română ANDREI TIBERIU CUCURUZ, ECATERINA ANDRONESCU, CRISTINA DANIELA GHIŢULICĂ, ANDREIA ILIE
Abstract
The purpose of this study was to improve the knowledge in the field of composite materials based on poly(methyl methacrylate) (PMMA) and silica (SiO2). For this purpose, two types of silica were taken into account: i) silica was synthesised in situu by sol-gel technique and ii) commercial silica was used. In both cases the polymer matrix was obtained by radical polymerisation.
The composite materials were then characterized from the phases point of view by Fourier transform infrared spectroscopy (FT-IR) and X-ray Diffraction (XRD) and from the morphology and compatibility between phases point of view by scanning electron microscopy (SEM).
The results showed that in situu formation of the silica network is preferred over commercial silica addition because it allows a better compatibility between the organic and inorganic compounds.
Keywords
poly(methyl methacrylate), silica, composite material, dental application
ANDREIA ILIE, ECATERINA ANDRONESCU, CRISTINA DANIELA GHIŢULICĂ, ANDREI TIBERIU CUCURUZ
Abstract
The scope of the present work was to study the release of methylene blue from a composite material based on collagen and hydroxyapatite.
The obtaining of the composite material was achieved by co-precipitation of hydroxyapatite in the collagen matrix (at a pH of 10.5). Later, methylene blue was added dropwise because the composite material is intended to act as support for releasing methylene blue; the release of methylene blue ensuring the antiseptic nature of the material.
The composites were then characterized by: Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) while the release process was monitored by UV-Vis spectroscopy.
The characterization of the collagen/hydroxyapatite composite material revealed a good mineralization of collagen matrix a high stability of the mineral phase, as well as the capacity to bind/absorb methylene blue.
From the point of view of the release process, the results showed a gradual release that was evidenced by UV-Vis spectroscopy, the release evolution being monitored at a wavelength of 663 nm, characteristic.
Therefore, studies suggest the use of collagen/hydroxyapatite composite material as support for tissular regeneration of bone tissue, methylene blue providing antiseptic properties.
Keywords
hydroxyapatite, collagen, drug release, methylene blue
MARIA SONMEZ, DENISA FICAI, ANTON FICAI, LAURENŢIA ALEXANDRESCU, GEORGETA VOICU, ECATERINA ANDRONESCU
Abstract
In this paper, the technology for obtaining polypropylene (PP) based composite materials reinforced with functionalized glass fibers (GF) is described. In the first step, glass fibers were functionalized by hydrolysis/condensation with (3-aminopropyl) trimethoxysilane as functionalization agent and in the second step, these materials were compounded at 180oC in a Brabender mixer with isotactic polypropylene. The obtained composites were morphologically and structurally characterized by X ray diffraction (XRD), infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Based on the obtained results it can be concluded that GF functionalization leads to a better glass fiber - polymer interaction, GF being covered by an intimate PP film.
Keywords
glass fibers, polymer composites, glass fibers functionalization
MIHAI BRATU, OVIDIU DUMITRESCU, OVIDIU VASILE, ALINA CONSTANTIN (CRISTEA), MARCELA MUNTEAN
Abstract
Noise is a ‘non-periodic sounds’ complex which affects biological and psychological state of people and other natural organisms. The present paper is dedicated to some new polymeric composites with sound-absorbing properties. The originality consists in obtaining new polymeric composites from formaldehyde resin and various waste types used as reinforcing agents. The sound-absorbing capacity of the new composites varies depending on the proportion of waste used. The absorbing coefficient is presented for each sample; it depends on the porosity of the composite material obtained at the interface between the matrix and reinforcing agent.
