Novel polyurethane polyols for waterborne and high solids coatings

Recently developed oligomeric β-hydroxyalkyl urethane polyols are finding application as modifiers and crosslinkers for waterborne and high solids coatings. In waterborne coatings, urethane polyols can be used as modifiers for acrylic, polyester or alkyd melamine resin crosslinked coatings to replace the cosolvent. In high solids coatings, polyurethane polyols are being employed to raise the application solids, increase film hardness and water resistance, and exterior durability.

There are also applications for polyurethane diols as resin intermediates and in the preparation of blocked isocyanate crosslinkers. β-Hydroxyalkyl urethane diol or polyols can be prepared by an isocyanate reaction with a diol, such as 1,2-propylene glycol, but also by non-isocyanate processes. The non-isocyanate routes to urethanes can utilize carbon monoxide, carbon dioxide, urea or organic carbonates as a carbonyl source for the carbamic acid ester.

It is possible to split these urethanes to the isocyanate, but interest has concentrated on using the urethane intermediates directly in coating applications without going through the isocyanate. The structures reported are bis-hydroxyalkyl urethane intermediates and derivatives of these compounds.     

A note on the aerodynamic diameter and the mobility of non-spherical aerosol particles

The aerodynamic diameter of a non-spherical aerosol particle is primarily related to the final settling velocity of the particle. The aerodynamic diameter is not obtained directly from mobility measurements by formally calculating a sphere diameter from the mobility equation for a spherical particle. Instead, a correction factor involving the dynamic shape factor of the non-spherical particle must be applied.     

Formation of α-Tocopherolquinone and α-Tocopherolquinone Epoxides in Plant Oil

The antioxidative activity of α-tocopherol in oil is necessary for the inhibition of lipid peroxidation. If no regeneration of antioxidants is possible in foods, oxidation products are formed to a measurable extent. The aim of this study was to investigate oxidation products of α-tocopherol in plant oil. The oxidation of α-tocopherol in plant oil leads to α-tocopherolquinone and to two epoxides (α-tocopherolquinone-2,3-epoxide, α-tocopherolquinone-5,6-epoxide). These three reaction products were identified and quantified in plant oil. The 2,3-epoxide is formed at lower temperatures (90°C) whereas at high temperatures (180–220°C) only the 5,6-epoxide appears. The kinetics show that the 5,6-epoxide is produced as long as α-tocopherol is present. With longer reaction times the concentration of the 5,6-epoxide starts to decrease. α-Tocopherolquinone is found at substantially lower concentrations.     

Unterscheidung von Palmölen und Palmöl-Fraktionen durch HPLC der Triglyceride

Analytical Characterisation of Palm Oil Fractions by HPLC of Triglycerides The increasing importance of palm oils and palm oil fractions in international trade makes it necessary to develop analytical criteria for the characterisation of these products. One problem is the correct identification of palm oleins, which are often difficult to distinguish from palm oils. These products frequently exhibit similar fatty acid by GLC and similar iodine values. The correct identification of palm stearins by GLC is comparatively more easy. Palm oleins and palm oils can be characterized by HPLC using conditions that permit not only the separation of triolein from less unsaturated triglycerides of the same carbon number, but also, at the same time, a separation of tripalmitin from triglycerides containing oleic acid. By establishing the peak area ratios for a number of selected triglycerides a clear differentiation between palm oils and palm oleins, as well as various other palm oil fractions and their mixtures is obtained.     

Einfluß der Produkteigenschaften auf die Trocknung

Influence of Product Properties on Drying. A number of items of information are required for selection and design of a drying process. Thermodynamic equilibrium as well as heat and mass transfer are the traditional prerequisites for describing the drying operation. In the development of a drying process further specific properties of the product must be known. These properties, such as chemical reactions or sticking properties, greatly reduce the number of possible drying processes. For this reason, the measurement of these properties plays an important role in the development of a drying process. Many of the bench scale tests in use do not have a physical basis, but have been developed empirically because the physical context is often unknown. Yet a number of physically well-defined methods are available for product characterization. In practical work a combination of empirical and scientifically defined methods is used.     

