中低相对分子质量聚氧化乙烯合成用氨钙催化剂的研究

摘 要：对环氧乙烷开环聚合制备聚氧化乙烯反应的氨钙催化剂,采用正交设计的实验方法,考察了氨：钙质量比、乙腈:钙质量比、环氧丙烷:钙质量比、氨钙反应时间、改性剂反应时间等制备因素对聚氧化乙烯分子量和聚合收率的影响,得到乙腈和环氧乙烷添加量是主要影响因素,并优化得到可用于工业化应用的催化剂制备条件。工业化试验结果表明,聚氧化乙烯产品聚合收率高于98%,产品粘均相对分子量在20至80万间可调。     

中低相对分子质量聚氧化乙烯合成用氨钙催化剂的研究

摘 要：对环氧乙烷开环聚合制备聚氧化乙烯反应的氨钙催化剂,采用正交设计的实验方法,考察了氨：钙质量比、乙腈:钙质量比、环氧丙烷:钙质量比、氨钙反应时间、改性剂反应时间等制备因素对聚氧化乙烯分子量和聚合收率的影响,得到乙腈和环氧乙烷添加量是主要影响因素,并优化得到可用于工业化应用的催化剂制备条件。工业化试验结果表明,聚氧化乙烯产品聚合收率高于98%,产品粘均相对分子量在20至80万间可调。     

催化剂陈化温度和用量对环氧乙烷聚合稳定性的影响

以碱土金属氨钙为催化剂,经环氧乙烷的开环聚合得到聚氧化乙烯(PEO),考察了陈化温度和催化剂用量对聚合反应的影响。结果表明,陈化温度对聚合收率的影响较小,但影响聚合物分子量的波动程度;陈化温度为60℃的催化剂表现最为稳定,不仅聚合收率保持在99%以上,不同批次间聚合物的分子量波动程度(以变异系数表示)也降至最低,达7.3%。通过改变催化剂用量,可以在保持高聚合收率的情况下稳定地合成不同分子量级别(39万~86万)的PEO。SEM、XRD和DSC表征结果进一步表明,所得PEO粉末是一种具有层状结构的部分结晶性聚合物,且结晶度随分子量的增加而增大。     

聚氧化乙烯的性质及其合成

介绍了聚氧化乙烯的主要性质，采用有机金属化合物为主体的多组分催化剂进行环氧乙烷的聚合试验，探讨了聚合收率，聚合物分子量与聚合时间的关系，催化剂浓度，聚合温度，催化剂贮存时间对环氧乙烷聚合的影响。在较佳的工艺条件下制得分子量主同于５００万的白色粒状聚氧化乙烯，聚合收率大于９５％（重量）。     

低相对分子质量聚氧化乙烯的聚合研究

用自制氨钙催化剂合成低相对分子质量的聚氧化乙烯(PEO),用主成分分析法分析了环氧乙烷用量、溶剂用量、反应温度和反应时间对产物的相对分子质量的影响,并用红外光谱、DSC对产物进行了表征,确认为聚氧化乙烯均聚物。实验结果表明,环氧乙烷74 g、溶剂2.5 L、反应温度25℃、反应时间7 h时,收率达99.1%,相对分子质量为33.1万。     

高分子量聚氧化乙烯的合成

本文采用三乙基铝、乙酰丙酮、水系催化剂使环氧乙烷聚合。探讨了水与三乙基铝的摩尔比、乙酰丙酮与三乙基铝的摩尔比、聚合温度、催化剂浓度、稀释剂用量、环氧乙烷质量同聚氧化乙烯平均分子量及聚合收率之间的关系。在较好的条件下,制得分子量达300万的白色块状聚氧化乙烯。考察了一些样品的降解情况,大多数样品存放半年后,平均分子量仍高于200万。     

聚乙二醇20000的合成工艺研究

通过共沉淀的方法制备一种镁、铝、钙的混合氧化物催化剂,用于环氧乙烷聚合合成聚乙二醇(PEG)20000,考察了催化剂的筛选,催化剂中Mg、Al、Ca质量比,催化剂用量,反应温度等工艺条件对合成聚乙二醇收率的影响。优化的工艺条件为:反应温度125℃,初始压力0.4 MPa,乙二醇和环氧乙烷物质的量比1∶470,m(Mg)∶m(Al)∶m(Ca)=2∶1∶0.3,催化剂占总物料量的0.2%。该工艺条件下,生产的聚乙二醇平均相对分子质量分布系数PDI约1.07,基本接近进口标准样品的平均相对分子质量分布系数PDI 1.03,平均相对分子质量分布较窄。混合氧化物催化剂反应结束后易分离,金属残留少,可回收循环利用,提高了产品聚乙二醇的品质,且降低了合成成本。     

