丙烯聚合用TiCl_4/MgCl_2催化剂的研究——内给电子体的作用

采用相同制备工艺 ,制备分别以邻苯二甲酸二异丁酯 (DIBP)和 9,9 双 (甲氧基甲基 )芴 (BMMF)为内给电子体和不加入内给电子体 3种催化剂 .研究了它们在无外给电子体时聚合性能 ,以及合成的聚丙烯的等规度 ,分子量及其分布 .并采用CRYSTAF和1 3C NMR对聚丙烯沸腾庚烷不溶部分结晶性能和序列结构进行分析 ,结果表明内给电子体对聚丙烯分子链序列结构有很大影响 ;BMMF催化剂、DIBP催化剂和无内给电子体催化剂合成的聚丙烯规整性依次下降 .对BMMF催化剂 ,当烷基铝为Et3Al时 ,铝钛比增加 ,等规度和活性明显下降 .当烷基铝i Bu3Al时 ,铝钛比增加 ,等规度略微下降而活性增加 ;但是1 3C NMR研究发现其 (铝钛比为 3 0 0时 )庚烷不溶物的规整性与DIBP催化剂的庚烷不溶物的规整性一致 .这表明内给电子体在聚合中的作用不在于是酯还是醚 ,在于它与氯化镁的络合强度 .络合越强 ,得到的聚丙烯分子链越规整     

不同结构烷基铝催化异戊二烯齐聚与聚合行为研究

烷基铝（AlR₃）作为Ziegler-Natta催化剂体系的助催化剂组分,起到烷基化、还原主金属化合物、参与活性中心形成与演变、链转移剂等重要作用.然而烷基铝自身对二烯烃单体也具有催化作用.本工作采用不同结构烷基铝如三乙基铝（AlEt₃）、三异丁基铝（Al（i-Bu）₃）、氢化二异丁基铝（AlH（i-Bu）₂）、一氯二乙基铝（AlEt₂Cl）、二氯一乙基铝（AlEtCl₂）,研究了烷基铝的种类和浓度对异戊二烯催化行为的影响.采用核磁共振氢谱（¹H NMR）、凝胶渗透色谱（GPC）、气相色谱-质谱联用（GC-MS）等对产物的微观结构（顺式-1,4-和反式-1,4-含量）和分子量及分布等进行了表征,探讨了不同结构烷基铝的催化行为.发现烷基铝不仅可以催化异戊二烯齐聚,与微量水作用后还可以引发异戊二烯阳离子聚合,得到顺反混合结构的线性聚合物.烷基铝浓度对其催化行为有较大影响.当n（Al）/n（M）=1050×10^-5时,AlEtCl₂的催化活性显著提高,产物主要为线性聚合物;而其他结构烷基铝的催化活性较低.当n（Al）/n（M）≤350×10^-5,烷基铝自身催化异戊二烯齐聚及聚合能力极弱.过低和过高的烷基铝浓度都不利于获得高分子量聚合物.这为深入理解Ziegler-Natta催化剂体系烷基铝组分的催化作用及其对聚合物的影响提供依据.     

MgBu_2/AlEt_2Cl为助催剂的钛催化剂上丙烯聚合动力学——Ⅰ.烷基金属浓度的影响

烯烃聚合催化剂种类繁多,改变金属离子或配位体能得到性能不同的烯烃聚合催化剂.可供选择的助催化剂主要有烷基铝,烷基氯化铝,铝氧烷和Cp_2MtMe化合物等(Mt=Ti,V,Zr,Hf).有实用价值的助催化剂只有烷基铝或烷基氯化铝.对丙烯聚合非载体钛系催化剂而言,AlEt_2Cl是较好的助催化剂,而对载体型MgCl_2/TiCl_4钛系催化剂,较好的助催化剂则是AlEt_3.如果将MgBu_2与AlEt_2Cl的混合物用     

