新型高效催化剂乙烯/1-丁烯气相齐聚和共聚制备弹性体及其结构与性能关系

用新型催化体系TiCl₄,Ti(OBu)₄/MgCl₂,SiO₂和ZnCl₂/醇/AlR₃催化乙烯与1-丁烯气相均聚及共聚,制得两种共聚物弹性体,发现新型催化剂体系具有独特的齐聚和原位共聚性能.采用¹³CNMR测定了共聚物链序列分布结构,观察到共聚单体在聚合物链中分布不均匀,存在较长的乙烯链段和较多的1-丁烯嵌段.产物DSC谱图表现出复杂的结晶熔融行为,存在多种结晶形态,出现熔融肩峰及双峰,与通常制得的LLDPE的结晶熔融行为有很大差别;结晶度和密度较低,并具有弹性体性质.     

短链支化聚乙烯的合成与表征

合成了两类结构明确的乙烯共聚物, 通过FTIR, GPC, ¹H NMR和¹³C NMR表征了产物的分子结构, 分别研究了分子量和短链支化含量对两类共聚物结晶性能的影响. 采用阴离子聚合制备分子量(M_w)20000~110000、分子量分布为1.1的1,2-结构摩尔分数为7%左右的聚丁二烯. 加氢反应后得到乙烯/1-丁烯模型共聚物的熔点和结晶度随着分子量的增加而下降. 采用茂金属催化剂Et[Ind]₂ZrCl₂催化乙烯与1-己烯共聚合, 制备分子量为100000左右, 共聚单体摩尔分数为0~5.5%的乙烯/1-己烯共聚物, DSC结果表明其熔点和结晶度随着共聚物中1-己烯含量的升高而降低.     

邻位大位阻取代基胺双酚钛(Ⅳ)配合物的合成、表征和催化乙烯(共)聚合研究

合成了一系列邻位大取代基四齿胺双酚配体钛配合物Me_2NCH_2CH_2N[CH_2-2-(3-R-5-~tBuC_6H_2)O]_2TiCl_2[2a,R=CPhMe_2;3a,R=CMePh_2;4a,R=CPh_3),对其结构进行了表征,研究了其催化乙烯均聚、乙烯/丙烯共聚及乙烯/1-己烯共聚性能,考察了配体结构及聚合反应条件对聚合行为的影响。与R=~tBu的已知配合物1a相比,这些新配合物在催化乙烯均聚和共聚时表现出较高的催化活性和良好的稳定性。在MAO活化下,催化乙烯聚合活性最高达1170kg PE/(mol Ti·h);在Al~iBu_3/Ph_3CB(C_6F_5)_4活化下,用配合物2a～4a得到的聚乙烯分子量最高可达113×10~4g/mol。在MAO活化下,1a～4a催化乙烯/丙烯共聚及乙烯/1-己烯共聚活性分别达到640kg polymer/(mol Ti·h)和1220kg polymer/(mol Ti·h);乙烯-丙烯共聚物分子量为3.1×10~4～17.4×10~4g/mol、乙烯-1-己烯共聚物分子量为4.9×10~4～15.5×10~4g/mol;所得乙烯-丙烯共聚物中丙烯单元含量最高可达36.9%(mol),乙烯-1-己烯共聚物中1-己烯单元含量最高为12.5%(mol)。催化剂配体空间位阻对共单体插入率有明显影响,随配体空间位阻增大,共单体插入率降低。     

本体共聚合制备丙烯/1-丁烯合金及表征

以球形高效负载的TiCl₄/MgCl₂/邻苯二甲酸二异丁酯(DIBP)为催化剂, 采用本体聚合方法进行丙烯与1-丁烯共聚合研究. 考察了共单体效应对共聚活性及聚合物立构规整性的影响; 表征了共聚物的结构. 结果表明, 随着1-丁烯/丙烯投料比的增加, 聚合活性呈先升高后降低的趋势, 在1-丁烯/丙烯摩尔投料比为0.26条件下聚合活性达到最高, 并随着共聚物中1-丁烯含量的增加, 共聚物的熔点明显下降, 分子量降低, 分子量分布变窄, 同时共聚物力学性能有明显提高, 透明度逐渐增加.     

