚合活性及产物分子量的影响,研究了其变化规律。结果表明,Cp^Ti(OAllyl)3/mMAO催化体系中钛的价态分布为Ti(Ⅳ)时对共聚合更为有利,制得了乙烯/丙烯无规共聚物弹性体。 相似文献
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本文考察了CoMo/TiO3和CoMo/γ-Al2O3催化剂的加氢脱硫性能及表面结构变化和预处理条件对其活性的影响.担体TiO2(A)和TiO2(B)分别采用TiCl4中和法和TiOSO4水解法制备.结果表明,催化剂的活性顺序为CoMo/TiO2(A)>CoMo/TiO2(B)>CoMo/γ-Al2O3催化剂的预处理条件对催化剂的加氢脱硫(HDS)和加氢(HYD)活性有很大影响,TiO2担体上Mo物种主要以八面体配位构型存在,Mo6+更易于还原成低价态. 相似文献
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Co-Mo/TiO2和Co-Mo/γ-Al2O3加氢脱硫催化剂的研究 总被引:8,自引:0,他引:8
本文考察了CoMo/TiO2和CoMo/γ-Al2O3催化剂的加氢脱硫性能及表面结构变化和处理条件对其活性的影响,担体TiO2(A)和TiO2(B)分别采用TiOSO4水解法制备,结果表明,催化剂的活性顺序为CoMo/TiO2(A)>CoMo/TiO2(B)>CoMo/γ-Al2O3,催化剂的预处理条件对催化剂的加氢脱硫和加氢活性有很大影响,TiO2担体上Mo物种主要以八面体配位构型存在,Mo^- 相似文献
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考察了复合催化剂AlCl_3/SbCl_3的不同配制方法和质子捕捉剂2,6-二异丁基-4-甲基吡啶(DTBMP)对α-蒎烯阳离子聚合反应的影响。结果表明,AlCl_3和SbCl_3加热熔融复合比简单复合的引发聚合活性更高;DTBMP对该复合催化剂的聚合反应速率及其产物分子量分布均无明显影响,证明该复合催化剂形成的活性种本质上与质子H活性种不同,是新型活性种。根据27AlNMR对该体系活性种分析结果,认为引发阳离子是[Sb(V)Cl_4],抗衡阴离子是[Al_2Cl_7] 相似文献
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新型高活性催化剂乙烯气相聚合的研究(I):气相均聚和共聚… 总被引:3,自引:2,他引:3
研究了新型高活性乙烯气相聚合催化剂TiCl4/MgCl2/ZnCl2/SiCl4/醇/Al(i-Bu)3体系中钛和醇组分含量对聚合反应和产物颗粒形态的影响。测定了乙烯气相聚合反应动力学曲线,确定了聚合动力学方程。用SEM,DSC,WAXD,^1^3CNMR对催化剂及聚合物的形态,结构和性能进行了分析和表征。 相似文献
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Junji Furukawa Eiichikobayashi Kazuo Haga 《Journal of polymer science. Part A, Polymer chemistry》1973,11(3):629-636
The copolymerization of butadiene and propylene was investigated. It was found that the catalyst system of TiCl4–Et3Al–COCl2 yields a random copolymer of high molecular weight with a small amount of gel polymer above room temperature. Tetrachloroethylene was a good solvent for the production of high polymer containing a high proportion of propylene units in high yield. The fractionation and the analysis of degradation experiments of copolymer indicate that the copolymer is of random distribution of propylene units in the copolymer. However, the monomer reactivity ratios, rBD = 6.36 and rPr = 0.42, suggest some degree of blocked character. The properties of the copolymer were superior to those of cis-1,4–polybutadiene, especially in resistance to thermal aging. 相似文献
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S. Cesca G. Bertolini G. Santi P. V. Duranti 《Journal of polymer science. Part A, Polymer chemistry》1971,9(6):1575-1598
A detailed investigation of the terpolymerization reaction of ethylene and propylene with 1-isopropylidene-dicyclopentadiene (II) was carried out by empolying vanadiumbased anionic coordinate catalysts [preferentially V(Acac)3? AlEt2Cl]. The influence of some polymerization parameters, i.e., concentration of II, of the catalyst; polymerization time, etc., were particularly examined. The catalysts were found to be active in C2H4? II copolymerization also, but neither C3H6? II copolymer nor II homopolymer were obtained. By using the 5,6-dihydro derivative of II as comonomer, it was found through ultraviolet, infrared, and NMR analyses that the incorporation of II in polyethylene or ethylene–propylene chains took place randomly and by selective opening of the norbornene double bond. The quantitative determination of the unsaturation present in C2H4? C3H6? II terpolymer was studied by means of absorption of iodine halides and through a spectroscopic ultraviolet method. Reference was made to terpolymer samples containing 14C-labeled II. The content of II was generally less than 35 wt-% both in copolymer and in terpolymer prepared. The relatively high reactivity of II is discussed in terms of norbornene ring strain and compared with the reactivity of 1-isopropylidene-3a,4,7,7a-tetrahydroindene (I) previously reported. 相似文献
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Junji Furukawa Hirotoshi Amano Ryuichi Hirai 《Journal of polymer science. Part A, Polymer chemistry》1972,10(3):681-688
Alternating copolymerizations of butadiene with propylene and other olefins were investigated by using VO(acac)2–Et3Al–Et2AlCl system as catalyst. Butadiene–propylene copolymer with high degree of alternation was prepared with a monomer feed ratio (propylene/butadiene) of 4. Alternating copolymers of butadiene and other terminal olefins such as butene-1, pentene-1, dodecene-1, and octadiene-1,7 were also obtained. However, the butadiene–butene-2 copolymerization did not yield an alternating copolymer but a trans-1,4-polybutadiene. 相似文献
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Masahiro Kakugo 《Macromolecular Symposia》1995,89(1):545-552
