română ȘTEFANIA MARIN, MĂDĂLINA GEORGIANA ALBU KAYA, GEORGETA VOICU, GRAȚIELA TEODORA TIHAN
Abstract
In this work the attention was focused on the superior properties of polyvinylalcohol – collagen hydrogels.Burns leads to exposure of the deeper layers of skin proportional to the size and depth of the wound. The pH level in the wound bed is a key parameter for assessing indicative of wound healing problems and temperature the same. The lower temperatures can stop the activity of the cells involved in the healing process.The aim of this study was to characterize hydrogels previously obtained in terms of pH and temperature sensitivity in order to choose the most appropriate formulation that could be used for burn healing. Hydrogels were made from collagen gel with initial concentration of 2.85% and polyvinyl alcohol having a molecular weight of 60 000 Da. The hydrogels obtained were lyophilized in order to be analyzed by microstructural appearance (SEM images) and also from the point of view of their sensitivity to different values of pH and temperature. Based on result obtained it was demonstrated that the sample with equal proportions of collagen and polyvinyl alcohol shows that it has the required properties in order to be used as a dressing in healing burns. This hydrogel will be basic support for new smart dressings with included nanoparticles, with targeted applications in medicine.
Keywords
composite, collagen, polyvinyl alcohol, hydrogels, pH, temperature
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Year
2017
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Issue
47 (1)
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Pages
78-83
GHEORGHE ION POPESCU, OLIVERA LUPESCU , MIHAIL NAGEA, DAN CORNECI
Abstract
Fibrin-based sealants are mainly based on fibrinogen and thrombin; in the presence of even small amounts of Factor XIII and calcium, fibrinogen is polymerised by thrombin into insoluble fibrin, which organises as a network with multiple functions: it has a major role into the coagulation cascade and it also enhance wound healing, thus playing a key role in human body reaction to any type of aggression, including the surgical procedures. Due to their properties, fibrin-derived materials have been intensively studied and enhanced, so that they nowadays represent a group of great interest for many medical fields. One of the most frequently performed orthopaedic procedures, hip arthroplasty is, in the same time, considerably invasive upon homeostasis, especially due to bleeding, which can lead to dramatic outcome of the patients, as well as upon the soft tissues, with different healing properties. Intensive studies have been thus performed in order to find materials able to diminish these effects, fibrin-based sealants proving themselves as able to fulfil these requirements. This paper reflects the clinical experience of using a Fibrin-based sealant in major orthopaedic procedures, revealing the advantages of using this type of materials for the outcome of the patients.
Keywords
fibrin sealants, hip arthroplasty, haemostatic, fibrin glue
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Year
2017
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Issue
47 (1)
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Pages
84-90
S. RAJESH, G. B. BHASKAR, R.SUBASH, K. PAZHANIVEL, S. SURESH SAGADEVAN
Abstract
The advancement in fiber composite technology puts back many dense materials by high strength to density ratio. Many attempts have been made with glass/carbon fiber for suspension system; still, not much has been done in the direction of optimization of the design of the leaf spring. This paper reports the work in which a new glass/carbon fiber composite material was made and tested under Tsai–Wu failure stress criteria. The Response Surface Methodology (RSM) was applied to identify the optimal composite leaf spring’s design with less stress-strain and deflection. The mechanical properties of the optimal geometry glass/carbon fiber composite leaf spring were experimentally evaluated and compared with the conventional leaf spring.
Keywords
Optimization; leaf spring; Composite; Suspension; Fiber Reinforced Plastic (FRP)
MAHAMASUHAIMI MASAE, LEK SIKONG , WITTHAYA SRIRIKUN
Abstract
Nanocrystalline TiO2 powder with and without Se doping were successfully synthesized at low temperature by a microwave-assisted sol–gel method. The synthesized TiO2 powders were characterized by XRD, UV-vis, FT-IR and SEM. It was found that anatase and brookite phase was formed after refluxed at 80°C using a domestic microwave oven. The study also investigated the efficiency of this compound to inhibit the growth of Escherichia coli with various concentrations of 0, 0.5, 1.0 and 2.0 mole% doping Se. The antibacterial activity against Escherichia coli was investigated with a vitro test, from which the mixture of conidial suspension and the Se-doped TiO2 powder was added to Macconkey Agar plates under fluorescent light irradiation. It was found that Se-doped TiO2 nanoparticles enhance photocatalytic activity and bacterial inactivation efficiency. In addition, 1.0 mole %Se doped TiO2 nanoparticles can destroy the bacteria within 10 min. Furthermore, the disinfection efficiency of Se-doped TiO2 is good activity is mainly related to the high OH radicals on its surface. The absorption threshold of the Se-doped photocatalyst shifted to the visible region of the spectrum.