Keywords
sound-absorbing properties, wastes, absorbing coefficients, porosity, interface
ADRIAN STROIA, CRISTINA ILEANA COVALIU, CRISTIAN CĂPITĂNESCU, GABRIELA GEORGESCU, IOANA JITARU
Abstract
Lucrarea de faţă prezintă sinteza unui nanomaterial Ni/Ag care a fost obţinut într-un sistem argint macroporos granular (suport) – carboxilat de Ni– alcool benzilic. Produsul sintetizat a fost caracterizat chimic şi structural prin următoarele tehnici de caracterizare: spectroscopie de absorbţie atomică (AAS), difracţie de raze X (XRD), spectroscopie de infraroşu cu transformată Fourier (FTIR), microscopie electronică în transmisie (TEM), spectroscopie de razei X cu dispersie de energie (EDX) şi măsurători ale magnetizaţiei. Materialul prezintă proprietăţi feromagnetice datorate conţinutului de Ni şi poate avea aplicaţii electrochimice şi / sau catalitice.
Keywords
macroporous silver, nickel carboxylates, Ni/Ag nanomaterial.
SORINA STROE, VLAD NAICU, ION PĂTRAŞCU
Abstract
The main objective of our research was to evaluate the PRF potential in bone regeneration of the periodontal bone defect. Using platelet gel for improving bone regeneration is a recent technique in oral surgery and implantology. In this study, based on casuistry, we have evaluated PRF’s local effect combined with the autogenous graft and freeze-dried bone allograft in order to improve bone regeneration in periodontal bone deficiency.
The personal study was accomplished on 5 subjects with various sized periodontal bone deficiencies. From the treated lot, we have selected the most significant clinical case, having an important bone defect in the maxillary frontal area. In the treatment lot we have resolved 3 clinical cases where we have applied peri implantary a mixture of synthetic bone and PRF, plus PRF superjacent membranes. We accomplished a sealing and colonization of the bone defect with the most biocompatible material, assuring quick local bone regeneration and healing. The mixture of PRF – autogenous bone and membrane (PRF), were also used to augment the sinus floor needed for the procedure of elevating the maxillary sinus.
Keywords
platelet concentrate, periodontal defects, maxillary sinus elevation
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Year
2014
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Issue
44 (2)
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Pages
189-194
NICOLAE ŢĂRANU, SERGIU POPOAEI, GABRIEL OPRIŞAN, PAUL CIOBANU, PETRU MIHAI, VLAD MUNTEANU
Abstract
The paper presents the results of a study including experimental tests and numerical modelling performed to investigate the influence of the edge distance and of the tightening torque on the behaviour of steel bolted lap joints of composite plates made of glass fibre reinforced polyesters (GFRP) manufactured by pultrusion.
The experimental program analysis and testing of eighty samples corresponding to four assembly configurations with a variable number of bolts, with different marginal distances and two steps of tightening torques.
Numerical models based on finite elements using ANSYS software package were designed for each assembly configuration tested experimentally, and the obtained results on bearing capacities for the studied joints have been compared.
Keywords
glass fiber reinforced polyesters, pultruded elements, bolted joints, bearing failure
MÜNIR TASDEMIR, SEZGIN ERSOY
Abstract
In comparison to metals, generally unfilled polymers have low thermal conductivity and low wear resistance. Therefore, various filler and reinforcements are frequently added to the unfilled polymers to improve their tribological and thermal properties. So, filled polymers are preferred for many industrial sectors such as aircraft, automotive, electrical/electronic and household application. Friction and wear behaviour is one of the most important properties of polymer and its composites. Therefore, many studies on friction and wear properties of polymer and its composites have been carried out.
In the present work, the friction and wear properties of high density polyethylene/talc and high density polyethylene/calcite polymer composites were studied. Fillers proportions in the HDPE were 5, 10, 15, and 20 wt%. The morphologies of the fracture surfaces of specimens were observed with a scanning electron microscopy (SEM). The result showed that the addition of fillers to the composite changed the friction coefficient and wear rate. For a specimens, wear loss increases with increasing load and sliding distance; meanwhile the friction (static and dynamic) coefficient increases. Wear rate of all HDPE composites is larger than that of pure HDPE. The static and dynamic friction coefficient of HDPE/talc (80/20) composite is slightly less than that of pure HDPE at each load. The modulus of elasticity, elongation, Izod impact strength and hardness values of the composites were also determined.
