Influence Of Surface Modification Research Articles

Surface Modification of Fumed Silica by Dry Silanization for PP/POE-based Dielectric Nanocomposites

A systematic study of the influence of surface modification of nanosilica with coupling agents having different polarities on the dielectric properties of a PP/POE/silica blend was performed. The main goal of this investigation was to tailor the chemical composition of the silica surface, in order to modify the charge trapping properties of the nanocomposites. For the modification of the silica surface, a “green” approach was utilized: a dry silanization method, which is performed without the need of a solvent. The results of the thermogravimetric analysis (TGA) indicate that the dry process is an effective method to perform silica surface modification using alkoxysilanes.The charge trapping properties were studied by Thermally Stimulated Depolarization Current (TSDC) measurements. The obtained TSDC results show significant differences in charge trapping properties of PP/POE composites filled with differently modified silicas. Polar functional groups attached to the surface of the silica appear to have a strong effect on the charge trapping properties: The trap depth distribution becomes deeper and the trap density decreases to significantly lower levels.All results show that incorporation of surface modified nanosilica into a PP/POE matrix is a promising approach to tailor its dielectric properties. Further development of these composites may lead to benefits for application in high-voltage cable and capacitor applications.Keywords: silica surface modification, dry silanization, charge trapping, PP, POE, TSDC, high voltage cable.

Influence of surface modifications on the degradation of standard-sized magnesium plates and healing of mandibular osteotomies in miniature pigs

Biodegradable magnesium alloys are suitable osteosynthesis materials. Despite the alloy composition, surface modifications appear to have an influence on the degradation process and biocompatibility. The aim of this study was to investigate the impact of hydrogenation and fluoridation of the surface in a mandibular osteotomy model. Standard-sized plates and screws were implanted in an osteotomy at the mandibular angle in nine miniature pigs. The plates and screws were harvested together with the adjacent tissues at 8 weeks after surgery and were investigated by micro-computed tomography and histological analysis. The bone healing of the osteotomy was undisturbed, independent of the surface properties. The adjacent bone tissue showed new bone formation at the implant surface; however, formation of some lacunae could be observed. The corrosion was between 9.8% and 11.6% (fluoridated<hydrogenated<non-modified) in histological specimens, while radiologically neither the volume nor the density of the osteosynthesis material was reduced in any treatment group. The soft tissues exhibited full biocompatibility with every surface property. In summary, surface modification by hydrogenation and fluoridation did not significantly influence bone healing, biocompatibility, or corrosion kinetics of the magnesium osteosynthesis at the mandibular angle.

Surface modification of Kevlar fibre fabric and its influence on the properties of Kevlar/epoxy composites

The present study addresses the enhancement of interfacial interaction between Kevlar and epoxy through surface modification of Kevlar fabric using various chemical treatments. The chemically modified aramid surface was examined by Fourier transformed infrared spectroscopy, energy dispersive spectroscopy, scanning electron microscopy (SEM), dynamic mechanical analysis and wettability characteristics. The Kevlar/epoxy composites were prepared using the hand lay-up process. Furthermore, the influence of surface modification was validated through the mechanical characteristics of Kevlar/epoxy composites. The study reveals that the chemical treatment of the Kevlar surface increases the polar functional groups and improves the interfacial adhesion between fibre and epoxy. The surface energy, work of adhesion and performance of Kevlar composites were studied for treated and untreated fibres. The tensile and flexural moduli were increased up to 38% in treated Kevlar fibre compared with untreated fibre. It was observed from SEM analysis that adhesive failure bonds rely on chemical bonds at the interface of fibre matrix composites and cohesive failure at the fibre matrix was decreased.

