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Novel composite poly(ethylene glycol) hydrogels with hydrophilic bentonite as the filler were synthesized by the polyaddition reaction between diepoxy-terminated PEG of 2000 Da, 6000 Da and 10000 Da molecular weights and ethylenediamine in aqueous solution at 60°C, in the presence of the clay. The hydrogels prepared were tested from the point of view of their swelling behaviour and mechanical properties. The results showed that the clay practically did not affect both the water absorption by the crosslinked polymer and the storage modulus of the hydrogels. This seems to indicate that the interactions between the PEG chains and bentonite were very small or absent within the hydrogels in the presence of water, although they occurred in dry state, as proven by FTIR and XRD measurements upon xerogels. Keywords: hydrogels; poly(ethylene glycol); bentonite; composite

The paper focuses on the synthesis and evaluation of biomineralization potential of composite materials based on bacterial cellulose and synthetic acrylic polymers with negative groups attached. The composite materials were obtained by grafting the monomers carrying negative groups onto the surface of bacterial cellulose. These grafted membranes were then subject to mineralization assay according to T. Kokubo protocol. Cytototoxicity test have shown that this kind of composites did not show a significant in vitro cytotoxicity and could be used for developing biomedical applications. Keywords: bacterial cellulose, acrylic monomers, biomineralization, hydroxyapatite

New systems based on poly(vinyl alcohol), unmodified and modified layered silicates were designed for drug delivery applications. Unmodified and modified montmorillonite with different agents were used as inorganic component in the hybrid structures. The thermogravimetric analysis (TGA), X-Ray Photoelectron Spectroscopy (XPS), X-Ray Diffractions (XRD) and FTIR analysis were useful to characterize the hybrid materials. The modifier agent type used for montmorillonite treatment and the presence of montmorillonite in the polymeric films strongly influence the hybrid materials properties and drug release profile. Keywords: poly(vinyl alcohol), hybrid materials, montmorillonite, 5-fluorouracil, UV-Vis, X-Ray Photoelectron Spectroscopy

The paper presents experimental data regarding morphology and hydrophobic character of some film building silica hybrids containing disperse dyes embedded or covalently linked into the inorganic network, used as coating materials for protein textile fibers. Thermo-mechanical properties of the textiles coated with the colored film forming materials are studied in relation with the coating materials composition. Keywords: thermo-mechanical properties, hydrophobic character, silica hybrids, disperse dyes,protein fibers

This paper has had as purpose rendering of some researches related to extrusion velocities while obtaining multilayer films with superior barrier and antimicrobial properties, of five layers of polymer with ionomer content, including antimicrobial. An installation comprising five extruders has been used for trials and the working velocities have been determined for each layer, as well as the shear stress at the wall of the nozzle. The results thus obtained made possible to settle the optimum parameters for the extrusion process able to ensure a stable flow of the molten polymer, which resulted in a uniform multilayer, faultless structural film, with superior barrier and antimicrobial effects. Keywords: polyethylene, EVA, EVOH, extrusion, co-extrusion, multilayer film

This paper presents the study of Vickers microhardness performed on a styrene-butyl methacrylate- methylacrylic acid copolymer and the analogous obtained by grafting with ampicilline. The creep properties and the glass transition temperature of the copolymers were investigated. Keywords: microhardness, styrene-butyl methacrylate-methylacrylic acid copolymer, creep,Tg

A simple manufacturing method to obtain bent shape tubes with variable cross-section from fibre reinforced composites with application in high performance handlebars for mountain-bicycles was used. The original procedure is able to assure constant pressure upon the reinforcement material, the result being a compact composite, good quality with an optimum reinforcement degree. Tests and analytical computations, based on classical laminated plate theory delivered the engineering constants that have been used in the finite element simulations of two important safety tests for the handlebar (bending and torsion). The experimental results obtained for lateral bending test (critical test) are in agreement with the finite element simulations. Keywords: bicycle handlebar, composite parts, mechanical testing, finite element simulation

The paper deals with the research of variety of non-standard samples of plastic material made by injection moulding. The samples were made of conductive plastic material (LNP Stat-kon Compound ZX05009). Brown Corundum F24 was used for blasting under different pressures. This conductive plastic material can be applied as a plastic electrode, it is therefore possible to make measurements and examination of electrical conductivity. The experiment is used in order to establish the extent, to which the pressure used at blasting measurably affects the electrical conductivity of plastic electrode. Keywords: physico-mechanical properties, casting, plastic electrode, injection holding

The objective of this work was the modification of the pigment Yellow 17 structure through a treatment with ZnCl2 and Na2SiO3 in order to improve its properties. The modifications that appear in pigment structure were revealed by UV-visible diffuse reflectance and EDX analysis. The synthesized pigments were used to colour the polypropylene. The chromatic modifications appeared through pigment colouring with modified pigments were evaluated by measuring the colour intensity and colour difference. The light fastness and UV protection of the coloured polypropylene samples were also highlighted. Keywords: organic pigments, polypropylene, colour measurements, light fastness, UV-protection

The present paper aims to investigate the effect of surface defects upon contact area shape and dimensions in the case of metallic spherical punches pressed against a flat, optically transparent surface. Experimental investigations were conducted using a previously advanced, optical method, based on surface reflectivity. Various surface defects were artificially generated on the surface of steel ball bearing balls with 12.775 mm in diameter. The considered defects were grooves and holes. The employed experimental method is based on the accurate evaluation of contact interface reflectivity of loaded contacts, by aid of laser profilometry, as described in previous works [1-9]. Keywords: surface defects, mechanical contacts, contact area, laser profilometry, reflectivity