Sharif Digital Repository

Ethylene vinyl acetate copolymer produces flexible products and is compatible with many polymers and additives, the reason is that it has Vinyl group which is polar and Ethylene group which is nonpolar. In fact, it consists of two parts. One is a hard and semi-crystalline Polyethylene region and the other is soft, flexible, polar, and amorphous Vinyl Acetate. Improving the properties of this copolymer can broaden its application. For this purpose, Ethylene Vinyl Acetate with 18 and 28% Vinyl Acetate was used as a matrix and nano-alumina as reinforcement in this project. The spherical structure and chemicallu active surface, along with significant mechanical properties, suggeats Alumina... 

Polyethylene (PE) is used as an insulation material for wires and cables because of its excellent electrical properties. For such application, it can be exposed to the high energy irradiation such as gamma ray and electron beam (EB), making possible crosslinking of the PE. Most of the properties of PE are improved greatly after irradiation, but it was harden and split easily. Due to the flexibility of EVA, depending on the vinyl acetate content, it can improve the toughness of the LDPE significantly upon addition to this polymer. As a result, radiation induced LDPE/EVA blend has been a good candidate for the wire and cable insulation. Also, upon addition of a few amount of OC, different... 

Blending different polymers to achieve a compound with modified Physical physical and mechanical properties, has interested researchers for years. Among all, LDPE and HDPE have attracted a great attention for this purpose; specially when a mineral filler like clay is another part of composite. In the related literature, it is proven that small amounts of clay can improve physical and mechanical properties in comparison to virgin blend. Focus of this research is on HDPE/EVA/Clay nanocomposite and its physical and mechanical properties. Having vinyl group, EVA is a compatibilizer that makes clay to disperse better; EVA can also makes the brittle HDPE tougher. At first, HDPE/EVA blend... 

A series of poly(ethylene-co-vinyl acetate) (EVA)-based hot melt adhesives containing either a raw rosin or a hydrogenated rosin ester have been prepared to investigate variation of viscosity, softening point and peel adhesion with composition. Adhesion of the prepared hot melt adhesive to the substrate was characterized by T-peel strength test. Increasing rosin had a prominent effect on the adhesion. Viscosity decreased and softening point increased as the wax content increased. Addition of zinc borate as a flame retardant decreased T-peel energy and increased the viscosity and softening point of the samples. Higher peeling strength accompanied with a good softening point and viscosity... 

In this thesis, polyethylene vinyl acetate and polyethylene shrinkable nanocomposite films with different percentages of an organoclay such as 0, 1, 3, 5 and 7% have been prepared via two-steps solution method. Morphological and properties of these films, including permeability and mechanical and rheological properties were investigated. Also the effect of addition of cross linking agent (DCP) was studied. Various tests including XRD, SEM, tensile and rheological properties were studied. XRD tests showed that the distance between a layer of or ganoclay increased to 32 percent. This indicates that the polymer chains between the layers of organoclay could be better. SEM examination showed that... 

The purpose of this project was to produce and examine the Poly(lactic acid)/poly(ethylene-co-vinyl acetate)/ nano-clay nanocomposite by solution casting that can be used for food packaging. In this study, it was observed that solvent evaporation at 4°C gives uniform films, without phase separation and free of voids, in a certain composition of polymers related to the rate of solvent evaporation.According to DMTA results Poly(lactic acid) and poly(ethylene-co-vinyl acetate) with 28% vinyl acetate, were compatible in less than 10% poly(ethylene-co-vinyl acetate) content in blend of them. Also, results of SEM tests showed that ethylene-co-vinyl acetate particle size in blends with 3 and 5... 

Wax precipitation is one of the major problems in the transfer of crude oil from field production to refineries. This wax with asphaltene compounds and some water and solids, closes the oil pipeline. One of the ways to reduce the amount of wax in pipes is to use additives (flow improvers) to crude oil and improve its rheological behavior. In this research, Five Iranian crude oils were characterized with SARA test and then the effects of various additives including ethylene vinyl acetate (EVA) in concentrations of 500 and 1500 ppm, alkyl phenol ormaldehyde resins (NPFR) with 1500 ppm and styrene-(ethylene-cobutylene)- styrene (SEBS) with 1500 ppm on viscosity, wax appearance temperature... 

In this research, the EVA/BT/MWCNT nanocomposites were prepared via the solution casting method in the various weight fractions of Barium titanate (BT) and multi-walled carbon nanotubes (MWCNT). Barium titanate-based ceramic material has a high dielectric constant, and it is used in the manufacture of sensors, capacitors, and electrical memories. On the other hand, multi-walled carbon nanotubes, due to electric charges on their surface and high electrical conductivity, can affect the dielectric properties combined with barium titanate and the hybrid of these two materials a polymer matrix suitable for special applications. In this study, ethylene-vinyl acetate (EVA) copolymer was used as a...