Influence of Surface Modification and Dispersive Additives on Dielectric and Electrical Properties of BiFeO3/Poly(methyl methacrylate) Composite Films

Surface modification plays an important role to enhance the dielectric constant and minimize the dielectric loss. In this study, poly(methyl methacrylate) (PMMA) composites filled with 2-aminoethanesulfonic acid-modified bismuth ferrite (BiFeO3; BFO) have been prepared via solution casting technique. The surface morphology of the composites provides a better homogeneous dispersion of the particles in the polymer matrix and increases interface compatibility between modified BFO and PMMA matrix. The experimental results show that the composites have high dielectric constant (≈ 147), alternating current (AC) conductivity (1 × 10−5) and relatively low loss (< 1) at 100 Hz. The percolation phenomenon is well observed in the composite having less than 30 wt.% of BFO particles. Further, the composites produce passivation layers on the surface of modified BFO particles which might improve the morphology and promote the space charges, interface effects and dielectric properties. Our strategy is to provide a simple and efficient approach to fabricate high-performance dielectric composites for energy storage applications.

Influence of surface modification on enhancement of luminescent properties of SiO2@SrTiO3:Dy3+ nanopowders: Probe for visualization of sweat pores present in latent fingerprints

The paper reports, novel SiO2@SrTiO3: Dy3+ (5 mol %) nanopowders fabricated via the low temperature sonochemical route by utilizing bio-surfactant Aloe Vera gel extract. The powder X-ray diffraction results display intense and narrow peaks confirm the monoclinic phase of SrTiO3. The photoluminescence emission spectra of SrTiO3:Dy3+ (5 mol %) with different layers of SiO2 coating display intense and characteristic peaks at ˜ 483 nm (4F9/2 → 6H15/2), 576 nm (4F9/2 → 6H13/2) and 664 nm (4F9/2 → 6H11/2). The broad thermoluminescence glow peak with maximum intensity at ˜ 200 °C for both with and without coated SrTiO3:Dy3+ (5 mol %) nanopowders was noticed. The optimized SiO2@SrTiO3:Dy3+ (5 mol %) nanopowders was most suitable for visualization of the latent fingerprints, revealing explicit specific ridge characteristics, including level I -III. Therefore, the present work opens a new possibility of use of prepared nanopowders for WLEDs, visualization of latent fingerprints and dosimetry applications.

Various influence of surface modification on permeability and phase stability through an oxygen permeable membrane

Good oxygen permeability and stability of oxygen transport membrane are highly necessary for practical applications. Herein, through different theories, the oxygen transport limitation step through the Ruddlesden-Popper (Pr0.9La0.1)1.9Ni0.74Cu0.21Ga0.05O4+δ ((PL)1.9NCG) membrane was demonstrated firstly, which suggest surface modification can be an effective approach to improve the oxygen separation performance. After coating, various influences of different side surface modification on permeability and phase stability were observed. The sweep-side coated membrane exhibits largely enhanced permeation fluxes than feed-side coated membrane, and the feed-side coated membrane shows better phase stability under the same conditions (these results reveal that the sweep side is the permeability limitation side and the feed is the phase stability limitation side). The both side coated membrane combines abovementioned advantages which shows 57% enhanced and stable oxygen permeation flux at 800 °C. The observed various modification effects on the permeation performance are discussed based on the surface exchange properties and the mechanism of the oxygen transporting membrane in detail.

What is the impact of surface modifications and particle size on commercial titanium dioxide particle samples? – A review of in vivo pulmonary and oral toxicity studies – Revised 11-6-2018

