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Mixed mode four-point testing is performed on polyurethane foams. This paper presents only the results on the stress intensity factors (SIFs) obtained experimentally for a density of 325 kg/m3, although tests were done for three foam densities. An asymmetric four-point bending setup was used for determining the critical SIFs in Mode I and Mode II, and discussions on the influence of the initial crack length on the SIF values are done. As initial crack length is increased the theoretical predictions give a better comparison to experimentally obtained results.

Composite materials based on synthetic leathers from Polyvinyl Chloride and Polyurethane with knitted fabric support are increasingly used in many sectors of industry. Two synthetic leathers have been analysed both through experimental and analytical methods in order to evaluate their elastic properties. The analytical evaluation of material elasticity was conducted based on a micromechanical approach, taking into account the Krenchel’s coefficient for Polyester fibre orientation and based on the analytical models of Leaf and Glaskin and Chamis. Experimental data was gathered using microscopic analysis and the mechanical impulse excitation test method. Results showed a good correlation with that from the experimental study. Thus, it was confirmed that the Leaf and Glaskin model and the Chamis model have a good accuracy in prediction of fibres orientation and respectively elastic properties of synthetic leather based on plain jersey.

Various techniques have been proposed for the fabrication of surgical guide templates in orthodontics. The objective of this paper is to review the associated literature and recent advancements in this field, based on design concept , materials and technique.

The surface relief map changes induced by methyl methacrylate (MMA) chemical treatment to the flat ridge lap area of the acrylic teeth in order to improve the bond strength to the denture base resin acrylic tooth interface, was investigated with a scanning electron microscopy (SEM), a classical non-invasive investigation method. The ridge lap area of 20 artificial acrylic molars was milled to flat. The samples were randomly assigned in two experimental groups, ten samples pertaining to each one of the groups. The flat surfaces of the acrylic molars were submitted to a different treatment. Group 1: (control group), no chemical treatment; Group 2: Chemical treatment with methyl methacrylate. Each specimen was submitted to SEM investigation with SEM: HITACHI TM3000 Scanning Electron Microscope. The SEM imaging captured data depicted obvious changes of the surface relief aspect of the samples treated with methyl methacrylate compared to control group. Acrylic teeth chemical treatment with methyl metahcrylate generates surface topography changes, visible in SEM imaging, topography aspects responsible for the improved adhesion of acrylic teeth to denture base resin.

Recently the removal of trace element using biodegradable polymers is important. This paper involves preparation and evaluation of chitosan/ polyethylene glycol blend served as a heavy metal removal system. The author prepared various blending system with different composition ratios and different crosslinking density. Experimental results indicated that swelling degree and thermal property of the blend film were correlated with blend ratio and crosslink density. The blend film was then investigated its metal-binding performance. Copper sorption capacity was one of major potential applications in a field of wastewater treatment.

Rubber is increasingly used in the industry of railway rolling stock, as elastic and damping element for the suspension of the vehicle or buffer and draw-gear devices. The simplicity of design, the lack of some special maintenance operations for the rubber elements and the high degree of shock and longitudinal oscillations absorption led to its increasingly use to shock isolators in order to equip railway vehicles.

A challenge of actual research in the field of epoxy resin composites is to find paths to modify the basic properties of these polymers but keeping unchanged their excellent mechanic properties when is about epoxy resins. One valuable way is to find appropriate solvents that are compatible with the used polymer and able to solvate specific salts such as using the solution to place metallic ions inside the polymer matrix. Such an attempt might be followed by solvent removal by various physical processes having as effect the presence of metallic ions in the polymer network with possible effects regarding the transport phenomena. There are some well-known solvents as 1,4-Dioxane, 1-Methyl-2-Pyrrolidinone and N,N-Dimethylformamide that can be used also as metallic complexes precursors and their effect on the properties of an epoxy resin should be known. Present study is concerning with the modifications induced by the use of above mentioned organic solvents together with glucose and starch as an attempt to create nano-structures inside the polymer. For this study three epoxy resins had been used and tribological behaviour had been studied on a TRM 1000 tribometer from Wazau (Germany).

The aim of our study was to establish the level of calculus and dental tissue loss, together with the quality of the dental root surface after the instrumentation performed by three techniques applied in the causal treatment of the periodontal disease – the Gracey curettes, the ultrasonic scaler and the reciprocating systems with Periotor inserts. The in vitro study was conducted on 33 extracted teeth by periodontal pathological reasons which were randomly distributed in three sample groups: group 1 (instrumentation with Gracey curettes), group 2 (ultrasonic piezoelectric scaling) and group 3 (instrumentation with reciprocating system). The quantitative evaluation of hard tissue loss after instrumentation was done by weighing each tooth before and after performing the procedure. For the qualitative analysis of the instrumented root surfaces we applied the Roughness Loss of Tooth Substance Index (RLTSI). The greatest weight loss in the samples was registered by Group 1 (Gracey curettes), but there were no statistically significant differences between the mean values of the weights between the study groups. The mean values of the RLTSI score were significantly different between groups 1 and 3, with better scores for the reciprocating system. Therefore, the results of our in vitro study revealed the fact that the scaling in deep pockets with the Periotor inserts was the least aggressive method, followed by the ultrasonic scaler and the Gracey curettes.

The aim of this study is to demonstrate that tanned waste leather can be successfully incorporated in cement matrix and the resulted composite material can be proposed as construction material. The composite leaching tests for total chromium (maximum concentration registered = 2.76 mg/kg), which is the most used tanning agent, shown low levels in leachate lower than maximum allowed concentration MAC for non-hazardous waste (MAC = 10 mg/kg). The study proposes a new environmentally friendly recycling method for tanned leather waste.

The effect of zinc oxide-eugenol material (Cariosan, Spofa Dental) on resin-based restorative materials (a composite resin - Premise, Kerr Company, a compomer - Dyract Extra, Dentsply, a giomer - Beautifil, Shofu) hardness was investigated. Surface hardness was evaluated using a digital microhardness tester (Micro-Vickers Hardness System CV- 400DMTM, CV Instruments Namicon). In contact with eugenol-based cement the hardness values of all tested materials significantly decreased. After cement storage in artificial saliva for 1 and 7 days, the hardness values of all three resin-based materials registered a significantly increase when compared to the samples where the materials were placed in contact with eugenol-based cement immediately after setting, but still significantly lower when compare to the samples having no contact with eugenol-based cement.