α-二亚胺镍(Ⅱ)催化甲基丙烯酸甲酯聚合

以4种不同结构的α-二亚胺镍(Ⅱ)催化剂[(t-Bu)—N CH—CH N—(t-Bu)]NiBr2(C1),[C6H5—N C(Me)—C(Me)N—C6H5]NiBr2(C2),[(2,6-C6H3(Me)2)—N C(Me)—C·(Me)N—(2,6-C6H3(Me)2)]NiBr2(C3)和[(2,6-C6H3(i-Pr)2)—N C(An)—C(An)N—(2,6-C6H3(i-Pr)2)]NiBr2(An=acenaphthyl)(C4),在甲基铝氧烷(MAO)作用下,对甲基丙烯酸甲酯(MMA)进行催化聚合.以C2为模型催化剂系统研究了Al/Ni摩尔比、单体浓度、聚合温度、聚合时间和反应溶剂对催化活性及聚合物分子量的影响.在较适合的聚合条件(催化剂用量为1.6μmol,Al/Ni摩尔比为800,MMA浓度为2.9 mol/L,甲苯为溶剂,聚合温度为60℃,聚合时间为4 h)下,讨论了催化剂结构对催化活性和聚合物分子量的影响.研究发现,催化剂C1~C3催化MMA聚合均得到富含间规结构的聚甲基丙烯酸甲酯(PMMA).催化剂结构中空间位阻增大导致催化活性降低,空间位阻最小的C1催化活性最高[达107.8 kg/(mol Ni·h)];而空间位阻最大的C4催化活性仅为7.8 kg/(mol Ni·h).催化剂结构中给电子效应增加有利于催化活性及聚合物分子量的增加.C2催化活性为62.5 kg/(mol Ni·h),所得聚合物的分子量为5.0×104;而具有较强给电子效应的C3催化活性达到96.9 kg/(mol Ni·h),并得到更高分子量的聚合物(7.6×104).     

Nd(C_8H_(11))Cl_2·3THF-R_3Al对丁二烯聚合的催化活性

Nd(C_8H_(11))Cl_2·3THF与不同烷基铝〔Et_3Al,i-Bu_3Al,HAl(i-Bu_2)〕组成的催化体系可催化丁二烯聚合。实验结果表明,催化剂活性取决于所用的烷基铝、铝钕比和催化剂用量,而溶剂对催化活性影响不大。聚合物的微观结构则不受烷基铝种类、溶剂、铬钕比和催化剂用量的影响,均可得到高顺式(97—98％)聚丁二烯。     

新型铁系催化剂聚合丁二烯

以铁化合物Fe(CF3SO3)2为催化剂,烷基铝为助催化剂,亚磷酸二异辛脂(P8)为给电子体,研究了该催化体系对丁二烯的聚合行为。 结果表明, 催化体系（n(Fe)∶n(P8)∶n(Al)=1∶4∶20）具有良好的聚合活性和间同立构选择性,并且聚合活性和间同立构选择性随聚合温度升高而增加,50 ℃时可得到1,2-结构含量大于85%、间规度达99%以上的间同1,2-聚丁二烯;该催化体系具有很好的立体选择性和温度耐受性,克服了以往铁系催化体系立体选择性差、需要低温聚合的缺点,并且催化体系不涉及使用有毒、有害的催化剂组分。     

氯化稀土乙二醇二甲醚配合物催化丁二烯聚合

以Nd2O3、(CH3)3SiCl和乙二醇二甲醚(DME)为原料,合成了NdCl3·2DME配合物,并将其用于催化丁二烯聚合。 考察了助催化剂种类与用量、陈化温度和聚合时间对聚合的影响。 结果表明,以烷基铝与MAO共同作为助催[JP2]化剂时具有高聚合活性,而单独以烷基铝或甲基铝氧烷(MAO)为助催化剂时聚合活性很低。 当n(Nd)∶n(AlR3)∶n(MAO)=1∶30∶45时,催化活性最高。 陈化温度对聚合活性、聚合物结构及相对分子质量均有较大的影响。 陈化温度过低或者过高,聚合活性、聚丁二烯cis-1,4含量和相对分子质量均降低;陈化温度为50 ℃时,具有最高聚合活性和最高cis-1,4含量。 NdCl3·2DME催化体系所得聚丁二烯的cis-1,4含量高达98.7%（IR）,而1,4-结构总含量高达99.6%（1H NMR）。     

8-苯胺-1-萘磺酸钛配合物的合成及催化乙烯与降冰片烯共聚合反应

合成了新型催化剂8-苯胺-1-萘磺酸钛配合物, 并应用于乙烯与降冰片烯的共聚合反应中. 分别考察了助催化剂种类[甲基铝氧烷(MAO)和三乙基铝(TEA)]、 降冰片烯浓度、 Al/Ti摩尔比、 聚合温度和聚合压力对催化活性与共聚性能的影响. 通过核磁共振、示差扫描量热和凝胶渗透色谱等对所制备的共聚物进行了表征. 结果表明, 在相同条件下, 以MAO为助催化剂时, 共聚催化活性更高, 催化剂为单活性中心, 可得到分子量分布较窄(PDI≈3)的共聚产物, 其共聚反应机理为加成聚合. 另外, 随着降冰片烯浓度的升高, 共聚物中降冰片烯单元的摩尔比呈线性上升趋势, 所得共聚物的熔点随之降低.     

