新型间同立构聚苯乙烯工程塑料

简要介绍新型工程塑料间同立构结晶型聚苯乙烯的结构、性能、加工及其应用。     

茂钛催化剂合成及苯乙烯间规聚合

介绍了茂钛催化剂ＣｐＴｉ（ＯＰｈ）３（Ｃｐ为环戊二烯基）的合成。使用ＣｐＴｉ（ＯＰｈ）３／ＭＡＯ均相催化体系,研究了工艺条件对苯乙烯间规聚合的影响。初步探讨了以带有反应性功能基团的聚苯乙烯为载体,负载ＣｐＴｉＣｌ３后进行的苯乙烯间规聚合。同时采用了不同配体的ＣｐＴｉ（ＯＲ）３催化剂用于苯乙与乙烯或丙烯共聚合,得到的共聚产物是一类应用前景良好的工程塑料。     

间规聚苯乙烯的合成与工业化研究

本文评述了间规聚苯乙烯（ｓＰＳ）的联合机理与工业化研究,介绍了茂金属催化剂和聚合反应器。强调要实现ｓＰＳ的工业化,尚需加强以聚合反应工艺和反应器开发为目标的聚合反应工程研究。     

间规聚苯乙烯催化剂研究进展

间规聚苯乙烯是一种高熔点的高分子材料,具有多方面优异特性,在多个领域有广泛的应用前景。综述用于苯乙烯间规聚合的单中心过渡金属催化剂的研究进展,总结各类催化剂用于聚合的特点。简单的单茂钛催化剂(Cp’Ti X3)是最早用于有效催化苯乙烯间规聚合的催化剂,但活性和间规聚合物含量都有待提高;结构如Cp’Ti Xn L的单茂钛催化剂,通过引进非茂给电子配体,可以大大提高聚合活性,提高间规聚合物比例,某些催化剂还可以实现活性聚合;ⅢB过渡金属(钪和稀土元素)化合物作为间规聚苯乙烯聚合催化剂的研究,有助于理解苯乙烯间规聚合,乃至烯烃配位聚合机理。对间规聚苯乙烯催化剂工业现状和研发需求进行分析。     

聚丙烯用茂金属催化剂的研究进展

介绍了国内外聚丙烯用茂金属催化剂的技术进展,阐述了茂金属催化剂的分子结构与聚丙烯分子构型的关系.按聚丙烯的结构特性,分析了无规聚丙烯、间规聚丙烯、半等规聚丙烯、等规聚丙烯和立构嵌段聚丙烯用茂金属催化剂的技术特点及技术进展.     

非茂金属催化剂用于苯乙烯间规聚合

研究开发了非茂金属催化剂用于苯乙烯的间规聚合，合成了β－二酮钛配合物／ＭＡＯ，引入烷氧基的β－二铜钛配合物／ＭＡＯ，８－羟基喹啉钛配合物／ＭＡＯ和β－联萘酚钛配合物／ＭＡＯ等催化体系，其中最好的催化体系用于苯乙烯本体聚合时，在８０℃和Ａｌ／Ｔｉ比为５００的聚合条件下，活性达到６×１０＾５ｇ（ＰＳ）／ｍｏｌ（Ｔｉ）．ｈ，聚合物间规度〉９５％，熔点达２７０℃，本文也能催化剂结构和性能关系的研究结果进行     

聚烯烃催化剂的研究进展及其应用

阐述了聚烯烃催化剂的最新进展。茂及非茂催化剂是当前催化剂行业研究和开发的热点,对国内外该领域的发展现状进行了对比,并对聚烯烃催化剂及茂金属聚烯烃的市场需求进行了预测。     

新型苦茂钛间规聚苯乙烯催化剂的研究

间规聚苯乙烯具有低比重、优良的电气特性、耐水解性、易成型以及良好的耐热性、耐化学药品性、尺寸稳定性,在未来的许多领域具有应用价值。上海石油化工院和中山大学已经完成了新型茂钛间规聚苯乙烯催化剂的研究,创制出具有自己专利技术的产品,产品性能已达到国外同类催化剂的先进水平,同时还对聚合物的加工做了更深入的研究。     

茂金属催化苯乙烯间规聚合物的颗粒形态

以均相单茂钛化合物［Cp*Ti(OPh)₃ 和Cp*Ti(OPhOMe)₃］为主催化剂,配以烷基铝氧烷（MAO）和三异丁基铝(TIBA),进行了苯乙烯的本体间规聚合.研究发现,聚合过程中生成聚合物的快速结晶对于避免反应体系的凝胶化,制得颗粒状产物十分重要.但正因为这种结晶成核机理,使所得颗粒的形貌极不规整,调控也十分困难.聚合过程中sPS种子的加入没有明显改善生成聚合物的颗粒形态.但当聚合体系中引入少量其他聚合物后,得到了较为规整的sPS颗粒,尤其当加入的聚合物与无定形sPS热力学不相容时（如mEPDM）,得到了十分规则的球状颗粒.     

