负载钛催化丁二烯-异戊二烯共聚合反应动力学的研究

研究了TiCl4 /MgCl2 负载型高效催化剂催化丁二烯 -异戊二烯共聚合的动力学特征 ,并对影响聚合速率的因素进行了考察。首先通过计算排除了扩散控制对反应总聚合速率的影响 ,测定了单体浓度和催化剂浓度的反应级数和表观活化能 (2 2 .8kJ/mol) ,建立的聚合速率方程为 :R =kp·f·[Ti]·[M]。     

不同二异氰酸酯三聚反应分子模拟与反应动力学研究

利用DMol3分子模拟软件对二苯基甲烷二异氰酸酯(MDI)、氢化二苯基甲烷二异氰酸酯(HMDI)、异佛尔酮二异氰酸酯(IPDI)3种异氰酸酯自聚反应进行了模拟计算;利用傅里叶变换红外光谱(FT-IR)对不同异氰酸酯在催化剂2,4,6-三(二甲胺基甲基)苯酚(DMP-30)作用下的三聚反应进行了跟踪,研究了不同催化剂用量、反应温度、反应时间下3种异氰酸酯的自聚反应动力学。结果表明,异氰酸酯自聚反应倾向生成稳定的六元环结构;3种异氰酸酯三聚反应均为二级反应,MDI在加入催化剂质量分数0.05%时,反应的活化能为26.1 kJ/mol,IPDI和HMDI在加入催化剂质量分数2%时,反应的活化能分别为13.5 kJ/mol和49.9 kJ/mol。     

负载钛催化1-丁烯本体聚合动力学

采用TiCl4/MgCl2-Al(i-Bu)3催化体系在10 L聚合釜中研究了本体法1-丁烯的聚合动力学.结果表明,在反应温度为20 ℃的条件下,聚合的速率方程为Rp=157[Ti]1.1[Bt]PH20.4;在10～30 ℃时的聚合活化能为46 kJ/mol.提高催化剂浓度、聚合温度和氢气压力均能明显提高单体转化率,加快聚合速率.     

橡胶改性尼龙6动力学

采用酰基己内酰胺封端的丁腈橡胶(CHTBN)或丁苯橡胶(CHTBS)与NaOH作为引发催化体系,反应温度在145～160℃之间,通过绝热法测定反应过程的温升曲线,计算得到了动力学参数。采用CHTBN/NaOH时反应级数为一级,活化能在72.91～73.16 kJ·mol-1之间,指前因子在3.22×10¹¹～3.38×10¹¹mol ^1-n·s^-1范围内;采用CHTBS/NaOH时反应级数在1.23～1.34之间,偏离了1级反应,活化能在85.55～86.88 kJ·mol-1之间,指前因子在4.52×10¹¹～5.09×10¹¹mol ^1-n·s^-1范围内。在前人工作的基础上建立了阴离子聚合绝热反应动力学模型并对反应过程进行了模拟,结果与实验温升曲线具有很好相关性,从而证明了模型的合理。     

不同结构多元醇与MDI的绝热反应动力学研究

用一系列不同结构的低聚物多元醇与4,4'-二苯基甲烷二异氰酸酯(纯MDI)进行本体聚合,比较了低聚物多元醇的结构单元、相对分子质量以及官能度等因素对绝热反应温度变化曲线的影响,同时用线性优化方法求取了它们的反应动力学参数.结果表明,含有极性较大的结构单元的低聚物多元醇,反应活化能较大;低聚物多元醇的反应速率受温度影响明...     

BuAENA合成过程中反应热的测定及动力学关联

用全自动反应量热器(RC1e)测定了丁基-叠氮乙基硝胺(BuAENA)合成过程的反应热,用Levenberg-Mar-quardt法获得叠氮化反应的宏观动力学参数。结果表明,在合成过程中BuAENA的反应焓变为-18.1kJ/mol,最大放热速率为25.4J/s,反应绝热温升为11.1K时,BuNENA、NaN3的反应级数分别为0.97、0.05,反应活化能为15.31kJ/mol,指前因子为0.27mol.m-3.s-1。     