Kinetic studies of the pyrolysis of sewage sludge by tga and comparison with fluidized beds

The pyrolysis of sewage sludge was examined by thermogravimetric analysis using different heating rates, particle sizes and final temperatures. A semi-empirical model was developed with four global consecutive/competitive reactions to volatile and solid products including also a heat balance. This model was extrapolated to isothermal reactor conditions and compared to experimental data on fluidized bed pyrolysis. Depending on the particle size and reactor temperature, about 90% of the maximum conversion in a fluidized bed takes place under external heat transfer control, the rest under kinetic control. Incomplete conversion occurs at short particle residence times, which were calculated approximately by the model.     

载重轮胎及一体化系统的发展

近来 ,载重轮胎行业获得了令人瞩目的发展。常规载重轮胎的功能已从一个可独立使用的制品变为汽车设计中一个一体化的配件。目前对轮胎的期望甚至包括轮胎应是一种其性能适应各种外部条件和行驶环境的智能轮胎。作为行驶动力学范畴的一个结构元素 ,轮胎是不同汽车系统中的部件 ,它们影响到出行和运输的经济性和生态环保等方面 ,而且还对驾车乐趣起决定作用。大陆公司的变化是分阶段进行的 ,第 1阶段从轿车开始 ,这一阶段用了 1～ 2年时间 ,随后便是载重轮胎和一体化系统的发展。1　新品种的开发开发新产品目前是而且以后仍将是大陆公司的核…     

Stationäre Chemische Energieumwandlung als Herausforderungen für den Verfahrensingenieur

Meeting future energy demands with more efficient, lower emission, and safe energy technologies has top priority in the medium term. Consumer-friendly energy concepts, integrated into regional and supraregional energy supply structures, represent further elements. These will make important contributions to resource-conserving and environmentally compatible power supplies utilizing local energy sources including renewable resources. Supplying energy to large areas involves additional tasks, from compensation of large amounts of fluctuating energy to the transport of fluctuating energy to the transport of renewable energy over long distances. Solar dish, parabolic section, and tower power generating plant have considerable economic and CO₂-reduction potential in sunny countries, such as in the Mediterranean region, However, the costs of solar-thermal electricity generation have to be reduced by a factor of 1.5 to 2. Fuel cell systems can attain particular significance as efficient low-emission energy conversion systems in power plant and automative engineering once their technical and economic potential can be realized.     

A Complete and Highly Effective Mothproofing Agent Comprising a Pyrethroid and a Hexahydropyrimidine

Pyrethroids, considered as a general class of compounds, have been shown to provide effective protection from the larvae of the keratin-digesting insects Tineola bisselliella H., Tinea pellionella Linn., Hofmannophila pseudo-spretella Station and Attagenus piceus Oliv. The position regarding the susceptibility of the furniture carpet beetle to pyrethroids is less clear, however. It has been reported that both deltamethrin and permethrin are effective against Anthrenus flavipes Le Conte, whilst permethrin is also reported elsewhere to be effective against the same species. Results obtained in our laboratory, however, have indicated that pyrethroids may offer inadequate protection against Anthrenus vorax Waterh. [1, 2]. This latter species is identical to Anthrenus flavipes var. seminiveus Casey, a colour variety of Anthrenus flavipes Le Conte. The 1,3-disubstituted5-phenylcarbamoyl-2,4,6-trioxo- and 4,6-dioxo-2-thione-hexahydropyrimidine derivatives described in this paper exhibit a surprisingly high and selective toxicity to the Anthrenus species. Thus, a combination of an appropriate hexahydropyrimidine with a suitable pyrethroid, e.g. permethrin, provides complete control of a wide range of commonly encountered textile insect pests. The influence of substituents on the mothproofing activity is discussed.     

Flow shop batching and scheduling with sequence-dependent setup times

This paper addresses the flow shop batching and scheduling problem where sequence-dependent family setup times are present and the objective is to minimize makespan. We consider violating the group technology assumption by dividing product families into batches. In order to reduce setup times, inconsistent batches are formed on different machines, which lead to non-permutation schedules. To the best of our knowledge, this is the first time that the splitting of job families into inconsistent batches has been considered in a flow shop system. A tabu search algorithm is developed which contains several neighbourhood functions, double tabu lists and a multilevel diversification structure. Compared to the state-of-the-art meta-heuristics for this problem, the proposed tabu search algorithm achieves further improvement when the group scheduling assumption is dropped. Also, various experiments conducted on the benchmark problem instances confirm the benefits of batching. Therefore, it will be prudent for the practitioners to consider adopting inconsistent batches and non-permutation schedules to improve their operational efficiency within a reasonable amount of computational effort.