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1.
分别以二茂二氯化钛(Cp2TiCl2)和二茂二氯化锫(Cp2ZrCl2)与钐茂金属催化剂复合组成催化体系,并以甲基铝氧烷为助催化剂,进行宽分子量分布聚乙烯合成研究。研究发现与使用Cp2TiCl2和二(甲基茂基)氯化钐复合体系相比,使用其与二(特丁基茂基)氯化钐[(t—BuCp)2SmCl]复合体系能得到具有较高粘均分子量的聚乙烯。同样,使用Cp2ZrCl2与(t—BuCp)2SmCl复合体系也能得到具有较高粘均分子量的聚乙烯。且使用含(t-BuCp)2SmCl复合体系得到分子量分布指数达3.5以上的聚乙烯。 相似文献
2.
Jari Koivumäki 《Polymer Bulletin》1995,34(4):413-418
Summary The comparison of the copolymers obtained with the Cp2ZrCl2/MAO and Cp2HfCl2/MAO catalyst systems showed that the catalyst having hafnocene was much more reactive towards 1-octadecene than zirconocene. The comonomer concentration had to be three times higher in the zirconocene copolymerization than in the hafnocene copolymerization when the level of 6 mol-% was reached. Although the hafnocene catalyst was more reactive towards 1-octadecene, the molecular weights were higher than in the copolymers obtained with the zirconocene catalyst.The total activity of the zirconocene was 10 times higher than with the hafnocene catalyst. With the zirconocene catalyst the activity towards ethylene was constantly increasing by increasing the comonomer concentration but stayed nearly constant with the hafnocene catalyst. It seemed that there is no rate enhancement effect upon comonomer addition with the hafnocene catalyst. 相似文献
3.
选用二氯二茂钛(Cp2TiCl2)作为丁苯嵌段共聚物加氢催化剂,用活性胶分别进行了催化剂用量、压力、温度对加氢效果的影响研究,得到了较好的加氢条件。用二氯二茂钛作加氢催化剂、催化剂用量为(0.2~0.4)mmol/100 g聚合物时,二烯烃段加氢度可大于98%。 相似文献
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5.
Jin-San Yoon Jae-Kwon Oh Kwang-Pyo Hong Ik-Mo Lee 《Korean Journal of Chemical Engineering》1996,13(2):207-210
Propylene polymerization behavior of a highly isospecific catalyst, Solvay/Cp2TiMe2, was investigated. Polypropylene from the Solvay/Cp2TiMe2 system showed higher 1.1% with less dependence on reaction temperature than that produced from the Solvay/DEAC system. 相似文献
6.
The kinetics and stereochemical control of propylene polymerization initiated by syndiospecific isopropylidene(1-η5-cyclopentadienyl)(1-η5-fluorenyl)-dimethylzirconium–methyl aluminoxane (1/MAO) and (1-fluorenyl-2-cyclopentadienylethane)-dimethylzirconium–MAO (2/MAO) were investigated. The influence of MAO concentration and polymerization temperature (Tp) on polymerization kinetics and polypropylene properties, such as molecular weight, molecular weight distribution (MWD), and stereoselectivity, have been studied in detail. The activity of both catalytic systems is very sensitive to the concentration of MAO. The 1/MAO and 2/MAO catalysts record maximum activity when [Al]/[Zr] ratio is around 1300 and 2500, respectively. The activity and the degree of stereochemical control are also sensitive to Tp. The 2/MAO catalyst is much more thermally stable than 1/MAO catalyst; the former shows maximum activity at 80°C, whereas the latter shows maximum activity at 20°C. The cationic active species generated by 2/MAO is not so stereorigid as those by 1/MAO so that 2/MAO catalyst produces sPP of broad MWD (4.43–6.38) and low syndiospecificity at high Tp. When Tp is above 50°C, 2/MAO catalyst produces completely atactic polypropylene. The results of fractionation of sPP samples produced by 1/MAO and 2/MAO demonstrate that 1/MAO catalyst is characterized by uniform active sites, but 2/MAO is characterized by multiple active sites. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 973–983, 1998 相似文献
7.
Maria de Fátima V. Marques Cristiane A. Henriques José Luiz F. Monteiro Sonia M. C. Menezes Fernanda M. B. Coutinho 《Polymer Bulletin》1997,39(5):567-571
Y zeolites with different aluminium contents obtained by dealumination with ammonium hexafluorosilicate were evaluated as
supports for bis(cyclopentadienyl)zirconium dichloride catalysts. The activities of the supported and homogeneous systems
were compared for ethylene polymerization. The most active heterogeneous catalyst was the one supported on the zeolite with
the higher Si/Al ratio and external area.
Received: 5 June 1997/Revised: 2 September 1997/Accepted: 9 September 1997 相似文献
8.
