Water sorption of poly(vinyl alcohol)/ poly(diallyldimethylammonium chloride) interpenetrating polymer network hydrogels

Temperature‐responsive interpenetrating polymer network (IPN) hydrogels constructed with poly(vinyl alcohol) and poly(diallyldimethylammonium chloride) using the sequential IPN method were studied. The characteristics of IPN hydrogels were investigated using the dynamic vapor sorption system. IPN hydrogels exhibited a relatively high sorption ratio, 180–360% at room temperature. The sorption ratio of hydrogels depended on temperature. Diffusion coefficients were calculated according to the Fickian Law at several temperatures. The apparent activation energy was 5.43 kJ mol^?1, which corresponds to typical diffusion processes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1389–1392, 2003     

Torque Transmission Capabilities of Bonded Polygonal Lap Joints for Carbon Fiber Epoxy Composites

Although carbon fiber epoxy composite materials have excellent properties for structures, the joint in composite materials often reduces the efficiency of the composite structure because the joint is often the weakest area in the composite structure.

In this paper, the effects of the adhesive thickness and the adherend surface roughness on the static and fatigue strengths of adhesively-bonded tubular polygonal lap joints have been investigated by experimental methods. The dependencies of the static and fatigue strengths on the stacking sequences of the composite adherends were observed.

From the experimental investigations, it was found that the fatigue strength of the circular adhesively-bounded joints was quite dependent on the surface roughness of the adherends and that polygonal adhesively-bonded joints had better fatigue strength characteristics than circular adhesively-bonded joints.     

Effect of the nature and structure of pillared clays in the catalytic behaviour of supported manganese oxide

In the present work, the complete oxidation of acetone has been studied over a series of supported manganese oxide catalysts on the unpillared and the Al- and Zr-pillared forms of two natural clays, a montmorillonite and a saponite. A significant influence of the clay supports characteristics on the catalytic performance has been found. The following order of improving catalytic performance is established with respect to the pillars composition: Al-pillared clays < unpillared clays < Zr-pillared clays.     

Solar barometric distillation for seawater desalting part I: Basic layout and operational/technical features

The report presents an innovative solar barometric distillation technology for seawater desalting (SW-SBD) which has several attractive features such as: (1) efficient vacuum solar collectors of simple construction; (2) a barometric layout for quasi-steady operation at subatmospheric pressure; (3) a demister system of simple mechanical construction; and (4) an electronic control system regulating plant productivity parameters on available solar radiation flux. The proposed seawater desalting technology consists of single-effect distillation with water vapor produced and heated at subatmospheric pressure in a solar collector loop; the basic layout, operational features, and energy efficiency are presented and analysed in detail. Subsequent reports will provide technico-economical data from prototype desalting plants in view of industrial implementation. A promising specific electric energy consumption,∼2 kWm³ offresh water produced, was found by estimating pumping power requirements of major SW-SBD plant pumps. A sizable reduction in produced water cost with respect to an existing solar seawater desalting plant in Abu Dhabi is expected on the basis of a preliminary economic evaluation for a ∼100 m³/d plant prototype.     

Effect of ethanol administration on fatty acid desaturation

The effect of ethanol on the fatty acid desaturation by rat liver has been studied using liquid diets of different composition. Acute ethanol administration increased triacylglycerols of total liver lipids, but did not modify significantly the lipidic composition of microsomes. The Δ6 and Δ5 desaturases were inhibited by ethanol whereas the Δ9 desaturase and fatty acid synthetase were apparently modified only by diet composition. NADH-cytochrome (cyt.) c reductase was partially inhibited, whereas NADH-cyt. b₅ reductase remained practically unaltered and NADPH-cyt. c reductase activity was enhanced. Decreased electrons supplied by the microsomal cyt. b₅ electron transport chain would not be the reason for the inhibition of Δ6 and Δ5 desaturases by ethanol.     

