Browse Articles

The paper deals with the synthesis of aminophosphonate polymer-silice hibrid. In the first step chloromethylated polysulphone was chemically functionalized with aldehyde groups by direct oxidation with DMSO, followed by “one-pot” reaction of polysulphone aldehyde with diphosphite and (3-aminopropyl) trimethoxysilane. Keywords: aminophosphonate groups, polysulphone, “one/pot” reaction

Failure mechanisms for composite materials and especially for laminated composites are different and more complex than for homogeneous and isotropic materials. That is why modeling and analysis of such structures are done having as main goal determination of the local stress states in the zones where high stress gradients occur: supports, points where load are applied, geometric discontinuities, junctions etc. In this paper the authors propose a methodology for the geometric and constructive optimization of the junctions in structures made from laminated composite materials. On the other hand due to the fact that the apparition of discotinuities in structures could lead to macro failures of the continuum, the modelling and analysis of discontinuities can be made using techniques adequate for local problems, such as sub structuring and sub modeling and the use of finite element method. Consequently, the purpose of this paper is to underline the importance of the study of discontinuities in mechanical structures and to present a methodology of approach (one of the many that can be used). Keywords: laminated composites, local stress states, macro failures, finite element method

Thermoplastic materials are used more and more in the technology of complete or removable partial dentures due to their superior qualities. We have tested an acetal resin, two polyamide resins and polyamide prefabricated clasps. By injection, we have manufactured several removable partial dentures without metallic structure. Thermoplastic resins are suitable for manufacturing a wide range of removable partial dentures without metallic structure, in optimal conditions of biocompatibility. Key words: removable partial dentures, thermoplastic materials, molding-injection devices

In this paper, aspects related to the energy absorption optimization of SafetyPlastic are presented. SafetyPlasticÒ is a patented impact energy absorbing technology currently used in the automotive industry as a countermeasure for occupant protection on head and side impact events. The optimization process is focused on properly changing the energy absorber wall thickness and shape, in order to promote an efficient buckling mode on the side walls. By using optimal thickness values along the height for different layers in which the particular absorber was divided, an outstanding improvement in Head Injury Criterion has been recorded. The results and the optimization procedure can be extended to various recesses shapes pertaining to the energy absorber. Keywords: optimization, polymeric energy absorber, buckling, finite element analysis

This paper presents a preliminary research activity to approach a new industrial technology to incinerate humid solid waste coming from a standard paper plant, 50% mixed with plastic waste resulted from prior recycling activities. The main part of this research activity has been focused upon the burning process technology of the industrial waste by CFD analysis in order to reduce the variation range of operational parameters’ values and to estimate the possibilities of dangerous emissions to occur. Working upon an existent 1 MWt solid fuel pilot furnace, a geometrical model has been constructed, meshed and then solved to produce information concerning the burning process and its dynamics. A chemical mechanism has been adopted from literature, to predict the kinetic chemical process inside the flame. The principal contributions of this research is to create a thermal treatment for the primary solid waste, capable to be realized inside an industrial installation at a competitive cost, to produce energy at the same time with tamping the waste at a high degree, to create the possibilities for an easy metal pieces separation and not to produce pollutant emissions. Keywords: industrial waste, plastic waste, incineration, CFD analysis, waste co-combustion

Due to the required high demands of quality products and to higher productivity rates, automated inspection systems have to be implemented in the industry. These inspection systems have to be reliable, fast, robust and flexible in their functionality in order to meet the high demands of the industry. An X-ray image of the product is taken and analysed by the system. The most important stages of the inspection process are the segmentation of the image into meaningful objects and the consequent analysis of these. This paper presents a Competitive Hopfield Neural Network (CHNN) for the segmentation of dual-band X-ray images of inspected product and a high-level detection of foreign bodies/defects based on fuzzy logic. Keywords: composite materials, image segmentation, Hopfield neural network, dual-band image, X-ray image, fuzzy logic

It was considered as contamination, the carbonyl growing in the primary and secondary polyolefins blends and as effects of contamination, the degradation rate increasing, the induction period and the service life diminishing of the products molded from these blends. Using the carbonyl time variation during the first life, it is possible to estimate, for a given contamination, the degradation rate, the induction period and the product service life molded from polyolefins post consumers goods and so the optimal solution for the polyolefins mechanical recycling. Keywords: Mechanical recycling, secondary polyolefins, mathematical model, contamination

Due to of their physical and mechanical properties composite materials, raise many problems regarding the drilling. This article contains, a series of experimental results and an analysis of the force when drilling into composite materials with polymeric matrix and glass fiber is made. Keywords: composite material, drilling, machining

This paper comprises the results of an experimental study about cyclotrimerisation using the 4,4’- biphenylmetan diisocyanats in order to obtain isocyanurat oligomers with practical importance as isocyanic component in varnishes, paints, adhesives, etc. The kinetic study was focussed on the influences of various catalysts and water (as component in the solvent) on the reaction mechanism and on physico-chemical properties of the final obtained product. The way to stop the cyclotrimerisation reaction was discussed. Keywords: isocyanic oligomers, cyclotrimerisation, 4,4’-biphenylmethan diisocyanat, reticulation agent

The films obtained through PVOH – starch compounds melt processing, are totally destroyed in nature, due to the starch biodegradability, on one hand, the water solubility of PVOH and the biodegradability of the resulted solution, on the other hand. The paper demonstrated that the utilization of compounds with proper chemical structure make possible the modification of the PVOH and starch morphology and the formation of a new one, in such manner that the resulted PVOH – starch blends have properties different from those of the blends without destructuration additives. Keywords: alcool polivinilic, amidon, compozite biodegradabile, compatibilizare prin încâlcire (“entaglement”)