There is an ongoing discussion on the influence of surface-modifications on the toxicity of commercial particulate materials and how alterations in physical-chemical properties of surfaces impact toxicity. Titanium dioxide (TiO2) is a poorly soluble particulate material of significant socioeconomic importance that largely exists as surface-modified particle-types in commerce. The observed toxicological effects of TiO2 are primarily due to particle effects rather than substance chemistry, as such TiO2 is commonly considered to be a poorly soluble low toxicity (PSLT) particle. This review provides an overview of the effect of surface modifications on the pulmonary and oral toxicity of commercial TiO2 particles with emphasis on in vivo studies with appropriate controls, and where both surface modified and untreated materials are present in the same study. Published literature findings involving pulmonary and oral exposures to surface modified TiO2 particles were reviewed and evaluated for quality and commercial relevance. Suitable publications involving animal studies were identified and summarized. Several studies were identified that have evaluated commercially-relevant surface-modified forms of titanium dioxide with appropriate data quality and with direct comparison to untreated counterparts. Hydrophilic inorganic surface modifications including silica, alumina/alumina hydroxide depositions have been tested along with common hydrophilic and hydrophobic-organic surface treatments. The results for both pigmentary and nanoscale materials demonstrate similar behaviour and indicate limited impact of particle size, surface chemistry, surface charge and surface wettability on observed pulmonary or oral toxicity effects. The low intrinsic toxicity of the TiO2 base particle and evaluated surface modifications may account for the observed outcomes. A few published studies have drawn different conclusions; however, these were either not conducted using commercial TiO2 samples (with surface coatings), had several confounding variables to investigate, or were carried out using mouse strains. The differences in experimental designs are described. The identified pulmonary and oral toxicity studies largely indicate that surface modifications and particle size alone have little or no impact on the lung toxicity of TiO2 particles, following pulmonary exposures when all constituent materials are comprised of chemicals of low specific toxicity particles. In addition, based upon the results of 2 oral toxicity studies, one with surface treated TiO2 particles (OECD 408) and one without surface treated (OECD 407) TiO2 particles, there appears to have been no adverse impact on toxicity with the surface-coated material, as both studies produced no adverse effects at the very high doses tested.

Improvement of structural and optical properties of ZnAl2O4:Cr3+ ceramics with surface modification by using various concentrations of zinc acetate

The influence of surface modification with various concentrations of zinc acetate solution on the structural and optical properties of ZnAl2O4:Cr3+ particles was studied. The X-ray diffraction peaks assigned to the spinel structure of ZnAl2O4:Cr3+ powders revealed a tiny shift towards the lower angle, and ZnO phase was detected when ZnAl2O4:Cr3+ crystals surface was modified. The results of X-ray photoelectron spectra confirmed that the antisite defects related to tetrahedral Al existed in the surface lattices of zinc aluminate crystals. The signal intensity of XPS assigned to tetrahedral Al decreased after surface modification, while that of XPS assigned to octahedral Zn increased. The results of transmission electron microscope showed that the surface lattices of ZnAl2O4:Cr3+ particles became more ordered after surface modification, and zinc oxide nanocrystals were observed as a coating layer or dispersed particles surrounding ZnAl2O4:Cr3+ particles when the concentration of Zn(AC)2 solution increased up to 1.5 mol/L. The red emission assigned to Cr3+ ions in spinel lattices was detected at room temperature, and the emission intensity was enhanced when ZnAl2O4:Cr3+ crystals was modified. While the emission intensity was reduced when the concentration of Zn(AC)2 solution increased up to 1.5 mol/L.

Influence of surface modification on wear behavior of fly ash cenosphere/epoxy syntactic foam

The present study deals with investigating the surface modification effect of fly ash cenosphere (as received and surface treated) on the friction and wear response of epoxy syntactic foams. Such lightweight syntactic foams have the potential in using them as tribo-materials for friction applications like in brake pad composites. This study also addresses the environmental linked disposal issues of fly ash cenospheres by incorporating them (up to 60 vol%) in the epoxy matrix. Cenosphere content and surface modification influence on the friction and wear response of cenosphere/epoxy syntactic foams is investigated against EN31 steel disc under dry sliding conditions. Wear behavior is studied at room temperature for different velocities (2 and 5 m/s), applied loads (30 and 50 N) and sliding distances (3, 5 and 7 km). Neat epoxy exhibits maximum wear rate as compared to foams. Wear rate decreases with increasing sliding distance and cenosphere content at all tested conditions. With the increase in the applied load and the sliding velocity, higher wear rate is noted for neat epoxy samples while it decreases with increasing filler loading. Surface modified cenosphere reinforced foams exhibit better wear resistance compared to as received cenosphere dispersed foams and neat epoxy for all the operating conditions owing to the good interfacial bonding of treated cenospheres with epoxy matrix. Specific wear rate decreases significantly with an increase in applied load. Further, the coefficient of friction decreases with higher filler loading and surface modifications. Scanning electron microscopy is used to study the wear mechanisms. Wear debris is analyzed and disc temperature is also reported. Finally, wear rate results are summarised and compared with the data available from literature and are presented in a property map.

