Sharif Digital Repository

Polyamides have found great attraction in the wide variety of application due to their desireable and tribological properties and appropriate processability. Due to their low mechanical strength reinforcing of these types of polymers has always been one of the important academic and industrial issues. In order to improve mechanical properties of such polymers, different kinds of reinforcement particles such as titaniom diaoxide, Nano clay, glass fibers (Short or long glass fiber), etc were used. Carbon nano tubes have high thermal and electrical conduction and mechanical properties; they are widely used as a reinforcement particle for polymer matrix. In this study, carbon nano tube and... 

Nanotechnology inrecent yearshas attractedthe attention of manyscientists and industrialists. Having atiny structure with extraordinary properties of nanoparticlesin the fields of electrical, mechanical and thermal, leading to their use isgrowing and newer application sarebeing found forth eseparticles. One of them Nanodiamond powderiswidely usedin the industryhas found wideapplication. Among these can be used in electrochemistry, chemical coatings, pastesand suspensions, add thepolymer, ceramic and industrial rubber and adhesives,adsorbentsand catalysts, filters and membranes, and finally cancer treat mentnoted. One of these applicationsisinPolymers and Rubber Industry. According to earlier... 

In this work nanocomposite CNT/polysulfone and CNT/polyethersulfone membranes for membrane contactor application in gas separation were fabricated. The two types of CNTs used for chemical and physical separation of H2S from a mixture of CH4 an H2S, had the outer diameter of 20-30nm and 50-100nm. One of the greatest concerns about using membrane contactors for gas separation applications is the wetting of membranes which consequently leads to decrease in separation performance. The aim of this study is to enhance the hydrophobicity of membranes by mixing hydrophobic carbon nanotubes in the polymeric matrix. The effect of factors like type of the polymer, diameter of the carbon nanotube and... 

Hospitals increasingly use control charts to monitor clinical processes and their outcomes. In medical context, control charts should have stable performance when different patients with different levels of risk enter the hospital. In order to monitor multi-attribute medical processes, we propose a new control chart with entities having different levels of risk. First, risk-adjusted multivariate cumulative sum control chart (RA-MCUSUM) is developed. Then, simulation experiences are performed to demonstrate the application and to evaluate RA-MCUSUM performance in terms of in-control average run length (ARL0) stability with the one of a standard MCUSUM chart.The results show that while the... 

In recent years, it has been interesting to to use nanodiamond (ND) in oreder to improve mechanical and electrical properties. Producing it in very low dimensions, make it more important to treat ND surface proportional to its application. Hence, with knowledge of influence of ND and its functional groups on curing process, in present research,carboxylic acid and amine were settled on its surface and in addition to untreated ND, they were dispersed in DGEBA epoxy as a reinforcement. Afterward, by adding triethylenetetramine kinetic cure of nanocomposites were investigated. For this purpose, conversion was determined using heat flow of reaction and then activation energy was calculated.... 

There are different types of sensors for measuring the concentration of gases that usually have high prices because of their complicated method of production. We can produce much cheaper sensors in special conditions by using polymer membranes. Different gases can be separated by using appropriate polymer membranes and the difference between diffusion rate of these gases is the basis of the separation method and gases pass through the membrane with different flow rates in the specific entrance pressure. The flow rate of total gas which flows will be different for a binary gaseous mixture at specific temperature and pressure with different concentrations because the flow rate is relative to... 

Preparation of binary polyamide 6 (PA6) / carbon nano tube (CNT) and ternary PA6 / EPR-g-MA / CNT has been carried out using melt mixing. Four PA6s were selected with different viscosities (and molecular weights) and molecular structures (linear or branched). Effect of CNT content (up to 2 wt%) and mechanical mixing conditions (rotor speed, temperature and time of mixing) have been investigated. Ethylene- propylene rubber grafted maleic anhydride (EPR-g-MA) was selected at 20 wt% as toughening agent for ternary nanocomposites and mixing sequence of PA6 , EPR-g-MA and CNT has been investigated. Morphological observations showed that dispersion of CNT is done by erosion mechanism at low melt... 

One of the ways that corrosion control is presented is the use of coatings that have good properties such as high adhesion, impact resistance, ultraviolet radiation, and so on. They also have other unique properties like anti-corrosion property. To achieve coatings with these advanced properties, they use special properties of nanocomposites. Nanocomposites can add or improve one or more properties to coating properties.In the present study, we tried to first synthesize NanoDiamond/Polyaniline hybrid nanoparticles in different percentages and then use this hybrid in epoxy ester coating. To characterize this hybrid, various analyzes such as FE-SEM, TEM, FT-IR, UV-Visible, TGA and XRD were... 

