Time filter

Source Type

Hajibeygi M.,Kharazmi University | Shabanian M.,Standard Research Institute SRI | Khonakdar H.A.,Islamic Azad University at Tehran
Applied Clay Science | Year: 2015

A new series of polyamide/Zn-Al layered double hydroxide (LDH) nanocomposites (PANC) was prepared by solution intercalation technique under ambient condition in dimethylformamide as solvent. The polyamide (PA) containing pyridine ring and imide group was synthesized using direct polycondensation reaction with good solubility and desired molar mass. Organo-modified Zn-Al LDH (OLDH) was produced by one-step method and used to improve mechanical, thermal and flame properties of PA. The extent of dispersion of OLDH sheets was quantified by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and the results showed a good dispersion for OLDH in the PA matrix. According to the results of mechanical tests, the tensile strength and the Young's modulus of PANC enhanced with increasing OLDH content. Thermal properties of PANC were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal property results in both nitrogen and air atmospheres showed that the addition of OLDH resulted in a substantial increase in the thermal stability and char yields of PANC as compared to the neat PA. Significant improvements in flame retardancy performance were observed for PANC from microscale combustion calorimeter (MCC) (reducing both the heat release rate and the total heat released). © 2015 Elsevier B.V.


Babaei A.,Arak University | Yousefi A.,Arak University | Afrasiabi M.,Arak University | Shabanian M.,Standard Research Institute SRI
Journal of Electroanalytical Chemistry | Year: 2015

A novel chemically modified electrode is constructed based on a multiwalled carbon nanotubes, nickel(II) hydroxide nanoparticles and MCM-41 molecular sieve composite modified glassy carbon electrode. It is demonstrated that the sensor can be used for the simultaneous determination of dopamine (DA), acetaminophen (ACT) and indomethacin (INDO). The measurements were carried out by the application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA). Under the optimum conditions the modified electrode provides a linear response versus DA concentrations in the range of 1.5-45 μM and 70-350 μM, ACT concentrations in the range of 0.2-20 μM and 20-220 μM and INDO concentrations in the range of 0.8-40 μM and 60-160 μM, respectively using the differential pulse voltammetry method. The modified electrode was used for determination of DA, ACT and INDO in real samples with satisfactory results. © 2015 Elsevier B.V. All rights reserved.


Shabanian M.,Standard Research Institute SRI | Basaki N.,Islamic Azad University | Khonakdar H.A.,Iran Polymer And Petrochemical Institute | Jafari S.H.,University of Tehran | And 2 more authors.
Applied Clay Science | Year: 2014

New long aliphatic chain polyamide/Mg-Al layered double hydroxide (LDH) nanocomposites were successfully prepared via a solution intercalation technique under ambient condition in N,N-dimethylacetamide as solvent. The polyamide was synthesized using direct polycondensation reaction from an oleic acid based monomer which was characterized by proton nuclear magnetic resonance and size exclusion chromatography. The polyamide showed a semi-crystalline structure with melting temperature of 223. °C. Organo-modified Mg-Al LDH was produced by one-step method and used to improve properties of the polyamide. Thermal properties and flame retardancy of the nanocomposites were studied by thermogravimetric analysis, differential scanning calorimetry and microscale combustion calorimeter. The thermal degradation results in both air and nitrogen atmospheres showed that the addition of organo-modified LDH resulted in a substantial increase in the thermal stability and char yields of the nanocomposites as compared to the neat polyamide. The flammability tests revealed that incorporation of the organo-modified LDH in the polyamide resulted in a reduction of the heat release rate, heat release capacity and total heat release. © 2014 Elsevier B.V.


