Browse Articles

This research is based on the study of the chemical polymerization of nanocomposites based conductors polypyrrole PPy(Cl) and the HY Zeolite type Faujasite as reinforcements, at room temperature and atmospheric pressure using FeCl3 as initiator of the reaction and dopant at the same time. After characterization commodity we methods primarily on the polymerization of pyrrole with different molar ratios of [FeCl3] / [Pyrrole] in an aqueous medium, followed by a series of characterizations for the polymers obtained. Won the right ratio was used for the preparation of nanocomposites PPy (Cl) / HY Zeolite. After each synthesis, the developed product is characterized by FTIR, SEM, UV-Vis, XRD, and electrical conductivity in order to confirm the success of the process of synthesis and study their properties to specific applications envisaged. Keywords: nanocomposite, polypyrrole, zeolite HY, conductor polymer

Coatings obtained on cellulose fabrics with nonionic dyes – silica hybrids have been investigated. Composition of the impregnation bath and parameters having a major influence on coloring properties were studied in relationship with washing and light fastness. It was found that cotton can be coated with organic-inorganic nonionic dyes - silica hybrids exhibiting fair washing and light fastness. Properties of the coated materials can be controlled by variation of parameters affecting sol obtaining procedures or impregnation conditions. The presence of only one trialkoxysilane group per chromogen makes the formation of a highly crosslinked silica network to be difficult. The partial condensation of DR1-PTES (Disperse Red 1 dye covalently linked to 3-isocyanatopropyltriethoxysilane) to the stage of oligomeric structures, together with the existence of silanol and unhydrolyzed alkoxysilane groups can explain leaching behavior of the coatings obtained with this type of hybrid materials. Keywords: nonionic dyes, silica hybrids, surface coating, cotton fabrics, sol-gel process

This paper presents the synthesis of some acrylic monomers with pendant carbazole groups. They were copolymerized with N-octyl methacrylate to obtain organic photosensitive materials used in the production of holograms with electrophotographic methods. Keywords: N-vinylcarbazole, N (2-hydroxymethyl carbazole), N-carbazolyl methlacrylate, octylmethacrylate

This paper presents the influence of processing temperatures of high-density polyethylene (HDPE), polymethyl methacrylate (PMMA), polycarbonate and acrylonitrile butadiene styrene blend (PC+ABS) on some mechanical properties when obtained through the injection of items from various industries. The HDPE samples were obtained at the following injection temperatures: 180, 190, 200, 210, and 220°C. The PMMA samples were obtained at the following injection temperatures: 220, 230, 240, 250, and 260°C, and PC+ABS samples were obtained at the following injection temperatures: 230, 240, 250, 260, and 270°C. Determining the mechanical properties was made using determining methods of tensile properties, of Izod impact test, and Shore Durometer hardness test. It was observed in the case of the three analyzed polymers that increasing the processing temperature hardly influences their respective hardness. The Izod shock resistance for the three analyzed polymers decreases along with the increase of the processing temperature by injection. The tensile strength at break is influenced by the processing temperature. The increase of the processing temperatures by injection in the case of the three analyzed polymers leads to the decrease of the tensile strength at break. The lowest values of the tensile strength at break occur at the highest processing temperatures. Keywords: high density polyethylene (HDPE), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene polycarbonate blend (PC+ABS), tensile tests, Izod impact test, Shore Durometer hardness test

Functionalization of multiwalled carbon nanotubes with carboxyl group (–COOH) and oxaliplatin (OX) was investigated using FTIR spectroscopy, high performance liquid cromatography (HPLC), transmission electron microscopy (TEM), inductively coupled plasma mass spectrometry (ICP-MS). Encapsulation efficiency was computed and in vitro behavior regarding MDA-MB-231 cells was studied. Keywords: carbon nanotubes, oxaliplatin, encapsulation, FTIR, TEM

This paper addresses the theoretical and experimental mechanical properties of specific to monolayer composite plates produced from urban and industrial recycling wastes with elastomeric matrix and fibrous protein reinforcement (leather, textile). Defining the theoretical model of composite material with its structural elements, as well as evaluating physical and mechanical characteristics essential to its default drive to an optimal and efficient design of all products made from such materials. By determining the theoretical and experimental parameters with maximum precision, which affects the properties of the composite structure, it is decided its use in specific technical industrial applications. Keywords: composite material, reinforced lamina, recyclable waste, fibrous material.