负载钛催化丁烯-1扩大溶液聚合反应过程

采用TiCl4/MgCl2-Al(i-Bu)3催化体系在10L聚合釜中用溶液法研究了丁烯-1聚合反应过程。结果表明,在反应温度为20℃条件下,聚合的速率方程为-d[Bt]/dt=41[Ti][Bt][PH2]0.4;在10～30℃,聚合的表观活化能为16kJ/mol;提高催化剂浓度、聚合温度、氢气压力能明显提高单体转化率、加快反应速率。     

负载型钛催化剂催化1-十二烯溶液聚合动力学

采用TiCl4/MgCl2-Al(i-Bu)3催化剂,溶液聚合法合成了聚1-十二烯烃油溶性减阻剂.使用Brookfield DVⅢ型流变仪对以正已烷、正庚烷和环已烷为溶剂的原料进行流变性研究,以此考察不同溶剂体系对聚合速率的影响,测定了主催化剂TiCl4/MgCl2浓度与助催化剂Al(i-Bu)3浓度的反应级数和聚合反应的表观活化能,并由此建立聚合反应速率方程,探讨了聚合速率对聚合物特性粘数的影响.结果表明,以正已烷、正庚烷和环已烷为溶剂时,聚合速率依次降低,但对单体浓度均呈一级反应;在本研究催化剂加量范围内,聚合速率对主催化剂浓度呈一级关系,而刘助催化剂浓度呈零级关系.聚合速率与特性粘数不成正比关系,需在合适聚合速率下才能得到较高特性粘数.在-5～5℃,聚合的表观活化能为56.64 kJ/mol.     

DABCO类离子液体的合成及其在Baylis-Hillman反应中的应用

以三乙烯二胺、溴代烷烃、四氟硼酸钠为原料初步合成了4种DABCO类离子液体,并将其用于催化芳香醛类与丙烯酸酯类的Baylis-Hillman反应,考察了DABCO类离子液体在Baylis-Hillman反应中的催化性能,讨论了反应溶剂、催化剂的烷基链链长、催化剂用量(摩尔分数,以芳香醛计)对反应速率及收率的影响,并对DABCO类离子液体进行回收利用实验。结果表明,在室温条件下,DABCO类离子液体在Baylis-Hillman反应中表现出了良好的催化效果,有效促进了反应的进行,缩短了反应时间;当催化剂[C_4dabco][BF_4]用量为80%、以水为溶剂时,7.0 h完成反应,收率为89.1%,回收后的催化剂循环使用6次仍能保持良好的催化活性。     

间十五烷基酚与丙烯酰氯酯化反应动力学

为开发间十五烷基丙烯酸苯酯(PDPA)制备工艺,及今后工业化生产提供基础的动力学数据支持。系统地研究不同温度下,无催化剂和以离子液体为催化剂条件下,间十五烷基酚(PDP)与丙烯酰氯合成PDPA的反应动力学。在无催化剂和敷酸剂条件下,酯化反应是二级可逆反应,正反应活化能64.8 kJ/mol,指前因子1.78×106L/(mol·min);逆反应活化能25.1 kJ/mol,指前因子2.25×103L/(mol·min)。在离子液体为催化剂、三乙胺为敷酸剂条件下,酯化反应是二级不可逆反应,反应活化能33.9 kJ/mol,指前因子5.05×103L/(mol·min)。     

Reaction kinetics of dicyclohexylmethane‐4,4′‐diisocyanate with 1‐ and 2‐butanol: A model study for polyurethane formation

Reactions of dicyclohexylmethane‐4,4′‐diisocyanate (H₁₂MDI) with 1‐ or 2‐butanol in N,N‐dimethylformamide using dibutyltin dilaurate (DBTDL), stannous octoate (SnOct), or triethylamine (TEA) as catalyst were conducted in stirred reactors at 40°C. Reactor contents were circulated through an external loop containing a temperature‐controlled FTIR transmission cell; reaction progress was monitored by observing decrease in height of the isocyanate peak at 2266 cm⁻¹. Catalyzed reactions were second order as indicated by linear 1/[NCO] plots; uncatalyzed reactions yielded nonlinear plots. In all cases, the reaction with a primary alcohol was faster than that with a secondary alcohol. DBTDL dramatically increased the reaction rate with both primary and secondary alcohols. For [DBTDL] = 5.3 × 10⁻⁵ mol/L (300 ppm Sn) the second‐order rate constant, k, was 5.9 × 10⁻⁴ (primary OH) and 1.8 × 10⁻⁴ L/(mol s) (secondary OH); for both alcohols, this represents an increase in initial reaction rate on the order of 2 × 10¹ when compared with the uncatalyzed reactions. The second‐order rate constant was observed to increase linearly with DBTDL concentration in the range 100–700 ppm Sn. SnOct and TEA showed little to no catalytic activity with the primary alcohol and only a slight increase in reaction rate with the secondary alcohol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

