Papers by Keyword: Surface Modification

Abstract: In this paper surface modification was adopted on 3 kinds of titanium alloy and TiO₂ nanotubes arrays were prepared on these surfaces by anodic oxidation method.nanoindentation and nanoscratch experiments were performed to test the mechanical properties of TiO₂ film, such as micro hardness and elastic modulus.Through comparing and analyzing,it is seen that,The film generated on the TC4 has better mechanical properties than the others and TC4 is better substrate for surface modification by anodic oxidation as the implanted materials.

Abstract: Titanium dioxide (TiO₂) possesses excellent photocatalytic activity and provides UV protection for polymeric materials. The nanosized TiO₂ particles with larger surface area to volume ratio and an increased surface reactivity shall impart better photocatalysis and UV protection efficiency to the rubber compounds, compared to the use of conventional micron-sized particles. Direct incorporation of TiO₂ nanoparticles (n-TiO₂) into non-polar rubbers faces incompatibility problem between the two phases. One of the solutions to overcome this problem is to treat the nanoparticle surface by using silane coupling agent such as bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT). This work prepared n-TiO₂ from commercial micron sized-TiO₂ by ultrasonication technique. Particle size of TiO₂ was measured by laser light scattering particle size analyzer. The morphology of TiO₂ nanoparticles was characterized by field emission scanning electron microscope (FESEM). The grafting reaction of silane on TiO₂ nanoparticles surface was studied at varying reaction temperatures and times. The purified grafted materials were characterized by energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The characterization data confirm a presence of grafted silane on the TiO₂ nanoparticles surface. The result shows that ultrasonication technique can effectively decrease particle size and the grafting reaction of silane coupling agent onto TiO₂ nanoparticles can be successfully carried out at 140°C for 8 h.

Abstract: We propose an innovative approach to impart graphene properties to the surface of thin-film composites polyamide. Specifically, biocidal properties were obtained by covalently binding graphene to the polyamide surface. Grafting of polymer onto graphene generate nanocomposites, which heighten anti-bacterial property by changing on morphology and graphene structure. Purpose of this survey is studying the degradation of bacteria wall by grafted graphene to polyamide. In this study, the graphene should be functionalized in order to boost the side activities, antitoxin property and dispersion in solution. Then, the covalent bonds are established between graphene and polyamide by a linkage function such as ethylendiamine. The result of grafting polymer has been characterized by TGA, SEM and XRD and evaluated for the anti-bacterial property of grafted polymer by analysis on E.Coil bacteria cells. The test of bacteria in present of grafted polyamide lead to destruction of 62% of bacteria in 1 hr.

Abstract: In the present work, we have focused on the synthesis and characterization of Polystyrene (PS) nanocomposites incorporated with anatase-TiO₂. The nanoTiO₂ particles were used in two forms including surface modified (mod TiO₂) and surface unmodified (unmod TiO₂). Accordingly, two PS/TiO₂ nanocomposites were synthesized, i.e. (PS/mod TiO₂) and (PS/unmod TiO₂), starting from styrene monomer in the presence of sodium dodecylsulfate (SDS) emulsifier. 4,4-Methylene diphenyldiisocyanate (4,4-MDI) was used for the surface modification of the nanoTiO₂ particles via urethanation reaction with terminal OH groups. After modification, optical behavior of the samples was determined. The chemical structure of pure polystyrene (pure-PS), (mod TiO₂), (PS/mod TiO₂), and (PS/unmod TiO₂) was confirmed by FT-IR spectroscopy. X-ray diffraction (XRD) analyses obviously showed the broad peak related to the (pure-PS) centered at 2θ of 20 ° as well as the sharp characteristic peak of the TiO₂ nanoparticles appeared at about 2θ of 25 °. Moreover, diffuse reflectance UV/vis spectroscopy analyses, (mod TiO₂) and (PS/mod TiO₂) samples showed strong visible absorption at the range of 400 to 600 nm.