MgCl_2/AlEt_n(OEt)_(3-n)负载单茂钛催化剂催化乙烯聚合研究

以MgCl2/AlEtn(OEt)3-n为载体,分别负载五甲基茂基三氯化钛(Cp*TiCl3)和五甲基茂基三苄氧基钛(Cp*Ti(OBz)3),得到两种负载催化剂,在较廉价的AlEt2Cl为助催化剂常压下可以高效地催化乙烯聚合.报道了载体的制备、聚合条件(不同的烷基铝助催化剂、聚合温度、铝钛摩尔比)对催化剂的聚合行为以及聚合物结构的影响.研究结果表明,两种负载催化体系对乙烯聚合具有较高的催化活性,可达105g PE/(molTi·h)数量级,所得聚乙烯的黏均分子量在105以上.经过13C-NMR和DSC分析,两种负载催化剂得到的均为线型聚乙烯.与均相催化剂相比,负载后的单茂钛催化体系的聚合反应动力学表现高效而平稳.这表明载体的微孔结构使活性中心得到了有效的分散,有效地提高了催化剂的活性,同时载体的受限空间有效抑制了聚乙烯增长链的β-H消除反应.     

烷基铝对球形MgCl_2负载的茂金属催化剂催化乙烯聚合的影响

以甲基铝氧烷(MAO)为助催化剂的茂金属催化剂虽然具有催化活性高、分子量分布窄、聚合物化学组成均匀等优点,但其极高的Al/Zr比和聚合物颗粒形态差等缺点限制了其工业化应用,因此对茂金属催化剂的负载化成为近年来的研究热点.在众多的载体中,球形MgCl2是研究得很少的一类载体,文献中曾采用先负载主催化剂茂金属配合物,聚合时再加入助催化剂MAO的方法[1],由于加入的MAO与主催化剂的络合能力很强,会使部分载上的主催化剂溶解下来,成为均相聚合[2,3],导致聚合物颗粒形态差,且粘釜现象严重.我们则采用相反的思路,即先将助催化剂MAO负载在球形MgCl2上,制得MgCl2/MAO,在聚合前再将MgCl2/MAO与Et[Ind]2ZrCl2混合陈化,并立即在少量烷基铝活化下引发乙烯聚合[4],实验结果表明,该催化剂聚合活性高、聚合物的颗粒形态好、且不粘釜,是一种新型的载体催化剂.由于烷基铝的加入可使催化剂的活性大幅度提高,所以本文将烷基铝也称作助催化剂,来研究其对该载体催化剂催化乙烯聚合的影响.     

催化裂化干气与苯烷基化催化蒸馏制乙苯反应网络热力学研究

 高温气相反应条件下的催化裂化干气制乙苯过程中，容易生成甲苯和二甲苯等副产物；在该过程中采用催化蒸馏技术，使苯与乙烯在低温条件下进行反应，可大幅度降低产品中二甲苯的含量．通过对催化裂化干气与苯烷基化催化精馏过程中的各反应步骤进行分析与热力学计算，结合反应的实际产物组成，提出了苯与乙烯烷基化的反应网络，探讨了苯与乙烯烷基化反应过程中甲苯和二甲苯的形成机理及影响因素．结果表明，增大苯／乙烯比对提高乙烯平衡转化率及乙苯收率有利；在较低温度下进行烷基化反应，可大大减缓C－C键裂解速度，抑制甲苯和二甲苯生成，提高乙苯产品质量．     

非晶态全同立构聚丙烯玻璃的结晶过程与玻璃化转变

以低于-75℃的干冰-乙醇淬火聚丙烯熔体薄膜,制得了全同立构聚丙烯玻璃。观察此试样在升温过程及等温过程中的比容变化和红外光谱变化,研究它的松弛过程和结晶过程,结果表明在-23℃以下它相当稳定,高于-20℃则有明显的松弛、结晶过程产生。非晶态全同立构聚丙烯的玻璃化转变温度大约稍高于-20℃。     

Crystal structure of the trigonal form of isotactic polypropylene as an example of density-driven polymer structure

Propene-hexene copolymers crystallize in a new polymorphic form of isotactic polypropylene when the concentration of hexene is higher than nearly 10-15 mol %. The hexene units are included in the crystals, inducing an increase of density that allows crystallization of 3-fold helical chains in a trigonal unit cell according to the space group R3c or Rc, where the helical symmetry of the chains is maintained in the crystal lattice. The structure of this new form is similar to those of isotactic polybutene and polystyrene and does not crystallize in polypropylene homopolymer because it would have too low density. The crystal structure of isotactic polypropylene is therefore no longer an exception to the principles of polymer crystallography, but the new structure represents the fulfillment of these principles and indicates that the packing of polymer molecules is mainly driven by density.     

