Mathematical Modeling of Homopolymerization on Supported Metallocene Catalysts

Summary: In this paper, a mathematical model describing olefin polymerization with metallocene catalysts is presented. It is an improvement of a previous model, the “particle growth model” (PGM) proposed by, among others, one of the authors of the present work and derives from the so‐called “multigrane model” (MGM). The main differences between this work and others is a more sophisticated approach to fragmentation with respect to the MGM. Additionally, there is a more specific modeling for the unfragmented core with respect to the PGM. The numerical results obtained by the model are compared with experimental data. The results of this work allow to extend the PGM to catalysts with lower activity. The importance of those catalysts depends on the fact that high activity catalysts could bring, in some cases, too poor polymer morphology.

Geometrical representation of the micro‐ and macroparticle.     

双[N,O]配体合镍配合物/甲基铝氧烷催化降冰片烯与苯乙烯的均聚和共聚

研究了新型双[N,O]配体合镍配合物双[水杨醛(对硝基苯)亚胺]合镍/甲基铝氧烷体系催化降冰片烯(NBE)和苯乙烯(St)的均聚和共聚的催化性能,考察了聚合温度、Al与Ni摩尔比对催化活性和均聚物相对分子质量的影响;考察了单体投料比对NBE和St共聚性能的影响。实验结果表明,NBE和St在较高温度(50℃)均聚时的催化活性分别为105g/(mol·h)和106g/(mol·0.5h);NBE与St共聚时的催化活性高达105g/(mol·h)。     

复合载体Ti系催化剂的乙烯均聚和共聚

研究了乙烯气相均聚、共聚合的复合载体钛系高效催化剂。催化剂基本组份为TiCl4 /ZnCl2 -MgCl2 -SiO2 /AlR3,各组份质量分数为Ti:1 8%～ 2 7% ,Mg2 + :3 0 %～ 4 0 %、Zn2 + :3 5%～ 5 1 %、SiO2 :51 %～ 66%。探讨了催化剂制备条件对聚合性能的影响 ,常压下乙烯气相均聚、共聚合催化效率 6960～ 1 2 1 0 0g/ g ,表观密度 0 3 3～ 0 4 2 g/cm3,2 0～ 2 0 0目聚合物颗粒质量分数为 98%。Φ1 0 0流化床共聚合 ,在 1 0MPa压力下 ,催化效率 4 45～ 887kg/ g ,聚合物MI2 16 为 0 2 6～ 50g/ 1 0min ,熔体流动速率比值MI2 1 6 /MI2 16 为 2 2 7～ 4 7 0 ,熔点 99 6～ 1 2 5℃ ,结晶度 2 0 %～4 9% ,密度 0 880～ 0 92 8g/cm3,支化度 1 1 0～ 4 7 5,该催化剂可制备LLDPE和ULLDPE。     

Norbornene polymerization and ethylene/norbornene copolymerization catalyzed by constrained geometry cyclopentadienyl-phenoxytitanium catalysts

Norbornene polymerization and ethylene/norbornene copolymerization were studied using constrained geometry complexes 2-(tetramethylcyclopentadienyl)-4,6-di-tert-butylphenoxytitanium dichloride (1), 2-(tetramethylcyclopentadienyl)-6-tert-butylphenoxytitanium dichloride (2), and 2-(tetramethylcyclopentadienyl)-6-phenylphenoxytitanium dichloride (3) as catalysts with AlⁱBu₃ and Ph₃CB(C₆F₅)₄ as cocatalysts. Polymerization results indicate that these catalyst systems are highly active for both the homopolymerization of norbornene and the copolymerization of ethylene with norbornene. The norbornene homopolymerization is vinyl addition polymerization. Ethylene/norbornene copolymers with high norbornene incorporation (>50%) were easily obtained with these catalyst systems by increasing the norbornene feed concentration. The produced polymers were characterized by ¹³C NMR, IR, DSC and GPC.     

Kinetic studies of the chemical polymerization of substituted aniline in aqueous solutions and characterization of the polymer obtained Part 1. 3‐Chloroaniline

Aqueous polymerization of 3‐chloroaniline (mCA) was studied using sodium dichromate as oxidant in the presence of hydrochloric acid. The effect of hydrochloric acid, sodium dichromate and monomer concentration on the polymerization rate, specific viscosity of the obtained polymer and ac conductivity was investigated. The initial and overall reaction rates increase with increasing hydrochloric acid concentration or sodium dichromate concentration, but decrease with increasing monomer concentration. The specific viscosity values (η_sp) increase with increasing hydrochloric acid concentration or monomer concentration, which means that the molecular weight of the polymer samples increases accordingly. On the contrary, the molecular weight decreases with increasing sodium dichromate concentration. The highest ac conductivity value of the obtained polymer was found for 0.0255 mol l⁻¹ of Na₂Cr₂O₇, 0.8 mol l⁻¹ HCl and 0.0956 mol l⁻¹ monomer concentration in the reaction medium. The order of the polymerization reaction with respect to hydrochloric acid, Na₂Cr₂O₇ and monomer concentration was found to be 1.0, 0.9 and 0.75, respectively. The apparent activation energy (E_a) for this polymerization system was found to be 13.674 × 10⁴ mol⁻¹. The obtained poly(3‐chloroaniline) was characterized by UV–visible, IR and ¹H NMR spectroscopy. X‐ray diffraction analysis and electron microscopy studies were carried out. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) results were used to confirm the structure. © 2001 Society of Chemical Industry     

聚甲醛的生产工艺

分别介绍了工业上甲醇氧化生产甲醛的三种方法:银法、铁钼法和甲缩醛催化氧化法,并对其生产工艺比较进行,探讨了各种方法的优缺点;分析了聚甲醛生产的均聚和共聚合成工艺;结合国内外各主要聚甲醛生产公司的生产运行情况,提出发展我国聚甲醛产业的一些建议。     

松香/GMA酯化物的自聚与共聚

利用松香与甲基丙烯酸缩水甘油酯(GMA)进行酯化反应,得到酯化产物(RG),然后进行了RG的自聚反应和与苯乙烯的共聚反应.利用红外光谱对产物结构进行表征,热重分析产物的热稳定性,差示扫描量热法测试产物的玻璃化转变温度,研究单体配比、反应温度、引发剂种类对RG与苯乙烯共聚反应产物分子量及其分布的影响.实验结果表明:成功合成了自聚物和共聚物;偶氮二异丁腈是共聚和自聚反应较优的引发剂;与苯乙烯共聚反应中,随着温度的升高,共聚物分子量增加,分子量分布变窄,随着苯乙烯用量的增大,共聚物分子量下降,分子量分布变宽;自聚物和共聚物的初始分解温度相近,但共聚物最大分解温度较高;共聚物的玻璃化转变温度高于自聚物.     

原料树脂对PET工程塑料性能的影响

在采用差示扫描量热法分析国产不同聚对苯二甲酸乙二酯(PET)树脂及其增强、增强阻燃材料的基础上,结合物理力学性能测试,讨论了PET原料树脂对材料性能的影响。结果表明,用固相增粘的中粘度均聚优级品PET作原料树脂,其增强、增强阻燃材料既有较快的结晶速度又有均衡优良的物理力学性能,而使用纤维级低粘度树脂则力学性能差,韧性尤其欠缺;用直接酯化法与酯交换法合成增粘的中粘度树脂,其增强阻燃材料性能基本一致,但后者在快结晶、易加工方面略优于前者;共聚高粘度树脂不宜用作要求热变形温度高和快结晶的材料。