Sharif Digital Repository

Low frequency (LF) O2 plasma was used to modify the surface of polysulfone (PSF) gas separation membranes. The effect of treatment time and plasma power input on the membranes was also investigated. Pure CO2 and CH4 gas permeation measurements were performed before and after plasma treatment. The results showed the increase of permeability of the treated membranes due to surface ablation and surface polarization. However, the CO2/CH4 permselectivity of the treated membranes varied from 7.7 to 45.3 depending on the treatment conditions. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy determined the introduction of oxygen containing polar groups on the surface... 

In this study, the effects of treatment time and power of Low-frequency (LF) O2 plasma has been investigated for the surface treatment of polyethersulfone (PES) gas separation membranes. PES membranes prepared using dry/wet phase inversion using ternary mixtures containing 1-methyl-2-pyrrolidone (NMP) as solvent, water as non-solvent. The optimum polymer concentration was 32 wt.% , 61 wt.% and 7 wt.% for PES,1-methyl-2-pyrrolidone and water respectively. Pure CO2 and CH4 gas permeation measurements were performed before and after plasma treatment. After treatment gas permeances of around 0.81 GPU for CO2, and 0.073 GPU for CH4 with selectivities of around 11.23 for CO2/CH4 were obtained.... 

A new technique for surface modification of flat sheet hemodialysis membranes has been investigated. This new strategy presents a dynamic surface modification for membranes in order to assess the hydrophilicity, antifouling, and biocompatibility effects of two functional monomers on dialysis membrane. PSF membranes containing polyvinylpyrrolidone were prepared via phase inversion technique. Afterward, free radical polymerization combined with surface polymerization used to introduce acrylic acid and 2-hydroxyethyl methacrylate onto polysulfone membrane surface. Various monomer concentrations were selected to obtain an optimum condition. Field emission scanning electron microscope (FE-SEM),... 

Celery residue modified with H2SO4 was utilized as a low-cost adsorbent for removal of hazardous dyes (methylene blue, malachite green and congo red) and heavy metals (Pb(II) and Cd(II)) from aqueous solution in batch adsorption process. Also, celery residue modified with cationic surfactant (CTAB) to enhance the removal of congo red (anionic dye). The treated and untreated adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). The efficacy of dye removal of the modified celery residue was investigated by varying adsorbent dose, contact time, pH, initial dye concentration, and temperature. Experimental data were fitted by three... 

Elastomers are flexible polymers with various uses in different industries. But this materials dont havevalid usages without correct fillers. Today Nano technology has a main role in the industry. one of the important reasons is rubber quality improvement with adding just a little amount of this clays, opposite to Carbon Black. To achieve a high quality polymer composite, it is necessary to learn about physical and mechanical properties of nano clays and the interaction between Nano clays and matrix. Because of the effect of nano clays on vulcanization, this issue is noticeable . Nano diamond is a nanoclay used to improve rubber quality. But this method is new because of the complicated... 

In recent years, nanodiamond (ND) has been used as reinforcement in polymeric nanocomposites in order to improve mechanical properties, thermal conductivity, etc. The surface of nanodiamond has several functional groups which make it appropriate adsorbent. In this study, nanodiamond was modified with dodecylamine corrosion inhibitor and was utilized (1wt %) in epoxy based nanocomposite. Fourier transform infrared spectroscopy (FTIR) analysis was used to confirm the surface modification of Nanodiamond. In order to estimate the loading amount of corrosion inhibitor, thermogravimetric analysis was investigated. FE-SEM analysis demonstrated nanoparticle dispersibility in epoxy matrix. Regarding... 

Surface modification is an important property of nano particles. In this project surface of silica nano particles modified with hydrophobic and hydrophilic groups to imrprove surface activity of nano particles. Purpose of this project is to study surface activity of surface modified silica nano particles in different temperatures from 20 to 70 degree centigrade. Also effect of salt and time on the surface activity is studied. At first nano particles modified just with haydrophobic groups and then just with hydrophilic groups (hydrophobic and hydrophilic nano particles) and after that, the surface modification done with both hyadrophilic and hydrophobic groups (amphiphilic nanoparticles).... 

One of the remarkable subject in advanced electrochemistry is, design and architecting new advanced materials with new electrochemical capabilities. One of the notable capabilities is electrocatalysis. Extensive researches are carrying out into the design and preparation of electrocatalyst materials to take advantage of these materials in fabrication of electrochemical sensors and storage/conversion devices. In this field nonoporous materials attracted a lot of attentions due to their unique features. In order to make use of the nanoporous materials as the electrocatalysts, these materials must be fabricated into continuous supported thin films on the electrode surface, which is the... 

The main focus of this thesis is based on surface modification of polystyrene in order to prepare extractive phases appropriate for extraction of analytes with a wide polarity range. This goal was achieved by increasing surface polarity. In fact, improved wettability and the possibility of interaction with polar analytes after addition of functional groups on polystyrene surface were the main reason for increased extraction capacity. In the first research, different functional groups including amine, nitro, carboxyl and acetyl were added on polystyrene particles by chemical bonding and to investigate their influence on extraction process, 22 analytes with a wide polarity range (LogP=-2 to... 

Nanoparticles can be applied as chemical agent in enhnaced oil recovery like surfactants and polymers. One of nanoparticles usefull capabilities is modification of their surface. This research investigates this capabilty of nanoparticles in enhanced oil recovery. Surface modification of nanoparticles with both agents can bring new abilities to these materials. Here surface of silica nanoparticles is modified by hydrophilic agent comprising PEG groups, hydrophobic agent comprising propyl group and both agents. FT-IR tests showed that grafting of modifiyng agents on surface of nanoparticles is well done. To investigate effect of nanoparticles surface modification on nanoparticles capability in... 