The mechanism of stereoselectivity of propylene insertion in propylene-ethylene copolymerization on a CS symmetrical zirconium complex i-Pr(Cp) (Flu) ZrCl2 catalyst is discussed. Calculation results indicate that not only the β-carbon in the growing chain end of the polymer but also the substituent of the β-carbon play an important role in the selectivity of the prochiral face of the next-coming propylene monomer. The stereoregularity of propylene units connected to an ethylene unit (PPE) in propylene-ethylene copolymer was observed to be lower than that in propylene sequences (PPP) in the 13C NMR spectrum, which supports the calculation results. Furthermore, the structure and properties of propylene-olefin (ethylene, 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene) copolymers prepared with the i-Pr(Cp) (Flu) ZrCl2 catalyst system were studied. Propylene-1-butene copolymer exhibits peculiarly lower melting point depression because 1-butene units enter into the unit cell of the crystal structure of syndiotactic polypropylene. 相似文献
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Summary : High-yield synthesis of gold microplates is achieved through autoreduction of hydrogen tetrachloroaureate (III) hydrate (HAuCl4 · 3H2O) in aqueous solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (Pluronic L64, EO13PO30EO13) at ambient conditions, in the absence of added energy, reductant, or other surfactants. The formation by the amphiphilic block copolymer of lyotropic liquid crystals (e.g., ordered cylindrical/hexagonal or lamellar phases) is not required for templating the formation of such microplates. 相似文献
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trans‐Dichlorotetrapyridineruthenium(II) [trans‐RuCl2(py)4] was synthesized and the structure was determined by single crystal X‐ray crystallography. Highly efficient formation of propylene carbonate (PC) from carbon dioxide and propylene oxide was achieved by using a catalyst system composed of trans‐RuCl2(py)4 and hexadecyl trimethyl ammonium bromide under mild conditions (4h, 80 °C, 3.0 MPa). PC was obtained in nearly 100% selectivity without the formation of a polymer. The catalyst could be recycled constantly many times without any significant loss of its catalytic activity. On the basis of the results, a mechanism for the reaction was proposed. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
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Shu Zhang Wen‐Chao Zhang Dan‐Dan Shang Yi‐Xian Wu 《Journal of polymer science. Part A, Polymer chemistry》2019,57(4):553-561
The quasi‐living copolymerization of ethylene with propylene was achieved by using N‐heterocyclic carbene (NHC) ligated vanadium complex ( V3 , VOCl3[1,3‐(2,6‐iPr2C6H3)2(NCH?)2C:]) due to the stabilization of active center by the introduction of bulky and electron rich NHC ligand with bulky isopropyl substituents at the ortho positions of the phenyl rings. The weight‐average molecular weight (Mw) of the resulting copolymer increases linearly with its weight in 20 min. The ultra‐high‐molecular‐weight (UHMW) ethylene‐propylene copolymer (Mw = 1612 kg mol?1) can be synthesized with V3 /Et3Al2Cl3 catalytic system. The novel complex V4′ (VCl3[1,3‐(2,4,6‐Me3C6H2)2(NCH?)2C:]·2THF) was constructed by the introduction of two coordinated tetrahydrofuran molecules and decrease in steric hindrance at the ortho positions of phenyl rings. The UHMW ethylene‐propylene copolymer (Mw = 1167 kg mol?1) can also be synthesized by using V4′ /Et3Al2Cl3 catalytic system. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 553–561 相似文献
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J. Bares 《Journal of Polymer Science.Polymer Physics》1971,9(7):1271-1285
The viscoelastic behavior of two different ethylene–propylene copolymers was studied as a function of the molar ratios of the components and the distribution of the lengths of the ethylene and propylene sequences. The glass transition temperatures Tg agree with the values calculated from relations between Tg and component ratio established by other authors. The copolymer with longer ethylene and propylene sequences was found to exhibit a relaxation spectrum with a slope less steep than ?0.5. This broadening is explained by the broader distribution of friction factors of the statistical segments in this copolymer and by differences in crystallike nearest-neighbor packing. 相似文献
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K. Patel P. Bahadur C. Guo J. H. Ma H. Z. Liu K. Nakashima 《Journal of Dispersion Science and Technology》2013,34(5):748-755
The effect of potassium chloride on the micellization of a poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) (PEO‐PPO‐PEO) triblock copolymer (Pluronic F88: EO103PO39EO103.) in water was studied by fluorescence, FTIR, 1H NMR, dynamic light scattering, and dye solubilization. The critical micellization temperature (CMT) values of the copolymer decreased with an increase of KCl concentration while micellar core gets progressively dehydrated. The results reveal the leading role of salt‐water interaction in promoting the micellization of PEO‐PPO‐PEO copolymer by the addition of salt. No significant micellar growth was seen even at temperatures close to cloud point. 相似文献