Abstract: Bacterial contamination of implanted devices is a common cause of their failure. Microbial contamination of the biomaterials differs from that of natural tissues. In fact, the contamination modalities of medical devices depend on many peculiar factors related to them: the chemistry of the biomaterial, the physical properties of the surface, the design of the medical device, the extension of surgical invasion, and the time of application. The environment and/or the conditions and response of the host also contribute to the development of infection. Viruses, fungi, protozoas and bacteria are all involved in biomaterial contamination. They are endogenous commensals of the mouth, not virulent in planktonic form, but pathogens when arranged in biofilm.In this paper we review the potency of application of Gallium doping to the surface biomaterials addressed for surgical implantation in order to contrast the bacteria biofilm formation

Abstract: Various kinds of materials have been found to bond to living bone and some of them are clinically used as important bone substitutes. However, they can not be used under load-bearing conditions, since their fracture toughness are not so high as that of human cortical bone. All of them are based on calcium phosphate or silicate. The present authors recently showed that even Ti metal and its alloys having high fracture toughness can show bone-bonding bioactivity, if they are subjected to simple chemical and heat treatments to form some kind of titanium oxide or titanates on their surfaces. They can show not only bone-bonding property, but also novel functions such as osteoinduction, release of antibacterial or bone-growth promoting ions etc.

Abstract: The surface of Ti6Al4V alloys was activated by a selective laser microstructuring and subsequent sintering of hydroxyapatite (HAp) nanopowders into the generated structures. For structuring, a novel q-switched CO₂ laser with pulse durations of about 600 ns and a peak power of up to 60 kW was used. This laser system provides defined blind holes and channel-like geometries with structural sizes in the range of 100-500 μm. The influence of different process gases (Ar, O₂, N₂) on the formation of titanium oxide (TiO₂) and titanium nitride (TiN) interfaces during laser structuring was investigated by GDEOS. HAp nanopowders prepared by a wet-chemical synthesis route were subsequently sintered into the generated structures using a CO₂ laser with continuous radiation intensities up to 2·10² W/cm². The homogeneously sintered structures consist of HAp as the major phase and minor amounts of tricaliumphosphate (TCP) and tetracalciumphophate (TTCP). The formation of TCP and TTCP during laser sintering can be minimized by adjusting sintering parameters (time, laser intensity) and by applying additional process gases (O₂, Ar).

Abstract: Electrokinetic potential (zeta potential) is a characteristic parameter for description of the surface chemistry of solid flat materials and it can be used for a fast analysis of materials modified by different chemical or physical methods. Due to its sensitivity, zeta potential is able to distinguish surface modified by coating with monolayers of various materials or nanostructures created after plasma treatment. Also metal nanostructures deposited on surfaces can be characterized by zeta potential. It can also be used for isoelectric point determination of materials. We present data on zeta potential in 0.001 mol/dm³ KCl at constant pH7.0 and also in pH range (2.5-7.0) for isoelectric point determination for pristine polymers PET, PTFE, PS, LDPE, HDPE, PLLA, PVF, PVDF, PMP and polyimides (Upilex R, Upilex S, Kapton). The zeta potential of selected polymers, modified by plasma and by chemical coatings (e.g. by biphenyldithiol or polyethyleneglycol) or by gold deposition was measured too. Zeta potentials of these modified materials were also studied to confirmation that electrokinetic analysis is acceptable method for their fast description.

Abstract: The experiment program was carried out to investigate strength performance and flexural properties of concrete containing recycled crumb rubber. The rubber contents of 10,20,30 and 40% by volume were selected to partially replace the fine aggregate with crumb rubber of 20 mesh, and sodium hydroxide (NaOH) solution was employed to modify the rubber surface, enhancing adhesion between rubber particles and cement paste. Uniaxial compression and four point bending tests showed that both compressive and flexural strength reduced as crumb rubber inclusion increasing. It is notable that surface modification by NaOH solution have positive effects on strength properties of crumb rubber concrete, and the failure mode tends to become ductile failure due to the rubber inclusion rather than brittle failure of normal concrete.

Abstract: Poly (methyl methacrylate) (PMMA)-graft-cellulose nanofibers (CeNFs) (PMMA-g-CeNF) were synthesized by means of graft-polymerization using Azo initiator in aqueous medium. The synthesized grafted fibers were characterized by Fourier transform infrared spectroscopy (FT-IR). Then, PMMA-g-CeNF were hydrolyzed by acid hydrolysis method with different acid constant and hydrolysis time and characterized by gel permeation chromatography (GPC). Finally, PMMA-g-CeNF was characterized by thermo-gravimetric and differential thermal analyses (TG-DTA).