聚合温度对负载型Ziegler-Natta催化剂催化丁二烯-异戊二烯共聚合的影响

非均相TiCl₄/MgCl₂-AlR₃型Ziegler-Natta（非均相Z-N）催化剂是聚烯烃工业最重要的催化剂,经烷基铝活化的非均相Z-N催化剂具有复杂的活性中心结构,改变聚合温度、聚合时间、烷基铝种类及浓度等均会影响活性中心结构与催化性能.本文研究了不同聚合温度下TiCl₄/MgCl₂-AlEt₃（三乙基铝）催化丁二烯（Bd）和异戊二烯（Ip）的共聚合动力学,研究发现,随着聚合时间的延长,聚合活性先升高然后降低,在50℃聚合活性最高.采用核磁共振波谱（¹H NMR）、紫外荧光定硫仪和凝胶渗透色谱（GPC）研究了共聚物的微观结构、活性中心数和分子量及其分布,发现随着聚合时间的延长及聚合温度的升高,活性中心数、共聚物中反式-1,4-结构、分子量及分子量分布均发生不同规律的变化.本文研究结果可为进一步理解非均相Z-N催化剂在不同聚合温度下催化共轭二烯烃聚合的动力学及其关键影响因素提供参考.     

苯氧基亚胺钛催化降冰片烯与1-辛烯共聚合

以3,5-二叔丁基水杨醛缩苯胺氯化钛(Ti)、三异丁基铝(Al)和四(五氟苯基)硼酸三苯基甲酯(B)组成的三元催化体系实现了降冰片烯(NBE)与1-辛烯(OC)的共聚合,得到NOC无规共聚物.探索了催化剂组成、聚合时间及聚合温度等对共聚合反应的影响.结果表明,当n(Al)/n(Ti)=5∶1,n(B)/n(Ti)=1∶1,n(Monomer)/n(Ti)=400∶1,n(NBE)/n(OC)=5∶5时,于40℃在甲苯中聚合6 h,共聚合产率达到43.7%,2种单体的竞聚率分别为rNBE=3.01;rOC=0.08.改变助催化剂三异丁基铝的用量可在一定范围内调节所得NOC无规共聚物的分子量及分子量分布(MWD),得到Mw=3.0×104~6.5×104,MWD=1.91~2.45的NOC共聚物.NOC无规共聚物具有饱和的主链结构且带有较长的侧链,其玻璃化转变温度较高(约87~174℃),并对NOC无规共聚物组成具有很强依赖性.NOC共聚物的热分解温度超过300℃,热稳定性能优异.     

新型高活性催化剂乙烯气相聚合的研究(Ⅱ)──改性剂、预聚合和聚合条件对乙烯气相聚合的影响

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体系中不同醇、不同C₂H₅OH/Ti摩尔比和正丁醚对聚合反应及产物颗粒形态的影响。研究了预聚合反应及乙烯气相聚合反应规律。用扫描电镜和图象分析对催化剂、预聚物及聚合产物的形态和颗粒分布的研究结果表明:新型高活性催化剂和经预聚合制得的乙烯气相聚合物的颗粒形态类似球形,颗粒长短轴比值和大小粒径比值相近。     

新型高活性催化剂乙烯气相聚合的研究(Ⅵ)——锌化合物对催化剂及产物性能的影响

研究了新型高活性乙烯气相聚合催化剂TiCl₄、Ti(OBu)₄/MgCl₂、SiO₂和ZnCl₂/醇/AlR₃体系中ZnCl₂-AlEt₃/SiO₂重量比和锌化合物含量对气相均聚合的影响,比较了2种不同催化剂Cat# A和Cat# B的聚合反应动力学及性能差异.催化剂中锌化合物作为复合载体的重要组分,可显著改善产物分子量调节效果.通过比表面积、SEM、DSC以及FTIR对催化剂和聚合物的形态、结构及性能进行了分析和表征.结果表明,均聚产物与采用MgCl₂作载体的催化剂制备的产物相比,支化度较高,结晶度较低,熔融峰较宽.发现Cat#B制得的均聚产物具有新颖的熔融双峰.     