Keywords
Antibacterial activity, low temperature TiO2 preparation, sol-gel.
Z. VULUGA. J. PACEAGIU, M. IORGA, A. MOANȚĂ, H. POP
Abstract
In this paper, new composites based on polypropylene (PP) filled with 5 ÷15% natural siliceous material and 20% styrene-butadiene –styrene block copolymer (SBS) were prepared. The siliceous fillers used in this work were the volcanic tuff and kaolinite clay. PP composites filled with mineral filler and SBS were prepared using extrusion compounding and injection molding by dynamical melt processing.
The influence of the mineral filler and SBS on the thermal properties (thermal conductivity and thermal stability evaluated by TG/DTA analyses) and mechanical properties (elasticity modulus, yield strength, elongation at break and Izod impact strength) of the PP matrix composites were studied.
The results showed that the elasticity modulus of new composites is enhanced with increasing the filler content. A better behavior is noticed in case of volcanic tuff using. The Izod impact strength is more enhanced (of 2.5 times) by adding of 20% SBS in the PP/mineral filler composites. Also, the thermal behavior of PP matrix composites is improved.
Keywords
organo-mineral composites, volcanic tuff, clay, mechanical properties, thermal properties .
ALIM KAŞTAN, YILMAZ YALÇIN, HÜSEYIN ÜNAL
Abstract
This study investigates the wear behavior of the composites such as wear rate-load, coefficient of friction-load and coefficient of friction-direction relationships. For this purpose, polyamide 6 (PA 6), high density polyethylene (HDPE), montmorillonite as nanoclay (NC) and the compatibilizer maleic anhydride-grafted-polyethylene (PE-g-MA) are used in this study. The HDPE, nanoclay (montmorillonite) and the compatibilizer are added to a PA 6 matrix material and their effect on the wear property of the composite is investigated. The wear tests are performed in a pin-on disk machine to determine these properties. Optical microscope examination of the wear surfaces is conducted by a transmission electron microscope (TEM) in order to find out more about the material characterization. As a result of the experiments, it is observed that 1% nanoclay (montmorillonite) added to the material has a positive effect on the wear. However, the wear is observed to increase with an increase in the rate of the nanoclay.
Keywords
Polymer, Nanocomposites, Polyamide 6, High density polyethylene, Wear
M.ZİYA KARATAŞ, TAMER RIZAOĞLU
Abstract
The development of materials that provide thermal comfort in buildings have become popular in recent years.The investigation of the technical characteristics of these products and the development on these characteristics have been accelerated in line with this trend. In this context, as well as the specifications of the materials used, the sensitivity to environment and economical processing are also important. In this study, particularly due to the low thermal conductivity of muscovite, mica schists were used as one of the components of the composites together with well-known natural isolation materials such as perlite and pumice. On the other hand, for the first time, the arenitized granite was used for this purpose. The physical and mechanical tests were performed on blocks (40x40x160 mm in size) prepared from the combination of the materials mentioned above and final products (isolation panels) produced after the application of the mixtures on Expanded Polystyrene foam (EPS), Extruded Polystyrene foam XPS and Mineral wool. Both blocks and plates provide the expected technical satisfaction for the physical and mechanical characteristics, according to ASTM and Turkish standards.
Keywords
Natural materials, Isolation plates, XPS, EPS, Mineral Wool
I.HUDIȘTEANU, N. ȚĂRANU, D. N. ISOPESCU, L. BEJAN, A. AXINTE, D. UNGUREANU
Abstract
The paper presents a comparative analysis of six cases of symmetrically balanced composite laminates, having the same stacking sequences in terms of fibre orientation angles, but different composite laminas. The purpose of the paper is to investigate the influence of the selection of the composite materials and configurations of the laminas on the mechanical performances of laminated composites.