烷基多苷硫酸酯铵盐的合成及性能

以烷基多苷为原料,用氨磺酸为硫酸化试剂,合成了烷基多苷硫酸氨。通过正交实验及优化实验确定了反应温度、反应时间、原料配比、溶剂、催化剂种类、催化剂用量等因素对产率的影响。得出了最佳合成条件为:以V(甲苯)∶V(吡啶)=7∶3为溶剂,以尿素为催化剂,m(APG)∶m(NH2SO3H)=1∶1.10,反应温度105℃;反应时间3.5 h。该条件下的烷基多苷硫酸铵收率达到86.6%。产品的水溶性、起泡性、增溶性较烷基多苷显著提高。     

八氟戊醇聚氧乙烯醚(3)的合成工艺研究

在酸性催化剂A作用下,以八氟戊醇和环氧乙烷为原料制备八氟戊醇聚氧乙烯醚(3)。利用红外光谱确定了产物;通过分析产品水溶液表面张力、分子量分布系数,考察了合成的各项影响因素,获得了反应的最佳条件:n(八氟戊醇)∶n(EO)=1∶3,酸性催化剂A用量为0.5‰,反应温度为40℃,反应时间为3.5h。在此条件下进行重复试验,结果为:产品水溶液表面张力为21mN/m,分子量分布系数为1.05,产品产率为99.8%。     

新型水溶性高分子化合物—聚氧化乙烯

以环氧乙烷为原料,制备高分子量的聚氧化乙烯。在适宜的催化剂组份和聚合条件下,可制得平均分子量为4×10~6、3×10~6、2×10~6、0.5×10~6、1×10~6、5×10~5、3×10~5的白色粒状聚氧化乙烯树脂。聚合收率大于85%,一个月后聚合降解率低于10%,符合用户要求。产品用于造纸、纺织、印染等行业中,作为粘合     

金属卟啉仿生催化制备环氧丙烷

制备了四苯基卟啉、四-4-甲氧基苯基卟啉、四-4-氟苯基卟啉及3种卟啉相对应的钴、锰、铁金属卟啉,并利用Cary紫外可见分光光度计(UV-vis)和傅里叶变换红外光谱仪(FTIR)对金属卟啉进行了表征;以制备的不同金属卟啉为催化剂,丙烯为原料,氧气为氧化剂,仿生催化丙烯氧化合成环氧丙烷。考察了金属卟啉催化剂类型、金属卟啉催化剂浓度、反应压力、反应温度、反应时间对反应的影响,结果发现上述因素对反应收率、转化率、选择性均有显著影响,且都有一个最佳值,获得的最优化反应条件为:选取四-4-氟苯基铁卟啉为催化剂,催化剂浓度为1.35×10^-5mol/L,反应压力1.75MPa,反应温度100℃,反应时间为2h。在最优化的反应条件下,环氧丙烷的收率达到了40.38%,丙烯转化率达到了47.09%,环氧丙烷选择性达到了85.75%。     

A comparative study of ethylene and propylene polymerization over titanium–magnesium catalysts of different composition

New data on the molecular weight characteristics of polypropylene (PP) and polyethylene (PE) were obtained from the polymerization over supported titanium–magnesium catalysts differing in their compositions (presence and absence of internal and external donors). Internal and external donors were found to affect the molecular weight of polymers in a different manner for ethylene and propylene polymerization. The introduction of the internal donor increases the molecular weight of PP and does not affect the molecular weight of PE. The effect of external donor introduced to catalytic system on the polymer molecular weight depends on catalyst composition: for a catalyst without internal donor, the introduction of the external donor increases the molecular weight of PP and does not affect that of PE. In the case of catalyst with the internal donor, the introduction of the external donor increases the molecular weight of PP and substantially decreases that of PE. The data on polymerization degree of the polymers produced under conditions when chain transfer with hydrogen was the dominant reaction were used to calculate the values for ethylene polymerization over the catalysts of different composition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40658.     

Organic/inorganic support for immobilizing (n‐BuCp)2ZrCl2/TiCl3 hybrid catalyst for use in the preparation of polymer blends

