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茂金属催化剂及烯烃高分子材料研究新进展 总被引:4,自引:0,他引:4
徐兆瑜 《化学推进剂与高分子材料》2005,3(4):19-24
介绍茂金属催化剂的一般组成、主要特性及在烯烃聚合催化技术所具有的显著优势和近年研究取得的一些新进展。详细叙述采用茂金属催化工艺技术合成的一些烯烃聚合物,如聚乙烯(PE)、聚丙烯(PP)、间规聚苯乙烯(sPS)、茂金属环烯烃、茂金属乙丙橡胶、茂金属乙烯-辛烯共聚物等。这些茂金属聚合物与传统催化剂合成的聚合物相比,具有更优良的特性和更广阔的应用范围。许多用传统催化剂难以合成的材料,在采用茂金属催化技术后变得容易进行。在烯烃聚合物合成中茂金属催化剂正在替代传统催化剂。茂金属催化剂在全球增长非常迅速,具有广阔的应用和市场前景。 相似文献
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茂金属聚烯烃的特性和应用 总被引:2,自引:0,他引:2
从90年代初以来应用茂类金属化合物催化剂体系合成聚烯烃的技术在很多公司进入工业化生产阶段,随之其加工性能研究和产品开发工作也进展很快.茂金属聚合物的特性引起人们的广泛关注,关于茂金属聚合物的信息和报道越来越多.本文选取了从1992年~1997年间的部分文献,综合介绍了茂金属聚合物(sPP、m-LLDPE、PS、和COC等)的物理性能、加工特性和产品应用的基本情况. 相似文献
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介绍了茂金属催化剂的主要特点及在烯烃聚合催化技术中所具有的显著优势,以及近年研究取得的一些进展。详细叙述了采用茂金属催化工艺技术合成的一些烯烃聚合物,如聚乙烯(PE)、聚丙烯(PP)的性能及应用。这些茂金属聚合物与传统催化剂合成的聚合物相比,具有更优良的特性和更广阔的应用领域。 相似文献
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Kshama Motha Ulla Hippi Kimmo Hakala Maija Peltonen Vuokko Ojanper Barbro Lfgren Jukka Seppl 《应用聚合物科学杂志》2004,94(3):1094-1100
This article reports a study of some functionalized polyolefins evaluated as compatibilizers in polyethylene nanocomposites. The functionalized polymers were prepared by direct metallocene‐mediated copolymerizations of ethylene and a functional comonomer. The prepared nanocomposites were evaluated for mechanical and barrier property enhancement. A good combination of mechanical and barrier properties was obtained with the metallocene‐based functionalized polyethylene. The toughness–stiffness balance was better than or comparable to that achieved with conventional functionalized polymers such as maleic anhydride grafted polyethylene. The results also indicated that these metallocene‐based functionalized polyolefins, when used as compatibilizers, could have relatively higher molar masses and lower functionality than those of conventional post‐reactor‐modified compatibilizers, and so the drawbacks associated with the latter could be avoided. Their inherent properties could also further improve the final nanocomposite properties. This was attributed to the more homogeneous nature of metallocene‐catalyzed polymers in comparison with post‐reactor‐modified products. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1094–1100, 2004 相似文献
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《塑料、橡胶和复合材料》2013,42(7):340-348
AbstractThis paper compares the rotomouldability and mechanical properties of conventional polyethylenes with metallocene polymers having a similar melt flowrate or the same density. The rotomouldability has been evaluated in terms of bubble removal, cycle times, and heat stability during the moulding process. The mechanical properties, such as tensile strength and peak impact energy, were measured on parts produced using a variety of moulding conditions. It was found that the metallocene polymers display greater toughness if subjected to the same moulding conditions as the conventional polymers. Conversely, the same toughness can be obtained in both materials if shorter cycle times are used for the metallocenes. This behaviour has been linked to the relaxation behaviour of the molecules in the solid state. Other material parameters, such as the nature of the comonomer, the long chain branching density, and the crystalline morphology were studied by NMR, DSC, and polarising light microscopy. The differences between the molecular structures of the two types of polyethylene can be used to explain why the metallocene materials possess many rheological and other characteristics that are desirable in rotational moulding. 相似文献
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The relationship between the molecular structure and the thermal and rheological behaviors of metallocene‐ and Ziegler–Natta (ZN)‐catalyzed ethylene copolymers and high‐density polyethylenes was studied. Of special interest in this work were the differences and similarities of the metallocene‐catalyzed (homogeneous) polymers with conventional coordination‐catalyzed (heterogeneous) polyethylenes and low‐density polyethylenes. The short‐chain branching distribution was analyzed with stepwise crystallization by differential scanning calorimetry and by dynamic mechanical analysis. The metallocene copolymers exhibited much more effective comonomer incorporation in the chain than the ZN copolymers; they also exhibited narrower lamellar thickness distributions. Homogeneous, vanadium‐catalyzed ZN copolymers displayed a very similar comonomer incorporation to metallocene copolymers at the same density level. The small amplitude rheological measurements revealed the expected trend of increasing viscosity with weight‐average molecular weight and shear‐thinning tendency with polydispersity for the heterogeneous linear low‐density polyethylene and very‐low‐density polyethylene resins. The high activation energy values (34–53 kJ/mol) and elevated elasticity found for some of our experimental metallocene polymers suggest the presence of long‐chain branching in these polymers. This was also supported by the comparison of the relationship between low shear rate viscosity and molecular weight. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1140–1156, 2002 相似文献