A finite element analysis in ANSYS Composite Pre/Post software is performed in order to study the mechanical characteristics under tensile loading of the composite laminates and to analyse the stresses and damage distributions on each layer with different fibre orientations.
The results are comparatively presented in terms of the in-plane and flexural engineering constants of the considered laminates, ultimate loads when first ply failure (FPF) and last ply failure (LPF) occur, and their corresponding equivalent stresses on the layers of the laminates.
The damage initiation and damage evolution on the layers of the composite elements are indicated for different loading steps.
Keywords
composite laminates, failure criteria, first ply failure, last ply failure, damage initiation and evolution
C. O. BURADA, M. M. STĂNESCU, C. M. MIRIŢOIU, A. BOLCU
Abstract
The research presented in this paper consists in obtaining some composite platbands from polyester resin with randomly disposed fiber glass fabric as reinforcement. For the obtained samples, tensile loading on an universal testing machine was made and their elasticity modulus has been determined. Then, the experimental results have been compared with the ones obtained from some analytical methods. In the second part of the paper, the platbands were clamped at one end and the other was left free. By placing an accelerometer at the free end, free vibrations were recorded. By analyzing the free vibrations, the damping factors per unit mass and length, the eigenfrequency, the dynamic Young modulus and the loss factor have been determined. Very close results have been obtained between the static and dynamic Young moduli and, in the end, an overall elasticity modulus for samples with different glass fiber volume fractions has been defined.
Keywords
elasticity modulus, static loading, damping factor, eigenfrequency, loss factor, free vibrations .
A. MOANȚĂ, I. MOHANU, J. PACEAGIU, D.C. NĂSTAC, I. PETRE, R.M. FECHET
Abstract
The paper presents the results of laboratory research concerning the possibility of replacement the pyrite cinder from the clinker’s raw mix, with other waste with high Fe2O3 content, like mill scale. An assessment of technological and qualitative aspects that involved this issue was taken into account. The influence of mill scale both on the raw mix burnability and clinker characteristics was investigated. The composition, mineralogical and structural – textural features of the resulted clinkers were characterised by wet chemistry, X-rays diffraction, and optical microscopy analysis. Also, theoretical consumption of heat at clinker formation was assessed. Cements CEM I were obtained from clinkers synthetised in the laboratory. These cements were characterized from physical-mechanical point of view, according to SR EN 197-1. The qualitative appreciations and the technological behavior were achieved in comparison with a raw mix, obtained from current raw materials, considered as reference. Presence of mill scale in raw mix did not modify qualitative characteristics of the clinker and cement, respectively. This finding sustains the possibility of replacement of the pyrite cinder with mill scale in clinker raw mix.
Keywords
clinker, steel mill scale waste, cement
C.VIVEKANANDHAN, P.S.SAMPATH, SURESH SAGADEVAN
Abstract
Composite materials are being widely employed in numerous modern applications. Fabrication of new composite materials has been holding the consideration of scientists worldwide and attempts are being made to improve the applicability of these materials. In perspective of this advancement in the research field, the present work attempts to concentrate the impact of nanoclay content on the structural and morphological behavior of epoxy composites. Epoxy materials were reinforced with various particulate portions of chosen nanoclay and the specimens were investigated. The structural examination of the polymer composite with X-ray diffraction showed that the nanoclay was distributed as an intercalated structure in the polymer matrix, and the d-spacing of layers decreased with increasing nanoclay content. SEM images analysis revealed that 2% nanoclay reinforced samples exhibited less number of but more uniform pores compared with 10% nanoclay reinforced samples.
Keywords
Composite materials, Nanoclay, Scanning electron microscopy, X-ray diffraction.