Khalili D.,Shiraz University | Banazadeh A.R.,Standard Research Institute SRI
Bulletin of the Chemical Society of Japan | Year: 2015

An efficient chemical method for the synthesis of benzimidazoles, benzothiazoles, and benzoxazoles has been developed through the condensation of various aldehydes with o-phenylenediamine, o-aminothiophenol, and o-aminophenol using graphene oxide (GO) as an oxidant in water. These benzazoles are also prepared through a one-pot oxidation/condensation tandem process by reacting alcohols with 2-amino-(thio)phenol/aniline in the presence of GO in poly(ethylene glycol) as a safe media. Moreover, this carbonaceous material could be readily separated using a simple filtration. © 2015 The Chemical Society of Japan.


Kord B.,Standard Research Institute SRI | Haratbar D.T.,Islamic Azad University
Journal of Thermoplastic Composite Materials | Year: 2016

In this article, the different chemical modifications of natural fiber on the physical and mechanical properties of polypropylene (PP)/wood flour (WF)/nanoclay hybrid composites were studied. To meet this objective, the chemical treatments on WF, namely alkali, acetylation, and benzoylation, were carried out. Then, the composites were prepared through the melt mixing of WF and PP at 50% weight ratios, with various amounts of nanoclay (0, 3, and 6 per hundred compounds (phc)) in Haake internal mixer and the test specimens were prepared by injection molding. The amount of coupling agent was fixed at 2 phc for all formulations. The tensile strength, impact strength, and water uptake of these composites were analyzed and the reinforcing properties of the chemically treated composites were compared with those of untreated composites. The chemical modification efficiency was verified by Fourier transform infrared (FTIR) analysis, and the dispersion state of nanoclay in the composites was examined using X-ray diffractometer and transmission electron microscopy. The results showed that the tensile modulus, tensile strength, and impact strength of the composites increased by applying chemical treatments. Modified composites had lower water absorption (WA) and thickness swelling than unmodified ones. Furthermore, the highest mechanical properties and the lowest water uptake were observed in the composite modified with acetic anhydride. FTIR spectra show that the intensity of O-H bond at 3444.2 cm-1 and formation of ester bond at 1741.4 cm-1 were indications of changes in the chemical structure of the fibers. The tensile modulus and strength increased with increase of nanoclay up to 3 phc and then decreased. However, the impact strength and WA decreased with increase of nanoclay loading. The morphological findings showed that the samples containing 3 phc of nanoclay had higher order of intercalation and better dispersion. © 2014 The Author(s).


Aminifar M.,Standard Research Institute SRI | Emam-Djomeh Z.,University of Tehran
Journal of Agricultural Science and Technology | Year: 2014

In this study, the effect of addition of three different levels of microbial lipase (0, 4, and 8.0 g lipase in 100 kg milk) was investigated on the physiochemical properties, free fatty acids, textural properties, and microstructure of Lighvan cheese during ripening. The addition of lipase did not significantly affect pH, acidity, moisture, and salt content of Lighvan cheese, but increased its free fatty acid content considerably. It also increased hardness and decreased the brittleness of Lighvan cheese in all stages of ripening. The number and the mean diameter of fat globules, which were entrapped in casein network, were affected by all levels of the added lipase. Following the addition of lipase to Lighvan cheese and after 90 days of ripening, individual fat globules or their aggregates totally disappeared and some fingerprints of fat were observed. Disappearance of fat globules along with increase in protein matrix junctions leads to uniform structure of casein consisting voids which are produced from fermentation.


Yamini Y.,Tarbiat Modares University | Faraji M.,Standard Research Institute SRI
Journal of Pharmaceutical Analysis | Year: 2014