Reactor blends of ultrahigh‐molecular‐weight polyethylene (UHMWPE) and low‐molecular‐weight polyethylene (LMWPE) were synthesized by two‐step polymerization using a hybrid catalyst. To prepare the hybrid catalyst, styrene acrylic copolymer (PSA) was first coated onto SiO₂/MgCl₂‐supported TiCl₃; then, (n‐BuCp)₂ZrCl₂ was immobilized onto the exterior PSA. UHMWPE was produced in the first polymerization stage with the presence of 1‐hexene and modified methylaluminoxane (MMAO), and the LMWPE was prepared with the presence of hydrogen and triethylaluminium in the second polymerization stage. The activity of the hybrid catalyst was considerable (6.5 × 10⁶ g PE (mol Zr)^?1 h^?1), and was maintained for longer than 8 h during the two‐step polymerization. The barrier property of PSA to the co‐catalyst was verified using ethylene polymerization experiments. The appearance of a lag phase in the kinetic curve during the first‐stage polymerization implied that the exterior catalyst ((n‐BuCp)₂ZrCl₂) could be activated prior to the interior catalyst (M‐1). Furthermore, the melting temperature, crystallinity, degree of branching, molecular weight and molecular‐weight distribution of polyethylene obtained at various polymerization times showed that the M‐1 catalyst began to be activated by MMAO after 40 min of the reaction. The activation of M‐1 catalyst led to a decrease in the molecular weight of UHMWPE. Finally, the thermal behaviors of polyethylene blends were investigated using differential scanning calorimetry. Copyright © 2011 Society of Chemical Industry     

无毒高相对分子质量PVA的合成与结构分析研究

以甲醇为溶剂,以环氧树脂为引发剂,乙酸乙烯酯与甲醇的质量比为25∶3.96,反应温度为(65±2)℃,引发剂用量为0.080 2 g,反应4.5 h,以溶液聚合法制备粘均相对分子质量为1.95×105的聚醋酸乙烯酯,经醇解得到无毒的聚乙烯醇,产品经UV,FTIR,1H NMR谱进行确认和结构分析。讨论了反应温度、反应时间、引发剂用量、原料质量比对醋酸乙烯酯相对分子质量的影响。     

Control of molecular weight distribution for polypropylene obtained by commercial Ziegler–Natta catalyst: effect of temperature

Polymerization of propylene was carried out by using MgCl₂-supported TiCl₄ catalyst in conjunction with triethylaluminium (TEA) as cocatalyst. The effect of polymerization temperature on polymerization of propylene was investigated. The catalyst activity was influenced by the polymerization temperature significantly and the maximum activity of the catalyst was obtained at 40 °C. With increasing the polymerization temperature, the molecular weight of polypropylene (PP) drastically decreased, while the polydispersity index (PDI) increased. The effect of the two-stepwise polymerization procedure on the molecular weight and molecular weight distribution of PP was studied and the broad PDI of PP was obtained. It was also found that the PDI of PP could be controlled for propylene polymerization through regulation of polymerization temperature. Among the whole experimental cases, the M _w of PP was controlled from 14.5 × 10⁴ to 75.2 × 10⁴ g/mol and the PDI could be controlled from 4.7 to 10.2.     

Cure and properties of unfoamed polyurethanes based on uretonimine modified methylene–diphenyl diisocyanate

The curing behaviour of a series of polyurethanes based on modified methylene–diphenyl diisocyanate (MDI) and poly(propylene oxide) polyols was studied using isothermal Fourier‐transform infrared spectroscopy (FTIR), temperature‐ramped differential scanning calorimetry (DSC) and adiabatic exotherm experiments. The effects of catalyst type and content, and of polyol molecular weight and functionality on the curing behaviour of the material were investigated. Increasing catalyst concentration or decreasing the polyol molecular weight raised the rate of reaction and shifted the DSC peak exotherm temperature to lower temperatures, but the heat of reaction was effectively constant. A marked increase in reaction rate was observed when a 1 °‐alcohol‐based polyol (from ethylene oxide end‐capping) was used in place of the standard poly(propylene oxide) end‐capped 2 °‐polyols. FTIR isocyanate conversion during polyurethane formation for a range of dibutyltin dilaurate (DBTDL) concentrations was satisfactorily fitted to second‐order kinetics. An approximately linear relationship between DBTDL catalyst concentration and reaction rate constant was found, but increasing the concentration of DBTDL was found to have no significant effect on the magnitude of the activation energy. The activation energy for polymerization was found to be independent of the molecular weight of the diol or triol systems. Dynamic mechanical thermal analysis revealed a linear increase of the glass transition temperature with decreasing triol weight fraction, and was in good agreement with a theoretical model based on copolymer and crosslinking effects. © 2000 Society of Chemical Industry     

四种乳酸聚合方法的比较

以乳酸为原料,辛酸亚锡为催化剂,采用乳酸直接聚合(一步法)、丙交酯开环聚合(两步法)、熔融-固相聚合、溶剂回流脱水等不同的实验方法分别合成出了不同相对分子质量的聚乳酸。实验结果表明:实验方法不同,所得聚合物的相对分子质量不同,其中丙交酯开环聚合(两步法)所得聚合物的相对分子质量最大,可达80万左右,溶剂回流脱水法的可达24000左右,熔融-固相聚合的为10800,乳酸的直接聚合(一步法)的只有5000。