Flat sheet membranes were obtained by the wet cast method from the system polyethersulphone-dimethylacetamide-non-solvent additive-water. The effects of propionic acid, propionic acid anhydride, butyric acid and butyric acid anhydride as individual additives in a polymer solution, in relation to phase separation process and membrane cross-section structure, were investigated. SEM analyses showed that a non-solvent additive significantly affected the structure of the membrane sublayer. The addition of non-solvent additives in a polymer solution inhibited the growth of macrovoids, which resulted in improved mechanical characteristics of the obtained membranes. The water fluxes through the membranes prepared from a polymer solution with a selected additive had lower values than those of a membrane prepared from a polymer solution without an additive. 22 refs. (Full translation of Vys.Soed.A, 47, No.7, 2005, p.1196-202)

Overall and local deflections of a single span of a continuous sandwich plate were evaluated under local contacts with a rigid indenter, at relative velocities of 10 and 20 m/s, to simulate the effect of impacts that can be applied to ship sandwich structures by floating objects or moorings. The sandwich plate was composed of laminated carbon-vinyl ester facesheets and a H100 PVC foam core, possibly separated from the impacted facesheet by a stiff and ductile PU interlayer. Particular attention was paid to the evaluation of contact forces and deflections of the facesheet and foam core interface and to the membrane or in-plane strains in the facesheet at the contact point. These parameters are well-known potential sources of damage, causing core crushing and facesheet delamination and/or penetration. 13 refs.

Several monofunctional initiators, such as s-butyllithium, 1,1-diphenyl-4-methylpentyl lithium, benzyl potassium, triphenylmethyl sodium and benzyl sodium, were evaluated for the polymerisation of n-hexyl isocyanate(HIC) in THF at -98C. The polymerisations were conducted either without or with additives, such as lithium tetraphenylborate, sodium tetraphenylborate and crown ether 18C6. The products were characterised by size exclusion chromatography, membrane osmometry and PMR spectroscopy. The best results for polymerisation yield, MWD and agreement between the stoichiometric and the experimentally-observed molec.wt. were obtained with the initiating system benzyl sodium/sodium tetraphenylborate in a molar ratio of 1/10. This initiating system was used for the synthesis of well-defined block copolymers of HIC with styrene or isoprene. 35 refs.

A generally-applicable method for determination of high oxygen permeabilities (up to Dk of about 800 barrers) of water-immersed membranes was developed, together with simple equipment. A theory for the methodology was also examined, giving particular attention to the boundary layer effect and the edge effect. The practical applicability of the technique was demonstrated by preparing and using highly oxygen permeable water-logged membranes, such as polydimethylsiloxane(PDMS) and polysiloxane copolymers of importance in medicine. From the measurements, the Dks of PDMS, dimethylsiloxane(0.80)-diethylsiloxane(0.20) copolymer and dimethylsiloxane(0.84)-diphenylsiloxane(0.16) copolymer were 792 + or -26, 505 + or -10 and 249 + or -10 barrers, respectively. The oxygen permeabilities of polysiloxanes were evidently markedly reduced by substituting the -OSiMe2- repeat unit with the structurally similar -OSiEt2- and -OSiPh2- repeats. 22 refs.

The factors governing the morphology and diameter of ultrafine zein fibres prepared by electrospinning from aqueous ethanol solution (80 wt%) were studied by SEM. Fibres of diameters around 700 nm were obtained. Their morphology was affected by electric field and zein concentration. At 18 wt% zein, wrinkled beads bridged by nanofibres were formed but at 21 wt% zein and 15 kV, ribbon-like fibres were obtained. When the field was increased to 30 kV, fibres could be produced from concentrations down to 18 wt%. 25 refs.

Blends of 84% deacetylated chitosan and sodium alginate, which spontaneously form polyion complexes, were converted to membranes for potential use in direct methanol fuel cells (DMFC). The membranes were characterised by FTIR, X-ray diffraction, DSC, TGA, tensile testing, ion exchange capacity, water and methanol absorption, methanol permeability and proton conductivity. The high water permselectivity of alginate improved the properties of chitosan, giving good conductivity and better mechanical and thermal properties. The low methanol permeability was 16.7% that of Nafion 117. Moderate water absorption of the blend imparted good proton conductivity (0.042 S/cm) without affecting the mechanical properties. The lower permeability, low cost and simple preparation procedure suggest that they will be suitable for use in DMFCs. 43 refs.

Interaction mainly by hydrogen bonding was observed when a new proton conducting material based on a polyimide and phosphoric acid composite was characterised by Fourier transform infrared spectroscopy. Preparation of the material was discussed and surface morphology of membranes prepared from the material was examined by environmental scanning electron microscopy. Proton conductivity increased with increasing phosphoric acid content, with the hydrogen bonding playing an important part. Permeability to methanol of membranes was examined, and this increased with temperature but decreased with increased methanol concentration. 25 refs.

Benzoylation to a high degree of polyphenylene oxide (PPO) was carried out, using Friedel Crafts reactions, with various aromatic acid chlorides having hydrogen, bromine, chlorine or methyl groups in the para- position. Polymers were characterised using Fourier transform infrared and nuclear magnetic resonance spectroscopies, thermogravimetric analysis, differential scanning calorimetry and wide angle X-ray scattering. Dense films of the polymer were cast and pure gas permeability to helium, argon, nitrogen, oxygen, carbon dioxide and methane was evaluated by a variable volume method. Benzoylation of PPO resulted in reductions in gas permeability in all cases, but selectivity was increased to some gases and reduced to others. Trends in permeability were discussed and explained in terms of molecular structure. 23 refs.

Surface modification of polytetrafluoroethylene membranes by an acetylene/nitrogen plasma treatment was investigated using attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle measurements. Hydrophilicity increased, and surface pore size decreased with nitrogen content of the plasma gas, radio frequency power and treatment time. A significant decrease in water contact angle was observed. 17 refs.

The preparation of novel proton conducting ionomers by attaching pendant sulphonated aromatic side chains to polysulphone is reported. The degree of substitution can be effectively controlled by the degree of lithiation in the first step of the synthesis as the second step proceeds with full conversion. This, in combination with the wide range of nucleophiles available for the second reaction step makes the method a versatile approach to the design of new ionomers. 21 refs.