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A phosphorus-containing copoly(ester-amide-imide) has been synthesized by solution polycondensation reaction of an aromatic dianhydride, namely 1,4-[2-(6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)]-naphthalene-bis(trimellitate)dianhydride, with 4,4´-oxydianiline and isophthaloyl chloride. The polymer was easily soluble in polar organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, tetrahydrofuran and chloroform. The polymer shows high thermal stability, the decomposition temperature being above 410 oC. The value of the glass transition temperature was 231oC. Due to the presence of phosphorus, the polymer gave high char yield in thermogravimetric analysis. Keywords: copoly(ester-amide-imide), phosphorus-containing polymer, thermal stability

In this paper, it is showed that a mechanical model with one degree of freedom can be used to study the vibrations of a bar in a certain point. The considered structures were made of epoxy resin reinforced with carbon and carbon-kevlar texture. The vibrations in the free end of the bar, clamped at the other end, were determined experimentally for four different lengths. Eigenfrequencies and damping factor for the first modes of vibration were obtained for each bar. Relationships for the eigenfrequency and damping factor are proposed, as a function of the length of the bar, for each of the studied materials. Keywords: Eigenfrequency, damping factor, composite bar

The paper presents the effects of the miscibility and of the micro-structure on the surface defects of some bio – hybrides based on starch, polyvinyl alcohol (PVOH) and multilayered silicates. At macroscopic level (100m) the studied starch bio-hybrids seem to be compact materials. If these materials are analysed at a microscopic level (10 m) depending on their type surface defects like voids, cracks and fractures can be observed. These defects are not a consequence of a poor miscibility, even in case of bio-hybrids that contain untreated silicate. These defects appear because of the bio-hybrids micro-structure. As the new bio – hybrids are probably disorderly ones, it can be estimated that the surface defects appear as a consequence of a poor distribution of the swollen silicate tectoids into the polymeric matrix, possibly as a consequence of the improper melt processing conditions. Keywords: polyvinyl alcohol, starch, multilayered silicate, surface defects, miscibility, bio-hybrides, micro-structure

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