High-voltage performance of LiCoO2 cathode studied by single particle microelectrodes –influence of surface modification with TiO2

The LiCoO2 particle with TiO2 coating presents improved columbic efficiency, overcharge performance, rate capability and cycling stability at high voltage. To gain deeper insight into the performance improvement mechanism of the TiO2-coated LiCoO2 cathode materials, the first-principles calculation combined with single particle microelectrode technique are employed in this work. The first-principles calculation is firstly used to simulate the bulk structure, electronic properties and lithium ion diffusion of TiO2-coated LiCoO2 at different delithiation states, while the microelectrode technique is used to evaluate the thermodynamic and kinetic behaviors of TiO2-coated LiCoO2 on a single particle level without interference of binder, conductive agent, and porous structure of the electrode. It has been revealed that from thermodynamics point of view, the improved electrochemical performance of TiO2-coated LiCoO2 can be ascribed to the reduced surface oxygen activity and surface oxygen loss, which should suppress the electrolyte decomposition and layered structure degradation of LiCoO2 at high voltage. From kinetics point of view, the increased Li-slab space and decreased Li ion transfer activation energy barrier facilitate Li ion diffusion in the solid state of LiCoO2 and Li ion transfer across the solid/electrolyte interphase.

Influence of surface modifications by laser shock processing on the acid chloride stress corrosion cracking susceptibility of AISI 304 stainless steel

Abstract The effects of laser shock processing (LSP) on stress corrosion cracking (SCC) behavior of AISI 304 stainless steel have been investigated using slow strain rate tests (SSRT) in acid chloride solution. Modifications of surface microstructure are characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Results show that LSP generate deformation twins and refined microstructures in the surface layer of AISI 304 stainless steel. Results of SSRT tests reveal that significant improvements in stress corrosion cracking (SCC) resistance are observed in acid chloride solution. These improvements have been attributed to surface microstructure changes and compressive residual stress induced by LSP. The results confirm that the application of LSP is of a practical option to improve SCC resistance of AISI 304 stainless steel.

Influence of surface modification with nitric acid on electrochemical performance of agroindustrial waste-based activated carbon

Two activated carbons (ACs) were superficially modified with nitric acid (HNO3). The ACs were obtained by chemical activation of palm kernel shell, the first one with KOH at a KOH/AC weight ratio of 2/1 and 700 °C (AC–KOH), and the second one with ZnCl2 at a weight ratio of 1/1 and 735 °C (AC–ZnCl2), both at 5 °C min−1. We modified both, the AC–KOH, and the AC–ZnCl2, taking into account the influence of temperature, impregnation time, chemical/precursor weight ratio on the morphology, textural properties, and electrochemical performance. The morphology was characterized by scanning electron microscopy, and the textural properties by N2 adsorption/desorption at 77 K. The superficial chemistry of the samples was characterized using X-ray photoelectron spectroscopy, and the electrochemical performance by electrochemical impedance spectroscopy in 1 M H2SO4. The best electrochemical behavior of approximately 15 μF cm− 2 was obtained with an impedance of 2.9 Ω with HNO3/AC–KOH weight ratio of 1/1 at 25 °C for 4 h. The increase in the interfacial capacitance is attributed to the high superficial nitrogen content (NXPS: 1.8%) that involved faradic processes, as well as to an enhanced hydrophilic character (wettability) and an improved electron transfer caused by the positive charge of nitrogen species in acid electrolytes.