Keywords
Friction and wear performance of HDPE-talc-calcium carbonate polymer composites against sliding distance and applied load
LORETTA BATALI, HORAŢIU POPA, GHEORGHE PANTEL, NATALIA BUTNARCIUC, ERNEST OLINIC, SANDA MANEA
Abstract
Construction materials made of polymeric fibres (geosynthetics) are a viable alternative to traditional materials (concrete, granular materials) as proven the last years. Their use in association to mineral materials as soils or granular fills leads to composite materials having improved physical and mechanical properties and allowing to build more efficient structures both from structural and environmental point of view. Paper presents the main aspects related to physical and mechanical properties of geosynthetics, the main applications, focusing on reinforcement, filtration and drainage functions. It presents the various interactions between geosynthetics and mineral materials and the properties of the resulted composite material.
Keywords
geosynthetic, mineral material, composite material, physical properties, mechanical properties, laboratory tests
MARIAN DIMA, CĂTĂLIN FRÂNCU
Abstract
This paper presents a method, tested experimentally by designing a stand for fatigue testing of glass fibre reinforced polymer composites (GFRPs) with polyester matrix used in construction. The test is carried out by applying a repeated stress (0 to max) cycle load. Through operating parameters of the stand the method allows the testing of joints (adhesive or mechanical) between parts of composites. The stand is designed for simultaneous testing of six samples and is characterized by high energy efficiency with a power of only 5.5 kW as opposed to 65 kW as required by a classical tensile testing machine with hydraulic drive.
Keywords
composites, fatigue testing, joints testing, repeated stress cycle load
NICOLAE ŢĂRANU, PAUL CIOBANU, SERGIU POPOAEI, PETRU MIHAI, MIHAI BUDESCU, VLAD LUPĂŞTEANU
Abstract
În această lucrare se analizează din punct de vedere teoretic, experimental şi prin modelare numerică, răspunsul structural al unor grinzi din beton armat consolidate cu fâşii înguste din compozite polimerice armate cu fibre din carbon (CPAFC), montate în zona din imediata apropiere a feţei întinse (NSM). Probele consolidate au fost testate la încovoiere sub încărcare monoton crescătoare până la cedare. Inserţia fâşiilor înguste din CPAFC a condus la o creştere semnificativă a capacităţii portante la încovoiere, de până la 220% şi la o reducere a deplasărilor transversale maxime de până la 49%, în comparaţie cu grinzile de control, neconsolidate. Validitatea rezultatelor experimentale a fost verificată analitic şi prin modelare numerică, utilizând programul pe bază de element finit ANSYS.
Keywords
reinforced concrete beams, carbon fibre reinforced polymer composites, strengthening with composite strips, structural response, numerical modeling
R. RAMAMOORTHI, P.S. SAMPATH
Abstract
This paper presents the investigations of thermo mechanical and free vibration properties by reinforcing halloysite nanotube (HNT) with various weight proportions (0,2,4,6,8, and 10wt%) in glass fiber reinforced epoxy (EP/GF/HNT) nanocomposites. Theoretical study was also carried out to study the vibration characteristics of EP/GF/HNT nanocomposites. It was found that the addition of HNT improved the thermo-mechanical and damping properties. Dynamic mechanical analysis showed an increase in the storage modulus and glass transition temperature up to 4wt% of HNT. Vibration analysis proved that the addition of HNT enhanced the internal damping and increased the natural frequency up to 4wt%.
Keywords
Composites, HNT, Epoxy, Vibration, Damping , DMA
OANA STĂNILĂ, DORINA ISOPESCU, NICOLAE ŢĂRANU
Abstract
Fibre reinforced polymeric (FRP) composites have been successfully utilized for strengthening elements made of traditional materials, such as wood. A research program carried out at The Faculty of Civil Engineering and Building Services of Iaşi tested the structural response of wood beams strengthening using carbon fibre reinforced polymeric composites, in different solutions.
The need for realistic analysis of structural behaviour of strengthened timber beams pushed researchers to find analytical and numerical evaluation methods that can correctly replace experimental programs, thus lowering the costs imposed by laboratory tests. The paper presents analytical computations and numerical modelling studies, involving three strengthening methods of timber beams using FRP composites.
Keywords
wood beams, reinforcing, FRP composites, numerical modelling, analytical computation