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Nanoxide based composites are suitable materials for advanced medical application. Fe3O4, CoFe2O4 and MnO2 nanoparticles, synthesized by different soft chemistry routes (precipitation in the presence of soft template and solution combustion) were coated by a biocompatible polymer, sodium alginate. The oxides and corresponding composites were structural and morphological characterized. The saturation magnetization for Fe3O4-based composite is 10.1 emu·g-1, resulting magnetic domains of 5.2 nm that suggests a superparamagnetic property. Radical scavenging capability of the composites was investigated by two different methods, Trolox Equivalent Antioxidant Capacity (TEAC) and peroxide-chronoamperometry. Keywords: ferrites, MnO2 , oxide-based composites, biopolymer matrix, radical scavenger

Thin films, in the range of tens of micrometers thickness, have been prepared by casting onto glass plates the N-methyl-2-pyrrolidone solutions of two poly(ether imide)s containing isopropylidene or hexafluoroisopropylidene groups. The polymers have been synthesized by solution polycondensation reaction of 4,4’-(1,3-phenylenedioxy)dianiline, with 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride or 1,1,1,3,3,3-hexafluoro-2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride. The dynamic mechanical analysis and dielectric spectroscopy were employed to study thermal and electrical behaviour of polymer films. Keywords: poly(ether-imide)s, thin films, dynamic mechanical analysis, dielectric spectroscopy

The paper focuses on rheokinetic investigations on matrix of a new composite material. A simple, yet effective, experimental method has been employed to measure several parameters that can help, by resin’ viscosity measurements, in finding resin kinetic hardening parameters. As it is shown by one of our papers [1.3,4] CFRAl (Carbon Fibers Reinforced Aluminum) is a new hybrid composite under development . It has unique and promising properties, with foreseeable excellent results in applications requiring a reliable, yet light, reinforcement material that can also withstand powerful thermal shocks. Keywords: rheokinetic model, composite material, carbon fibers, bullet-proof material

Polysulfone based membranes with controlled porosity pore density, size and orientation were synthesized. The predicted pore characteristics are obtained by adding magnetite (nano or micro) particles into the polysulfone gel and the pores obtained by applying different magnetic fields. The pore density, size and orientation can be designed based on the magnetite particle concentration, on the magnetite particles size and respectively based on the angle between membrane surface and magnetite field. The pore density, size and orientation of the membranes were analyzed by SEM. FTIR was used to investigate the membrane composition and to prove the possibility of removing the magnetite particles by acidic dissolution or by extended membrane exposure to the magnetic field. The complex thermal analysis was used to characterize the thermal behaviour of the synthesized membranes. Keywords: polysulfone membranes, pore characteristics, predicted porosity and separation ability, scanning electron microscopy

This study refers to the obtaining of mortar plasters using perlite and polymer additives additions. The performed study has outlined the infuence of the polymeric additive nature and content as well as perlite addition on mortar plasters based on hydraulic binders characteristics. Keywords: mortar plasters, polymeric additive, perlite, redispersabile powders, cellulose ethers

The increasing of the field usage of high frequency (HF) welding joints technique of thermoplastic polymers gives advantages regarding productivity, quality of welded joints and high reproducibility of results. Base of experiments, this debate analyzes the main types of failure, the causes of the failure and the prevention method for HF welding of polyvinyl chloride PVC foils. Keywords: HF welding, polymers, failures

The paper proposes new structures to replace the polystyrene, which is well known to be a toxic and inflammable material, non-biodegradable, used on a large scale for residence and civil thermal insulation and for packaging. The proposed structures are intended to be light structures, easy to manipulate, easy to be cut at the sizes needed, compact enough to not be damaged during the transport or during the mounting time, easy to fix on the building walls and of course with similar thermal insulating properties as polystyrene. First agglomerated composites were proposed. The materials used in these structures are green and biodegradable, found as inserts of wood (flakes or fibers) and textiles (wool or jute) and binders as wheat flour, clay or ecological acrylic copolymers. The density and thermal conductivity coefficient were determined for each structure and compared with the expanded and extruded polystyrene values and finally the more appropriate structures were recommended. To some of the structures flakes of polyethylene were added, in order to constitute a steam barrier of the new product. The addition of the polyethylene proved to be a disadvantage for the thermal insulation property of the structure and also for its compactness and reliability. The agglomerated composites mentioned above were pressed at a normal temperature (20-22oC) and conditioned at a temperature of 40-50oC. Two other structures were also proposed in this paper for the same purpose: a sandwich one, obtained after pressing it at 200oC, containing jute, wood fibers and polyethylene granules for the core and beech wood veneers for the faces and a panelled board made of waste of polyethylene and jute core and fiberboard faces. Keywords: polystyrene, polyethylene, thermal insulation density, composites

In this paper a modern multi-objective optimization of the pneumatic ejectors of the plastic injection mold is presented. For this Pareto multi-objective optimization, two objective functions (volume and efficiency of the ejector) and four genes were taken into consideration and a set of twelve constraints were formulated. In solving the optimization problem we used an original two-phase evolutionary algorithm (2PhEA) inspired from the concept of “punctuated equilibrium”. 2PhEA is implemented in Cambrian v.3.2 which is in operation at the Optimal Design Centre of the Technical University of Cluj-Napoca, Romania. The study on the individuals along the obtained Pareto front reveals some important conclusions useful in the design of the pneumatic ejectors. Keywords: optimal design, evolutionary algorithms, pneumatic ejector, injected part

The extraction of surface geothermal energy using heat pumps represents a recent topic in specialty literature. This paper presents a numerical model for modelling the thermal field around the heat exchangers mounted in the soil. The purpose of modelling is to reveal the dynamics of heat exchange between the soil and the polyethylene pipes and highlighting the variation in temperature field around the heat exchanger. Keywords: Geoexchange, heat pump, polyethylene, thermal field

In the recent years the utilization of polymeric materials increased due to their good mechanical properties and easy manufacturing. Starting from automotive industry up to food industry polymeric materials are used for obtaining components by molding or by machining. Taking into account the wide range of applications, it is important to know the mechanical behaviour of these materials in different loading conditions. Accordingly, this paper presents an experimental study to determine mechanical properties on 11 commercial polymeric materials. Tensile and shear static tests and impact tests on notched and un-notched specimens were performed. The results are presented comparatively, and two new parameters were introduced for material selection purpose. Keywords: mechanical testing, polymer materials, tensile strength, shear strength, impact strength