Synthesis of isophorone diisocyanate (IPDI) based waterborne polyurethanes: Comparison between zirconium and tin catalysts in the polymerization process

In this work, a comparative study of the catalytic activity of tin and zirconium compounds in the polymerization of isophorone diisocyanate (IPDI) based waterborne polyurethanes is presented. Zirconium acetyl acetonate is much less toxic than the commonly used dibutyltin diacetate but it is deactivated in the presence of acid groups. Nevertheless, acid groups are commonly used in the synthesis of waterborne polyurethanes and therefore these groups have to be neutralized in advance for carrying out the synthesis using the zirconium catalyst. Moreover, FTIR and ¹³C NMR results have shown that in the presence of triethyl amine and tin catalyst, the secondary isocyanate group is more reactive than the primary group, while using the zirconium catalyst, the two isocyanate groups show the same reactivity.     

Gold based catalysts on ceria and ceria-alumina for WGS reaction (WGS Gold catalysts)

Gold catalysts supported on ceria-alumina have been studied in WGS reaction. A high and stable activity was established for the catalysts supported on ceria-alumina, prepared by mechanochemical activation in comparison to the corresponding samples, where ceria-alumina support was prepared by coprecipitation. The catalysts were characterized by means of XRD, TPR, Raman and XPS spectroscopy. A correlation between WGS activity and the redox activity was found. On the basis of the results obtained a model of the reaction mechanism and of active sites was proposed.     

Hierarchical structure and properties of rigid PVC foam crosslinked by the reaction between anhydride and diisocyanate

Rigid crosslinked poly(vinyl chloride) (c‐PVC) foams by forming semi‐interpenetrating network (SIPN) structure via the reaction of phthalic anhydride (PA) and diisocyanate were prepared. The influence of PA on hierarchical structure and mechanical properties of c‐PVC foam was studied. The Fourier transform infrared spectrometer results showed that the presence of PA resulted in the formation of imide structure in the SIPN of obtained c‐PVC foams, which introduced a structural defect of SIPN. Thus, the residue (gel) from tetrahydrofuran extraction of the foams decreased with the increase of PA content. Dynamic thermal analysis showed the presence of three aggregation state structures in the c‐PVC foams, depending on the loading of PA. The addition of PA in the formulations affected cellular structure and mechanical properties of the obtained foams. Furthermore, the influence of chemical environment of anhydride compounds on the formation of imide structure in the crosslinking network of c‐PVC foams was discussed. A strategy for reducing defect of crosslinking network and improving mechanical properties was put forward. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46141.     

Kinetics of reaction of C21 cycloaliphatic dicarboxylic acid and ethylenediamine

Kinetic studies were carried out on the reaction between ethylenediamine and C₂₁ cycloaliphatic dicarboxylic acid, prepared from dehydrated castor oil fatty acids and acrylic acid, in melt phase. The reaction was performed at six different temperatures ranging from 210 to 260°C and followed by determining the acid value of the product. The polyamidation reaction was found to follow an overall third order kinetics with an activation energy of 15.5 kcal/g mol.     

MDI的生产及市场

介绍了国内外MDI的生产、应用及市场情况 ,并对影响MDI市场的关键因素进行了分析     

Pt-CS负载物催化硅氢加成反应的研究

通过壳聚糖负载铂制备了一种硅氢加成反应用多相催化剂(Pt-CS);并采用聚醚F-6与低含氢硅油的硅氢加成反应体系,比较了不同铂含量的Pt-CS负载物与氯铂酸异丙醇溶液的催化活性。结果表明,当Pt-CS负载物中的铂含量与均相催化剂相当时,其催化活性不如均相催化剂;Pt-CS负载物中的铂含量约为均相催化剂的12倍时,反应达到平衡所需的时间比采用均相催化剂时缩短了1 h;其催化活性与均相催化剂接近,重复使用13次后,催化活性没有明显下降。     

Revisiting the concepts of competition between reaction and diffusion in poisoned catalysts

