Sharif Digital Repository

Pseudopolyrotaxanes, Ps-PR, consisting of α-cyclodextrin rings, polyethylene glycol axes and end triazine groups were prepared and then were capped by amino-functionalized quantum dots, NH 2-QDs, to achieve polyrotaxanes. The amino-functionalized QDs stoppers of polyrotaxanes were used as core to synthesize polyamidoamine, PAMAM, dendrons divergently and hybrid nanomaterials were obtained. Synthesized hybrid nanomaterials were characterized by different spectroscopy, microscopy and thermal analysis methods. They were freely soluble in water and their aqueous solutions were stable at room temperature over several months. Due to their biocompatible backbone, high functionality and water... 

High strength Al-AlN composites were synthesized via high-energy milling and sintering technique. Al-X wt.% AlN (X = 0, 2.5, 5 and 10) composite powders were milled in a planetary ball mill for 25 h. Morphology, particle size distribution, crystallite size, micro-strain, and microhardness of milled powders were studied. Ball-milled powders were degassed at 400 °C for 30 min. After uniaxial cold compaction, composite compacts were sintered at 650 °C for 20, 30 and 60 min under N2 atmosphere. Effects of reinforcement content, degassing treatment and sintering time on the sinterability of powders were investigated. The results revealed that the sinterability was degraded by increasing the... 

High-energy milling technique was used to synthesize Al-10 wt.%AlN-nanostructured composite powder in a planetary ball-mill under argon atmosphere up to 25 h. To show the role of AlN particles, process was conducted for monolithic aluminum. The changes in powder characteristics were investigated by time. Microstructure of powders was studied after different milling times by scanning electron microscope (SEM). The morphological evolutions showed that relative equiaxed powder could be synthesized after 25 h milling. Structural analysis was performed by X-ray diffraction method (XRD) to determine the grain sizes and lattice strain. Furthermore, particle size analysis (PSA) revealed the... 

The compressibility behavior of Al-AlN nanostructured composite powder with different amount of reinforcement content was studied. The composite powder was synthesized by blending and high-energy milling process for 25 h. Williamson-Hall method was applied to determine the crystallite size after milling process. To investigate the role of reinforcement particles in consolidation of composite powders, monolithic aluminum powder was examined. Samples were made at different pressures and relationships were established between the compaction pressure and the density of the compacts. The modified Heckel equation was used to assume the pressure effect on yield strength and then was compared with...