可见光下高催化活性不同结构Sr/TiO2催化剂的制备和表征

采用分步沉积法制备不同Sr/Ti 摩尔比例的Sr/TiO₂催化剂, 以X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外(FT-IR) 光谱、紫外-可见漫反射光谱(UV-Vis RDS)等手段对样品进行了表征, 以可见光催化降解亚甲基蓝为模型反应考察样品光催化活性. 结果表明, 催化剂的活性和结构随Sr/Ti 摩尔比(n(Sr)/n(Ti))的变化而变化, 当n(Sr)/n(Ti)≤3/2 时, 催化剂呈由TiO₂和SrTiO₃组成的球状结构; 而当n(Sr)/n(Ti)在3/2 与4/1 之间时, 催化剂呈片状结构, 且随着n(Sr)/n(Ti)增大, 催化剂组成由SrTiO₃ 和Sr₂₄ 变为Sr₂₄和Sr(OH)₂·H₂O; 当n(Sr)/n(Ti)=9/1 时, 催化剂呈以Sr(OH)₂·H₂O为主的针状结构. 其中, n(Sr)/n(Ti)=4/1的样品表现出最高的光催化活性, 一级反应速率为SrTiO₃钙钛矿催化剂的5.0倍, 商用P25的86.7倍.     

有机镁化合物提高乙烯聚合催化效率的作用

本文报导了有机镁化合物能促进提高几种钛系载体催化剂的乙烯聚合催化效率,载体MgCl₂含量增加,这种促进作用增大.认为有机镁具有促使载体疏松化和改变催化活性中心Ti的配位基电效应等作用.     

Ethylene/1-hexene copolymerization with TiCl4/MgCl2/AlCl3 catalyst in the presence of hydrogen

A TiCl₄/AlCl₃/MgCl₂ (Cat-B) catalyst containing 5.2 wt.% Al was prepared by the reaction of TiCl₄ with ethanol adduct of AlCl₃/MgCl₂ mixture. A TiCl₄/MgCl₂ catalyst (Cat-A) without doped AlCl₃ was also prepared by the same method. Ethylene-1-hexene copolymerization catalyzed by Cat-B in the presence of hydrogen showed slightly higher efficiency and higher 1-hexene incorporation than Cat-A. Comonomer incorporation was markedly increased when the cocatalyst AlEt₃ was replaced by Al(i-Bu)₃. Adding Ph₂Si(OMe)₂ as external donor in the catalyst system caused decrease in polymerization activity and 1-hexene incorporation. Each copolymer sample was fractionated into three fractions: n-heptane insoluble fraction (fraction A), n-heptane soluble and n-hexane insoluble fraction (fraction B) and n-hexane soluble fraction (fraction C). In most cases the amount of intermediate fraction (fraction B) was smaller than the other fractions and did not increase as the total 1-hexene content increase, indicating the presence of two classes of copolymer fractions with greatly different comonomer content and clear bimodality of the copolymer composition distribution. Doping AlCl₃ in the catalyst, changing cocatalyst and adding external donor mainly changed the weight ratio of fraction A to fraction C, but exerted little influences on their composition. According to the sequence distribution data of the fractions, doping AlCl₃ in the catalyst resulted in slight decrease of product of reactivity ratios (r₁r₂) in both fraction A and fraction C.     

Copolymerization of ethylene and 1-hexene with TiCl4/MgCl2 catalysts modified by 2,6-diisopropylphenol

A supported TiCl4/MgCl2 catalyst without internal electron donor (O-cat) was prepared firstly. Then it was modified by 2,6-diisopropylphenol to make a novel modified catalyst (M-cat). These two catalysts were used to catalyze ethylene/1-hexene copolymerization and 1-hexene homopolymerization. The influence of cocatalyst and hydrogen on the catalytic behavior of these two catalysts was investigated. In ethylene/1-hexene copolymerization, the introduction of 2,6-iPr2C6H3O-groups did not deactivate the supported TiCl4/MgCl2 catalyst. Although the 1-hexene incorporation in ethylene/1-hexene copolymer prepared by M-cat was lower than that prepared by O-cat, the composition distribution of the former was narrower than that of the latter. Methylaluminoxane (MAO) was a more effective activator for M-cat than triisobutyl-aluminium (TIBA). MAO led to higher yield and more uniform chain structure. In 1-hexene homopolymerization, the presence of 2,6-iPr2C6H3O-groups lowered the propagation rate constants. Two types of active centers with a chemically bonded 2,6-iPr2C6H3O-group were proposed to explain the observed phenomena in M-cat.     

