Amirkabir University of Technology

About: Amirkabir University of Technology is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Nonlinear system & Finite element method. The organization has 15254 authors who have published 31165 publications receiving 487551 citations. The organization is also known as: Tehran Polytechnic & Tehran Polytechnic University.

Self assembly of graphene oxide at the liquid–liquid interface: A new route to the fabrication of graphene based composites

Abstract: Dispersion of graphene in a polymer matrix as mono layers is an important step towards fabricating high performance polymer–graphene nanocomposites. In this paper, a novel method based on Pickering emulsion polymerization has been introduced that assures fine dispersion and enhances loading. The major idea is to use a high affinity of graphene oxide (GO) for assembly at the liquid–liquid interface for Pickering emulsion polymerization. A guideline for ensuring stable hybrid colloids of polymer–graphene oxide with an appropriate polymer particle size has been introduced. Then a system of poly (methyl methacrylate) (PMMA)–GO has been selected and the nanocomposites have been made by Pickering emulsion polymerization to examine the theory. TEM studies of the products show various interesting arrangements of PMMA and GO for a different size ratio of nanolayers to polymer particles. The new method paves the way for an environmentally benign process for the production of high quality polymer graphene nanocomposites as it is water-based (no organic solvent is employed) and soap free. Furthermore, resulting hybrid particles were melt mixed with PMMA as a master batch. The resulting nanocomposites with 0.3 wt% graphene showed improved thermal stability and stiffness.

Hydrothermal synthesis of ZnO nanorod arrays for photocatalytic inactivation of bacteria

Abstract: Arrays of ZnO nanorods were synthesized on ZnO seed layer/glass substrates by a hydrothermal method at a low temperature of 70 °C. The effect of pH > 7 of the hydrated zinc nitrate–NaOH precursor on the morphology and topography (e.g. size, surface area and roughness), the optical characteristics (e.g. optical transmission and band-gap energy), hydrophilicity and antibacterial activity of the grown ZnO nanostructure and nanorod coatings were investigated. For pH = 11.33 of the precursor (NaOH concentration of 0.10M), a fast growth of ZnO nanorods on the seed layer (length of ~1 µm in 1.5 h) was observed. The fast growth of the ZnO nanorods resulted in a significant reduction in the optical band-gap energy of the nanorod coating, which was attributed to the formation of more defects in the nanorods during their fast growth. The surface of the ZnO nanorod arrays was relatively hydrophilic (with a water contact angle of 16°) even after the subtraction of their surface roughness effect (with a contact angle of ca 27°). This hydrophilicity of the ZnO nanorods was assigned to the observed surface OH bonds. These characteristics caused the ZnO nanorod arrays to show an excellent UV-induced photocatalytic degradation of Escherichia coli bacteria. Furthermore, the synthesized ZnO nanorods were found to be strong photo-induced antibacterial material, even without considering their high surface area ratio.

Effect of type, form, and dosage of activators on strength of alkali-activated natural pozzolans

Abstract: It is possible to synthesize environmentally friendly cementitious construction materials from alkali-activated natural pozzolans. The effect of the alkaline medium on the strength of alkali-activated natural pozzolans has been investigated and characterised. This paper highlights the effect of the type and form of the alkaline activator, the dosage of alkali and the SiO2/Na2O ratio (silica modulus, Ms) when using water–glass solutions and different curing conditions on the geopolymerisation of natural pozzolans. Activation of natural and calcined pozzolan for production of geopolymeric binder was verified by using Taftan andesite and Shahindej dacite from Iran as a solid precursor. The optimum range for each factor is suggested based on the different effects they have on compressive strength. The concentration of dissolving silicon, aluminium and calcium in alkaline solution, the formation of gel phase and the factors affecting this have been studied by using leaching tests, ICP–AES, and FTIR.