A new methodology to assess ion diffusion in side-chain modified AEMs reveals separate roles for ... more A new methodology to assess ion diffusion in side-chain modified AEMs reveals separate roles for functionality and side-chain length: the former determines hydrophilic pathway morphology and the latter regulates anion diffusion rate in the channels.
The use of catechol-containing comonomers as a general property enhancer to achieve unique proper... more The use of catechol-containing comonomers as a general property enhancer to achieve unique properties has received particular attention for designing bioinspired polymeric materials.
Polyaniline/graphene oxide composites of different morphologies were synthesized by oxidation pol... more Polyaniline/graphene oxide composites of different morphologies were synthesized by oxidation polymerization method without using conventional oxidants. By changing the type of acid (doping agent) and its concentration, two different morphologies including worm-like morphology and flaky- or scalelike morphology were obtained. Morphology of these composites was studied by scanning electron microscopy (SEM). In order to achieve a better characterization of the polyaniline/graphene oxide composite, they were also investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). XRD analysis showed that, unlike in worm-like composite, crystallization was induced in flaky- or scale-like composite and the graphene oxide sheets were well exfoliated. To study electrochemical properties of the composites, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used. The synthesized polyaniline/graphene oxide composites were evaluated by meas...
The significant breakthroughs of flexible gel electrolytes have attracted extensive attention in ... more The significant breakthroughs of flexible gel electrolytes have attracted extensive attention in modern wearable electronic gadgets. The lack of all-around high-performing gels limits the advantages of such devices for practical applications. To this end, developing a multi-functional gel architecture with superior ionic conductivity while enjoying good mechanical flexibility is a bottleneck to overcome. Herein, an architecturally engineered gel, based on PVA and H3PO4 with different molecular weights of PVA for various PVA/H3PO4 ratios, was developed. The results show the dependence of ionic conductivity on molecular weight and also charge carrier concentration. Consequently, fine-tuning of PVA-based gels through a simple yet systematic and well-regulated strategy to achieve highly ion-conducting gels, with the highest ionic conductivity of 14.75 ± 1.39 mS cm-1 have been made to fulfill the requirement of flexible devices. More importantly, gel electrolytes possess good mechanical ...
There is a common knowledge that the dynamic and structural behavior of polymer chains in the vic... more There is a common knowledge that the dynamic and structural behavior of polymer chains in the vicinity of nano-fillers is rather different from the bulk. Despite the extensive literature on this topic, this phenomenon is not yet fully understood. Apart from several experimental methods to study it, molecular simulations, in particular molecular dynamics (MD) methods, are good candidates for such study. In other words, MD simulation techniques give us a remarkable ability for mechanistic studies of dynamic and structural properties of polymer chains in nano-scales and they are proved to be highly reliable methods for estimating such properties. Therefore, in this study, we developed a time and spatially-resolved molecular dynamic method by which the structural and dynamic properties of two polymers, i.e., polypropylene (PP) and polyvinyl alcohol (PVA), are studied as a function of distance from graphene (G) and graphene oxide (GO) nano-layers.
The present work explores a facile route to prepare a durable conductive fabric by using reduced ... more The present work explores a facile route to prepare a durable conductive fabric by using reduced graphene oxide and polypyrrole. Prior to coating of active materials, polyester surface experienced a modification which resulted in high uptake of materials. Then, dipcoating approach was used to deposit graphene oxide on the modified polyester. After reduction of graphene oxide, polypyrrole particles grew on the fabric surface through an in situ polymerization method. SEM, XRD, FTIR, and TGA were employed to investigate the morphology and chemical structure of the samples. A high electrical conductivity of 0.98 S.cm-1 was obtained which arises from establishing the numerous conduction routes in the structure. A mere decrease in conductivity after 20 laundry cycles confirms the excellent washing durability of the conductive fabric. Moreover, a high specific capacitance of 8.3 F.g-1 was recorded for this fabric by cyclic voltammetry in a three-electrode measurement system.
