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Construction of passive insulation elements in neoprene single microstructure mixture has demonstrated that the isolators can have the necessary elastic characteristics but low internal damping. The reduced scale models have in the structure viscoelastic materials basing on natural rubber symmetrically distributed in respect to the geometrical reference system chosen for the isolator. The materials consisting of natural or synthetic rubber are used as filling elements symmetrically located so that, globally, the isolator can be properly characterized both at compression and shear. For the present paper there were used two material types modelled as Voigt-Kelvin and Hooke-Maxwell elements. Key words: rheological modelling, antivibrating isolator, composite neoprene

Pralidoxime chloride (PAM) was encapsulated in biopolymeric membranes in order to evaluate the kinetics of release in aqueous solution. PAM is an efficient cholinesterase reactivator with a pronounced hydrophilic character. The biopolymeric membranes were prepared by crosslinking, directly in aqueous solution and the monodisperse spherical microcapsules made by this method had diameters between 1 and 3 mm. PAM was embedded “in situ” in microcapsules prepared from natural polymers as sodium alginate, chitosan and gelatin. The release data were fitted by first order kinetic equation, Weibull, Peppas and Higuchi semiempirical equations to obtain the kinetic parameters of controlled PAM release. The embedding of PAM in biopolymeric membranes was achieved in order to prepare a sustained release pharmaceutical formulation for oral administration. Keywords: biopolymeric microcapsules, Pralidoxime chloride, drug release

The most modern restorative interventions in dental practice are mainly based on a new generation of composite materials specialy designed for this kind of applications. Their complex structures offer a quasi-plastic behavior concerning the special tribological phenomenon developed in the intraoral environment. Starting from this, the paper intends to present the experimental data obtained as research results for two composite materials - InLine (IVOCLAR) and HeraCeram (HERAEUS Kulzer). The study is focused on the influence of the most important mechanical factors from occlusion areas such as loads, lubricants, speeds, composite materials hardness concerning the wear processses and their influence onto the mastication areas. Keywords: composite materials, tribology, wear, dental medicine

The aim of this study is to obtain and characterize a range of hybrid polymeric films with different collagen content and synthetic poly-alcohol as polyethylene glycol (PEG). Films were obtained using a “casting solution method” by a cross-linking process at room temperature. The new collagen hybrid biofilms are devoted to cell growth and proliferation. Keywords: collagen gel, hydroxyapatite, ternary hybrid biofilms

Lyocell fibers are ecological cellulose regenerated fibers and represent the most important discovery in the field of “artificial fiber engineering”. These fibers can be situated at the border between natural fibers (in terms of comfort, biodegradability) and chemical fibers (by high resistance in dry and wet environment, low contraction). In order to characterize the structural Lyocell fiber properties, electronic microscopy analyses, birefringence and X-ray diffraction have been accomplished. The present analysis on the structural properties of Lyocell fibers allowed to conclude that the microscopic images depict that Lyocell fibers present uniform longitudinal aspect and regular cross-section; the Lyocell fiber birefringence is 1.6 times higher than similar feature of viscose fiber (0.04263 as compared to 0.0265) and the diffraction analysis reveals that the distortion degree of the crystal lattice of Lyocell and viscose fibers is in accordance with the crystalline factor. The average tenacity – deformation diagrams for Lyocell and viscose fibres, in conditioned and in wet medium, allowed to determine the rheological parameters of the fibers. Keywords: Lyocell fiber properties, electronic microscopy, birefringence, diffraction analyses

Lactic ester of maleoabietic acid (RAMALA) was obtained by chemical reaction between Diels-Alder adduct of resin acids with maleic anhydride (RAMA) and lactic acid (LA). The obtained product was characterized by elemental analysis and by spectroscopic methods (IR and NMR). Curing reaction of three epoxy resins (diglycidylether of bisphenol A (DGEBA), diglycidyl ether of hydroquinone (DGEHQ) and diglycidylaniline (DGAN), with (RAMALA) in the presence of triethylbenzylammonium chloride (TEBAC) as catalyst was examined by differential scanning calorimetry (DSC) at different heating rates. Using the literature methods the kinetic parameters of crosslinking reactions were obtained. The activation energies of the curing reactions varied in the range of 48 to 85 kJmol-1 depending on epoxy systems. The thermal behaviour of cured products was also investigated using dynamic thermogravimetric analysis (TGA) technique. The cured products present good thermal stability and the activation energies of the degradation process exhibit values between 82 to 155 kJ×mol-1. Keywords: Diels-Alder adduct of resin acids, lactic ester of Diels-Alder adduct of resin acids with maleic anhydride ,epoxy resin, crosslinking reactions, thermal properties

The qualitative and quantitative information concerning the dependence between the kinematic viscosity and the activation energy of the viscous flow by the polyvinyl chloride – thermoplastic polyurethane blends composition were obtained. The results reveal that the blend composition and the melt temperature are the most important parameters that control the PVC – TPU blends melt processing. A high injection speed increases both the tensile strength and the breaking elongation. The shorter time for the mould loading increases the tensile strength and decreases the breaking elongation. The measurement of the rheological properties based on the MFI methods is a good instrument for the estimation of the rheological properties of the polymeric blends in practical conditions Keywords: polyvinyl chloride -thermoplastic polyurethane blends, rheological properties, kinematic viscosity, melt viscous flow, activation energy of the viscous flow

The optimization of the ultrasound welding of composed materials means finding an objective function that comprises all acoustic, mechanical and technological parameters and determining the minimum cost of the process or the maximum productivity in obtaining a superior quality of the welded join.In the paper there are presented the dependency of the quality of composed materials welded joins on acoustic parameters and mechanical and technological parameters. Key words: ultrasounds, welding, plastic material, technology

Experimental investigations of a diblock copolymer (polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) film doped selectively with tetrakis(4-carboxyphenyl)porphine (TCPP) into the nanoscale spherical domains of P4VP) used as target in a Nd: YAG laser (l = 532 nm) ablation process, were performed. The ionic current oscillations and the velocity of diblock copolymer plasma plume were experimentally obtained . Keywords: polymer, laser ablation

Polymer plasma laser ablation has been investigated theoretically. An elegant mathematical tool using the fractal structure of space-time was developed. The model was verified with good accuracy on the existing experimental results. Keywords: polymer, laser ablation, fractal space-time theory