جستجوی مقالات مرتبط با کلیدواژه « polystyrene » در نشریات گروه « شیمی »

In this research, Fe3O4, Fe3O4/polystyrene and Fe3O4/polyaniline nanocompounds were prepared and compared on the removal of methyl orange from aqueous solutions. The chemical structures of the synthesized compounds were studied using FT-IR. The crystalline phase of Fe3O4, Fe3O4/polystyrene and Fe3O4/polyaniline nanocompounds was characterized by XRD. SEM was used for detecting morphology of the synthesized samples. The magnetic property of the prepared samples was successfully checked. The prepared nanocompounds were used to remove methyl orange as an anionic dye from aqueous solutions. Based on results, Fe3O4/polyaniline nanocomposite showed higher efficiency in the removal of methyl orange, which is partly due to the oppositely charged methyl orange and Fe3O4/polyaniline. Effective variables on the removal of methyl orange such as adsorbent dosage, pH,  and contact time were studied and optimized. At the optimum situations the pH, catalyst dosage, and time were 3-4, 450 mg L-1, and 50 min, respectively. For detecting the type of adsorption isotherm, Langmuir, Freundlich, and Dubinin Radushkevich adsorption isotherms were studied. According to Langmuir model, Fe3O4/polyaniline magnetic absorbent showed the highest methyl orange adsorption capacity of 48.76 mg g−1. Kinetic studies proved that methyl orange adsorption was explained more accurately via pseudo-second order model compared to the pseudo-first order model. Under controlled reaction conditions, Gibbs free energy (ΔG˚) varied from -1.41 to -1.69 kJ mol-1, besides, the resulting ΔH˚ and ΔS˚ quantities were obtained 4.07 kJ mol-1 and 0.018 kJ mol-1K-1, respectively. Therefore, it can be considered that the adsorption of methyl orange  onto the Fe3O4/polyaniline magnetic absorbent is a spontaneous and endothermic procedure.

In this research work silver/polystyrene nanocomposite has been prepared using polymerization of w/o microemulsion system with two various types of surfactants. In order to investigate effect of surfactant-polymer interaction on the quality of final nanocomposite product, AOT as anionic surfactant and tween 80 as non-ionic surfactant, isobuthanol as co-surfactant and styrene monomer as oil phase were used to prepare microemulsion systems. Surface tension of the microemulsions was measured as a criterion for the reaction media properties. The microemulsion systems were polymerized by benzoyl peroxide initiator following formation of Ag nanoparticles in the fluid medium. The UV-vis absorption analysis has been used to trace the growth process in the microemulsion system. Scanning electron microscopy (SEM) was used to determine the morphology, particle size and dispersion of the Ag in the synthesized nanocomposites. The idea established in current work can potentially be used to synthesis uniform and morphologically well-defined nanocomposites by microemulsion method.

A simple and easy synthetic route for preparing PP-g-PSt/O-MMt nanocomposite was synthesized using a combination of ring-opening polymerization and reversible addition–fragmentation chain transfer polymerization techniques. Firstly, MAH (maleic anhydride) was reacted with PP (polypropylene) followed by the opening of an anhydride ring with ethanolamine to obtain a hydroxyl group including polypropylene (iPP-OH). Secondly, the produced PP-OH was treated with 4-cyano-4-[(phenylcarbothioyl) sulfanyl] pentanoic acid to synthesize of PP-RAFT macroinitiator. Then, the styrene monomer was grafted onto PP using RAFT approach to produce a well-defined (PP-g-PSt) copolymer. Finally, Polymer/clay nanocomposite was synthesized through a solution intercalation method. The successful synthesis of all materials was proved using FT-IR and 1H NMR spectroscopy. The structural morphology and thermal properties of the grafted copolymer /O-MMT nanocomposite were examined using SEM, TGA, and DSC. This approach employed via the RAFT method is an easy and alternative strategy for synthesizing new materials.

