Sharif Digital Repository

Polypropylene matrix nanocomposites reinforced with organoclay are investigated and their ability to replace some polyamide automotive parts is evaluated. This is so interesting from industrial point of view because of cost saving and ease of processing and recycling. This work is focused on different nanocomposite systems which are PP/nanoclay, and PP/PA/nanoclay. Also the effect of compatibilizer is presented here. Structure of these systems are studied by using WAXD, TEM and SEM. Mechanical properties of specimens are studied using uniaxial tensile test. As it will be demonstrated, nanoclay sheets tend to disperse in PA particles. On the other hand, introducing nanoclay into PP/PA blends... 

A magnetic nanocomposite consisting of nanoparticles–polybutylene terephthalate (MNPs–PBT) was electrospun and used as an extracting medium for an on-line μ-solid phase extraction (μ–SPE)–high performance liquid chromatography (HPLC) set–up with an ultraviolet (UV) detection system. Due to the magnetic property of the prepared nanofibers, the whole extraction procedure was implemented under an external magnetic field to enhance the extraction efficiencies. The developed method along with the synthesized nanocomposite were found to be appropriate for the determination of trace levels of selected drugs including furosemide, naproxen, diclofenac and clobetasol propionate in the urine sample.... 

In this study, a fast and sensitive flow injection μ-solid phase extraction (FI-μ-SPE) technique based on an electrospun polyaniline (PANI) nanocomposite in conjunction with gas chromatography-mass spectrometry (GC-MS) was developed. The PANI-based nanocomposite was synthesized by electrospinning of a solution containing polyvinyl alcohol (PVA)/PANI. The majority of PVA template was subsequently removed from the whole PVA/PANI nanofibers blend by exposing the electrospun nanocomposite to hot water. The homogeneity, porosity and characterization of the electrospun nanofibers were investigated by the scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Due to... 

In this study, a fast and sensitive flow injection μ-solid phase extraction (FI-μ-SPE) technique based on an electrospun polyaniline (PANI) nanocomposite in conjunction with gas chromatography-mass spectrometry (GC-MS) was developed. The PANI-based nanocomposite was synthesized by electrospinning of a solution containing polyvinyl alcohol (PVA)/PANI. The majority of PVA template was subsequently removed from the whole PVA/PANI nanofibers blend by exposing the electrospun nanocomposite to hot water. The homogeneity, porosity and characterization of the electrospun nanofibers were investigated by the scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Due to... 

The present work deals with a novel approach for grafting a sol-gel based sorbent, using diazonium salts for preparation of an unbreakable capillary microextraction (CME) device in on-line combination with high performance liquid chromatography (HPLC). The use of diazonium salts modifier allowed all types of metallic and non-metallic substrates to be used without any limitation. Substrates including copper, brass, stainless steel and polytetrafluoroethylene (PTFE) were chosen to be functionalized by chemical or electrochemical reduction of 4-amino phenyl acetic acid. Then, 3-(trimethoxysilyl)propylamine (3TMSPA) was selected as the precursor and the only reagent for preparation of the... 

Switchable photochromic dyes have benefited greatly from the use of heterocyclic chemicals. The imidazole group is particularly essential because it can be transformed into dimers, which can then be radicalized in the presence of light photons. Imidazole dimers have been optimized throughout thirty years of research, allowing derivatives with diverse colors, quick reversibility, and sensitivity to different wavelengths from UV to near IR ranges. These imidazole dimers are interesting to be used in the matrices of polymers, hydrogels, glasses, solar cells, and even pharmaceuticals. The goal of this review is to look at the history, development, and future of imidazole dimers. We will also... 

A molecularly imprinted xerogel (MIX) for fentanyl was successfully prepared on the inner surface of a copper tube by sol-gel technology. Primarily, the tube was treated by self-assembly monolayers of 3-(mercaptopropyl) trimethoxysilane and then [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane was employed as a precursor for imprinting the template molecule in acidic conditions. During the sol-gel process influential parameters including volume and concentration of fentanyl were carefully investigated to obtain the most efficient and appropriate xerogel. In parallel, a non-imprinted xerogel (NIX) was synthesized in the absence of fentanyl. The extraction efficiencies achieved from MIX and NIX,... 

In this study, Cu-TiC nanocomposites were produced by high energy ball milling of elemental powders and in-situ formation of TiC in the copper matrix. Cu-40wt% Ti powder mixture were milled for 60 h, then graphite powder was added, subsequently milling was continued for further 10 h. Based on theoretical calculations, at this composite, the amount of TiC as reinforcement should be 60.25vol% (45.47wt%). The effect of milling time on solution progress of titanium in the copper lattice was studied by X-Ray diffraction analysis (XRD) with CuKα radiation. Considering XRD of Cu-40wt%TiC after 60 h milling data and Williamson-Hall relation, crystallite size and lattice strain of copper were... 

Although curcumin is highly cytotoxic against cancer cells, its hydrophobicity and fast degradation at physiological pH limit its effective practical application. To prevent such limitations, inexpensive curcumin-loaded starch particles are synthesized in this research. Particles are prepared by water-in-oil (W/O) miniemulsion technique and an adsorption method is used for curcumin loading. Also, encapsulation efficiency (%EE) is improved by using pluronic F-127 in the drug solution. Particles are characterized, swelling studies are performed, and MTT assays against human adipose mesenchymal stem cells (hAMSCs) and MG-63 cells are utilized for investigations. Results indicate that... 