Any improvement in drilling technology is critical for developing the oil and gas industry. The s... more Any improvement in drilling technology is critical for developing the oil and gas industry. The success of drilling operations largely depends on drilling fluid characteristics. Drilling fluids require enough viscosity to suspend the particles and transport them to the surface and enough capability to control the fluid loss into the formation. Rheology and filtration characteristics of drilling fluids are crucial factors to consider while ensuring the effectiveness of a drilling operation. Graphene oxide (GO), xanthan gum (XG), and low-viscosity carboxymethyl cellulose (CMC LV) are being utilized in this research to produce high-performance, low-solid water-based drilling fluids (WDFs). Rheological and filtration behaviors of GO/XG/CMC LV-WDF were investigated as a function of GO, XG, and CMC LV at low concentrations (0.0−0.3% w/w) and atmospheric conditions. According to the findings, GO improved the rheological and filtration capabilities of the WDF. By adding 0.15 wt % GO, shear stress could be doubled, especially at a high shear rate of 1022 s −1. The plastic viscosity of the fluid could be expanded from 6 to 13 centipoise, and a fluid loss of 8.7 mL over 30 min was observed during the API fluid test, which would be lower than the suggested fluid loss value (15.0 mL) for water-based mud. At the same concentration of XG and CMC LV, XG had a more significant influence on rheological characteristics in the presence of GO. Adding 0.3 wt % XG could increase fluid shear stress from 20.21 to 30.21 Pa at a high shear rate of 1022 s −1. In contrast, CMC LV had more impact on filtration properties, acting as a filtration control agent by decreasing the API fluid loss of fluid from 21.4 to 14.2 mL over 30 min. The addition of XG and CMC LV to the GO solution may influence the microstructure of the filter cake, resulting in a treeroot morphology. Indeed, in the GO/CMC LV solution, the individual platelets may bind together, form a jellyfish shape, and block the micropores. The incorporation of CMC LV helped develop compact filter cakes, resulting in excellent filtration. Five rheological models were employed to match the fluid parameters quantitatively. The Herschel−Bulkley model outperformed the other models in simulating fluid rheological behavior. The findings of this study can be utilize to provide low-cost, stable, and environmentally compatible additives for drilling low-pressure, depleted, and fractured oil and gas reservoirs.
Alkenes - Recent Advances, New Perspectives and Applications, 2021
Naphtha is one of the crude oil distillation products, bringing almost the lowest value-addition ... more Naphtha is one of the crude oil distillation products, bringing almost the lowest value-addition to crude oil, compared to other refinery products such as liquid petroleum gas, gasoline, and diesel. However, Naphtha can be converted to one of the highest value products at the end of the value chain, i.e., polyolefins. Although the production of conventional commodity polyolefins from crude oil, is considered as one of the final products in alkenes’ value chain, there are specialty polyolefins with higher values. Specialty polyolefins are small volume, high-performance thermoplastics with high-profit margins compared to traditional commodity polyolefins. Recently, some special purpose functionalized polyolefins have been developed as efficient substituents for high-performance engineering thermoplastics. Polyolefins are exploited as cost-effective platforms to produce these functionalized thermoplastics. They are promising candidates for replacing high-performance polymers with high-...
Electrochemical nonenzymatic biosensors with no immobilization and degradation problem, have rece... more Electrochemical nonenzymatic biosensors with no immobilization and degradation problem, have recently attracted growing attention due to stability and reproducibility. Here, a comparative study was conducted to precisely evaluate the nonenzymatic glucose sensing of pure/oxidized Ni, Co, and their bimetal nanostructures grown on electrospun carbon nanofibers (ECNFs). This method provides a low-cost free stand electrode. The prepared nanostructures with superb physiochemical features exhibited sensitivity (from 66.28 to 610.6 μA mM−1 cm−2), linear range of 2-10 mM, limit of detection in the range of 1 mM, and response time (<5 s), besides outstanding selectivity and applicability for glucose detection in the human serum. Regarding Co-C and Ni-C phase diagrams, solid-state diffusion phenomena, and rearrangement of dissolved C atoms after migration from metal particles was discussed. This study undoubtedly provides new prospects on nonenzymatic biosensing performance of mono-metal, b...
Abstract Manufacturing proper electrodes for supercapacitors including high capacitance is of gre... more Abstract Manufacturing proper electrodes for supercapacitors including high capacitance is of great importance for current increased demand for energy storage devices. In this paper, we evaluated metal nanoparticles infused in electrospun carbon nanofibers (ECNF) synthesized by electrospinning, followed by thermal treatment for supercapacitors’ electrode applications. The electrodes were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry. The characterization results indicated that the metal/ECNF samples have fibrous morphology, porous structure with a high specific surface area, including dispersed metal nanoparticles. The effect of embedding various transition metals, such as Co, Ni, and Cu on the electrochemical performance of ECNF has been investigated. The incorporation of Cu into ECNF resulted in the highest specific capacitance. At the scan rate of 5 mV s−1, the specific capacitance of the Cu/ECNF sample was 332 F g−1 while it was 4 F g−1 for the ECNF sample.