C. RAMESH, C. MANICKAM, T. MARIDURAI, V.R. ARUN PRAKASH
Abstract
In this present work particulate epoxy composite was prepared with thermo assisted surface treated Fe2O3 fine particles. The principal aim of this work is to improve wear resistance of epoxy resin by reinforcing iron oxide particles. Particle size of 800nm and 200nm were used to fabricate particular composites. Particles were heat treated from 30º C to 900º C in a muffle furnace to relive induced stresses which are gained in pre processes and getting magnetite phase. The resultant phase change in iron oxide particles were confirmed by X-ray diffraction. The heat treated particles were again surface treated with a silane coupling agent 3-Aminopropyletriethoxysilane (APTMS). The composites were prepared with reinforcement of 1wt%, 3wt% and 5wt% of iron oxide filler into epoxy resin. All proportions of composites were cured by an aliphatic hardener triethylenetetramine (TETA). Wear characters of epoxy-iron(III)oxide system was studied with pin-on-disc setup. Wear resistance was improved significantly for particle loaded composite in which heat treated siliconized iron oxide-epoxy system gave better result. Scanning electron microscopic images revealed filler dispersion on epoxy matrix.
Keywords
Particulate composite; APTMS; SEM; Optical microscopy; Pin-on-disc
ALEMDAR ONGUN, AHMET AVCI, ALI ERIŞEN
Abstract
This study was conducted for the purpose of examining the mechanical relations of the multi-walled carbon nanotube (MWCNT) and the nanoclay (NC) with each other on the carbon fiber composite materials. Samples were prepared by reinforcing the MWCNT and the NC into the epoxy matrix at various rates to have them absorbed into the carbon fiber laminates via the vacuum infusion method. Carbon nanotube (CNT) was added into all the epoxy samples at a rate of 0.3 wt% of the epoxy weight, while the nanoclay was added at rates of 1 wt%, 3 wt% and 5 wt% of the epoxy weight. Additionally, the only CNT-reinforced samples (also, not reinforced with NC) were also readied in order to observe the difference. Tensile tests and three point bending tests were conducted to determine the mechanical properties. The NC and the CNT were observed to adhere to the carbon fiber filaments in the scanning electron microscope (SEM), and NC-based bridge cracks were noted.
Keywords
Multi Walled Carbon Nanotube, Nanoclay, Tensile Test, Three Point Bending Test
DRAGOȘ UNGUREANU, NICOLAE ȚĂRANU , DORINA NICOLINA ISOPESCU, VLAD LUPĂȘTEANU, PETRU MIHAI, IULIANA HUDIȘTEANU
Abstract
This paper presents the outcomes of a comparative study between two fibre reinforced polymer (FRP) composites adhesively bonded joints, namely the single lap joint (SLJ) and the thick adherents joint (TAJ). Thus, 18 distinct models have been conceived and analysed. The variable parameters which are considered in this study are: the bond length and the thickness of the adhesive.
The two general types of joints have been modelled in Ansys Workbench finite element analysis software. Each model has been loaded longitudinally with a tensile force of 1000 N. The parameters that characterise the surface of the FRP composite elements have been determined based on microscopic studies, through graphic and numerical processing of the images.
Based on the outcomes numerical analysis, the variation of the stresses along the bond length has been graphically illustrated. The results delivered by the numerical analysis have been compared with the ones obtained analytically, by applying the available theoretical models. It was concluded that the two methods, provide similar predictions regarding the distribution and the peak values of the shear stresses.
Keywords
adhesive joint, glass fibre reinforced polymer composite, finite element modelling, analytical models
DANIELA FIAT
Abstract
The paper presents the results of the studies performed on the influence of redispersible powders and of the cellulose ethers in mineral plasters applied as the last layer in exterior thermal insulation composite systems. Starting from traditional recipes, using polymeric additives specific for ETICS, there were developed original products in which the polymer additive (redispersible powder) concentration was modified with impact on physical and mechanical characteristics.
The using of the cellulose ether led to obtaining some light compositions (smaller density) and good workability at application.
The using of the redispersible powders has contributed to obtaining some mortars with low water permeability, high water vapour permeability and good support adherence, significant advantages for the products durability.
There have been highlighted the chemical interactions between the redispersible powders and the Ca2+ ions released during the cement hydration process. The redispersible powders act as a second binder in the system, thus leading to improved performance.
Keywords
mortar plasters, polymeric additives, cellulose ether, redispersible powders