Sharif Digital Repository

polyamides have found great attractions in wide variety of applications due to their desirable mechanical and tribological properties and appropriate processability. Pure polymers are not suitable for this kind of application due to their low mechanical strength. High strength materials are needed for abrasive applications. Polytetrafluoroethylene (PTFE) is one of the most popular materials for abrasive applications. In this study the effect of PTFE and surface modification on PA/PTFE composite properties is investigated. duo to modification of PTFE powder, PTFE is exposed to sodium naphtalenide (Na/naphtha) etchant so as to deflurinate the surface for obtaining carbonyl, carboxyl and... 

Polypropylene/clay nanocomposites are considered as a group of widely used nanocomposites in industrial applications due to their desired properties, yet reasonable cost. However, dissimmilar chemical nature of polypropylene and clay do not allow perfect dispersion of silicate layeres in the matrix and thus restricts full advantages of these composites.An earlier investigation in this group considered solving this shortcoming through incorporation of PA6 as an intermediate phase to enhance clay platelets dispersion. The current project follows this route via studing the influence of molecular weight of the PP matrix, compatibilzer and the mixing procedure of the compound. To investigate the... 

For the sake of decrease in energy and force of earthquake, seismic isolators are used. Regular seismic isolators are too heavy and damaged by chemical materials, therefore in this research a new approach is used that steel shim plates replaced by carbon and polyamide fibers. The aim of this research is to obtain the dynamic and mechanical properties of carbon and polyamide fiber reinforced isolators in comparison with steel reinforced isolators. In this approach, firstly some specimens have been designed and manufactured, then compresional and cyclic shear tests were carried out on them. All three type isolators are cylindrical and have identical diameter and height. The steel, carbon fiber... 

Electrospinning is a simple and versatile technique for producing polymeric and ceramic nanofibers. The conventional procedure for fabrication of ceramic nanofibers is a combination of sol-gel techniques and electrospinning. The main challenge is the spin polymer nanofiber in fabricate of fibers with diameter from 1 to 100 nm, while their standard deviation are as low as possible. Uniform beads free polyamidenanofibers with lower diameter were fabricated.A 18% w/w of polyamide in formic acid was chosen and the effect of magnetic field, adding magnetic ionic liquid surfactant, auxiliary electrode on the main fiber were investigated. They termsfiber 1 to fiber 5. The mean diameters of 489,... 

Reverse osmosis membrane one of the common methods used for water desalination, today membrane, thin film composite(TFC) include three layers, top the these layers named selection layer, this poly amid layer contacted with feed water, sensitivity to chlorine in polyamide layer lead to high membrane chlorine sensitive. Difference methods used for enhance the chlorine resistance in polyamide membrane that categorized in three general categories, covering and protection of sensitive areas method has best results in comparison to other methods. In this research protection method choose and used, material that used, sanitized by result from surface analysis of commercial membrane manufactured in... 

In the past decades, electrospinning has been widely used for the production of micro/nanofibers. In spite of the simplicity and effectivity of the conventional electrospinning for fabricating nanofibers, compact structure and small pores of the nanofibers hinder the efficient penetration of analytes during the extraction process. In order to overcome this issue, an applicable strategy called wet electrospinnig has been employed to enlarge the pore size of the electrospun scaffolds. By applying this technique, a collector was placed at the bottom of a solvent bath and highly porous foam from polyamide nanofibers was produced immediately after freeze-drying (3D electrospinning).... 

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...