Abstract Conductive inks are considered very promising for device fabrication on flexible substra... more Abstract Conductive inks are considered very promising for device fabrication on flexible substrates and large areas. Silver (Ag)-graphene hybrid inks offer many opportunities, including cost/conductivity optimization for different applications. In this work, several conductive hybrid ink formulations containing Ag nanostructures and graphene derivatives were prepared using different processing strategies and thoroughly characterized. SEM and morphological studies were used to explore the probable reasons for the difference in electrical conductivity of various inks. Strong interaction between Ag nanoparticles and graphene layers prevented the formation of island structures in films, especially at high temperatures. While Ag nanowires and graphene layers formed a uniform, dense three-dimensional network, offering high electrical conductivity. Additionally, an improvement of electrical conductivity by using graphene quantum dots as a graphene component in hybrid inks was observed, which was related to creating new conductive bridges. The highest conductivity of prepared inks varied in the range of 2.67 × 102 S/cm to 4.0 × 104 S/cm. Finally, formulation guidelines were offered to be used for inks by several printing methods.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020
Nanoparticles/surfactant interplays can robustly manipulate interfacial properties, while it is s... more Nanoparticles/surfactant interplays can robustly manipulate interfacial properties, while it is still unclear how their interactions affect interface behavior. This research recap unprecedented research for determination of dynamics of adsorption and dynamic surface properties of amphiphilic sheet-like nanoparticles in anionic surfactant mixtures and generalizing their characteristics in industrial and macroscopic applications by controlling microscopic active mechanism, particularly tuning foam properties and controlling its behavior. Amphiphilic nanosheets are surface-active particles which tend to self-assemble at the air-water interface. In this study, a system of an anionic surfactant (sodium dodecylsulfate (SDS)) and an amphiphilic nanoparticle (Graphene oxide (GO)) is studied at different ratios. It appears that there is a critical value for the minimum number of surfactants per nanosheets (> 160) to make the amphiphilic nanoparticle more hydrophilic. The results set out that below this critical ratio, the amphiphilic nanoparticles are partially hydrophobic and they are surface-active enough to be adsorbed considerably at the air-water interface. The nanoparticle adsorption causes an increase in surface elasticity and a decrease in surface tension (ST). As SDS/GO ratio increases, GO particles are heavily surrounded by SDS molecules rendering them hydrophilic particles. The hydrophilic GO particles start traveling back into the bulk, drastically decreasing elasticity and increasing the ST. When SDS concentration approaches the pure SDS critical micelle concentration (CMC), there appears that some of GO/SDS complexes are still on the airwater interface to slow down the dynamics of ST. The presence of GO/SDS complexes at the interface also
Abstract In this research, the fabrication of a hybrid structure of polyaniline hollow fibers (PA... more Abstract In this research, the fabrication of a hybrid structure of polyaniline hollow fibers (PANI-HF) and reduced graphene oxide (rGO) has been reported and the hierarchical structure and electrochemical performance of the system has also been studied. The formation of the hierarchical hybrid structure has been proved by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR), and X-ray diffraction (XRD). Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cyclic stability were employed to evaluate the electrochemical performance of the composites. PANI-HF has provided a superior structure for enhanced electrocapacitance due to its higher specific surface area. Decorating the PANI-HF by rGO sheets has resulted in better specific capacitance (Cs) at high scan rates. At the scan rate of 20 mV s−1, the specific capacitance of PANI-HF/rGO hybrid was found to be 449 F g−1 while it was 425 F g−1 for PANI-HF. Furthermore, rGO has provided a solid network in hybrid sustaining PANI-HF during the long-term charge-discharge cycles and improved the cyclic stability. In addition, only 16% of the initial capacitance of PANI-HF/rGO hybrid has been lost after 2000 cycles.