Pressure effects on polymerization of syndiotactic polystyrene

Polymerization pressure has a direct effect on the synthesis of syndiotactic polystyrene (s-PS) with metallocene as a catalyst. The polymerization rate, yield rate, and average molecular weight show a linear relationship with pressure, that is, they all increase with increased polymerization pressure. However, under 1000 psi, the yield of s-PS increases with polymerization duration while the yield rate decreases. As a whole, this syndiotactic polymerization proceeds relatively fast in comparison with ordinary vinyl polymerization. Optimal conditions (pressure, temperature, and duration) for the synthesis of s-PS have been explored. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1747–1752, 1998     

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     

制备间规聚苯乙烯的新型催化剂的研究

对位卤素取代的苯酚与五甲基三氯单茂钛在三乙胺存在下进行酯化反应，制得4种五甲基茂基三(对—卤代苯氧基)钛的新型茂钛化合物[Cp^*Ti(O—C6H4—X)3,(X为F、Cl、Br、D)]。经元素分析、质谱、核磁共振谱证实了上述结构。在甲基铝氧烷和三异丁基铝活化下，4种茂钛化合物对苯乙烯间规聚合显示出极高的催化活性，制得的间规聚合物间规度(大于96％)和熔点(大于270℃)高。4种茂钛化合物的活性从大到小依次为：五甲基茂基三(对—氟苯氧基)钛、五甲基茂基三(对—氯苯氧基)钛、五甲基茂基三(对—溴苯氧基)钛、五甲基茂基三(对—碘苯氧基)钛。     

Kinetics of slurry phase polymerization of styrene to syndiotactic polystyrene with pentamethyl cyclopentadienyl titanium trimethoxide and methyl aluminoxane. I. Reaction rate analysis

The kinetics of syndiospecific slurry polymerization of styrene in heptane has been investigated with pentamethyl cyclopentadienyl titanium trimethoxide [Cp??Ti(OMe)₃] catalyst with methylalmuninoxane. The experimental studies at different styrene/heptane ratios indicate that no global gelation occurs at low styrene/heptane ratios even at high styrene conversion. The effective propagation rate constant tends to decrease as polymerization rate is increased at higher initial styrene concentrations. To analyze the effect of catalyst deactivation, a novel three‐stage polymerization experiment has been designed and carried out where monomer is added during the polymerization. The experimental results show that the catalyst activity is very high at the beginning of polymerization but it decreases significantly as catalyst sites are occluded in the solid phase. We also observe that the catalyst remains active for more than 3 h and the rate decay is not solely due to intrinsic catalyst deactivation. Our experimental data suggests that physical transport effects cause the decay in the polymerization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2132–2137, 2003     

Preparation of syndiotactic polystyrene/montmorillonite nanocomposites via in situ intercalative polymerization of styrene with monotitanocene catalyst

Syndiotactic polystyrene (sPS)/montmorillonite nanocomposites were prepared via in situ intercalative coordination polymerization using mono‐(η⁵‐pentamethylcyclopenta‐ dienyl) tribenzyloxy titanium [Cp*Ti(OBz)₃] complex activated by methylaluminoxanes (MAO) and triisobutylaluminum (TIBA). The influences of polymerization conditions, such as the weight ratio of montmorillonite and styrene, temperature, and monomer concentration, on the preparation of sPS/montmorillonite nanocomposites was investigated. The intercalation spacing in the nanocomposites, as well as the exfoliation of the montmorillonite interlayers, was characterized with wide angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM). The dispersibility of the nanoscale elements depended on the polymerization conditions and the surfactant treatment. The crystallizability and thermal properties of these nanocomposites were determined by differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA). Experimental results indicated that the degree of crystallinity of the sPS nanocomposite increased with increasing montmorillonite content and with higher T_g and thermal decomposition temperature than pure sPS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1412–1417, 2005     