The competition between diffusion and first‐order irreversible reaction in poisoned catalysts is revisited. Two cases are considered for isothermal slab catalysts: uniform and shell‐progressive (or pore‐mouth) poisoning. Analytical concentration profiles are derived, and the implications on catalyst performance are evaluated in different regimes (chemical‐ or diffusion‐controlled) for different levels of poisoning. It was found that depending on the poisoning mechanism, the activity decay can be more or less pronounced. Being of particular concern is the pore‐mouth poisoning at high Thiele modulus, conditions under which catalyst performance is drastically affected. The reagent concentration profiles allowed the explanation of the phenomena occurring at the particle scale, in particular the effectiveness factors, observed reaction rates, and poisoning factors' dependence on the Thiele modulus and fraction of the poisoned catalyst; it was found that such relationships are dependent on the mechanism of deactivation. © 2012 Canadian Society for Chemical Engineering     

Novel nucleophilic/basic and acidic organocatalysts for reaction between poorly reactive diisocyanate and diols

Original basic or acidic organic compounds derived from guanidine or phenyl phosphonic acid were specifically designed and tested as new catalysts for the bulk synthesis of polyurethane prepolymers from a precursor system with particularly low reactivity (secondary alcohol + aliphatic isocyanate at low temperature). Both families showed interesting catalytic activities at 60–80 °C, but must nevertheless be used in much higher amounts (1 mol%, i.e. between 0.15 and 0.50 wt%) than traditional metal-based catalysts. The efficiency of guanidine derivatives seems to be related to their nucleophilicity, whereas that of phosphonic acid derivatives depends on their acidity. However, the solubility of the considered species in the reactive medium also plays a major role. The water/alcohol selectivity of the catalysts, especially at room temperature, was then examined as an additional criterion. Guanidines are not selective and favor the reaction of isocyanate groups with water as much as that with alcohols. Phenyl phosphonic acid derivatives are more selective, and particularly pentafluorophenyl phosphonic acid displays a remarkable catalytic activity together with an acceptable selectivity and could represent an interesting and safer alternative to toxic tin and mercury derivatives for many industrial polyurethanes.     

Kinetic study of the reaction between hydroxyl-terminated polybutadiene and isophorone diisocyanate in bulk by quantitative FTIR spectroscopy

A kinetic study of the reaction between a hydroxyl-terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI) was carried out in the bulk state by using quantitative Fourier transform infrared (FTIR) spectroscopy. The reaction is shown to obey a second-order rate law, being first order in both the HTPB and IPDI concentrations. The activation parameters obtained from the evaluation of kinetic data are ΔH‡ = 41.1 ± 0.4 kJ mol, ΔS‡ = −198 ± 2 J K⁻¹ mol⁻¹ and E_a = 43.8 ± 0.4 kJ mol⁻¹, which are quite different from the solution values. However, they are in agreement with the results obtained on propellants by torsional braid measurements. The large negative value of the activation entropy is indicative of an associative mechanism, which is in accord with the second-order rate law for the polyurethane formation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1979–1983, 1997     

生物质油催化加氢脱氧（HDO）反应机理及催化剂研究进展

对近年来生物质油催化加氢脱氧催化剂的制备、催化性能和反应机理的研究进展进行了整理总结。重点对贵金属催化剂、过渡金属催化剂和硫、氮、碳、磷等金属化合物催化剂的制备方法、催化性能和作用机理进行了概述,并分析了加氢脱氧催化剂的失活原因,同时提出生物质油加氢脱氧反应催化剂的未来发展方向：三维有序大孔（3DOM）钙钛矿氧化物的应用可能在提高催化剂的催化性能有作用。     

