New fire‐protective intumescent coatings for wood

Polyurethane coatings are highly flammable, and because of their widespread applications on different substrates (wood, steel, and building materials), there is a need to increase their fire‐safety properties. Intumescent additives sharply suppress the flammability properties of polyurethane coatings. Two problems accompany intumescent additives: their high loading percentage and incompatibility with polyurethane coatings. In this research, we succeeded in increasing the compatibility by mixing intumescent additives with a butyl acrylate polymer and in lowering the flame‐retardant additive loading (up to 20%) by incorporating newly modified montmorillonite. The flammability properties of the new intumescent coatings were characterized with a cone calorimeter. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of functional group of ferrocene redox substance on the transport properties of newly designed ion exchange membrane prepared from polymer gel

A different newly designed cationic exchange polymer membrane and anionic exchange polymer membrane were introduced, and also the transport properties of these polymeric membranes were investigated in this study. The transport properties of these polymer membranes in contact with ferrocene redox derivatives were estimated by using electrochemical techniques such as cyclicvoltammetry, chronopotentiometry, and chronoamperometry techniques, respectively. The used ferrocene redox substances, which have different functional groups, were (Ferrocenylmethyl) trimethylamonium iodide, FcMA, Ferrocenedimethanol, FcDM, and Ferrocene carboxylic acid, FcCA. It indicated that the performance of a membrane depended on the content of polymer gel, anionic exchange polymer site (20 wt % and 50 wt %) or cationic polymer exchange site (20 wt % and 50 wt %), and the efficiency of the functional groups of cationic and anionic exchange polymer site as well. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of polyaniline films using Fenton reagent

The chemical oxidation of aniline to form polyaniline (PANI) films and powder samples was made using Fenton reagent as an oxidizing agent in aqueous sulfuric acid medium. The PANI films were monitored by using the quartz crystal microbalance and the electronic absorption techniques. The optimum concentration was determined and the results were justified by measuring the UV–vis absorption spectra for the in situ PANI films. The conductivity for the PANI films and powder samples, prepared in different conditions, was measured. Also, the IR spectra, X‐ray and the thermogravimetric analysis for the PANI powder formed in the bulk were measured and compared with the polymer prepared using ammonium peroxydisulfate. A preliminary investigation to the dielectric properties of the polymer powder was measured and discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Coincidence Doppler broadening spectroscopy in polyvinyl chloride after doping with Al2O3

Coincidence Doppler broadening of annihilation radiation (CDBAR) and Vickers hardness techniques were performed to study pure Al₂O₃, pure polyvinyl chloride (PVC), and doped PVC with different concentrations of Al₂O₃ (10–50%). The CDBAR ratio curves with respect to pure PVC were presented and reflect the momentum distribution of all the samples. The peak around 14.5 ×10^?3 m_oC in the CDBAR ratio curves suggests a large contribution of positron annihilation with the Al₂O₃. There is a linear correlation between the height of this peak and the Al₂O₃ concentration. The S‐ and W‐parameters were extracted from the CDBAR spectra and increase with increasing the Al₂O₃ concentration showing discontinuity at 30% of Al₂O₃ concentration on PVC. The present data confirmed that there is no positronium formation in pure Al₂O₃ as a result of smaller S‐parameter. The Vickers hardness increases with increasing the Al₂O₃ concentration in PVC showing a linear dependence with two different slopes depend on the Al₂O₃ concentration range. A correlation between the Vickers hardness (macroscopic data) and the W‐parameter (microscopic data) was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel thermally and mechanically stable hydrogel for enzyme immobilization of penicillin G acylase via covalent technique

κ‐Carrageenan hydrogel crosslinked with protonated polyethyleneimine (PEI⁺) and glutaraldehyde (GA) was prepared and evaluated as a novel biocatalytic support for covalent immobilization of penicillin G acylase (PGA). The method of modification of the carrageenan biopolymer is clearly illustrated using a schematic diagram and was verified by FTIR, elemental analysis, DSC, and INSTRON using the compression mode. Results showed that the gels' mechanical strength was greatly enhanced from 3.9 kg/cm² to 16.8 kg/cm² with an outstanding improvement in the gels thermal stability. It was proven that, the control gels were completely dissolved at 35°C, whereas the modified gels remained intact at 90°C. The DSC thermogram revealed a shift in the endothermic band of water from 62 to 93°C showing more gel‐crosslinking. FTIR revealed the presence of the new functionality, aldehydic carbonyl group, at 1710 cm^?1 for covalent PGA immobilization. PGA was successfully immobilized as a model industrial enzyme retaining 71% of its activity. The enzyme loading increased from 2.2 U/g (control gel) to 10 U/g using the covalent technique. The operational stability showed no loss of activity after 20 cycles. The present support could be a good candidate for the immobilization of industrial enzymes rich in amino groups, especially the thermophilic ones. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Water and salt permeability of reinforcement polymer‐gel composite membrane