The aim of this research is to fabricate a novel temperature sensor for any calorimetry system. A new mixed solution method was introduced to prepare polystyrene/multiwall carbon nanotube nanocomposite samples with different weight percentages as 0.05, 0.1, 0.28, 1, and 2 of MWCNTs. To demonstrate the dispersion state of the inclusion into the polymer matrix, the SEM analysis was applied. Also, XRD and Raman spectroscopy analyses were carried out. The electrical percolation threshold was investigated and achieved at about 0.28 weight percent of the inclusion. Finally, the electrical resistance of the samples was measured from room temperature up to ~100ºC. Consequently, positive temperature coefficient and negative temperature coefficient effects were observed before and after Tg for the most nanocomposite samples, respectively. The best linear response of the resistance-temperature curve was achieved at 20-50ºC, which using a second-order fitting curve it can be used up t0 ~70ºC. Results show that the polystyrene/multiwall carbon nanotube nanocomposite near the percolation threshold can be used as a temperature sensor for calorimetric purposes.

A hybrid nanocomposite composed of polyaniline-polystyrene-chitosan/zinc oxide was prepared via a simple in situ polymerization method. The synthesized copolymers were analyzed using Fourier Transform InfraRed (FT-IR), and UltraViolet-Visible (UV–Vis) spectroscopies, ThermoGravimetric Analysis (TGA), and Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction, energy dispersive,  X-ray photoelectron spectroscopy and cyclic voltammetry. The chemical bonding established between polyaniline-polystyrene and polyaniline-polystyrene-chitosan/zinc oxide, confirmed by FT-IR, is likely to be responsible for the enhanced chemical stability. From SEM observation, the ratio of ZnO nanoparticles to nanocomposite altered the morphology of the hybrids from granular to plate-like structure, which was confirmed by EDXS. The thermal property was studied using TG/DTA analysis shows the residual weight (TGA curves) and its weight derivative (DTA curves) of the polyaniline-polystyrene-chitosan/zinc oxide are more stable than chitosan and polyaniline-polystyrene-chitosan. Also, the cyclic voltammetry on the obtained hybrid materials revealed that the plate-like structure was more advantages for electrochemical stability. Overall, the results show that the introduction of the ZnO nanoparticles into the polyaniline-polystyrene-chitosan matrix enhanced the thermal and electrode stability.

The first stage to have access to a reservoir is the drilling operation. The proper development of this operation plays a major role in increasing productivity. It must be pointed out that the drilling fluid (mud) is pivotal in achieving this objective. Among these fluids, water-based fluids are the most common ones, which have been utilized to drill approximately 80% of all wells and are more economical compared with oil- or synthetic-based fluids. In this study, synthesis of core-shell carboxymethyl cellulose nanoparticles with polystyrene by miniemulsion polymerization was performed. The synthesized core-shell and modified carboxymethyl cellulose nanoparticles were characterized by particle size analyzer, fourier transform infrared spectroscopy, thermo gravimetric analysis and scanning electron microscope. The result showed that the average sizes of carboxy methyl cellulose and core-shell nanoparticles are approximately 47 and 80 nm, respectively. The core-shell nanoparticles have spherical shape with a smooth outer surface. Indeed, the produced core-shell improved the thermal resistance of carboxymethyl cellulose nanoparticles in comparison to bulk carboxymethyl cellulose.

In this research, the magnetite polystyrene maleic anhydride (MPSMA) was synthesized and structure and morphology characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy techniques. The obtained nano-structured inorganic material was employed as a novel magnetic nanosorbent for separation and pre-concentration of Methyl violet (10B) dye from aqueous solutions, which can be spectrophotometrically monitored at λ = 585 nm after pre-concentration by solid phase extraction (SPE). The effect of several parameters including pH of the sample solution, amount of the sorbent, extraction and desorption times, and elution conditions and sample volume were investigated and optimized. UV–Vis spectrophotometer was used for determination of MV (10B) concentration after desorption of the dye by nitric acid solution. Under the optimum experimental conditions, the limit of detection and the relative standard deviation were 0.08 µg L–1 and 1.10 %, respectively. The enrichment factor of 200 was achieved and the calibration graph using the presented solid phase extraction system was linear in the range of 0.3 – 1500 µg L–1 with a correlation coefficient of 0.9989. The method was successfully applied to pre-concentration of MV (10B) from several textile waste water effluents.