Research on super capacitance properties of modified activated carbon in sodium sulfate electrolyte

In order to improve the specific capacity and energy density of activated carbon electrode materials activated carbon was modified by surface treatment using hydrogen peroxide. The modified carbons were characterized the changes of pore structure and functional groups before and after modification by N2 adsorption-desorption isotherms and FTIR spectroscopy. The three electrode system was assembled with modified activated carbon as electrode materials and Na2SO4 as the electrolyte. The influence of surface modification on the performance of EDLCs was studied by galvanostatic charge-discharge, cyclic voltammetry, and alternating current impedance. The results show that the surface chemistry of the modified activated carbon material has changed, the specific surface area has changed and the pore size has not changed much with the introduction of new oxygen-containing functional groups. The specific capacity of the activated carbon material modified by 5h is 75F/g, which is 86.1% higher than that before the modification. It can be seen that the change of functional group after the modification of activated carbon can help to increase the specific capacity.

Advancements in three-dimensional titanium alloy mesh scaffolds fabricated by electron beam melting for biomedical devices: mechanical and biological aspects

We elucidate here the process-structure-property relationships in three-dimensional (3D) implantable titanium alloy biomaterials processed by electron beam melting (EBM) that is based on the principle of additive manufacturing. The conventional methods for processing of biomedical devices including freeze casting and sintering are limited because of the difficulties in adaptation at the host site and difference in the micro/macrostructure, mechanical, and physical properties with the host tissue. In this regard, EBM has a unique advantage of processing patient-specific complex designs, which can be either obtained from the computed tomography (CT) scan of the defect site or through a computeraided design (CAD) program. This review introduces and summarizes the evolution and underlying reasons that have motivated 3D printing of scaffolds for tissue regeneration. The overview comprises of two parts for obtaining ultimate functionalities. The first part focuses on obtaining the ultimate functionalities in terms of mechanical properties of 3D titanium alloy scaffolds fabricated by EBM with different characteristics based on design, unit cell, processing parameters, scan speed, porosity, and heat treatment. The second part focuses on the advancement of enhancing biological responses of these 3D scaffolds and the influence of surface modification on cell-material interactions. The overview concludes with a discussion on the clinical trials of these 3D porous scaffolds illustrating their potential in meeting the current needs of the biomedical industry.

Investigation of Effective Modification Treatments for Titanium Membranes

Titanium membranes are used for guided bone regeneration in implant therapy. However, as a bioinert material, titanium does not have the ability to accelerate bone formation. Various titanium surface treatments to confer bioactivity have been demonstrated; however, there are concerns about the influence of chemical treatments for thin titanium membranes. This study investigated the influence of surface modifications on the structure of titanium membranes. Titanium membranes of 20 μm thickness were treated with acid or alkali solutions, and we evaluated their surface structure, wettability, thickness, and mechanical strength compared to non-treated membranes. Alkali-treated titanium membranes displayed the formation of nanoscale pore structures on their surfaces, enhanced hydrophilicity, and almost same thickness compared with acid-treated membranes. Furthermore, the tensile strength of alkali-treated membranes was comparable to non-treated membranes. These results suggest that alkali treatment is an appropriate surface modification method for titanium membranes.

Stealth Biocompatible Si-Based Nanoparticles for Biomedical Applications.

