Ti(OC4H9)xCl4-x/MgCl2催化体系引发异戊二烯聚合

以Ti(OC4H9)xCl4-x/MgCl2催化体系对异戊二烯进行聚合,研究了含丁氧基值不同的催化剂以及n(Ti)/n(IP)、n(Al)/n(Ti)及不同温度对异戊二烯聚合转化率的影响.通过红外谱图、核磁共振谱图表征了聚合产物的微观结构.研究结果表明,聚合体系的催化效率随催化剂含丁氧基量的增大而降低,最佳聚合条件随催化剂含丁氧基值的不同而不同,转化率随n(Ti)/n(IP)的增加而增加,最佳聚合转化率的n(Al)/n(Ti)随丁氧基值的增加有降低的趋势;最佳聚合温度范围为30～40 ℃;在负载Ti(OC4H9)3Cl催化剂得到的聚合物样品中,1,4-结构、3,4-结构的质量分数分别为95.7%、4.3%.     

正辛醇改性负载钛催化体系聚合异戊二烯

以正辛醇改性TiCl4/MgCl2催化剂,将其用于异戊二烯聚合以期制得综合性能较为优异的3,4-聚异戊二烯／反式-1,4-聚异戊二烯(3,4-PIp／TPI)新型复合材料。当n(Al)／n(Ti)为10-20,催化剂和异戊二烯的摩尔比为1×10-4,聚合温度为60℃时,改性催化剂催化异戊二烯效率最高;改性催化剂(正辛醇和催化剂摩尔比为15)聚合所得聚异戊二烯中3,4-链节的质量分数达45．01％,聚合产物的熔点及结晶度均低于传统的TPI。     

负载钛-三乙基铝体系催化异戊二烯聚合

以负载钛(TiCl4/MgCl2)为主催化剂、三乙基铝为助催化剂催化异戊二烯聚合,研究了n(Ti)/n(Ip)、n(Al)/n(Ti)及温度等对单体转化率和催化效率的影响。采用FTIR和1H-NMR对聚合产物的微观结构进行测试表征,DSC测定聚合产物的熔点和结晶度。结果表明,所得聚合产物为反式-1,4-结构摩尔分数达98%的异戊橡胶;聚合体系的单体转化率随n(Ti)/n(Ip)的增大而升高,催化效率则先升高后降低;随n(Al)/n(Ti)和聚合温度的增大,催化效率和单体转化率均先升高后降低,最佳n(Al)/n(Ti)值为110~120,最佳聚合温度为20~25℃。     

正辛醇改性负载钛催化体系催化异戊二烯聚合的研究

以不同用量正辛醇改性负载钛催化体系(TiCl4/MgCl2)催化异戊二烯配位聚合,考察了催化剂用量、Al剂用量及反应温度对聚合的影响,通过1H-NMR法表征了聚合产物的微观结构,通过DSC表征了聚合产物的熔点及结晶度。结果表明:改性负载钛催化体系的催化效率随正辛醇用量的增大而降低,当聚合条件为n(Al)/n(Ti)=50,n(Ti)/n(Ip)=5×10-4,聚合温度60℃时,催化效率最高。聚合产物的相对分子质量随正辛醇用量的提高而增大、随主催化剂用量的提高而降低,Al剂用量及反应条件对聚合物相对分子质量的影响同对催化活性的影响基本一致。所得聚异戊二烯的3,4-结构质量分数为8.2%,反-1,4-结构质量分数为91.8%;聚合产物的熔点及结晶度均低于TPI。     

负载钛-三异丁基铝体系催化苯乙烯聚合Ⅰ.聚合条件对苯乙烯聚合的影响

考察了负载钛(简称Ti)-三异丁基铝(简称Al)催化体系聚合条件对苯乙烯(St)聚合的影响.实验表明随着n(Al)/n(Ti)的增加,催化剂效率先升高后降低,最高为12 kg/(mol·h).随着聚合温度升高,催化剂效率逐渐升高,但增幅逐渐减缓.最佳聚合条件St初始浓度为5 mol/L,Ti浓度为1.3 mmol/L,n(Al)/n(Ti)为30,聚合温度为60℃;同时,聚合物的相对分子质量和全同立构含量均随n(Al)/n(Ti)和聚合温度升高而降低,全同立构含量可通过调节n(Al)/n(Ti),使之在40.4%～90.0%.     

