合成高分子量无规聚丙烯—在烷烃溶剂中聚合及性能初步表征

丙烯聚合;茂金属催化剂;立体结构;合成高分子量无规聚丙烯—在烷烃溶剂中聚合及性能初步表征     

丙烯聚合中硅烷类外给电子体及其复配技术研究进展

聚丙烯是一类重要的通用塑料,主要用于汽车工业、家用电器、电子、包装及建材家具等领域。在现有聚丙烯工业生产中,通常加入外给电子体来影响丙烯聚合过程,达到调控产品物理性能的目的。本文对丙烯聚合中硅烷类外给电子体及其复配技术进行了综述,并对外给电子及其复配技术在聚丙烯新产品开发上的应用进行了分析。     

含糖聚合物可控合成研究进展

活性聚合技术的进步,使设计合成结构可控的含糖聚合物成为可能.本文介绍了阴离子聚合、阳离子聚合、原子转移自由基聚合、可逆加成断裂链转移聚合、硝基氧介导聚合、开环聚合和开环易位聚合等一系列可控/"活性"聚合技术在合成含糖聚合物中的应用,并对这一领域所取得的研究进展及现状进行了综述.     

过渡金属催化的环丙烯聚合反应研究

环丙烯是一类最小的不饱和环状化合物,其在有机化学中是十分重要的合成中间体,同时在高分子聚合中也是一类独特的单体.尽管环丙烯的研究大部分集中于有机化学领域,近年来有关过渡金属催化的环丙烯聚合反应也逐渐引起了人们的兴趣.综述了环丙烯聚合反应的研究进展,主要包括加成聚合和开环复分解聚合(ROMP)两类聚合反应,并从聚合物合成...     

3—甲基丙烯酰胺基—9—乙基咔唑—过硫酸钾氧化还原体系引发 …

合成了可聚合芳香叔胺－３－甲基丙烯酰胺基－９－乙基咔唑,并与过硫酸钾组成氧化还原引发体系引发丙烯酰胺水溶液聚合,测定了聚合反应动力学,得到了超高分子量的聚丙烯酰胺。     

用于丙烯聚合的MgCl2负载Ziegler-Natta催化剂研究进展

综述了用于丙烯聚合的MgCl2负载Ziegler-Natta催化剂研究进展,包括内给电子体的发展及其作用研究,催化剂活性中心的模型,用MgCl2负载的Z-N催化剂制备抗冲聚丙烯合金.     

丙烯聚合用TiCl_4/MgCl_2催化剂的研究——聚合温度和烷基铝的影响

研究了不同助催化剂和不同聚合温度对催化剂TiCl4/MgCl2/9,9-双(甲氧基甲基)芴(BMMF)丙烯聚合性能的影响.研究结果发现该催化剂在高温(100℃)聚合时,采用还原能力和络合能力较弱的烷基铝(Hex3Al)为助催化剂可以得到高的立构选择性(97%)和高活性.100℃聚合时不同的助催化剂对催化剂得到的聚丙烯结构有重要影响.助催化剂为Me3Al聚合得到的中等等规聚丙烯含量比其他烷基铝高.助催化剂为Et3Al聚合得到聚丙烯链结构中含有少量乙烯共聚单元;而助催化剂为Me3Al,iBu3Al和Hex3Al聚合得到聚丙烯链结构中没有发现共聚单元.     

丙烯聚合催化剂的研究进展

自从上个世纪五十年代发现Ziegler-Natta催化剂以来，对丙烯定向聚合的研究一直没有中断过．五十年来，聚丙烯催化剂从低活性、低规整性的第一代TiCl3催化剂已经发展到了第四代超高活性和高定向性的球形大颗粒催化剂，近年来又发现茂金属是有效的丙烯聚合催化剂．茂金属有清晰的组成和立体结构，这为研究结构和性能的关系带来了方便，因而在学术界和企业界引起了新一轮对聚丙烯合成研究的兴趣．本文对负载型经典Ziegler-Natta催化体系和茂金属催化体系催化丙烯聚合的研究进展作一个综述．     

Cp*TiCl2N[Si(CH3)3]2/MAO催化剂合成无规聚丙烯弹性体

合成了Cp TiCl2 N[Si(CH3) 3]2 甲基铝氧烷 (MAO)催化体系 ,以该体系进行丙烯聚合得到无规聚丙烯 ,具有高的分子量及良好的弹性 ,玻璃化温度为 - 8 8℃ .产物经DSC、1 3C NMR、DMA等方法表征 .结果表明 ,催化活性随着丙烯压力的增加 ,有明显的增大 .催化活性在 4 0℃下有最高的催化活性 ,而产物分子量随着温度的下降有明显增大 ,在 0℃～ 5 0℃范围内分子量MW =(2 0～ 6 0 )× 10 4 .     

低表面能聚合物的聚合进展

低表面能聚合物材料是低表面能材料中重要的一类.这类材料性能独特,用途广泛,尤其体现在涂料领域,用作防污涂层.目前,低表面能聚合物主要有氟碳树脂、有机硅树脂及氟硅树脂三种.有关这三种材料的合成研究十分活跃,出现了众多的合成研究报道.按合成过程对应的聚合机理划分,主要有基团转移聚合、阳离子聚合、阴离子聚合、自由基聚合、活性官能团间的反应.本文按聚合机理划分方法对低表面能聚合物近期的合成研究进展进行综述.     