The charged mosaic polymer membrane (CMM) without reinforcement and the composite charged mosaic polymer membrane (CCMM) with reinforcement were investigated in terms of salt and water transport (permeability). The composite charged mosaic polymer membrane (CCMM) with reinforcement showed a unique transport behavior such as preferential material transport L_p and ω. Water permeability coefficient, L_p and salt permeability coefficient, ω were estimated by taking account of active layer thickness of composite polymer gel. The L_p and ω values of CCMM with reinforcement were larger than those of CMM without reinforcement. On the other hand, the reflection coefficient of CCMM, σ, showed negative value, which suggested preferential material transport to solvent transport. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Free volume and permeabilities of O2 and H2 in Nafion membranes for polymer electrolyte fuel cells

The mechanism of gas permeation in Nafion membranes for polymer electrolyte fuel cells has been investigated from the viewpoint of free volume. Three different samples, a membrane with ionic exchange capacity (IEC) = 0.92 meq/g, and recast samples with IEC = 0.92 and 1.00 meq/g were used after drying. Free volume was quantified using the positron annihilation lifetime (PAL) technique and gas permeabilities were measured for O₂ and H₂ as functions of temperature and relative humidity. Good linear correlations between the logarithm of the permeabilities at different temperatures and reciprocal free volume indicate that gas permeation in dry Nafion is governed by the free volume. Nevertheless permeabilities are much smaller than the corresponding flexible chain polymer with a similar free volume size due to stiff chains of the perfluoroethylene backbone. In highly hydrated Nafion above 60% relative humidity, where the O₂ permeability varies oppositely to the free volume, gas permeation proved to be controlled by the gradual increase in overall flexibility of the Nafion–water system.     

Antimicrobial finishing of regular and modified polyethylene terephthalate fabrics

An effective two-stage method has been developed for imparting antimicrobial properties to regular polyethylene terephthalate (R-PET), polyethylene glycol modified polyethylene terephthalate (PEG-M-PET), R-PET/Cotton blend (R-PET/C) and PEG-M-PET/Cotton blend (PEG-M-PET/C) fabrics. The method consists of partial hydrolysis of the fabrics to create carboxylic groups in PET macromolecules followed by subsequent reaction with dimethylalkylbenzyl ammonium chloride (DMABAC) under alkaline conditions. The reaction conditions such as pH, reaction temperature and time, carboxylic content, and DMABAC concentration were studied. Characterization of the finished fabrics was carried out through scanning electron microscopy (SEM) and Fourier transform infrared spectra (FTIR). All the modified PET fabrics showed excellent antibacterial activity towards Gram-positive (Bacillus mycoides), Gram-negative (Escherichia coli), and nonfilamentous fungus (Candida albicans). The achieved antimicrobial functions on the PET fabrics are durable in repeated laundering processes. Even after laundering 10 times the fabrics could still provide more than 85% of its antimicrobial activity against B. mycoides, E. coli, and C. albicans. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Finite element simulation of the mechanics of flat contact pad fretting fatigue tests

An understanding into the macro kinetic and kinematic behaviour of fretted surfaces is provided. Making use of a modified version of a previously developed in‐house two‐dimensional elastic–plastic finite element analysis numerically simulates flat contact pad fretting fatigue tests. Basic macro mechanics concepts are adopted to idealise two bodies with rough contact surfaces and loaded at two different sites with arbitrary axial loading profiles. A time scale factor is devised to recognise the earliest candidate out of the events possibly accommodated at each loading increment. The present analysis utilises a relevant experimental set up developed in the Structural Integrity Research Institute of the University of Sheffield as an application. Computational results accurate to within 1.2% and corresponding to one contact pad span and six constant normal loads acting individually with four amplitudes of two sinusoidal axial load cycles are presented. The present computations include (1) the development of the global and local normal and tangential reactions and relative sliding displacement acting along the fretting surfaces and (2) contact pad deformation, generated stress fields and plasticity development within the neighbouring region of the fretted area.     

Tornado: A self-reconfiguration control system for core-based multiprocessor CSoPCs

In this work we present a self-reconfiguration control focused on multiprocessor core-based systems implemented on FPGA technology. An infrastructure of signals, protocols, interfaces and a controller is exposed to perform safe hardware/software reconfigurations. This infrastructure is part of the Tornado framework that includes other elements such as a multi-context assembler for a reconfigurable processor or a custom design flow developed for the Wishbone IP-Core interconnection specification. We present two applications where the presented control system has been applied, and it is compared with other available approaches.