改性五氯化钼催化剂合成3,4-聚异戊二烯

利用正辛醇改性五氯化钼催化体系催化异戊二烯聚合得到了3,4-聚异戊二烯。研究了n(Mo)/n(Ip)、n(Al)/n(Mo)、间甲酚用量等聚合条件对聚合活性和聚合产物相对分子质量的影响。利用红外对聚合物进行了表征,并且通过红外谱图研究了聚合温度对聚合物3,4-结构含量的影响。结果表明,改性五氯化钼催化得到的聚合产物与铁系低分子聚合物具有相近的3,4-结构含量(质量分数为55%～61%),并且3,4-结构含量随着聚合温度升高先升高后降低。对聚合物进行特性粘数和GPC的表征表明,合成的3,4-聚异戊二烯特性粘数为1.2～2,多分散系数小于3。     

低温预制钛系催化剂合成cis-1,4-聚异戊二烯

采用Ziegler-Natta配位聚合制备了高顺式聚异戊二烯,主要考察了非均相催化体系四氯化钛-三异丁基铝二组分催化剂的预制方法以及催化剂预制条件对异戊二烯体系聚合规律的影响。讨论了催化剂配比、预制催化剂温度和陈化温度对催化剂活性及聚合物的凝胶含量、特征黏度、微观结构含量等方面的影响。同时讨论了催化剂用量、聚合温度和聚合时间对聚合活性及聚合物的凝胶含量、特征黏度、微观含量等方面的影响。研究结果表明,合成高cis-1,4-聚异戊二烯的最佳实验条件为:Al/Ti摩尔比1.0,催化剂预制温度-40℃,陈化2 h,Ti/Ip摩尔比6×10^-3,聚合温度50℃,聚合时间5 h。所得聚合物最高转化率为87.1%,cis-1,4结构含量为91.76%。     

双组分钛基催化剂合成反式-1,4-聚异戊二烯/3,4-聚异戊二烯复合胶

以钛酸正戊酯[Ti(C5H11O)4]-TiCl4/MgCl2(简称Ti)-Al(Et)3(简称Al)组成的双组分钛基催化剂引发异戊二烯(Ip)聚合,原位合成反式-1,4-聚异戊二烯(TPI)/3,4-聚异戊二烯(PIp)复合胶,考察了聚合活性和复合胶在汽油中可溶性的影响因素,表征了复合胶的微观结构,并研究了复合胶的特性黏数。结果表明,在Ti/Ip(摩尔比)为6×10-5、Ti(C5H11O)4/Ip(摩尔比)为1.2×10-3、Al/Ti(C5H11O)4(摩尔比)为10的条件下,聚合活性最优;复合胶的汽油可溶物部分含量变化的趋势遵循以下规律:随着Ti(C5H11O)4用量的增加而增大;随着Al/Ti(C5H11O)4的增大先升高后降低最后趋于平稳;随着Ti/Ip的增大而逐渐降低。TPI的相对分子质量大于3,4-PIp。     

钛酸丁酯、负载钛/复合铝体系引发异戊二烯聚合

以钛酸丁酯、负载钛/复合铝(AlEt3/Al(i-Bu)3)组成的双组分钛催化体系引发异戊二烯(Ip)聚合,研究了n(AlEt3):n(Al(i-Bu)3)对聚合活性和特性黏数的影响。对聚合物进行溶解分离得到汽油可溶物和不可溶物,分别对汽油可溶物进行红外并且定量分析,对汽油不可溶物进行红外和DSC分析。结果显示,汽油不可溶物部分为反式-1,4-聚异戊二烯,汽油可溶物部分为3,4-聚异戊二烯,且3,4-结构含量及汽油可溶物的特性黏数随着AlEt3比例的提高而升高,而反式-1,4-聚异戊二烯的特性黏数则随着AlEt3量增加而下降。     

钛酸丁酯/负载钛体系催化异戊二烯聚合

以钛酸丁酯[Ti(C_4H_9O)_4] 和TiCl_4/MgCl2(简称Ti)为主催化剂、三异丁基铝(简称Al)为助催化剂催化异戊二烯 (Ip)聚合,考察了Ti(C4H9O)4和Al用量对聚合物在汽油中可溶性及单体转化率、催化效率(CE)的影响,并对聚合物进行了表征.结果表明,当Ti/Ip(摩尔比)一定时,聚合物在汽油中的溶解度随着Ti(C_4H_9O)_4/Ip(摩尔比)的增加而增大,Ti(C_4H_9O)_4/Ip为3×10~(-3)时,单体转化率达到最大值;当主催化剂配比及用量一定时,聚合物在汽油中的溶解度随着Al/Ti(C_4H_9O)_4(摩尔比)的增加先增大后减小,当 Al/Ti(C_4H_9O)_4为10～15时,单体转化率和CE存在最大值;该催化体系制得的聚异戊二烯以反式-1,4-结构为主,同时包含一定量的3,4-和1,2-结构.     