Synergistic Effects of the ZnCl2-SiCl4 Modified TiCl4 /MgCl2 /THF Catalytic System on Ethylene/1-Hexene and Ethylene/1-Octene Copolymerizations简

The copolymerizations of ethylene with 1-hexene or 1-octene by using TiCl4 /MgCl2 /THF catalysts modified with different metal halide additives(ZnCl2, SiCl4, and the combined ZnCl2-SiCl4) were investigated based on catalytic activity and copolymer properties. It was found that the catalyst modified with mixed ZnCl2-SiCl4 revealed the highest activities for both ethylene/1-hexene and ethylene/1-octene copolymerization. The increase in activities was due to the formation of acidic sites by modifying the catalysts with Lewis acids. Based on the FTIR measurements, the characteristic C―O―C peaks of the catalysts modified with metal halide additives were slightly shifted to lower wavenumber when compared to the unmodified catalyst. This showed that the modified catalysts could generate more acid sites in the TiCl4 /MgCl2 /THF catalytic system leading to an increase in activities as well as comonomer insertion(as proven by13C-NMR). However, Lewis acidmodifications did not affect the microstructure of the copolymers obtained. By comparison on the properties of copolymers prepared with the unmodified catalyst, it was found that polymers with ZnCl2 and/or SiCl4 modification exhibited a slight decrease in melting temperature, crystallinity and density. It is suggested that these results were obtained based on the different amount of α-olefins insertion, regardless of the types of Lewis acids and comonomer.     

Substituent effect of bisindenyl zirconene catalyst on ethylene/1-hexene copolymerization and propylene polymerization

Nonbridged bis-substituted indenyl zirconene complexes were used as the catalysts for ethylene/1-hexene copolymerization and propylene polymerization. The complicated “comonomer effect” on the activity of ethylene/1-hexene copolymerization was observed. The effect also worked on the incorporation of comonomer. The number and the position of the substituents were important for the copolymerization behavior and the microstructure of the resultant copolymer as well as for propylene polymerization.     

Polymer-supported Ziegler–Natta catalysts. II. Ethylene homo- and copolymerization with TiCl4/MgR2/poly(ethylene-co-acrylic acid) catalyst

A novel polymer-supported titanium-based catalyst shows high activity and nondecaying kinetic profiles for ethylene polymerization. The presence of 1-hexene comonomer drastically increases the catalyst activity, exhibiting a similarity to the MgCl₂-supported catalysts. However, the nondecaying kinetic profiles of copolymerization distinguish this catalyst from the latter. Infrared analysis indicates that the transition metals were immobilized on the polymer support via functional groups. The effects of polymerization conditions on catalyst activity have been assessed. Characterization of the resulting polymer product by means of ¹³C-NMR, DSC, and SEM demonstrates a branch-free structure with high melting point, high crystallinity, and high molecular weight for the ethylene homopolymer. The reactivity ratios of ethylene-1-hexene copolymerization are evaluated from ¹³C-NMR analysis data. © 1994 John Wiley & Sons, Inc.     

Preparation of ethylene/α-olefins copolymers using (2-RInd)2ZrCl2/MCM-41 (R:Ph,H) catalyst,microstructural study

(2-RInd)₂ZrCl₂ (R:Ph,H) catalyst was supported on MCM-41 and ethylene copolymerization behavior as well as microstructure of copolymers were studied. A steady rate–time profile behavior was observed for homo and copolymerization of ethylene using supported catalysts. It was noticed that increasing the comonomer content can result in lower physical properties. The obtained results indicated that (2-PhInd)₂ZrCl₂/MCM-41 had higher ability of comonomer incorporation than the non-substituted supported catalysts. The CCC, CCE, and ECC (C: comonomer, E: ethylene) triad sequence distribution in backbone of copolymers were negligible, that means no evidence could be detected for comonomer blocks. The polymer characterization revealed that utilizing 1-octene instead of 1-hexene as the comonomer leads to more heterogeneous distribution of chemical composition. The heterogeneity of the chemical composition distribution and the physical properties were influenced by the type of comonomer and catalyst. (2-PhInd)₂ZrCl₂/MCM-41 produced copolymers containing narrower distribution of lamellae (0.3–1 nm) than the copolymer produce using Ind₂ZrCl₂/MCM-41 (0.3–1.6 nm).     