In this research, modification of polysolfune ultrafiltration membranes is investigated. The enhancement is done via grafting of the acrylic acid as a hydrophilic monomer on the membrane surface. This is a free radical grafting method in which free radicals are formed via redox reaction of ammonium persulfate and sodium metabisulfite as an initiator. Water contact angle, molecular weight cut-off, pure water flux and fouling experiments were used to figure out the optimum conditions for the membrane performance. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were utilized to determine morphological changes of the membrane surface. Furthermore, Fourier... 

This thesis is a research corresponding to Super-Hydrophobic condensation substrates with Nanometer texture. In this study, the foresaid surfaces are fabricated by two methods that are Nano-composite paint and Electrophoretic coating. As a summary for the first method (the Super-Hydrophobic Nano-composite paint), the hybrid coating contains two mineral and organic phases; The organic phase is a two-part clear-coat polyurethane and plays the role as a polymer matrix in Nano-composite structure. Silica Nano-particles are the mineral phase and the two phases of Nano-composite have made connection with silane compounds. Also, surface-modification in Nano-particles for giving hydrophobicity... 

Silica nanoparticles is one of the most important mineral particles. In this study, Sodium silicate, Sulfuric acid and Sodium aluminate is used in order to synthesis of the modified Silica nanoparticles. The effects of temperature, reaction time and the molar ratio of regents were tested and optimized. Synthesized nanoparticles were characterized by use of XRD, FT-IR and SEM techniques. The results show that by controlling the reaction conditions, nanoparticles with an average size of 26.2 nm is obtained. The increase of temperature and reaction time alters the structure of the particles of amorphous state to a crystalline needles. The particle surface modification process was performed by... 

According to human needs and in line with the development of advanced technologies, different biomedical Engineering fields like hard tissue implants are growing rapidly. Despite significant biotechnology Developments in recent years, some problems to the recognition of implants related osseointegration phenomena persist. The deficient osseointegration and implant-associated infections are key issues for the long-term clinical success of titanium and titanium alloy implants, while development of multifunctional surfaces that can simultaneously overcome these problems remains highly challenging. Therefore, the ultimate goal of this paper was to improve bone cell attachment and simultaneously... 

Reverse osmosis membranes are one of the most common methods of desalination of water in the world today. In the meantime, aromatic polyamide thin-film composite reverse osmosis membranes have one of the best performances and can be widely used in industry. This project aims to make surface modifications on the made raw membranes and increase the degree of crosslinking to improve the functional properties of the membrane, such as the percentage of salt rejection and the flux of permeate, and the reduction of fouling. For this purpose, polyvinyl alcohol and l-arginine along with maleic anhydride as the crosslinking agent and hexamethylene diisocyanate were used for surface modification of the... 

Today because of increasing use of fuel, environmental problems and problems due to heavy structures in different industries it is important to use structures with high specific strength. Using different materials in structures like polymers accompanying aluminum could be useful. Polymers are light, heat insulating and have a high corrosion resistance. Polypropylene is one of the useful polymers which can have high impact energy and strength via adding Elastomer and Talc powder, relatively. One of the common ways in joining metal to polymer uses adhesive. It has variety of benefits such as low distortion in joining, different materials joints and having joints with complex geometry. Welding... 

One of the most efficient and effective methods of water and wastewater treatment is the use of membranes and can be a good alternative to traditional methods such as adsorption, chemical coagulation and .... One of the limitations of this method is membrane fouling, which limits its use in industry.In this study, ultrafiltration membrane made by phase inversion method from a combination of PVDF and SPES polymers and surface modified with hyperbranched polyethylene imine and its performance in cationic coating paint purification was investigated. Also, the performance of this membrane has been investigated by calculating the separation rate, pure water flux, contact angle and specifications... 

Bio-based shape memory polymers with fast-response have high potential for use in medical applications. In this study, biocompatible and biodegradable nanocomposites based on shape memory polyurethane acrylates (SMPUA)/cellulose nanocrystals (CNC), were synthesized by in-situ polymerization. CNC is a natural and renewable nanoparticle that has been considered for medical applications due to its excellent mechanical and biological properties and surface chemistry. At the first phase of this study, in order to synthesize UV-curable shape memory polyurethane acrylate, polycaprolactone diol (PCL-Diol), hexamethylene diisocyanate (HDI) and hydroxyethyl methacrylate (HEMA) were used as an reactive... 

Formation damage is one of the most important challneges in hydrocarbon production; drilling mud invasion is one of its common types. This damage is caused by the penetration of the drilling fluid into the porous media, which its filtrate and solid pareticles block the pores and cause permeability reduction. The main purpose of this thesis is to investigate the pore-scale mechanisms of the formation damage induced by invert-emulsion drilling fluid and to investigate the effect of adding nanoparticles to the drilling fluid on the severity of the damage using microfluidic technique. According to the latest published articles, there has not been any research conducted at the pore-scale with... 

This study investigates the effect of adding hydroxyapatite nanoparticles and multi-walled carbon nanotubes in pure and modified form on the flexural properties and hardness of denture base Polymethyl Methacrylate. Polymethyl Methacrylate (PMMA) is still the most common denture base material. In fact, the mechanical properties of this resin have played a significant role in expanding its use in dentistry. But in the long-term use of resins, defects such as low resistance to crack growth, low flexural strength and brittleness can be seen. In fact, flexural fatigue occurs as a result of repeated flexural stresses, and it can be described as the main reason for crack growth and propagation in...