乙酸乙烯合成钯基催化剂及反应机理研究进展

概述了近年来国内外乙烯气相法合成乙酸乙烯（VAc）钯基催化剂表面结构和表面反应、组分金的作用及VAc合成反应机理的实验及理论研究进展,着重介绍了Pd-Au催化剂及其催化反应的研究。对比分析了不同研究方法得到的共性研究成果及存在的问题。单晶钯基催化剂表面原位反应及表征技术等实验研究结合模型催化剂上分子模拟等理论研究,能够很大程度上克服因催化剂合成难以实现结构的微观可控而导致的无法清晰认识其构效关系的局限,将成为该领域未来研究的主要趋势。     

The reaction of glass fiber with diisocyanate and its application

The synthesis of reactive glass fiber having isocyanate groups were tried by reacting silanol groups on the surface of glass fiber with diisocyanate compounds. The effect of solvent, influence of the structure of diisocyanate, and effect of amine catalyst were examined, and results that the reactivity increased with increasing the polarity of solvent, when aromatic diisocyanate was used, and with increasing the basicity of amine catalyst were obtained. Further, glass fiber having isocyanate groups was addition-reacted with diol, and diol added glass fiber was synthesized.     

Behaviour of Ag,Cu and Ag-Cu catalysts in the gasification reaction of a lignite char in air. Effect of SO2 on these catalysts

The effect of several Ag, Cu and bimetallic Ag-Cu catalysts have been studied on the gasification reaction of a lignite char in dry air. In the bimetallic catalysts, the existence of alloy particles have been detected by SEM. The reactivity of the char with the bimetallic catalysts is higher than the addition of those obtained for the pure metals with the same metal amounts. The effect of SO₂ is to reduce the reactivity of the char in the catalysed reactions. An explanation for this phenomenon is given. The presence of Cu in Ag increases the resistance of some bimetallic catalysts to poisoning with SO₂.     

Selectivity of isophorone diisocyanate in the urethane reaction influence of temperature, catalysis, and reaction partners

In a model study of the selectivity of isophorone diisocyanate (IPDI) in the urethane reaction, the influence of the type of catalyst, temperature, and type of OH-group was demonstrated using primary and secondary butanol as reaction partners. In particular, the choice of catalyst has a dramatic effect on the composition of the final product mixture. The most important conclusions of the model study were confirmed in NCO-prepolymer synthesis. GFB LR-AT, D-45764 Marl, Germany. R. LOM?LDER received a Ph.D. Degree in Chemistry from the University of Münster, Germany. Dr. Lom?lder joined the research and development team for the coatings raw materials division of Hüls AG, Marl, Germany in 1989, where he worked with polyurethanes. Since 1992, Dr. Lom?lder has been working with IPDI and its derivatives in Hüls AG’s technical services department for polyurethane raw materials. FRIEDRICH PLOGMANN joined Veba Chemie’s technical services laboratory for polyurethane raw materials in 1976. In 1979, when Veba’s chemical activities were transferred to Hüls AG, Mr. Plogmann continued to work in the laboratory. PETER SPEIER joined the research and development department of Hüls AG in Marl, Germany in 1960, initially working with polybutadiene resins and later with saturated polyester resins. Since 1985, Mr. Speier has been working with polyurethanes raw materials in Hüls AG’s technical service laboratories in Marl.     

Effect of diisocyanate structures on the properties of liquid crystalline polyurethanes

Thermotropic liquid crystalline polyurethanes (LCPUs) were synthesized through the polyaddition reaction of 2,4‐toluene diisocyanate (2,4‐TDI), 4,4′‐diphenylmethane diisocyanate (MDI), or o‐toluidine diisocyanate (ODI) with 4,4′‐bis(6‐hydroxyhexoxy)biphenyl, and the effect of the structures of the diisocyanates on the properties of LCPUs were investigated. Intrinsic viscosities of the polymers were in the range of 0.23–0.30 dL/g. Mesomorphic behavior of the polyurethanes were investigated by differential scanning calorimetry, polarized optical microscopy, and wide‐angle X‐ray scattering. Different mesomorphic behaviors were observed according to the different structural characteristics of diisocyanates. Polyurethanes employing 2,4‐TDI and MDI exhibited monotropic behaviors, while that with ODI showed enantiotropic behavior. POLYM. ENG. SCI., 47:439–446, 2007. © 2007 Society of Plastics Engineers.     

