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We have used light-cured experimental (Restacril, Nanopacryl, C-foto T, CP-AD1, CP-AD3) composites colouring tests ”in vitro”. The tests were performed on samples of 30 mm diameter and 2 mm thickness, which were immersed in coffee, red wine, and two food colouring agents (red, containing Sunset yellow (E110) and carmoisine (E122), and yellow, containing Sunset Yellow, tartrazine (E102) and Ponceau 4R (E124)). The samples were subsequently removed from the solutions, rinsed with water and dried, and then measured after three days and later after 2 months. On the 2 months-old samples, a bleaching gel was applied (G4, 35%), and the samples were again measured after three hours and after 24 h. The measurements were performed with a UNICAM UV-Vis spectrophotometer. For analyzing the color DE*= f((L*a*b*)) with a spectrophotometer, three discs per composite were prepared. From the reflection spectrum the color coordinates (Da*, Db* DL*) were determined and the color difference. Keywords: dental composites, colour, dental bleaching

The paper reports the performances of the polysulfone-polyaniline (PSf-PANI) porous composite membranes for various ratios PSf / PANI in membranes. Polysulfone-polyaniline porous composite membranes are obtained by phase inversion with chemical reaction. PANI is obtained in-situ by oxidative aniline polymerization. Composite membranes are morphologically studied by electron microscopy and characterized by thermal analysis and water solutions permeation at different pH and pressures. Polysulfone-polyaniline porous composite membranes UF processes performances to BSA separation are also reported. Keywords: PSf-PANI membranes, phase inversion, hydrodynamic characteristics, rejection, BSA

(Nano)composites based on maleated ethylene propylene diene terpolymer (EPDM-g-AM) and organically modified montmorillonite (OMMT) has been prepared by melt intercalation procedure. The materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), dynamic scanning calorimetry (DSC) and mechanical tests. XRD data show the increase of the distance between the silicate layers indicating the intercalation of polymer chains in the montmorillonite galleries. The incorporation of OMMT in composites determines the increase of melting peak temperature (Tm) and heat of fusion (DHf) suggesting a supplementary nucleation increase due to the OMMT presence. The mechanical properties were analyzed as a function of the OMMT level in the composite and the results reveal remarkable improvement relative to the conventional composite. Keywords: EPDM-g-MA/OMMT nanocomposites, XRD, TGA, DSC, mechanical properties

The paper shows in its first part the role, efficiency, types, factors and mechanisms of using the synthetic polymeric flocculants in the paper industry. The experimental part shows the research carried out to determine comparatively the efficiency of using the single component retention systems, with micro/nano particles in the modern alkaline paper production compared to the conventional acid process. Keywords: paper, flocculation, retention aid, zeta potential, micro/nanoparticles

Mechanical properties of the new bromobutyl rubber-based composite (BrBR) were evaluated in comparison with similar NBC protection materials, used either in Romanian Army or in other NATO country armies. The following parameters were determined: mechanical strength, tensile strength and elongation, and the tear force – trouser-shaped test specimen. From the data obtained, a real improvement of the break parameters of BrBR, both in warp and in weft, versus the performances of Romanian materials in use was noticed. Also, versus the foreign materials, the material obtained presents properties basically between the French material and the German one. Keywords: NBC protection, composites, mustard gas, mechanical properties

Porous polysulfone (PSF) beads and composite beads (PSF-Cu-MT-Sil) obtained by incorporating copper-metallothionein functionalized silica in a polysulfone solution were prepared using the phase inversion method. Their characteristics were investigated with experiments of swelling, Fourier transform infrared (FTIR) spectroscopy and SEM microscopic analysis. Polysulfone and composite beads were used in catalase (CAT) immobilization. The kinetics of the biocatalytic process, stability under different temperature conditions and the inhibitors effect were studied as major factors on the immobilized catalase activity. The present work is meant to demonstrate the potential of crosslinked polysulfone and especially polysulfone with copper- metallothionein beads for the enzyme immobilization process. Keywords: polysulfone, composite beads, catalase, enzyme immobilization

Composite materials of different composition were obtained by utilizing either a polyethylene or polypropylene matrix and a wood flour filling. In order to characterize these materials, a series of experiments were conducted to determine density, electric strength, complex dielectric constant components and and dielectric loss factor tgd for various electric field frequencies and at different temperatures. The results show that the dielectric properties are heavily influenced by the filler content with very high registered values in the case of low frequency electric fields and high temperatures. It can be ascertained that samples having a polypropylene matrix have superior electric properties than those having a polyethylene matrix. Finally, the opportunity for utilization within low voltage and industrial frequency electrical engineering applications of the tested composite materials is shown. Keywords: wood-polymer composites, dielectric properties, dielectric spectroscopy

A polyurethane (PU) based on 4,4’diphenylmethane diisocyanate (MDI), copolyester poly(ethyleneadipate) diol (PEA) and extended with butylene glycol (BG) was synthesized via a two steps polymerization technique. The thermal stability of the PU was investigated by thermogravimetric analysis (TG) at temperatures between 30 and 600oC. The synthesized PU was irradiated in an UV exposure unit as such the spectral distribution of the light was a good match for terrestrial solar radiation (200 h, l > 300 nm, Ia = 30 mW cm-2). The modifications in the chemical structures of the PU before and after irradiation were characterized using Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) technique. The yellowing index variation (YI) exhibited a systematic trend increase with irradiation time. Our results are in agreement with the formation of quinoide structures, which are colored products resulting from photo-degradation of PU. Keywords: polyurethane, thermal analysis, photostability, thermal stability

In this study, blends of biodegradable matrix as poly(3-hydroxybutyrate) (PHB) and fibers provided by renewable resources were prepared by a melt blending method. Improvement of the compatibility between fibers and polymer was studied using coupling agents: maleic anhydride (MA) respectively, succinic anhydride (SA). Mixtures with two types of fibers were investigated in terms of microscopy, torque, density, tensile strength, melting temperature and contact angle. It is found that the mechanical properties of PHB with cellulose fibers blends were better than PHB and wood fibers. Keywords: polyhydroxybuthyrate, wood fiber, cellulose fiber, coupling agent, blend

When the plastic materials products are obtained by injection into the mould, the fluid plastic mass takes the shape of the cavity and then, in a technological time, the obtained product cools until a temperature which makes possible its unloading without any deformation. Each product or more products may be realized during a period which means the time of one manufacturing cycle. An optimum manufacturing process is a continuous process without waiting times. The paper presents a methodology for the calculation and adjustment of some injection parameters which influence the time of one manufacturing cycle for the plastic materials products realizing. Keywords: plastic materials manufacturing, thermal processes of the polymers injection