Sharif Digital Repository

In the first part of this work, citric acid monomer was selected to produce dendrimer through the divergent method using logical conditions (for controlling its functional groups) on the base of poly (ethylene glycol) as the core. Triblock copolymers (ABA-type) of citric acid and poly (ethylene glycol) (PCA-PEG-PCA) as biocompatible compounds were synthesized in four different molecular weights and applied as nanocarriers. The structure definition of the molecules and nanoparticles were carried out using different spectroscopy methods. Diameter of the synthesized copolymers was investigated using dynamic light scattering (DLS) experiments and transmission electron microscopy (TEM) and it was... 

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... 

The main object of the presented thesis is manufacturing ultra high molecular weight polyethylene(UHMWPE)/Graphene nanocomposites by insitu polymerization using Ziegler Natta catalysts. In this study, three types of Ziegler Natta Catalysts such as Magnesium ethoxide supported, single-supported and bi-supported have been studied. Experimental conditions are optimized (from point of productivity and molecular weight) by Design expert software with response surface methodology (Box-Behnken design). Effect of process parameters like temperature, pressure and [Al]/[Ti] molar ratio on productivity and Molecular weight are investigated. Also, the effect of hydrogen presence and type of cocatalyst... 

Recently, due to the increase of environmental concerns, a significant raise in applying films and packaging containers, pollution produced from petroleum-based plastics packaging and problems arising from the various methods of waste disposal, the researchers have concentrate to replace these materials with biodegradable ones. In this study, a nanocomposite based on alloy matrix of thermoplastic starch and polyethylene which is reinforced with different amounts of Montmorillonitenanoclay has been constructed by the extrusion process. Furthermore, in order to increase the compatibility between the polar and non-polar components in the group of samples, compatibilizer was used and its... 

Ultra high molecular weight polyethylene has attracted the attention of numerous researchers and industries. This polymer due to its strong properties can be used in advanced military industries, medical engineering and cases in which high strength and high abrasion resistance is required. Present study aims to fabricate UHMWPE/Molybdenum disulfide composites, using in-situ polymerization. Before carrying out the polymerization process, nanoparticles of molybdenum disulfide underwent various processes such as oxidation, pickling, ultrasonic and thermal shock, in order to increase the interlayer distance and creating functional groups on the surface, then various analyzes, such as XRD, FESEM,... 

Nowadays filtration process is increasingly used in various areas such as water purification, food industries, filtering the air dust and other separation applications. In this work, the HDPE microporous filters have been fabricated at different temperature, pressure and time conditions via sintering process and then were characterized by different techniques. It can be expected that microstructure and mechanical properties of the samples could be controlled by changing the fabrication parameters of the process and also by changing the properties of the resin such as powder shape, particle size and rheological properties. In the first step, by using DSC, MFI, rheology test and optical... 

Vortex flow is one of the most sophisticated fluid movements in nature which has great industrial and scientific importance. In this dissertation, in order to study the combustion process due to a vortex flow, a new experimental model of a cold wall vortex engine, was designed, fabricated and tested with oxidizer issuing tangentially toward the end of the chamber. The cold wall effect in these chambers is a result of the cool layer of oxidizer which significantly reduces the amount of heat transfer to the chamber’s wall. This experimental model was designed to withstand the massive temperature rise resulting from the usage of Polyethylene as fuel and Nitrous oxide as oxidizer. In a series of...