In This thesis the properties of a compatible rubber compound for a specific chemical environment (acidic media) with high temperature and high pressure (HTHP) is studied. After primary studies, six formulations are designed on the basis of Nitrile rubber. after tensile and hardness tests at ambient temperature and 120 °C, samples putted in aging reservoir for aging tests. After that, tensile and hardness tests were performed again. Finally, by analyzing the results, the best formulation have chosen. Test results show that the NBR / PVC compound with higher filler load, has the best chemical resistance  

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... 

In this study, polyethylene films made of LDPE / LLPE / reinforced with mechanical barrier of clay and reactant of iron nanoparticles were made in their optimal combination and necessary improvements were made on them. Investigations show that, independent of volume fraction, the addition of spherical nanoparticles does not have much effect on reducing the polymer matrix’s permeability. In nanocomposites containing cylindrical particles, for considerable reduction of the permeability, over 20 volume percent of nanoparticles it is required, while in platelet nanoparticles, less than 10% vol is sufficient. In clays with modifier concentration above the cation exchange capacity, there is less... 

Ezafe is regarded as one of the most controversial and challenging issues in different Persian Language Processing (NLP) fields. It is recognized and pronounced but usually not written. So, this results in a high degree of ambiguity in Persian texts. Dependency grammar plays a significant role in optimization problems. So, to recognize the position of Ezafe in a sentence, this grammar is used in this current study. This method helps speed up computer operations and use low memory. Within this framework, first we take a close look at Ezafe distribution in Persian text. We use Uppsala Persian Dependency Corpus (2015) to analyze parsed sentences. The Ezafe constructions under study include... 

The precise measurement of fluid flow in different fields of the industry is vitally important. In addition, due to enormous hydrocarbon reservoirs, Iran is the biggest owner of gas reservoirs in the world and exact measurement of fluids is of considerable importance to consumption or export. Ultrasonic flowmeters that are the most useful ones of them consist of three elements made of piezoelectric, impedance matching layer and backing material. In this study, on the contrary to former backing materials which usually use of titanium, tungsten, and aluminum oxide as a composite Filler, for the first time, tungsten oxide is used. In order to do this, composite samples were built of tungsten... 

Composite membranes are one of the promising membranes for overcoming the limitations of conventional membranes in gas separation application by improving the permeability and selectivity. However, it is still very challenging to achieve adhesion interface between the top selective layer and the bottom support layer. The present study demonstrates that this challenge can be overcome appropriately by utilizing a series of adhesive polymer as selective layer to prepare composite membrane. To this end, in the first section a series of acrylate-terminated polyurethanes (APUs) based on poly(ethylene glycol) (PEG) with different molecular weights (Mn) of 600, 1000, 1500, 2000 and 4000 g/mol,... 

In this study, metal-organic frameworks (MOFs) UiO-66 and NH2-UiO-66 were prepared and loaded with 2-mercaptobenzothiazole as corrosion inhibitor .Epoxy coatings containing inhibitor loaded nanoparticles were applied on mild steel to corrosion protection in 3.5 wt.% NaCl solution. Fourier transform infrared spectroscopy (FTIR) was used to confirm Inhibitor loading. In order to estimate the loading amount of corrosion inhibitor, thermogravimetric analysis was investigated. FE-SEM images demonstrated nanoparticle dispersibility in epoxy matrix.The results of electrochemical impedance spectroscopy (EIS) alalysis showed improvement of the corrosion resistance of the coatings containing... 

Flexible polymers (elastomers) are especially suitable for dynamic applications, and carbon based fillers are well-known filler for elastomers. These types of fillers are widely used in elastomer matrices for various commercial applications. Some of carbon nano fillers like Nanodiamond cannot (ND) impart such high degree of reinforcement to polymer matrices mainly because of improper filler dispersion and lack of strong filler-polymer interaction.In this effort, we examine the effects of nanodiamond/UiO-66 hybrid nanostructured materials when they are incorporated in styrene-butadiene rubber (SBR) in terms of mechanical, thermal and electrical properties of the nanocomposites.Different... 

Recycling of polymers, with the aim of environmental protection and economical benefits, is important procedure, which is constantly developing. In this study the effect of the incorporation of recycled PET(r-PET) and recycled polypropylene/Flax(r-PP/Flax) to PP at low (20wt %) and medium content (40wt %) of r-PET was investigated. Polymer compounds were prepared by twin screw extruder followed by injection moulding. The effect of r-PP/Flax and r-PET on PP was evaluated using different techniques such as scanning electron microscopy (SEM), differential scanning calorimetery (DSC), rheological behavior, and mechanical properties (tensile modulus, yield strength, and charpy notched impact...