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This paper presents the study of sorption kinetics and thermodynamic equilibrium of chloroform and methanol sorption in thin polyvinyl acetate (PVAc) films. Experiments were conducted on a laboratory set-up using a pressure-decay technique. The obtained data were compared with other literature data obtained using other experimental method and are in good agreement. Comparison between the actual experimental and other literature data obtained using different investigation techniques are in good agreement. Keywords: polymer films, solvent sorption, pressure-decay technique

In this paper are presented structural parameters that influenced the metachromatic phenomenon induced by two maleic acid copolymers in form of sodium salts, as anionic partners. One is hydrophilic, namely the copolymer sodium maleate-vinyl acetate, (NaM-VA), and the other is a hydrophobic one, namely sodium maleate-styrene copolymer (NaM-S). The cationic dye was Methylene Blue. The correlations between UV-Vis spectrum data and those of spectral remission are also discussed. Keywords: maleic acid copolymers, Methylene Blue, metachromasy, Melana fiber, spectral remission, K/S values

Asphalt nanocomposites were prepared by mixing nanoparticles of calcium carbonate with a solution of bitumen in xylene in the presence of a solution of polymer in xylene. Calcium carbonate nanoparticles were obtained by wet milling and their characterization was performed by dynamic light scattering (DLS). The polymers used were either polyacrylate type and polystyrene homopolymers or copolymer of polyacrylate-polystyrene type synthesized by solution process. Asphalt nanocomposites prepared were characterized by dynamic mechanical analysis (DMA). The results indicate a close behaviour of nanocomposite based on polyacrylate and polystyrene homopolymers and polyacrylate-polystyrene copolymer. Keywords: asphalt nanocomposites, calcium carbonate, dynamic mechanical analysis

The objective of our study was to assess the “in vivo” wear of cross linked polyethylene in contact with different materials surfaces. Thus, we compared the polyethylene acetabular cups wear when they function in a couple with ceramicized metal heads (zirconium oxide) with those in a couple with cobalt chromium metal heads, in total hip arthroplasties. The polyethylene wear was quantified by digital measurements on standardised digital front and lateral view X-rays and the differences were statistically analysed. Keywords: ceramicized metal, polyethylene, hip prosthesis

Thin films of polyamide 6 (with various concentrations) were deposited by spin-coating method (at various rotation speeds) and surface morphology of these films was analyzed by scanning electron microscopy. Following this analysis it was revealed that deposited film thickness depends on solution density, its viscosity, rotation speed and rotation time. In the context of multi-scale type theories, a theoretical model which explains our experimental results is established. Keywords: spin-coating, polyamide, thin film, multi-scale theory

Nowadays, the growing environmental awareness throughout the world has triggered a paradigm shift towards designing environmentally friendly materials. The interest in cellulose fibers as reinforcement agents in composite materials with polymer matrices has increased dramatically in the last decades, the main reasons associated with this upsurge being their renewable and ubiquitous character, good mechanical properties, low density, low cost and recyclability. Focus on dielectric spectroscopy technique, the article makes a comparison between the dielectric properties of transformer board and composite materials obtained by mixing recycled polyethylene with wood powder or lignin in different percentages. Keywords: recycled polyethylene, transformer board, dielectric spectroscopy analysis

The present study makes a comparative study of various cylindrical assemblies using the analytical models developed by minimizing the potential energy associated with the stress field and using variational methods and some assumptions. All the components of the stress field were defined function of the s(1)zz(z) stress in the first element and then introduced into the potential energy formulation. A variational method applied on the potential energy of deformation help us to obtain the minimum. This applied model can predict the optimal overlap length. Finally, a failure criterion of Tsai-Hill type was established. Keywords: stress analysis; stress distribution; adhesive joints; analytical method

In order to design/redesign an optical sighting device used on an automatic weapon, several issues related to the behaviour under loads that appear during shooting should be taken into account .Also, in order not to influence the effectiveness of the weapon, the mass and the volume of the device must be as small as possible. In this paper, a comparative analysis of the behavior of the the ensemble sighting device - clamping system, subject to inertia forces is undertaken in the following two cases: the ensemble parts are made of duralumin and, in the second case, of polyester resin. The study is performed by means of numerical calculus, on the model being applied an acceleration in steady state mode. Keywords: sighting, optical, finite element, plastic material

For this study the creams, based on collagen or lanolin and active principles from: Viscum album, Ocinum basilicum, Rosa canina, for cosmetical and medical use, were prepared. The active principles from the obtained vegetal extracts were identified on classes and / or compounds by spectrophotometric and chromatographic methods. The choice of the active components, from the selected plants, that will be included in the creams was performed depending on their biocompatibility with the derma and on the obtaining of some complexes with the collageneous protein, with high content of bioactive substances. The biocompatibility was intended to evidence the tolerance and the affinity between the biopreparation and the coetaneous constituents. This affinity was correlated with the biological origin of various used compounds, generally, with the ones which exhibit resemblance or even similarity with the derma constituents. Keywords: creams, collagen, vegetal extracts, biopreparations

The study aims at analysing the effect of the glass microfiber content on the variation of the cutting forces in the orthogonal turning process of two types of polytetrafluoroethylene: PTFE and PTFE S25 (25 [wt%] glass microfibers) with a polycrystaline diamond (PCD) tool. The influence of the process parametres (cutting speed and feed rate), as well as that of the geometrical parametres of the cutting part of the tool (rake angle g when the clearance angle a and the incidence angle c are constant) on the two components of the cutting force (cutting force, Fz, and feed force, Fx). The values of the turning forces were recorded with a Kistler piezoelectric dynamometer (type 9257B). Experimental results indicated that the value of the cutting force decreases with the increase of the cutting speed. Moreover, the glass microfiber content influences the value decrease of the main cutting force component. A statistical mathematical model, determined by linear regression, was developed to analyze the influence of varying parametres on the cutting force components (Fz and Fx). Keywords: PTFE, orthogonal cutting, cutting force, PCD tool