乙烯-丙烯-1-丁烯三元共聚合

采用自制的ziegler-Natta催化剂催化乙烯-丙烯-1-丁烯三元共聚合.考察了1-丁烯/丙烯、铝钛比、反应温度和压力等对三元共聚合的影响.结果表明.三元共聚物中支化度约为26门000 C,其中乙基支链为18/1 000 C、丙基支链为8/1 000 C.在聚合温度为60℃、压力为0.8 MPa、乙烯分压百分数为70%、1-丁烯分压百分数为5.7%和丙烯分压百分数为24.3%时,催化活性最高,为10.5 kg/g.当n(Al)/n(Ti)大于100时,催化活性增加趋势变缓.聚合压力超过0.8 MPa时,催化活性变化不大.聚合平行实验结果表明,上述条件稳定,所得三元共聚物的表观密度为0.32g/cm3,拉伸强度为11～12 MPa、断裂伸长率为540%～560%.     

Preparation and Characterization of UHMWPE/Graphene Nanocomposites Using Bi-Supported Ziegler-Natta Polymerization

Ultrahigh-molecular-weight polyethylene (UHMWPE)/graphene nanocomposites with molecular weights as high as 3 × 10⁶ g/mol were prepared via in situ polymerization using a bi-supported Ziegler-Natta catalytic system. Effects of [Al]/[Ti] molar ratio, temperature, monomer pressure, and polymerization time on productivity of the catalyst have been investigated. Increasing [Al]/[Ti] molar ratio from 128 to 320, increased productivity from 1667 g PE/mmol Ti.h to maximum value which was 2420 g PE/mmol Ti.h. Further [Al]/[Ti] ratio decreased the productivity. Reaction temperature effect investigation reveals that the optimal activity was obtained at 60°C. the polymerization productivity increases with monomer pressure and decreased with polymerization time. Morphological information was determined by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Obtained results show that graphene layers in these nanocomposites were completely exfoliated and dispersed uniformly in the polyethylene matrix while no nanoparticle cluster has been formed.     

The synthesis of high molecular weight polybutene‐1 catalyzed by Cp★ Ti(OBz)3/MAO

A new stereoregular polybutene‐1 was synthesized with a novel catalyst precursor η⁵‐pentamethyl cyclopentadienyl titanium tribenzyloxide (CpTi(OBz)₃) and methylaluminoxane (MAO). The effects of polymerization conditions on the catalytic activity, molecular weight and stereoregularity of the products were investigated in detail. It was found the catalyst exhibited highest activity of 91.2 kgPB mol Ti⁻¹ h⁻¹ at T = 30 °C, Al/Ti = 200. The catalytic activity and molecular weight were sensitive to the Al/Ti (mole/mole), polymerization temperature; they also depended on the Ti concentration. The molecular weight of the products increased with decreasing temperature. The structure and properties of the polybutene‐1 were characterized by ¹³C NMR, GPC, DSC and WAXD. The result showed the microstructure of polybutene‐1 extracted by boiling heptane was stereoregular, whereas the ether‐soluble fraction was atactic. The molecular weight of polybutene‐1 was over one million g mol⁻¹ and its molecular weight distribution ( M _w/ M _n) was from 1.1 to 1.2. © 2001 Society of Chemical Industry     