Arms bearing ureido-pyrimidinone functional groups with self-association capability (through quadruple hydrogen bonds) were successfully grafted onto hydroxyapatite nanoparticles. The supramolecularly modified nanoparticles (nHApUPy) exhibited enhanced colloidal stability compared to the original hydroxyapatite nanoparticles and were uniformly dispersed in supramolecular polycaprolactone in PCL(UPy)2/HApUPy nanocomposites at different filler loadings. The combined atomic force microscopy, mechanical, and rheological analyses confirmed a high degree of compatibility of HApUPy nanoparticles with the polymer matrix. The temperature dependence of the supramolecular structure in PCL(UPy)2/HApUPy... 

A series of herbal extract incorporated into poly(lactic acid) (PLA) composite nanofibrous scaffolds were successfully prepared by using electrospinning technique. Equisetum arvense extract (EE) and nanohydroxyapatite (nHA) in different quantities were loaded into PLA solution to fabricate composite nanofibrous webs under various electrospinning conditions. Uniform nanofibers were obtained with an average diameter of 157 ± 47 nm in the case of those containing the herbal extract. Characterization of the webs was carried out by means of Fourier transform infrared (FTIR) spectroscopy, field emission-scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and... 

Purpose: The nanofluid flow and heat transfer within a heat exchanger, with different thermal arrangements of internal active bodies, are investigated. Design/methodology/approach: For the numerical simulations, the lattice Boltzmann method is utilized. The KKL model is used to predict the dynamic viscosity of CuO-water nanofluid. Furthermore, the Brownian method is taken account using this model. The influence of shapes of nanoparticles on the heat transfer performance is considered. Findings: The results show that the platelet nanoparticles render higher average Nusselt number showing better heat transfer performance. In order to perform comprehensive analysis, the heatline visualization,... 

TiO2 nanotubes (TNTs) were synthesized hydrothermally and modified by Cu2O using a sol-gel method to provide photocatalytic activity in visible light. Cellulose nanofiber (CNF)-based films were prepared by adding TiO2, TNTs, and Cu2O-modified TNT (TNT-Cu2O). The TiO2-based nanoparticles (TiO2, TNTs, and TNT-Cu2O) were uniformly distributed in the base polymer to make compatible and flexible films. The incorporation of nanoparticles significantly enhanced the UV-shielding properties of the film while slightly decreasing the transparency. Incorporating nanofillers improved the film's mechanical and water resistance properties depending on the nanoparticle type. The TNT-Cu2O-added CNF film... 

In this study, ZnO-GO, and ZnO-ROG nanocomposites were synthesized by the green chemistry method to study their antibacterial activity. XRD pattern and XPS confirmed that the nanocomposites successfully were synthesized. The UV–vis spectroscopy results showed the bonding between ZnO nanoparticles and GO sheets can engineer the semiconductor band gap and shift the absorption edge to longer wavelengths as compared to pure ZnO. The inhibition rate of ZnO nanoparticles, GO, and RGO sheets after 12 h of contact with E. coli were 84 %, 81 %, and 73 %, respectively. Inhibition rate for Z-1GO, Z-5GO, Z-10GO, Z-1RGO, Z-5RGO, and Z-10RGO nanocomposites were 89 %, 92 %, 94 %, 85 %, 89 %, and 91 %... 

The growth of harmful microorganisms is a severe threat to human life. Nowadays, it is necessary to prepare antimicrobials materials with high biocompatibility properties. Hence, the use of nanomaterials and their nanocomposites has been proposed as a suitable way to obtain safe and potent antibacterial materials. Recently, several studies have been conducted on the antibacterial properties of metal oxide and graphene oxide (GO) nanomaterials individually. This study investigated the synergistic effect of GO and copper oxide (CuO) as a nanocomposite. CuO-GO nanocomposite containing 5%, 15%, 25%, 50%, and 75% of GO were synthesized to study antibacterial properties. X-ray diffraction (XRD)... 

The growth of harmful microorganisms is a severe threat to human life. Nowadays, it is necessary to prepare antimicrobials materials with high biocompatibility properties. Hence, the use of nanomaterials and their nanocomposites has been proposed as a suitable way to obtain safe and potent antibacterial materials. Recently, several studies have been conducted on the antibacterial properties of metal oxide and graphene oxide (GO) nanomaterials individually. This study investigated the synergistic effect of GO and copper oxide (CuO) as a nanocomposite. CuO-GO nanocomposite containing 5%, 15%, 25%, 50%, and 75% of GO were synthesized to study antibacterial properties. X-ray diffraction (XRD)... 

A novel, efficient, and very mild one-pot synthesis of methyl 2-[(Z)-4-aryl-5-morpholino-3-oxo-2,3-dihydrothiophen-2-ylidene]acetate derivatives under kinetic control has been developed. The title compounds were prepared by the reaction of thioacetomorpholides with dimethyl acetylenedicarboxylate (DMAD) in the presence of K2CO3 in a non-polar solvent with excellent yields. © 2005 Taylor & Francis  

Free Content Selective synthesis of conjugated enynes from α-arylalkynols using LiCl-Acidic Al2O3 under solvent-free conditions  

7H-benzimidazo[2,1-a]benz[de]isoquinolin-7-one compounds were prepared in a selective manner by reaction between o-phenylenediamines and appropriate 1,8-naphthalenedicarboxylic anhydrides using acidic alumina under microwave irradiation  

The effect of loading rate on toughening mechanisms of rubber-modified epoxy resin was investigated using amine-terminated butadiene acrylonitrile (ATBN) rubber. Rubber-modified samples were tested at various loading rates in the range of 1-1000 mm/min. At low loading rates, modified resin exhibited a high fracture toughness, which decreased by increasing the rate of loading. At higher loading rate a transition region was observed, where the fracture toughness did not change noticeably with increasing the loading rate. Beyond the transition region, the resin fracture toughness dropped dramatically to the level of unmodified epoxy. Fractography of the damage zone showed different toughening...