采用半连续种子乳液聚合法,得到了粒径为280 nm左右的以聚甲基丙烯酸甲酯 (PMMA)为核、聚苯乙烯(PS)为壳的PMMA/ PS核壳结构聚合物和以PS为核、PMMA为壳的PS/PMMA核壳结构聚合物.并分别以上述二种核壳聚合物为载体,超临界CO2为溶剂,采用超临界流体浸渍法负载二氯二茂钛(Cp2TiCl2)催化剂,得到PMMA/PS-Cp2TiCl2和PS/PMMA-Cp2TiCl2两种负载型的茂金属催化剂颗粒.通过对二种催化剂颗粒的乙烯淤浆聚合动力学的研究发现,PMMA/PS-Cp2TiCl2催化剂颗粒的聚合反应速度有很大的滞后效应,聚合最大反应速率出现在第9 min,而PS/PMMA-Cp2TiCl2催化剂颗粒动力学行为与Cp2TiCl2催化剂均相聚合相似. 相似文献
9.
《Catalysis communications》2007,8(8):1209-1213
Nano-sized and micro-sized silica particles were used to support Cp2ZrCl2/MAO catalyst for ethylene polymerization. Nano-sized catalyst exhibited much better ethylene polymerization activity than micro-sized catalyst. At the optimum temperature of 60 °C, nano-sized catalyst’s activity was 4.35 times the micro-sized catalyst’s activity, which was attributed to the large specific external surface area, the absence of internal diffusion resistance, and the better active site dispersion for the nano-sized catalyst. Polymers produced were characterized with SEM, XRD, DSC, and densimeter. SEM indicated that the resulting polymer morphology contained discrete tiny particles and thin long fiberous interlamellar links. 相似文献
10.
《Inorganic chemistry communications》1999,2(5):191-193
The titanocene(III) complexes Cp2TiX(PMe3) (X=F, Cl, Br, I, Me, SMe) are readily synthesized by comproportionation reactions of Cp2Ti(PMe3)2 and Cp2TiX2. The products are characterized by EPR spectroscopy. 相似文献
11.
Xiaochen Dong Li Wang Guohua Jiang Tianxu Sun Zhenrong Zhao Haojie Yu Tao Chen 《应用聚合物科学杂志》2006,101(3):1291-1294
Nanowires were prepared by ethylene polymerization in situ with carbon nanotubes (CNTs)‐supported Cp2ZrCl2 catalyst. It was found that the metallocene catalyst was first adsorbed on the surface of the CNTs and then the polymerization of ethylene was initiated. The resulting PE could encapsulate on the surface of the CNTs to form nanowire. The diameter of nanowire could be controlled easily by the polymerization conditions. The possible mechanism of formation of nanopolyethylene wire is proposed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1291–1294, 2006 相似文献
12.
In this work, ethylene was polymerized by using Cp2ZrCl2 supported on silica pretreated with methylaluminoxane (MAO) as the catalyst system. The influence of the conditions for the preparation of the heterogeneous catalyst, such as temperature, washing method of the catalytic solid, MAO and metallocene concentration in the support treatment, time of MAO, and metallocene immobilization on the support, type of alkylaluminum used in the support pretreatment, and calcination temperature of the support were investigated. Aluminum and zirconium content fixed on the silica surface were determined by inductively coupled plasma emission spectroscopy. Polymer characteristics were determined by gel permeation chromatography and differential scanning calorimetry. According to the results, the activity of some supported catalysts were far higher than with the homogeneous system. Moreover, polyethylene with very high molecular weights were also obtained and with molecular weight distribution larger than those produced with the homogeneous precursor. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2054–2061, 2002 相似文献
13.
《Inorganic chemistry communications》2003,6(2):210-212
Dialkylzirconocenes react with molybdenum or tungsten hexacarbonyl and iodine or NBS to form cyclopentadiene molybdenum or tungsten tricarbonyl iodine or bromide. 相似文献
14.
以四氢呋喃为溶剂 ,合成了含Sn、Fe的环戊烯基二羰基铁的异核双金属化合物 ,并对配合物进行了元素分析、IR光谱分析 ,使用SimensP4单晶衍射仪测定了配合物的晶体结构。结构分析表明 ,该配合物属于三斜晶系 ,空间群P - 1。晶胞参数 :a =10 0 79(2 )A° ,b =10 975 0 (10 )A°,c =17 14 5 (3)A° ;a =82 0 30 (10 )° ,β =77 770 (10 )°,γ =6 3 70 0 (10 )° ,Z =2 相似文献
15.
