Variational principles and membrane finite elements with drilling rotations for geometrically non-linear elasticity

Variational principles for geometrically non-linear continuum with independent rotation field are constructed based on the polar factorization theorem. Their regularized forms are next discussed suitable for the finite element implementation. The considerations are specialized to a two-dimensional membrane problem, and standard isoparametric interpolations are used in order to construct membrane elements with drilling rotations. The elements are evaluated on a set of problems in geometrically non-linear elastostatics.     

Poly(acrylic acid‐co‐vinylsulfonic acid): Synthesis,characterization, and properties as polychelatogen

The synthesis of the water‐soluble poly(acrylic acid‐co‐vinylsulfonic acid) at different feed monomer ratios, while maintaining constant the total number of mol, was carried out by radical polymerization. The copolymers were characterized by FTIR and ¹H‐NMR spectroscopies. The copolymer composition was determined by its sulfur content and by potentiometric titration. The metal ion binding properties for Ni(II) and Cu(II) in the aqueous phase were studied using the liquid‐phase polymer‐based retention (LPR) technique for two values of ionic strength. For comparison, the retention properties of both homopolymers were included. The complexing ability of the polymer was determined by the relative amount of carboxylic acid groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1698–1704, 2003     

The Role of Permeability and Related Properties in the Design of Synthetic Hydrogels for Biomedical Applications

Synthetic hydrogels are a versatile range of materials which are of value in several biomedical applications, particularly those where permeability is important. Because the equilibrium water content of the gel governs permeability processes and has a marked influence on other important properties, the permeability requirements of a material often influence other aspects of its behaviour. The design of hydrogels for contact lenses demands an understanding of these interrelationships and thus provides a valuable basis for extending hydrogel design to other applications.     

Effects of the diluent mixing ratio and conditions of the thermally induced phase-separation process on the pore size of microporous polyethylene membranes

Microporous polyethylene (PE) membranes having a controlled pore size were produced via the thermally induced phase separation process by manipulation of the phase boundary of the PE/diluent blend and process conditions. The phase boundary of the PE blend, caused by upper critical solution temperature type phase behavior, was controlled by the use of a diluent mixture, that is, an isoparaffin/soybean oil mixture. The phase-separation temperature of the PE/soybean oil blend was always higher than that of the PE/isoparaffin blend. In PE/(isoparaffin/soybean oil) ternary blends, the phase-separation temperature of the ternary blend rapidly increased with increasing soybean oil content in the diluent mixture. Furthermore, the phase-separation temperatures of ternary blends were always higher than that of the PE/soybean oil blend, regardless of the blend compositions, when the diluent mixture contained more than 50 wt % soybean oil. The observed phase behavior of the ternary blends was analyzed with interaction energy densities calculated with the Flory–Huggins theory and ternary stability conditions. The growth of droplets caused by both coalescence and the Oswald ripening process was observed after the onset of phase separation. As the blends became less stable, the droplet growth rate increased, and larger equilibrium droplets were formed. Microporous membranes with the desired pore structure could be prepared by control of the phase boundary and the variation of processing conditions such as the quenching depth, annealing time, and cooling rate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A new ambient temperature crosslinking system for emulsion polymers

A new system is proposed for the crosslinking of urea-groups dispersions with dialdehydes at ambient temperature. Film properties are comparable with those achieved by the best standard crosslinking reactions.     

油水分离膜的研究新进展

对含油污水处理中应用日益广泛的油水膜分离技术的研究进展作了综述，论题如下。引言：膜分离方法，优点和分类；油水膜分离机理：膜分离，膜分相及传质机理；油水分离膜：特性，聚合物疏水膜和亲水膜，陶瓷膜和各种无机氧化物膜，有机膜的表面亲水化改性；影响分离效果的主要因素：操作压力，操作时间，污水含油量，膜厚度，温度，膜表面流体流速，膜制作方法，电解质和表面活性剂，表面粗糙度。参39。     

Effects of mixed diluent compositions on poly(vinylidene fluoride) membrane morphology in a thermally induced phase‐separation process

The effects of a mixed diluent (MD) composition [dibutyl phthalate/dioctyl phthalate (DOP)] on poly (vinylidene fluoride) (PVDF) membrane morphology were investigated with scanning electron microscopy, and a bicontinuous morphology could be obtained with MD in a thermally induced phase‐separation process. The reasons for the morphology formation were explained according to the effect of MD on the phase diagrams. In addition, the effects of the PVDF concentration on the membrane morphology were examined. For the system with less DOP, the large spherulite morphology was obvious under all investigated concentrations, whereas no large spherulite structure existed in the membrane as the DOP content increased to concentrations other than 20%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymeric membranes for lipase immobilization

Lipase triacylglycerol acylhydrolase, (E.C. 3.1.1.3) is an enzyme that is fully active on aggregated substrates and practically inactive on monodisperse systems. A lipase immobilized on polymeric membranes has been applied for sunflower oil hydrolysis. The influence of membrane properties on enzyme activity is studied. Membranes made of poly(vinyl chloride), collagen, cellulose acetate and polytetrafluoroethylene were used for adsorption of lipase. The porosity and hydrophobicity of membranes did not influence the lipase activity. The difference of the work of adhesion for the water/membrane system and oil/membrane system reflected the activity data, while work of adhesion for water or oil (done separately) did not. For oil hydrolysis to occur on the membrane surface, accessibility of two liquid phases is important, and the lower the difference of work of adhesion between water and oil, the greater the activity of immobilized lipase.     

分子筛炭膜的形态结构研究

由扫描电镜照片可以看出，分子筛炭膜由一种致密结构和一种由粒子堆积而成的多孔结构所组成，在这些膜结构中，有可能存在两种类型的孔：微孔和大孔。讨论了孔系统、膜的形态结构、和结构缺陷的形成，以及它对膜特性的影响。