四氯化钛/三异丁基铝体系催化降冰片烯与异戊二烯的共聚合

以传统Ziegler-Natta催化体系TiCl4/Al(#em/em#-Bu)3催化降冰片烯(NBE)和异戊二烯(IP)的共聚合, 制得可溶于常规有机溶剂的共聚物, 其数均分子量为2.0 × 104~6.5 × 104, 分子量分布指数为1.5~2.9, 降冰片烯结构摩尔含量为26%~60%. 考察了助催化剂用量、 聚合温度及2种单体投料比对共聚合的影响. 结果表明, 当降冰片烯与异戊二烯的投料摩尔比为4∶6时, 于40 ℃聚合6 h, 得到的共聚物产率为96%, 数均分子量为6.5×104, 降冰片烯结构含量45%. 用 1H NMR, 13CNMR, GPC和DSC等方法表征了共聚产物的微观结构与热性能. 13C NMR DEPT结果表明, 共聚反应中降冰片烯单体以加成方式聚合. DSC结果显示, 共聚物只有一个玻璃化转变温度(Tg=20~40 ℃). 通过Kelen-Tüdös方法得到2种单体的竞聚率分别为rNBE=0.07, rIP=0.44.     

Ethylene/1-Hexene Copolymerization and Synthesis of LLDPE/Nanocarbon Composite through In Situ Polymerization

Copolymerization of ethylene/1-hexene using a modified ZN-type catalyst was carried out in the presence of triethylaluminium as cocatalyst. The optimum copolymerization activity was obtained at Al: Ti = 357: 1, 60°C and the comonomer concentration of 0.6 mol/L in the range studied. Copolymer/nanocarbon (including multiwalled carbon nanotube, graphene nanoplatelet) composites were prepared via in-situ polymerization. The copolymerization activity decreased by addition of the nanocarbon into the reactor. The presence of graphene nanoplatelet in nanocomposites reduced the melting temperature and increased heat of fusion, crystallinity and density of the obtained polymer. In the copolymer/carbon nanotube nanocomposites, decreasing of melting temperature was observed in comparison to pure copolymer, whereas, heat of fusion, crystallinity and density increased. The results of TGA analysis showed that the addition of nanocarbons has improved the thermal stability of obtained copolymers.     

Copolymerization of ethylene with acrylonitrile promoted by novel nonmetallocene catalysts with phenoxy‐imine ligands

A series of novel nonmetallocene catalysts with phenoxy‐imine ligands was synthesized by the treatment of phthaldialdehyde, substituted phenol with TiCl₄, ZrCl₄, and YCl₃ in THF. The structures and properties of the catalysts were characterized by ¹H NMR and elemental analysis. These catalysts were used for copolymerization of ethylene with acrylonitrile after activated by methylaluminoxane (MAO). The effects of copolymerization temperature, Al/M (M = Ti, Zr, and Y) ratio in mole, concentrations of catalyst and comonomer on the polymerization behaviors were investigated in detail. These results revealed that these catalysts were favorable for copolymerization of ethylene with acrylonitrile. Cat. 3 was the most favorable one for the copolymerization of ethylene with acrylonitrile, and the catalytic activity was up to 2.19 × 10⁴ g PE/mol.Ti.h under the conditions: polymerization temperature of 50 °C, Al/Ti molar ratio of 300, catalyst concentration of 1.0 × 10^–4 mol/L, and toluene as solvent. The resultant polymer was characterized by FTIR, cross‐polarization magic angle spinning, ¹³C NMR, WAXD, GPC, and DSC. The results confirmed that the obtained copolymer featured high‐weight–average molecular weight, narrow molecular weight distribution about 1.61–1.95, and high‐acrylonitrile incorporation up to 2.29 mol %. Melting temperature of the copolymer depended on the content of acrylonitrile incorporation within the copolymer chain. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Effect of 1-Hexene Comonomer on Polyethylene Particle Growth and Kinetic Profiles

Summary: The polymer growth and the microstructure of the final polymer are greatly affected by mass transfer, especially in the early stages of polymerization. In the present work, the catalytic system (nBuCp)₂ZrCl₂/MAO immobilized over SiO₂-Al₂O₃ has been tested in ethylene-1-hexene copolymerizations using different amounts of comonomer. The catalytic activity shows a positive comonomer effect up to 1-hexene concentration of 0.724 mol/L since larger amounts of 1-hexene lead to a decrease in the activity. Copolymer properties analyzed by ¹³C NMR, GPC, CRYSTAF and DSC point to the presence of important amorphous regions in the growing polymer chains as the 1-hexene concentration increases. In order to study the incorporation of 1-hexene during ethylene polymerization, several experiments were performed with 0.194 mol/L of 1-hexene, 5 bar of ethylene pressure and different polymerization times. The incorporation of 1-hexene decreases slightly at polymerization times above 20 minutes. From cross-sectioned SEM images it can be concluded that the presence of 1-hexene helps catalyst fragmentation which could be related with the filter effect proposed by Fink.