等规聚丙烯/聚丁烯-1釜内合金的结构与性能

高分子材料的组成、 组分分布及链结构与宏观性能紧密相关. 因此, 分析多组分釜内合金材料的链结构特点与性能之间的关系至关重要. 采用升温淋洗分级的方法对两种采用序贯两段聚合原位合成的等规聚丙烯/聚丁烯-1(iPP/iPB)釜内合金在-30 ℃~140 ℃温度范围进行分级, 采用核磁共振波谱仪、 傅里叶变换红外光谱仪、 差示扫描量热仪和凝胶渗透色谱仪等表征了级分的链结构及序列分布、 热行为、 分子量(M_w)及分子量分布(M_w/M_n)等. 结果表明iPP/iPB合金主要由5种级分组成, 高等规聚丁烯(iPB)为主要组分, 同时含有少量的丁烯-丙烯嵌段共聚物(PB-b-PP)和等规聚丙烯(iPP)等. 随淋洗温度升高, PB-b-PP级分中PP嵌段长度逐渐增加, PB嵌段长度逐渐减小; 在相同的淋洗温度, 合金B的嵌段共聚物级分中PP嵌段较长且结晶较完善; 合金B中iPB组分及嵌段共聚物组分含量较高, 使得合金B具有较高的拉伸强度、 弯曲强度、 优异的抗冲击性能、 较高的维卡软化温度及较快的晶型转变速率.     

Exploring Si/Mg composite supported Ziegler-Natta Ti-based catalysts for propylene polymerization

A series of(Si_O2/MgO/ID/MgCl_2)·TiClx Ziegler-Natta catalysts for propylene polymerization has been prepared with a new method. These catalysts were synthesized using soluble Mg-compounds as the Mg-source and the preparation progress was relatively simple. The catalyst could copy the spherical shape of the carrier very well. The propylene polymerization results showed that the catalyst revealed the best activity with 9,9-di(methoxymethyl)fluorene(BMMF) as internal donor at 50 °C with the optimal molar ratio Al/Ti = 5, which was much lower than what the industrial polypropylene catalyst used(at least molar ratio Al/Ti = 100), resulting in great cost saving. Additionally, the polymerization kinetics of the catalyst exhibited very stable property after achieving a relatively high value. These catalysts possessed rather high activity and good hydrogen response. The isotactic index(Ⅱ.) value of the PP products could be higher than 98% in the presence of both internal and external electron donors. Moreover, temperature rising elution fractionation method was used to understand the influence of donors and H2 on the properties of the PP products.     

Polymerization Kinetics of Propylene with the MgCl_2-Supported Ziegler-Natta Catalysts——Active Centers with Different Tacticity and Fragmentation of the Catalyst

The catalytic activity and stereospecificity of olefin polymerization by using heterogeneous TiCl_4/MgCl_2 Ziegler-Natta(Z-N) catalysts are determined by the structure and nature of active centers, which are mysterious and fairly controversial. In this work, the propylene polymerization kinetics under different polymerization temperatures by using Z-N catalysts were investigated through monitoring the concentration of active centers [C*] with different tacticity. SEM was applied to characterize the catalyst morphologies and growing polypropylene(PP) particles. The lamellar thickness and crystallizability of PP obtained under different polymerization conditions were analyzed by DSC and SAXS. The PP fractions and active centers with different tacticity were obtained with solvent extraction fractionation method. The catalytic activity, active centers with different tacticity and propagation rate constant k_p, fragmentation of the catalyst, crystalline structure of PP are correlated with temperature and time for propylene polymerizations. The polymerization temperature and time show complex influences on the propylene polymerization. The higher polymerization temperature(60 ℃) resulted higher activity, k_p and lower [C*], and the isotactic active centers C_i* as the majority ones producing the highest isotactic polypropylene(iPP) components showed much higher k_p when compared with the active centers with lower stereoselectivity. Appropriate polymerization time provided full fragmentation of the catalyst and minimum diffusion limitation. This work aims to elucidate the formation and evolution of active centers with different tacticity under different polymerization temperature and time and its relations with the fragmentation of the PP/catalyst particles, and provide the solutions to the improvement of catalyst activity and isotacticity of PP.     