A challenge regarding the design of nanocarriers for drug delivery is to prevent their recognition by the immune system. To improve the blood residence time and prevent their capture by organs, nanoparticles can be designed with stealth properties using polymeric coating. In this study, we focused on the influence of surface modification with polyethylene glycol and/or mannose on the stealth behavior of porous silicon nanoparticles (pSiNP, ~200 nm). In vivo biodistribution of pSiNPs formulations were evaluated in mice 5 h after intravenous injection. Results indicated that the distribution in the organs was surface functionalization-dependent. Pristine pSiNPs and PEGylated pSiNPs were distributed mainly in the liver and spleen, while mannose-functionalized pSiNPs escaped capture by the spleen, and had higher blood retention. The most efficient stealth behavior was observed with PEGylated pSiNPs anchored with mannose that were the most excreted in urine at 5 h. The biodegradation kinetics evaluated in vitro were in agreement with these in vivo observations. The biocompatibility of the pristine and functionalized pSiNPs was confirmed in vitro on human cell lines and in vivo by cytotoxic and systemic inflammation investigations, respectively. With their biocompatibility, biodegradability, and stealth properties, the pSiNPs functionalized with mannose and PEG show promising potential for biomedical applications.

Influence of surface modification by sulfuric acid on coking coal's adsorption of coking wastewater.

Coking coal, the raw material of a coke plant, was applied to the adsorption of coking wastewater. In this study, coking coal was directly treated with sulfuric acid to improve its surface properties and adsorption ability. Acid treatment was carried out at various concentrations, by varying from 0.001 to 1 mol/L. The samples were characterized by ash content analysis, scanning electron microscope (SEM), N2 adsorption-desorption analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), wettability analysis, and zeta potential analysis. These results demonstrated that H+ could react with inorganic minerals, which resulted in a significant variation of the chemical composition and the structure of coal surface. Furthermore, both the ash content and the surface content of O = C-O, C = O and C-O groups declined gradually as the concentration of sulfuric acid increased, while the surface area and pore volume of micropore, the lipophilic and hydrophobic properties, and zeta potential magnitude increased, resulting in enhanced hydrophobic and Van der Waals' forces between the fine coal and organic pollutants. Characterization modification showed a better performance in adsorption, the removal rate enhanced from 23% to 42% after treated by 1 mol/L sulfuric acid. It was concluded that the acid activation modified the lipophilic and hydrophobic properties, the surface charge properties, surface area and pore volume, the content of oxygen functional groups, all of which could be potentially useful in wastewater adsorption.

The influence of surface modification, coating agents and pH value of aqueous solutions on physical properties of magnetite nanoparticles investigated by ESR method

The article presents the results of electron spin resonance (ESR) studies for aqueous solutions of functionalized superparamagnetic iron(II,III) oxide nanoparticles. The samples studied differed in type of organic ligands at the magnetite surface, type of coating agent and pH value of aqueous solutions. The ESR spectra of the samples were obtained at room temperature and at 230K. The field cooling (FC) experiment was performed for selected samples, and the effective anisotropy field (HK2) and the first order magnetocrystalline anisotropy constant (K1) was calculated. The process of the nanoparticles diffusion in different environments (human blood, human serum) forced by an inhomogeneous magnetic field was monitored and their interactions with different solvents have been discussed. It has been shown that ESR method is useful to observe the impact of organic ligands at the magnetite surface, type of coating agent and pH value of aqueous solutions on the properties of iron(II,III) oxide nanoparticles.

Influence of Surface Modification on Combustion Characteristics of Charcoal and Its Performance on Emissions Reduction in Iron Ore Sintering

Influence of Surface Modification on Combustion Characteristics of Charcoal and Its Performance on Emissions Reduction in Iron Ore Sintering

Modifikasi Permukaan Elemen Peredam Bising dengan Profil Berbentuk Prisma

The influence of surface modification by using prism shaped profile on the sound absorption of absorber element was investigated experimentally. A prime number based configuration of the two types opened and closed type rism shaped profile inclusion was tested by using impedance tube according ASTM E1050 standard. The result shows that sound absorption at low frequency band below 200 Hz increased with the increasing of closed prism number. It is related to the coupling effect between the cavities of the absorber element and the prisms that changes reactance of the coupled structure. In the other side, a half wave resonance like effect occur on the use of opened prisms inclusion, which is increase the sound absorption performance at mid to high frequency range between 800 Hz to 1.25 kHz.