Sharif Digital Repository

In this project, polymer nanocomposites containing graphene oxide were prepared and used for adsorption of several cationic and anionic dyes. In most cases, these nanocomposites were prepared as three-dimentional polymer networks which contain graphene oxide. Nanocomposites with direct grafting of polymer chains onto the surface of graphene oxide were also prepared. Graphene oxide is an oxidized carbonaceous material with unique properties. This material has high surface area, good mechanical strength and various functional groups. Polymeric compounds with different functional groups, structures and properties can be prepared and used. By preparing composites of graphene oxide and polymers,... 

Polymer/layered silicate nanocomposites are good candidates to improve polymer matrices due to enhanced interfaces between nanoclay reinforcement and matrix. So many attempts has been done to improve fabrication methods of these nanocomposites. Polypropylene is a common used engineering material in many industrial applications (general and special). So there is many researches focused on PP/Clay nanocomposites. In this research we tried to investigate the role of clay loading, compatibilizer loading and processing sequence on clay delamination and layer dispersion. We used a blend of two different PPs with different MFI values as matrice. It seems that the blend achieves acceptable... 

The amino groups present in the chemical structure of chitosan have made this material a prominent dye absorbents. But researchers have always taken steps to improve conditions and increase absorption. One of the materials that has attracted most researchers today is metal-organic frameworks. These porous materials with high surface area, optimum thermal resistance and adsorbent dye functional groups have been used as the reinfocing in the chitosan polymer field to adsorb anionic dye (methyl orange) from the aqueous media. One of metal-organic frameworks is UiO-66, which was selected as a reinforcing phase in the polymer field, due to its good stability in aqueous solutions, good thermal... 

In the experimental approach, graphene and Graphene Oxide (GO) were synthesized through a chemical method. In order to study the quality of GO, characterization tests were performed. Then, reinforced polymer with GO and graphene was made. Moreover, tension, compression and Split- Hopkinson pressure bar tests were performed on standard samples of reinforced polymer nanocomposite. The experimental data show that nanoparticles have a destructive effect in very low and high percentages for extension test as well as in high percentages for compression test. On the other hand, graphene is more effective than GO on improving material properties. Furthermore, comparison of compression results in... 

In the present research, we have applied reverse non-equilibrium molecular dynamics (RNEMD) to investigate the thermal conductivity (λ) of carbon nanotube (CNT) bundles, CNT-polyamide (PA) nanocomposites, and nanoconfined PA in the vicinity of graphene layers. First, transversal heat transport in CNT bundles with and without intertube chemical bonds are examined. It is found that the transversal λ of samples with cross linkers can surprisingly increase ~9 times than that of neat CNT bundles (0.26 W m-1K-1). According to the simulation results, key parameters are overlapping vibrational density of state (DOS) profiles between the atoms forming the bridging units, cross linker in the direction... 

The use of nanocomposite materials in various industries such as aerospace, oil and gas, automotive, etc. has become increasingly widespread due to its unique thermal and mechanical properties. Due to the problems and costs of the production process and experimental testing for optimal construction, it is necessary to propose a low-cost method for estimating the mechanichal properties of these materials. In this research, the mechanical properties of polymetric nano carbon nanocomposites have been estimated by multi-scale method with using finite element analysis by Abaqus software. the mechanical properties of nanocarbon composites have been extracted by using the multi-scale method that... 

Articular cartilage resides in a complex and dynamic mechanical and biophysical environment in vivo. Chondrocyte physiology and biosynthetic activity is influenced by these signals, allowing them to modulate the structural organization and function of tissue at all stages, including development, growth and repair. . In articular cartilage, during physical activity and mechanical loading, electric signal have been observed in form of stress-generated electric potential following the movement of the positive mobile ions (in interstitial fluid) away from the fixed negative charges.Despite increasing evidence that mechanical and electrical stimuli have positive effects on chondrogenesis, to... 

Active packaging is a novel approach that can ensure food safety by removing undesirable compounds such as Oxygen, ethylene, moisture, and microbial contamination from fresh produce's environment and reducing product loss by extending shelf life. Current research on active food packaging materials focuses on using biopolymers such as carbohydrates, proteins, and lipids as alternatives to non-degradable petroleum-based packaging materials. Active nanomaterials are commonly used to impart functionality to packaging materials. However, the lack of functionality limits their industrial application.Therefore, the main objective of this work was to fabricate bioactive nanocomposite films by... 

Cellulose nanocrystals as a reinforcement in polymer nanocomposites are part of current research for reasons such as source renewable, biocompatibility, nanoscale dimensions, high specific surface area, and surface chemistry. This research used cellulose nanocrystals as a corrosion inhibitor carrier in epoxy-based composite with 1% by weight. In order to load the corrosion inhibitor, firstly, cellulose nanocrystals were surface modified by aniline so that they can spread well in the hydrophobic epoxy matrix. Different corrosion inhibitors were tested for adsorption on the surface of cellulose nanocrystals modified with polyaniline, but finally the acidic agent of phosphoric acid showed... 

According to human needs and in line with the development of advanced technologies, different biomedical Engineering fields like hard tissue implants are growing rapidly. Despite significant biotechnology Developments in recent years, some problems to the recognition of implants related osseointegration phenomena persist. The deficient osseointegration and implant-associated infections are key issues for the long-term clinical success of titanium and titanium alloy implants, while development of multifunctional surfaces that can simultaneously overcome these problems remains highly challenging. Therefore, the ultimate goal of this paper was to improve bone cell attachment and simultaneously...