A simple, rapid and sensitive method termed as magnetic solid phase extraction (MSPE) combined with high-performance liquid chromatography- ultraviolet detector (HPLC-UV) has been proposed for the determination of trace amounts of chlorpromazine (CPZ) in water, urine and plasma samples. The separation and determination was performed on a C18 column under the optimal chromatographic conditions. Several factors influencing the extraction efficiency of CPZ, such as pH, surfactant and adsorbent amounts, ionic strength, extraction time, sample volume and desorption conditions, were studied and optimized. Under the optimal MSPE conditions, the extraction percentage of CPZ was 74%, 27% and 16% in water, urine and plasma samples, respectively. The limits of detection (LODs) of the proposed approach were 0.1, 5.0 and 10 ng/mL in water, urine and plasma samples, respectively. The relative standard deviations (RSDs) based on five replicate determinations at 10 ng/mL level of CPZ was 1.2%. Good linear behaviors over the investigated concentration ranges (0.25-300 ng/mL) with good coefficient of determination, R2>0. 9998, were obtained. Good spike recoveries with relative errors less than 9.0% were obtained when applying the proposed method to water, urine and plasma samples. © 2014 Xi'an Jiaotong University. Production and hosting by Elsevier B.V. All rights reserved.


Kord B.,Standard Research Institute SRI | Hosseinihashemi S.K.,Islamic Azad University at Karaj
Mechanics of Composite Materials | Year: 2014

The influence of fungal decay on the hygroscopic thickness swelling rate of lignocellulosic filler-polyolefin biocomposites has been investigated. Composites based on polypropylene (PP), bagasse fiber (BF), and a coupling agent (PP-g-MA) were made by melt compounding and injection molding. The weigt ratio of BF to PP was controlled at 60/40 for all blends. The amount of coupling agent was fixed at 2% for all formulations. The samples obtained were exposed to the action of brown-rot (Coniophora puteana) and white-rot (Trametes versicolor) fungi for 8, 12, and 16 weeks according to the Kolle-flask method. The thickness swelling of the samples was evaluated by immersing them in water at room temperature for several weeks. The morphology of the composites was characterized using the scanning electron microscopy (SEM). The results indicated that the fungal decay had an adverse affect on the dimensional stability of BF/PP composites due to an increase in the thickness swelling rate. The thickness swelling of white-rotted samples was higher than that of brown-rotted ones and control samples. Also, the thickness swelling of BF/PP composites increased with increasing time of fungal decay. In addition, after 16 weeks of exposure to white-rot fungi, the composites exhibited a higher parameter of swelling rate K SR than control samples. The K SR of the composites was influenced both by the type of rooting and the exposure time. Furthermore, the SEM micrographs showed that the extent of degradation increased with growing exposure time to fungi. © 2013 Springer Science+Business Media New York.


Hafezi B.,Standard Research Institute SRI | Majidi M.R.,University of Tabriz
Analytical Methods | Year: 2013

A fast, sensitive and accurate electrochemical sensor based on copper nanostructures for electrocatalytic determination of nitrate has been developed. Cyclic voltammetry and hydrodynamic amperometry were employed to characterize the response of the sensor to nitrate that changes linearly in the concentration range from 1 to 35 μM. The repeatability of measurements for nitrate was evaluated as 2.3% (N = 15) and the limit of detection of the method was found to be 0.59 μM (S/N = 3). The content of nitrate in foodstuffs and mineral water samples was determined by the proposed and the reference method based on Griess protocol at the 95% confidence level. No interferences were observed from nitrite ions on the nitrate analysis. The interference from chloride ions was also examined. © 2013 The Royal Society of Chemistry.


A green, convenient and efficient procedure is reported for the synthesis of S-aryl dithiocarbamates by a simple one-pot three component Ullmann-type condensation of an amine, carbon disulfide and an aryl iodide. Magnetically separable and reusable copper oxide (Fe3O4-CuO) nanoparticles are used as a heterogeneous catalyst under base- and solvent-free conditions. Nanoparticles with an average size of 10-20 nm has been successfully prepared by a simple precipitation method in aqueous medium from readily available inexpensive starting materials. The catalyst could be easily separated from the reaction mixture by using an external magnet and recycled four times without significant loss in its activity. © 2016 The Royal Society of Chemistry.

Loading Standard Research Institute SRI collaborators
Loading Standard Research Institute SRI collaborators