A nano-hybrid based on polystyrene derivatives and magnetite was introduced as a new sorbent for pretreatment and determine the trace amount of malachite green from aqueous solution by spectrophotometry after preconcentration by solid phase extraction (SPE). UV–Vis spectrophotometer was used for determination of MG concentration after desorption of the dye by hydrochloric acid solution in the solutions. Different variables affecting the separation/pre-concentration conditions, including pH of the sample solution, amount of the sorbent, extraction and desorption times, sample volume, and elution conditions were obtained in the range of 1–2000 ng/mL dye, with the correlation coefficient of 0.998. The enrichment factor of 133 was achieved. The limit of detection was 0.2 ng·mL−1 and the relative standard deviation for the determination of malachite was 1.4 % (n=6(. Langmuir, Freundlich, adsorption isotherm models were studied and the experimental results were addressed by Freundlich isotherm model. The maximum sorption capacity of the adsorbent for malachite green was 148.6 mg. g-1, indicating high potential of MSMA in the adsorption of malachite green. The adsorption kinetics was studied with the pseudo-first-order, pseudo-second-order models. The method was successfully applied to determine malachite green in natural waters and satisfactory recoveries were obtained >98 %.from this.

In this research, firstly polyaniline-zinc oxide (PANI-ZnO) nanocomposite was successfully synthesized by chemical polymerization of aniline in the presence of ZnO nanoparticles and then, 5%, 10% and 15% solutions of PANI–ZnO nanocomposites were mixed with a solution of polystyrene (PS) in tetrahydrofurane (THF) and PANI-PS-ZnO nanocomposites were obtained. The prepared nanocomposites were used as coating on iron coupons by solution casting method and their anti corrosive performance were studied by open circuit potential (OCP) and Tafel techniques in 3.5% NaCl solution as corrosive environment. The obtained results showed that the coating of PS-[PANI-ZnO 10%] nanocomposite had superior corrosion protection effect on iron sample compared to that of pure PANI, PANI–ZnO nanocomposite, PANI-PS composite and two other PANI-PS-ZnO nanocomposite coatings. Cyclic voltammetry (CV) studies showed that the prepared PS-[PANI-ZnO 10%] nanocomposite was electroactive and this property was reversible and stable. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques were used to characterize the composition and structure of PS-[PANI-ZnO 10%] nanocomposite. To study thermal stability of PS- [PANI-ZnO 10%] nanocomposite, thermogravimetric analysis (TGA) was used.

Polypropylene / polystyrene blends containing montmorillonite (MMT) were prepared using a twin screw extruder followed by fiber spinning. The melt intercalation of PP and PS alloys was carried out in the presence of a compatibilizer such as maleic anhydride-g-polypropylene (MPP). The crystallization morphology, thermal behaviors and mechanical properties of polypropylene/polystyrene (PP/PS) nanoclay blends nanocomposite fibers were investigated in the present work. The improved adhesion between the phases and fine morphology of the dispersed phase contributed to the significant improvement in the properties and thermal stability of the final nanocomposite materials. On the basis of this result, we describe a general understanding of how the morphology is related to the final properties of OMMT- incorporated PP/PS blends.

Polymer nanocomposites containing metals have been used in a wide range of applications due to their versatility, and tunable characteristics including physical, chemical, biological and mechanical properties. In this research work polystyrene-silver nanocomposite has been produced using polymerization of a w/o microemulsion system. Styrene monomer was used as the oil or continues phase of the microemulsion system and polymerized following formation of Ag nanoparticles in the fluid medium. The UV-vis absorption and dynamic light scattering methods have been used to trace the growth process and size distribution of the Ag nanoparticles in the microemulsion system. Scanning electron microscopy (SEM) was used to determine the morphology and particle size of the Ag particles in the synthesized nanocomposites.