Kinetic evaluation of tin‐POMS catalyst for urethane reactions

We report the activity for a new tin‐polyhedral oligomeric metal silsesquioxane (POMS) catalyst in 1‐butanol and 2‐butanol model reactions with 4,4′‐methylenebis(cyclohexylisocyanate) (H₁₂MDI) in toluene and N,N‐dimethylformamide (DMF). Kinetic rate constants for varying levels of tin‐POMS ranging between 100 ppm and 1000 ppm tin are reported. We observed urethane reactions in toluene to follow second order reaction kinetics, whereas similar reactions in DMF followed first order reaction kinetics. We determined tin‐POMS is an efficient catalyst system for urethane reactions and found the new catalyst to be easy to handle, soluble, and very effective for catalyzing urethane reactions. By direct comparison of a model reaction between tin‐POMS and dibutyltin dilaurate (DBTDL), tin‐POMS was found to be quite similar to DBTDL for urethane catalytic activity. In addition, we show the efficacy for tin‐POMS to be an excellent polyurethane reaction catalyst through a model reaction of H12MDI with 2000 g/mol poly(ε‐caprolactone) diol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Development of cell morphologies in manufacturing flexible polyurethane urea foams as sound absorption materials

The effect of water content and a type of gelling catalysts [Triethylenediamine (DABCO) and dibutyltin dilaurate (DBTDL)] on chemical and physical structures of the flexible polyurethane foams (the flexible PUFs) is explored by a fourier transform infrared spectroscopy with attenuated total reflectance and a scanning electron microscope techniques. The amount of water usage plays a crucial role in controlling the sizes of cavities and pores of the PUFs. From the two gelling catalysts, the DBTDL reduces the rate of urea formation and NCO (isocyanate functional group) conversion due to the reduced molecular activity from the sterically hindered catalyst structure, comparing with the DABCO catalyst case. Strong gelling effect of the DBTDL can prevent the coalescence of the cavities and thus produce high number of well dispersed pores, but poor cavity and pore morphologies are observed in case of the fast reactions between isocyanate and water with the DABCO catalyst. The size uncertainties of cavity and pores with DBTDL catalyst are relatively smaller than with DABCO catalyst. In the sound absorption characteristics, uniformly distributed cavities and pores show better efficiency than the non-uniform cases.     

Synthesis of poly(urea–formaldehyde) encapsulated dibutyltin dilaurate through the self-catalysis of core materials

Polymeric microcapsules (MCs) filled with catalyst can be controlled to release the catalyst to initiate the polymerization reaction. In the present work, poly(urea–formaldehyde) (PUF) MCs filled with DBTDL (PUF/DBTDL MCs) were prepared using urea (U) and formaldehyde (F) as the wall shell materials by in situ polymerization. The U–F resins could easily polymerize in the presence of the core material DBTDL to produce PUF polymers, then they deposited on the surface of the DBTDL droplets, forming PUF/DBTDL MCs. The decomposition temperature (T _d) at 5 % weight loss of PUF/DBTDL MCs was about 245 °C. The application of PUF/DBTDL MCs to cyanate ester resins preliminarily showed the reaction control capability of the MCs due to the slow release of DBTDL through the wall shell.     

Influence of the catalyst on the kinetics of a RIM formulation

The influence of three different catalysts [triethylendiamine (TD), stannous octoate (SO), and dibutylindilaurate (DBTDL)] and their blends (TD + SO and TD + DBTDL) on the kinetics of a RIM formulation, based on a high functionality polyether–polyol and a polymeric MDI, has been studied using the adiabatic temperature rise method and Fourier transform infrared spectroscopy. The synergism observed in the DBTDL/TD systems is explained by means of complex formation between the amine-based and metal-based catalysts. Infrared spectroscopy data support this complex formation. The SO/TD systems do not exhibit synergetic behaviour, being the reaction rate controlled by the metal catalyst which complexes the isocyanate group.     