Formation of poly(urethane-isocyanurate) networks from poly(oxypropylene)diols and diisocyanate

Summary Reaction conditions leading to the smallest amount of unreacted isocyanate groups for the preparation of poly(urethane-isocyanurate) networks based on 2,4-tolylene diisocyanate and ,-dihydroxypoly(oxypropylene) (M _n = 425–) were found. A tertiary amine, POLYCAT^* 41, was used as a cyclotrimerization catalyst. The networks were prepared by prepolymer two-stage technique. The content of isocyanate groups in the prepolymers and networks was determined by potentiometric titration. Model reactions in 1,4-dioxane were used for the estimation of possible reaction intermediates during poly(urethane-isocyanurate) synthesis.     

A reaction between CO-adsorbed sulfur and butadiene on the Pt(111) surface

The desorption of methylthiol and propylthiol has been observed, induced by the co-adsorption of hydrogen, butadiene and sulfur on Pt(111). This phenomenon goes with increase of the total amount of sulfur adsorbed on the surface by a factor of 20%.     

Toughening of cycloaliphatic epoxy resins by poly(ethylene phthalate) and related copolyesters

Poly(ethylene phthalate) (PEP) and poly(ethylene phthalate–co‐ethylene terephthalate) were used to improve the brittleness of the cycloaliphatic epoxy resin 3,4‐epoxycyclohexylmethyl 3,4‐epoxycyclohexane carboxylate (Celoxide 2021?), cured with methyl hexahydrophthalic anhydride. The aromatic polyesters used were soluble in the epoxy resin without solvents and effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20 wt % PEP (MW, 7400) led to a 130% increase in the fracture toughness (K_IC) of the cured resin with no loss of mechanical and thermal properties. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 388–399, 2002; DOI 10.1002/app.10363     

The role of Rh on Pt-based catalysts: structure sensitive NO + H2 reaction on Pt(110) and Pt(100) and structure insensitive reaction on Rh/Pt(110) and Rh/Pt(100)

The catalytic activity of the Pt(110) surface for the reaction of NO + H₂ was much less than that of the Pt(100) surface. However, the catalytic activity of the Rh deposited Pt(1l0) surface was almost equal to that of the Rh deposited Pt(100) surface. That is, the catalytic reaction of NO + H₂ on Pt(110) and Pt(100) surfaces is highly structure sensitive, but it changes to structure insensitive by the deposition of Rh atoms. These results are rationalized by formation of an active overlayer on the Pt(110) and Pt(100) surfaces, which is very analogous to the Rh-O/Pt-layer formed on Rh/Pt(100), Pt/Rh(100) and Pt-Rh(100) alloy surfaces during catalysis. The formation of the common overlayer of Rh-O/Pt-layer during catalysis is responsible for the structure insensitive catalysis of Rh deposited Pt-based catalysts, which is an important role of Rh in a three way catalyst.     

The kinetics of the polymerization reaction of toluene diisocyanate with HTPB prepolymer

The uncatalysed and catalysed polymerization of a hydroxyl-terminated polybutadiene with toluene diisocyanate has been studied in toluene solution at four different temperatures. The rate constants (k₁, k₂) and the activation parameters (Ea₁, Ea₂, ΔS₁^?, ΔS₂^?) for the isocyanate groups in the 4 and 2 positions were calculated. It was found that the catalysts enhance the reactivity of the 2 position isocyanate group rather than the 4 position isocyanate group. It was also found that diethylcyclohexylamine has higher selectivity than dibutyltin dilaurate to enhance the reactivity of the isocyanate group in the 2 position. The effect of solvent has also been studied. The reactivity decreased in the following order; benzene = toluene > chlorobenzene > dioxane > nitrobenzene. © 1993 John Wiley & Sons, Inc.