复合载体法制备聚丙烯-蒙脱土复合材料

将传统Z-N催化剂TiCl4负载于蒙脱土．乙醇镁复合载体上,进行丙烯常压原位聚合,制备聚丙烯-蒙脱土纳米复合材料,克服了单-蒙脱土作载体时聚合活性低、产物分子量小的缺点。对比不同制备过程的催化剂,发现TiCl4的后处理可以大幅提高催化活性。引入苯乙烯可有效降低Mg—MMT／Mg(OEt)2/TiCl4/EB体系制备的Cat5催化聚合时所需的Al／Cat比。由Mg—MMT／Mg(OEt)2/Ti(OBu)4/TiCl4/EB体系制备的Cat6具有活性高,所需Al／Cat低的优点,为合适的制备聚丙烯-蒙脱土纳米复合材料的催化剂。WAXS和TEM表明复合材料中蒙脱土主要呈剥离杰分散干聚丙烯基体中。产物的熔点和商用聚丙烯的熔点接近。     

Study on propene polymerization using a novel spherical Ziegler‐Natta catalyst and its kinetics

The effects of the Al/Ti ratio and external donor (ED) on the catalytic activity and kinetics of propene polymerization catalyzed by a spherical Ziegler‐Natta (Z‐N) catalyst were investigated. The preparation conditions of the catalyst play an important role in the polymerization kinetics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3737–3740, 2003     

Novel monotitanocene and methylaluminoxane catalyst for syndiospecific polymerization of styrene

Syndiotactic polystyrene (sPS) was synthesized with a novel monotitanocene complex of η⁵‐pentamethylcyclopentadienyltri‐4‐methoxyphenoxy titanium [Cp*Ti(OC₆H₄OCH₃)₃] activated by methylaluminoxane (MAO) in different polymerization media, including heptane, toluene, chlorobenzene, and neat styrene. In all cases bulk polymerization produced sPS with the highest activity and molecular weight. Solution polymerization produced much better activity in heptane than in the other solvents. Using a solvent with a higher dipole moment, such as chlorobenzene resulted in lower activity and syndiotacticity because of the stronger coordination of solvent with the Ti(III) active species, which controlled syndiospecific polymerization of styrene. With bulk polymerization at a higher polymerization temperature the Cp*Ti(OC₆H₄OCH₃)₃–MAO catalyst produced sPS with high catalytic activity and molecular weight. The external addition of triisobutylaluminum (TIBA) to the Cp*Ti(OC₆H₄OCH₃)₃–MAO system catalyzing styrene polymerization led to significant improvement of activity at a lower Al:Ti molar ratio, while the syndiotacticity and molecular weight of the yields were little affected. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1243–1248, 2001     

Syndiotactic polymerization of styrene: Study of catalyst components and polymerization conditions

Syndiotactic polystyrene (s‐PS) was prepared using monotitanocene catalyst of cyclopentadienyl titanium trichloride (CpTiCl₃) activated by methylaluminoxane (MAO). Solution polymerization was carried out in toluene using different polymerization conditions. Syndiotacticity index (SI) between 68 and 91.6% was obtained. Increasing Al/Ti molar ratio shows an increase in both conversion percentage and SI. The conversion increased linearly with increasing Al/Ti molar ratio in the range studied. The conversion reached to an optimum value of about 65% at styrene/Al molar ratio of 2.83, while no regular behavior of SI was observed with changing the ratio. Effect of temperature of the range 50–80°C on polymerization was studied. The most favorable temperature for the polymerization regarding activity is 70°C; however SI decreased with temperature up to 80°C. H₂ value to 140 mL/100 mL solvent increased the productivity of the catalyst, however further increase of H₂ reduced the activity of the catalyst. Polymerization time of 15 to 125 min shows a decrease in activity. The decrease was sharper for about 30 min of polymerization than longer time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2216–2221, 2006     

Synthesis,structure, and properties of syndiotactic polystyrene catalyzed by Cp*Ti(OBz)3/MAO/TIBA

The synthesis of syndiotactic polystyrene (sPS) catalyzed with Cp*Ti(OBz)₃/MAO/TIBA and toluene as the solvent and the effects of polymerization temperature and the external addition of TIBA on polymerization behavior were investigated. The study revealed that catalytic activity increased with polymerization temperature. The greatest activity, 619 kg sPS mol^?1 Ti h^?1, was exhibited up to 90°C. TIBA also improved catalytic activity. The molecular weight of the polymer obtained decreased with polymerization temperature and the amount of TIBA. The structure and properties of syndiotactic polystyrene were characterized by ¹³C‐NMR, FTIR, DSC, and GPC methods. It was confirmed that the sPS obtained featured all‐trans planar zigzag conformation and higher syndiotacticity, molecular weight, and melting point. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 501–505, 2007