Il Kim Ki Tae Kim Min Hyung Lee Youngkyu Do Hoeil Chung 《Polymer Engineering and Science》2001,41(6):899-907
Copolymerizations of ethylene with 1‐decene have been carried out by using two syndiospecific metallocenes synthesized by modifying the bridge: highly syndiospecific isopropylidene(1‐η5‐cyclopentadienyl)(1‐η5‐fluorenyl)‐dimethylzirconium (Me2C(Cp)(Flu)ZrMe2, 1 ) and less syndiospecific (1‐fluorenyl‐2‐cyclopentadienylethane)‐dimethylzirconium (Et(Cp)(Flu)ZrMe2, 2 ), in the presence of [Ph3C][B(C6F5)4] as a cocatalyst. The ethano bridged 2 compound of smaller dihedral angle showed much higher activity than 1 compound. The catalytic activities of the two compounds were enhanced about twice when a suitable amount of 1‐decene comonomer is present in the feed. The compound 1 showed better comonomer reactivity than 2 . The properties (Tm, density, and crystallinity) of copolymers seem not to be affected by the type of bridge of the metallocenes, and mainly depend on 1‐decene content in the copolymer. 相似文献
16.
S. Srinivasa Reddy 《Polymer Bulletin》1996,36(3):317-323
Summary The effect of [A1]/[Zr] mol ratio and temperature on the cocatalytic effects of tetraisobutyldialuminoxane (TIBDAO) and methylaluminoxane (MAO) for ethylene polymerization using Cp2ZrCl2 catalyst were studied. The decay type kinetic profile was observed for both TIBDAO and MAO cocatalyzed ethylene polymerizations. Catalytic activity and rate of polymerization were found to be low for TIBDAO cocatalyzed ethylene polymerization when compared to MAO cocatalyzed ethylene polymerization. The differences in catalytic activity and rate of polymerization for ethylene polymerization catalyzed by Cp2ZrCl2-TIBDAO and Cp2ZrCl2-MAO were discussed with respect to the structures of MAO and TIBDAO. An active species for Cp2ZrCl2-MAO and Cp2ZrCl2-TIBDAO catalyzed ethylene polymerizations was also discussed. The polyethylene was characterized by intrinsic viscosity measurements. 相似文献
17.
采用量子化学的密度泛函理论计算,提出并研究了金属有机化学气相沉积(MOCVD)气相过程中p型掺杂剂Cp2Mg的反应机理。特别判断了不同温度下各反应进行的可能性。发现Cp2Mg主要有两条相互竞争的反应路径,加合路径和氢解路径。对于加合路径,在293~573 K的温度范围内,会形成络合物Cp2Mg∶NH3或Cp2Mg∶(NH3)2。对于氢解路径,气相中的H自由基是一把“双刃剑”。一方面H自由基对Cp2Mg的分解有积极的辅助作用,明显降低了Cp2Mg的分解温度;另一方面由于钝化作用会形成Mg-H气相络合物,影响p型掺杂效果。 相似文献
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19.
Combination of 8‐aminoquinoline nickel dichloride and Cp2ZrCl2 catalysts for ethylene polymerization
Zilong Li Ning Zhu Wen‐Hua Sun Changxing Shao Yucai Ke Youliang Hu Jiasong He 《Polymer International》2001,50(12):1275-1278
Polyethylene has been modified and synthesized in situ by a combination of Cp2ZrCl2 and 8‐aminoquinoline nickel dichloride catalysts with methylaluminoxane co‐catalyst. The results indicate that the crystallinity and Tm of polyethylene both decrease with increasing Ni/Zr mol ratio when the Ni catalyst is added first. Oligomers formed by 8‐aminoquinoline nickel dichloride within a certain Ni/Zr mol ratio could be completely converted into polymer. Three methods used to introduce catalysts to the reaction system resulted in different products. Polyethylene with the lowest melting point, crystallinity and the highest degree of branching resulted when the Zr catalyst was added after that of the Ni compound. © 2001 Society of Chemical Industry 相似文献
20.
In this work, the preparation and characterization of metallocene‐catalyzed polyethylene (PE)/kaolin composites were presented. The composites was prepared by the so‐called polymerization‐filling method in which the PE matrix was formed directly on the kaolin surface by ethylene polymerization with the prefixed Cp2ZrCl2/methylaluminoxane (MAO) catalyst system on the kaolin surface. SEM, FTIR, and DMA were carried out to characterize the composites. The experimental results showed the new composites had homogeneous distribution of kaolin particles in the PE matrix and strong interfacial interaction between the PE matrix and kaolin particles. At the molecular level, the interfacial interaction caused the decrease of the mobility of PE molecular chains. In addition rheological testing showed that the introduction of kaolin by polymerization filling could improve the rheological behavior of prepared composites. The relationship between the rheological behaviors and the interfacial conditions were discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2913–2921, 2002 相似文献