Tests on wearing clothes are complex methods of analysis that mainly consist of recordings of physiological reactions in the body. During wearing tests physical parameters of the environment and biometric parameters were measured. Five garments, blouses, were tested under dynamic conditions; the products were worn by 5 subjects, female students. In the performed tests there were determined the following parameters: the skin temperature and the electrical resistance of the skin, under dynamic wearing conditions (repose, effort, recovery). The study demonstrated that the tests of wearing garments under certain conditions, through their complexity, provide a series of information and emphasize certain aspects that cannot be found in the laboratory tests results on textile materials. The performance of these types of tests and the accomplishment of the objectives imply the contribution of complex teams. Only through an interdisciplinary approach can the issues regarding wear comfort be solved. Keywords: clothing, wear tests, warm environment, dynamic conditions, comfort, evaluation, biometric parameters

The manufacturing of hydraulic turbine runners designed for experimental research on the model is carried out, usually, by precision casting or CNC machining. These processes involve technological difficulties, high manufacturing times and high production costs, which are generated by the complex geometry and the small dimensions of the runner. Rapid prototyping technologies allow the manufacturing of mechanical components at a high precision and for a significantly lower manufacturing time and production costs compared to the conventional technologies. The use of components made of polymers, through rapid prototyping, in experimental research, may be limited by the properties of the polymer and the mechanical stress occurred. In order to verify the possibility of using polymers in the manufacture of turbine component models, a Pelton runner was made through rapid prototyping. The stress-strain state that occurs on the runner blade was analyzed and experimental investigations were performed on a micro-turbine equipped with the polymer runner. Keywords: polymer, rapid prototyping, stress, Pelton runner

To determine if acrylic or composite resins are favorable choices for the single crown on implants. It was performed a FE Analysis using the IBM Autodesk Inventor 2014 for a single 3.75x8mm mandibular implant, a straight titanium abutment, three crowns (acrylic, metal-composite and metal-ceramic) and a type III bone with a 1mm cortical component. For the implant, the maximum stress was 178.7MPa (acrylic crown), 96.38MPa (metal-composite crown) and 86.17MPa (metal-ceramic crown). For the abutment, the maximum stress was 312.4MPa (acrylic crown), 140.8MPa (metal-composite crown), and 121.5MPa (metal-ceramic crown). For the retainer screw, the maximum stress was 75.67MPa (acrylic crown), 33.66MPa (metalcomposite crown), and 34.64MPa (metal-ceramic crown). For the metallic component of the crown, the maximum stress was 248.7MPa (metal-composite crown), and 207.1MPa (metal-ceramic crown). For the aesthetic component of the crown, the maximum stress was 28.93MPa (acrylic crown), 22.45MPa (metalcomposite crown), and 28.13MPa (metal-ceramic crown). For the cortical bone, the maximum stress was 62.74MPa (acrylic crown), 37.63MPa (metal-composite crown), and 40.3MPa (metal-ceramic crown). For the trabecular bone, the maximum stress was 7.147MPa (acrylic crown), 4.995MPa (metal-composite crown), and 4.973MPa (metal-ceramic crown). For the metal-composite crown, the stress distribution in the trabecular bone is more uniform, comparing to the acrylic crown, which is an advantage. For the metalceramic crown the stress distribution in both bone components is similar as for metal-composite crown. The safety factor shows that there is no risk of plastic deformation, nor for acrylic or for the composite resins. The composite resin on Cr-Ni alloys is still the best material for the single implant crown. The acrylic resin and ceramics on Cr-Ni alloys proved a similar resistance to stresses. Keywords: acrylic crown, metal-composite crown, single implant, FEA

Hernia prostheses have become, naturally, the standard in the surgical treatment of parietal defects. The development of this surgery led, besides the general complications relating to the surgery, to the occurrence of complications due to the prosthetic material used. Septic complications due to prosthetic material are difficult to treat, with long-term evolution and decrease in the patient’s quality of life. The objective of this study is to demonstrate that the incidence of septic complications can be reduced if morphological properties and clinical implications of the implants are known. Prosthesis susceptibility to infection is directly related to its structure, porosity and type of filament, these being the main criteria to be taken into account, especially when intra-operative septic times are expected. In conclusion, the incidence of chronic sepsis can be reduced by choosing, when clinical conditions allow, monofilament macroporous materials less susceptible to chronic infection. Key words: mesh infection, hernia, mesh porosity, polypropylene, ePTFE, polyester