Recent advances in the polymerisation of propylene

Since its discovery, the field of olefin polymerization using Ziegler-Natta catalysts has undergone rapid development both in terms of industrial catalysis as well as fundamental understanding of this polymerization process. This paper reviews some aspects of the recent developments with specific regard to propylene polymerizations. Presented at the Symposium on ’Polymer Science and Engineering during the Annual Meeting of the Academy, Nainital, October 1982     

乙烯和丙烯自由基共聚反应的多尺度模拟模型

结合量子化学和传统过渡态理论计算了乙烯和丙烯自由基聚合反应的速率常数.利用速率常数定义了聚合反应几率(Pijl),构造了乙烯和丙烯共聚合反应的粗粒化动力学模拟模型,并利用该模型研究了不同组成比的乙烯和丙烯的共聚合反应.发现反应速率常数和链端自由基周围的单体浓度都影响链上组分的序列分布.     

Effect of Polymerization Temperature on Propylene Polymerization with Cs-symmetric Metallocene Catalyst

The synthesis of bridged ansa metallocenes usually gives a diastereomeric mixture ofracemic and meso metallocene isomers and in many cases the meso form is about 50 % ofthe product of metallocene synthesis"'. The amount of desired racemic isomer is ratherpoor and can be separated from the meso isomer by fractional crystallization'. The racemicansa-metallocene isomer acts as catalyst for propylene polylnerization to produce isotacticpolypropylene (PP) while the corresponding meso isomer gives a…     

CS-1型和CS-2型高效催化剂的研制、生产和应用

CS-1型和CS-2型高效催化剂已成功应用于国内外许多聚丙烯生产厂。工业应用表明,催化剂具有高效率、高立构定向性、良好的形态和氢调性能,以及PP等规指数可调性,对丙烯原料的适用性强等性能特点。本文简述CS型高效催化剂的开发,工业生产和工业应用情况。     

乙烯与丙烯在负载型钛系催化剂上的共聚合行为

乙烯与α-烯烃配位共聚速率明显高于乙烯均聚速率~[1～4],其原因可归结为化学促进作用或单体扩散的影响.本文通过考察乙烯-丙烯在负载型钛系催化剂上的共聚动力学行为、催化剂-聚合物颗粒形态及改变聚合中单体的组成,以期进一步了解乙丙共聚反应的特征. 1 实验部分 1.1 催化剂及聚合 载体催化剂由无水MgCl_2、TiCl_4和EB共研磨而成,使用前用     

POLYMERIZATION OF ETHYLENE AND PROPYLENE WITH VCL4-BUTYLLITHIUM CATALYSTS

Polymerization of ethylene and propylene with VCl₄-BuLi (Bu = n-Bu, sec-Bu, tert-Bu) catalysts was investigated. The VCl₄-BuLi catalysts were found to initiate the polymerization of ethylene and propylene. The VCl₄-BuLi catalysts gave an ultra high molecular polyethylene. The effect of the Li /V mole ratio on the polymerization of ethylene with the VCl₄-BuLi catalysts was observed, an the catalyst gave an optimum rate at the Li/V ratio of about 3.0. The polyethylene obtained with the VCl₄-BuLi catalyst was found to be a linear structure. In the polymerization of propylene with the VCl₄-BuLi catalyst, the polymers contain mm contents of 56–66% were produced.     

THE INFLUENCE OF SUBSTITUENTS IN METALLOCENE ON PROPYLENE POLYMERIZATION*

Two new unbridged zirconocenes, bis(2,4,7-trimethyl indenyl)zirconium dichloride (Met-Ⅰ) andbis(2-methyl-4,7-diethyl indenyl)zirconium dichloride (Met-Ⅱ) were prepared in order to investigate thesteric effects of substituents on the nature of the catalysts for the polymerization of propylene. A mixture ofmethyl aluminoxane (MAO) and triisobutylaluminum [Al(iBu)_3] was used as cocatalyst to activate thesecatalysts. The decrease in steric bulkiness of substituents at 4 and 7 positions of the indenyl ring resulted inan increase of both activity and molecular weight as well as the isotacticity.     

Comparison of the role of new ethers and conventional alkoxysilanes as external donors in the polymerization of propylene using the industrial Ziegler-Natta catalyst

Two new ethers were synthesized using the Williamson reaction from related alcohols and were used as external donors in propylene polymerization in the presence of the industrial diisobutyl phthalate-based MgCl₂-supported Ziegler-Natta catalyst. For comparison the propylene polymerization was carried out in the presence of silane and in the absence of external donors. The produced polymers were characterized by differential scanning calorimetry, xylene extraction, melt flow index, scanning electron microscopy and gel permeation chromatography. The isotacticity, molecular weight and molecular weight distribution, melt flow index, crystallinity degree and thermal properties of polypropylenes were influenced by the type of external donors.     

SUBSTITUENT EFFECTS OF tert-BUTYL GROUPS ON FLUORENYL LIGAND OF [t-BuNSiMe2Flu] ZrMe2

[t-BuNSiMe_2(2,7-t-Bu_2Flu)]ZrMe_2 and[t-BuNSiMe_2(3,6-t-Bu_2Flu)]ZrMe_2 were synthesized,and the solid structure of complex[t-BuNSiMe_2(2,7-t-Bu_2Flu)]ZrMe_2 was elucidated by single crystal X-ray analysis.These complexes were applied for propylene polymerization using dried modified methylaluminoxane as a cocatalyst at 0℃and 20℃in toluene.Both systems did not show activity at 0℃,but they conducted the polymerization at 20℃.The introduction of t-butyl substituents to the fluorenyl ligand improved the ac...