Application of tin(IV) porphyrin complexes as novel catalysts for the synthesis of new copolyurethanes with cyclopeptide moiety

New electron deficient tin(IV) porphyrins were used as efficient catalysts for the reaction of 4,4′‐methylene‐bis‐(4‐phenylisocyanate) (MDI), with L‐leucine anhydride cyclodipeptide (LAC) and polyethyleneglycol‐400 (PEG‐400) and the results were compared with those obtained in the presence of a commercial catalyst, dibutyltin dilaurate (DBTDL). Molar ratio of catalysts to MDI, polymerization reaction time, viscosity, and yield of the resulting poly(ether‐urethane‐urea)s (PEUU) were compared in the presence of different catalysts. The rate of N?C?O conversion in the presence of each catalysts under the same reaction conditions was also compared and followed by FT‐IR N?C?O absorption band. FT‐IR, GPC, and viscosity studies have shown that tin(IV) porphyrins afford higher viscosity and reaction progress. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

KINETICS OF FAST URETHANE POLYMERIZATION IN REACTION INJECTION MOULDING

The kinetics of dibutyltin dilaurate(DBTDL) catalyzed fast urethane polymerization of polyoxypropylenepolyoxyethlene triol with uretonimine modified 4, 4'-diphenylmethane diisocyanate (l-MDI) in RIM was studied by infrared spectroscopy and adiabatic temperature rise. For isothermal reaction, the overall reaction order was found to change from 3/2 to 2 with increasing reaction temperature. For adiabatic reaction, the overall reaction order was found to change from 3/2 to 2 with increasing catalyst concentration and hard segment content. The phase separation occured during the RIM urethane polymerization leads to a deviation of the kinetics relationships for higher conversion from those for lower.     

Low‐temperature cure high‐performance cyanate ester resins/microencapsulated catalyst systems

The encapsulated catalyst can be released under stimulation conditions to control the polymerization reaction. In this study, poly(urea‐formaldehyde) (PUF) microcapsules (MCs) filled with dibutyltin dilaurate (DBTDL) catalyst (PUF/DBTDL MCs) were applied to bisphenol A dicyanate ester (BADCy) resins to develop a novel low temperature cure high performance BADCy/MCs systems. The effect of PUF/DBTDL MCs on the reactivity of BADCy was investigated. The mechanical property, the thermal property, the water uptake, and the dielectric property of cured BADCy/MCs resin systems were discussed in detail. Results indicate that roughly varying the content of the encapsulated DBTDL can easily and safely adjust the polymerization temperature. The BADCy systems with proper content of MCs cured at low temperature show excellent mechanical property, good thermal property, low water uptake, and low dielectric property. When the content of MCs is 0.125 wt%, the cured BADCy/MCs system has the optimal integrated properties owing to the formation of more uniform crosslinked structure and high conversion of cyanate ester (? OCN) groups resulting from the slow release of DBTDL catalyst through the wall shell under heating condition. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Microwave‐assisted and classical heating polycondensation reaction of bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine with diisocyanates as a new method for preparation of optically active poly(amide imide)s

A new class of optically active poly(amide imide)s were synthesized via direct polycondensation reaction of diisocyanates with a chiral diacid monomer. The step‐growth polymerization reactions of monomer bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine (BPABTL) (5) as a diacid monomer with 4,4′‐methylene bis(4‐phenylisocyanate) (MDI) (6) was performed under microwave irradiation, solution polymerization under gradual heating and reflux condition in the presence of pyridine (Py), dibuthyltin dilurate (DBTDL), and triethylamine (TEA) as a catalyst and without a catalyst, respectively. The optimized polymerization conditions according to solvent and catalyst for each method were performed with tolylene‐2,4‐diisocyanate (TDI) (7), hexamethylene diisocyanate (HDI) (8), and isophorone diisocyanate (IPDI) (9) to produce optically active poly(amide imide)s by the diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.09–1.10 dL/g. These polymers are optically active, thermally stable, and soluble in amide type solvents. All of the above polymers were fully characterized by IR spectroscopy, ¹H NMR spectroscopy, elemental analyses, specific rotation, and thermal analyses methods. Some structural characterization and physical properties of this new optically active poly(amide imide)s are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1647–1659, 2004