Schiff碱钛配合物催化n-辛基联烯聚合

采用简便的方法, 合成了Schiff碱钛配合物Ti(Salen)2Cl2[Salen为N,N-(3,5-di-tert-butylsalicylidene)anilinato]并与Al(i-Bu)3组成二元催化体系用于n-辛基联烯的聚合. 实验结果表明, 在单体与催化剂摩尔比为100, n(Al)/n(Ti)=50, 催化剂于80 ℃陈化时间1 h后, 于80 ℃本体聚合16 h得到聚n-辛基联烯, 转化率100%, 分子量Mw=1.1×105, MWD=1.77, 1,2聚合链节单元质量分数为50%.     

硅烷类外给电子体的取代基变化对丙烯聚合影响的研究

合成了2种新型硅烷化合物双环己基二甲氧基硅烷(Donor-H)、双哌啶二甲氧基硅烷(Donor-Py),将其与工业化的环己基甲基二甲氧基硅烷(Donor-C)分别作为外给电子体,用于MgCl2负载的Ziegler-Natta催化剂催化丙烯聚合,通过DSC、GPC、SSA和13C-NMR等分析手段研究了3种外给电子体取代基的变化对催化剂的催化活性、氢调敏感性、聚丙烯的等规度、分子量分布、结晶能力、等规序列分布的影响.结果表明,随着外给电子体取代基体积的增大,外给电子体的给电子能力逐渐增强.与Donor-C相比,随着外给电子体取代基体积的增大,合成的具有较大取代基的Donor-H和Donor-Py用于丙烯聚合时都表现优异的催化性能,特别是新型含有N杂原子的氨基硅烷类Donor-Py为外给电子体的催化剂的催化活性和制备的聚丙烯的等规度最高,聚丙烯的熔融指数可调范围最宽,结晶能力更强.氨基硅烷类Donor-Py制备的聚丙烯SSA热分级后的高等规组分含量最多,可高达64.5%,聚丙烯等规序列长度最长,聚丙烯的等规序列分布最窄,而且13C-NMR结果也表明聚丙烯等规序列长度MSL最长,聚丙烯的分子链最规整.     

Epitaxial growth of isotactic polypropylene on oriented polyethylene from solution

Oriented polyethylene (PE) films with surfaces bounded by the (100) plane were prepared. On the film surfaces, isotactic polypropylene (iPP) was crystallized epitaxially from solution as quadrits with their sides parallel and perpendicular to the polyethylene chain axis. In the through wide-angle x-ray diffraction pattern (taken with incident x-rays normal to the polyethylene film surface), the 111 iPP reflections was observed on the meridian (Parallel to the polyethylene chain axis). In the edge patterns (taken with x-rays incident on the edge of the polyethylene film), 040 and 060 reflections were observed on the equator. From the diffraction patterns, the following lattice coincidence was observed between polyethylene and isotactic polypropylene: (010)iPP//(100) PE, [101]iPP//[001] PE. The Small-angle x-ray scattering patterns showed that edge-on isotactic polypropylene lamellae 9 nm thick were arranged with their long axes inclined at an angle of 40° from the polyethylene axis. Molecular chains were oriented within the lamellae normal to the surfaces.     

Morphology of isotactic polypropylene-polyamide 66 blends and their mechanical properties

Compounds were prepared with isotactic polypropylene (iPP) matrix and recycled polyamide 66 fibres (PA66), which were obtained as soft waste in industrial production process. Blends with pristine PA66 pellets were prepared as comparison. The blends showed the presence of PA66 particles dispersed in the PP continuous phase. Considering the incompatibility of the two polymers the addition of isotactic polypropylene grafted with maleic anhydride (iPPgMA) as compatibilizer was investigated: the blends were characterized by thermal, mechanical, dynamic-mechanical and morphological analyses. The presence of the compatibilizer significantly influences the morphology of the blends, inducing a finer dispersion and promoting interfacial adhesion. The characterization of pristine and recycled PA66 did not show a meaningful difference in the value of molecular weight, on the other hand marked differences were presented in the flexural moduli of the two materials; analogous differences were exhibited by the blends: compounds prepared with recycled PA66 showed flexural moduli higher than compatibilized blends with pristine PA66.