Grafted syndiotactic polystyrene synthesized via melting graft copolymerization used as a compatibilizer for immiscible syndiotactic polystyrene/polyadimide 66 blends

A new grafted syndiotactic polystyrene (g‐sPS), to be used as a compatibilizer for syndiotactic polystyrene (sPS)/polyadimide 66 blends, was prepared by the melting graft copolymerization of sPS and monomers composed of itaconic acid and dibutyl maleate with dicumyl peroxide as an initiator. The resulting g‐sPS possessed a side‐chain structure identified by IR spectra, and the results of mechanical testing show that a good impact strength and tensile strength were obtained for g‐sPS at a 7.16‐phr addition of monomer with a 3:1 proportion of dibutyl maleate and itaconic acid. Differential scanning calorimetry and scanning electron microscopy analysis indicated that the g‐sPS maintained a high glass‐transition temperature and a crystalline structure. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1659–1666, 2005     

Effects of residual and external alkylaluminum on the synthesis of syndiotactic polystyrene with cyclopentadienyltitanium tribenzyloxide–methylaluminoxane catalyst

The effects of residual trimethylaluminum (TMA) in methylaluminoxane (MAO) and external alkylaluminum (AlR₃) on styrene syndiotactic polymerization with CpTi(OBz)₃ as a catalyst precursor have been investigated by comparison of the polymerizations using a series of MAOs containing various amounts of residual TMA. The results indicated that the residual TMA plays a deciding role in the reduction of Ti and promotes formation of the active centers for styrene polymerization. The variations in the catalytic activity and molecular weight of the polymer caused by additions of external AlR₃, AlMe₃, AlEt₃, Al(i-Bu)₃, and AlEt₂Cl, into the catalyst systems are quite different, depending the properties of MAO used and the type of the external AlR₃. It was found that there is an optimum range of concentration ratio of the free AlR₃, including the residual TMA and external AlR₃, to the total Al compounds, 25–35 mol %, for maximum catalytic activities. The catalytic activities decrease at the ratios either above or below the range. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 765–770, 1998     

Effects of maleated syndiotactic polystyrene on the morphology,mechanical properties,and crystallization behavior of syndiotactic polystyrene/polyamide 6 blends

The compatibilization of syndiotactic polystyrene (sPS)/polyamide 6 (PA‐6) blends with maleic anhydride grafted syndiotactic polystyrene (sPS‐g‐MA) as a reactive compatibilizer was investigated. The sPS/PA‐6 blends were in situ compatibilized by a reaction between the maleic anhydride (MA) of sPS‐g‐MA and the amine end group of PA‐6. The occurrence of the chemical reaction was substantiated by the disappearance of a characteristic MA peak from the Fourier transform infrared spectrum. Morphology observations showed that the size of the dispersed PA‐6 domains was significantly reduced and that the interfacial adhesion was much improved by the addition of sPS‐g‐MA. As a result of reactive compatibilization, the impact strengths of the sPS/PA‐6 blends increased with an increase in the sPS‐g‐MA content. The crystallization behaviors of the blends were affected by the compatibilization effect of sPS‐g‐MA. A single melting peak of sPS in the noncompatibilized blend was gradually split into two peaks as the amount of the compatibilizer increased. A single crystallization peak of PA‐6 in the noncompatibilized blend became two peaks with the addition of 3 wt % sPS‐g‐MA. The new peak was a result of the fractionation crystallization. As the amount of sPS‐g‐MA increased, the intensity of the new peak increased, and the original peak nearly disappeared. Finally, the crystallization peak of PA‐6 disappeared with 20 wt % sPS‐g‐MA in the blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2502–2506, 2003     

Synthesis and characterization of acetylated syndiotactic polystyrene

Acetylation of highly stereoregular syndiotactic polystyrene has been accomplished in a heterogeneous process by using carbon disulfide as the dispersing medium, and acetyl chloride and anhydrous aluminium chloride as acetylating agent and catalyst, respectively. The acetylation reaction can be well controlled and carried out to a high degree of acetylation. The resultant polymer was characterized by FTIR and NMR spectroscopy. The incorporation of acetyl groups into syndiotactic polystyrene was found to have an effect on the thermal properties of these new materials. The degree of crystallinity was decreased by the presence of acetyl groups, while the glass transition temperature increased. Copyright © 2004 Society of Chemical Industry