Composition and thermal properties of Rhea oil and its fractions

The rhea (Rhea americana) is a large running bird of the ratite family, native to South America. Oil extracted from rhea fat tissue is used in cosmetic manufacture. Here, the thermal behaviour and the fatty acid and triacylglycerol composition of Uruguayan rhea oil are studied. The results are compared with those obtained from two commercial samples of emu oil. The fatty acid profiles of emu and rhea oils are similar. Small variations are reflected in the non‐identical thermal behaviour of the oils. The solid content of both oils is fairly similar at room temperature. Thus, emu oil and rhea oil may replace one another in certain formulations, without resulting in important changes in physicochemical behaviour. The semisolid rhea oil was fractionated in two successive stages: an olein was obtained at 15 °C, which was refractionated at 10 °C. The thermogram of the olein obtained by cooling at 15 °C does not have the peak found at 34 °C in the thermogram of the original oil and is a softer product than the original oil. A further stage of fractionation of this olein produced a new liquid phase of slightly different thermal behaviour from that of the original olein. This product has a solid fat index around 7% at 15 °C and has melted completely at 20 °C. This second olein has more appropriate physical characteristics than those of the olein obtained from the first fractionation when used in liquid cosmetic formulations.     

Fiber Coating Concepts for Brittle-Matrix Composites

The current interest in tough, high-temperature materials has motivated fiber coating development for brittle-matrix composites with brittle reinforcements. Such coatings are needed for controlled interface debonding and frictional sliding. The system investigated in this study was sapphire fiber-reinforced alumina. This system is thermochemically stable for severe use conditions, exhibits little thermal expansion mismatch, and utilizes the excellent strength and creep resistance of sapphire reinforcements. Porous oxide and refractory metal coatings which satisfy requirements for toughness improvement in these composites were identified by employing a variety of newly developed mechanical testing techniques for determining the interfacial fracture energies and sliding resistances.     

An Experimental Study of Fatigue Strength for Adhesively Bonded Tubular Single Lap Joints

In this paper, manufacturing technology of the tubular single lap adhesive joint was studied to obtain reliable and optimal joint quality. In addition, a surface preparation method and a bonding process for the joint were devised. The effect of the adhesive thickness and the adherend roughness on the fatigue strength of the joint was experimentally investigated. From experiments, it has been found that the fatigue strength of the joint increased as the adhesive thickness decreased and the optimal arithmetic surface roughness of the adherends was about 2 μm.     

Sulfate attack of concrete building foundations induced by sewage waters

A case history of a severe degradation of concrete foundation plinths and piers of an about-35-year-old building located in Northern Italy is described. Significant amounts of gypsum, near ettringite and/or thaumasite were detected by X-ray diffraction analyses performed on ground concrete samples. Large gypsum crystals were mainly located at the interface between the cement paste and aggregates, as observed by scanning electron microscopy coupled to energy-dispersive spectroscopy microanalysis. The degradation effects increased with decreasing the distance of concrete structures from an absorbing well located in the courtyard of the building. The well was recognized as the sulfate source due to the microorganism metabolism of sulfur compounds present in the sewage. Consequences of this attack were a very poor bond strength between cement paste and aggregates and a severe cracking of the concrete cover of the steel reinforcement.     

Hybrid materials based on metal oxides and poly(organophosphazenes)

In this paper the sol-gel preparation of hybrid materials made of metal oxide and polytorganophosphazenel components is described. The main problem focused on during this research was to avoid phase separation in order to get homogeneous materials. This problem was pursued looking at the formation of genuine chemical bonds between the exploited polyphosphazenes and the inorganic composite networks. Investigations on the thermal, mechanical, and electroconductive properties of the synthesized, phosphazene-containing composite materials showed that these matrices presented improved mechanical and thermal features with respect to those of the original phosphazene macromolecule, while the ionic conductivities of the prepared molecular hybrids doped with lithium or silver trillate are of the same order of magnitude as those measured for the neat, original phosphazene substrate.Presented at the Ist Italian Workshop on Cyclo- and Polytphosphazenel Materials. February 15–16, 1996. at the CNR Research Area in Padova, Italy.