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We synthesized and characterizated two bromine containing monomers, 2-(2-bromopropyloxy) ethyl methacrylate (BPEM) and 2-(2-bromoisobutyriloxy) ethyl methacrylate (BIEM), to be used as radiopaque agents in acrylic bone cements. Using methyl methacrylate (MMA) and each one of the bromine containing monomers in different concentrations we have synthesized ten copolymers. The copolymerizations were carried out directly in the thermostatic, cell of an NMR Spectrometer. Analyzing the 1H-NMR spectra, we have determined the reactivity ratios of the monomers. Preliminary studies showed that acrylic bone cements which include in the liquid phase these bromine containing acrylic monomers, have a very good radioopacity. Keywords: bromine containing monomers, copolymerization, parameters of reactivity

This article presents literature data regarding the synthesis and properties of some sulfonated aromatic polymers, such as polyethersulfones, poly(etherketone)s, polybenzimidazoles, polyimides, which can be used for proton-exchange membrane in fuel cell applications. The polymers were prepared by two procedures: postsulfonation of existing polymers and direct copolymerization of sulfonated monomers. Some characteristics of the sulfonated polymers in correlation with their structure were also presented. Key words: sulfonation, sulfonated polymers, good solubility, thermal properties

The influence of propylene, polyethylene and maleinized polyethylene on the characteristics of thermoplastic elastomers based on maleinized ethylene-propylene terpolymer rubber was investigated. As the amount of the added polyolefine is increased, the hardness, tensile strength and tear strength increase, and elasticity and elongation at break decrease. The resistance to swelling in toluene and resistance to 50 % nitric acid and 40 % sodium hydroxide are also increased with the increase in the amount of the added polyolefine. The blends containing maleinized PE show higher characteristics than those with PE as such. The rheologic characteristics of the above mentioned blends were studied and compared. The thermoplastic ionic elastomers based on maleinized EPDM and polyolefines can be used in obtaining some materials with specific characteristics (high hardness, tensile strength, elasticity, resistance to acids and alkalis, resistance to swelling in toluene etc.). Key words: polyolefines, maleinized EPDM, thermoplastic ionic elastomer

The paper presents some technological aspects related to a new procedure for centrifugal casting in moulds made of silicone rubber. The procedure has been enhanced by the American company Tekcast Industries Inc. and is applicable for the casting of plastics and metallic alloys of zinc and led, in the case of small production and unique items. Keywords: silicone rubber, centrifugal casting, moulds, zinc alloys

A survay on the radiothermoluminescenceof 25 polymers is presented. The RTL glow curves were recorded on the temperature range starting from 77 K up to room temperature after 60Co irradiation. The most RTL peaks occur at temperatures similar to those assigned to the onset of specific molecular motins, suggesting that the peaks are due to the liberation of electrons from traps formed by the chains of polymer. The RTL glow curves are generally in good agreement with the results reported by other researchers. This paper includes the experimental data obtained from each glow curve (temperature and intensity of maxima). The activation energies of some of the peaks were obtained using several methods. The peaks with lower activation energies generally are located at lower temperatures. Keywords: polymers, elastomers, radiothermoluminescence, characterization, activation energy

In the previous article [1], results concerning the bonding of cured non-polar elastomers supports with adhesive formulations based on non-cured non-polar elastomers have been presented. This research is dedicated to obtain additional information regarding the adhesion mechanism and to study the adhesion strength executed on cured polar elastomers supports with composition based on non-cured polar elastomers. We have used two types of polar cured elastomers basic supports, polychloroprenic rubber and nitrile rubber, and two non-cured adhesive compositions of the same elastomers type. Keywords: adhesives, elastomers, polychloroprene rubber, nitrile rubber

The paper presents the changes in chemical composition and hardness of cylindres used for grinding of rubber wastes. Based on experimental results obtained, some technical solutions can be suggested in order to determine a considerabile growth the life equipment. Keywords: rubber waste grinding

The use of Rapid Prototyping (RP) processes in manufacturing cellular solids offers the advantages of controlling the distribution, dimensions and interconnection of cells, which influence their micro and macro-structural properties. But not all RP processes are able to build cellular solids with closed cells, this article analyzing the capacity of Fused Deposition Modeling (FDM) process to manufacture this type of structures from ABS material. Using a test part containing cubic and spherical cells, it is shown that FDM can manufacture structures with completely enclosed voids, but only for a certain range of dimensions. This approach opens new study directions such as the possibility to analyze the mechanical behaviour of this type of cellular materials with closed cells and controlled geometry, or to use them as test parts for detecting voids in injection moulded parts. Keywords: fused deposition modeling, rapid prototyping, ABS polymer material, cellular solids, closed cells

In this paper the experimental results obtained at grain refining of 6082 aluminum alloy are presented, using an original method which consists in insertion of refining master alloys in two stages: in the first stage the AlTi5 elaborated at low temperature, and in stage number two AlTi5B1 classic ternary master alloy. The method ensures into the solidification process, both the elements that act by stopping the grain growth (Ti) and the nucleation centers (TiB2, AlB2, (Ti, Al)B2). Keywords: prealloys, refining

The microelectronic package continues to evolve in order to improve the performance and integrate new technology such as multidie architectures, thinner substrates, increasing integration of passive components, increasing thermal design power and lead free interconnects. Package materials must be designed to enable the electrical and thermal performance requirement and to provide high-reliability performance. Maximum heat dissipation is a requirement for today’s higher power integrated circuit devices. The maximum heat dissipation is achieved by mounting active devices directly to high thermal conductivity heat sinking substrates or packages. Direct attachment requires a compatible coefficient of thermal expansion (CTE) value of the heat sink material to avoid stress failure of the IC device. In this paper, the thermal behavior of polymers used in cooling electronics with nonlinear electrical lumped elements as a function of temperature, physical properties and sizes of a heat sink element were modeled. Keywords: high thermal conductivity polymers, heat sink, safe operating area, nonlinear thermal impedance electrical model