Engineered cementitious composites containing polymeric fibers such as poly(vinyl alcohol) show h... more Engineered cementitious composites containing polymeric fibers such as poly(vinyl alcohol) show high tensile ductility and toughness. The aim of the current study was to evaluate the effect of crystallinity degree of poly(vinyl alcohol) fibers on fiber debonding from cementitious matrix in the bending test. In this work, two types of poly(vinyl alcohol) fibers and one grade of polypropylene fiber were separately incorporated in cementitious composites. The chemical structure, surface chemistry, roughness, and microstructure of fibers were examined by Fourier transform infrared, attenuated total reflection, atomic force microscopy, and wide-angle X-ray diffraction tests, respectively. The compression and flexural behaviors of cementitious composites were also assessed. Attenuated total reflection results were indicative of similar surface chemistry for both poly(vinyl alcohol) fibers, while the main difference was observed in the case of degree of crystallinity, which plays an import...
In this research, an attempt was made to stabilize reduced graphene oxide (rGO) in all pH ranges,... more In this research, an attempt was made to stabilize reduced graphene oxide (rGO) in all pH ranges, incorporating both chitosan (CS) and hydroxyethyl cellulose (HEC) to make a proper drug carrier with suitable stability and drug release behavior. The stability of rGO-CS-HEC nanohybrid was assessed using field emission scanning electron microscopy (FE-SEM), ultraviolet-visible spectroscopy (UV-VIS) and Zeta potential measurements. Results depicted that the novel synthesized nanohybrid was stable in all pH ranges, due to the utilization of HEC, while without incorporation of this material, the rGO-CS nanohybrid aggregated at neutral and alkaline media, due to the ionic nature of chitosan. In addition, drug loading and release behaviour of folic acid (FA), as a model drug, was investigated to assess the role of chitosan on the release behavior of FA from the rGO-CS-HEC nanohybrid in comparison with rGO-HEC and rGO-CS nanohybrids. It was proved that the resultant nanohybrid could release nearly 27% more FA than the rGO-HEC nanohybrid and only 9% lower than the rGO-CS nanohybrid during 120 hours. Moreover, the biocompatibility of the resultant nanohybrid was also checked to introduce the novel rGO-CS-HEC nanohybrid as a suitable candidate for drug delivery application.
In this paper, convective heat transfer coefficient of Grapheneewater nanofluid in a laminar flow... more In this paper, convective heat transfer coefficient of Grapheneewater nanofluid in a laminar flow through a circular pipe with uniform wall heat flux is investigated experimentally. To achieve this aim, the nanofluid is synthesized chemically in various concentrations, and a testbed is constructed. The effective thermal conductivity and viscosity of the Grapheneewater nanofluids are measured via hot wire method and an Ubbelohde viscometer, respectively. Results show that addition of low amounts (up to 0.02% volume fraction) of Graphene nanoparticles to water considerably increases the thermal conductivity and the convective heat transfer coefficient of the working fluid. Maximum enhancements are observed at 0.02% concentration. These enhancements are 10.3% for thermal conductivity and 14.2% for heat transfer coefficient at Re ¼ 1850. Moreover, the stability of the prepared nanofluids is examined by using the UVevis spectroscopy and is proved to be acceptably high. Finally, the results of the taken AFM images implied no agglomeration of nanoparticles.
Journal of Thermoplastic Composite Materials, 2016
Early stage crystallization kinetics of polypropylene (PP)/clay composites is studied using rheom... more Early stage crystallization kinetics of polypropylene (PP)/clay composites is studied using rheometery. Relaxation modulus of composites is measured at low frequencies near liquid–solid transition. Small amplitude oscillating shear flow is applied at low frequencies to obtain relaxation modulus. Relaxation modulus of polymeric materials at the liquid–solid transition follows [Formula: see text], at long times ( λ < t < ∞), where λ is the time to crossover to a different relaxation regime, s is the gel stiffness, and n is the relaxation exponent. Inverse quenching technique is then employed to retain degree of crystallization while rheological measurements are made. Lower gel time is observed as clay concentration increased, indicating the formation of more nuclei. An improvement to Avrami’s equation is proposed to predict crystallization kinetics for PP/clay composites. There is a good agreement between predicted relative crystallinity values and empirical values.
Dispersion of nanomaterials in polymeric matrices plays an important role in determining the fina... more Dispersion of nanomaterials in polymeric matrices plays an important role in determining the final properties of the composites. Dispersion in nano scale, and especially in single layers, provides best opportunity for bonding. In this study, we propose that by proper functionalization and mixing strategy of graphene its dispersion, and bonding to the polymeric matrix can be improved. We then apply this strategy to graphene-epoxy system by amino functionalization of graphene oxide (GO). The process included two phase extraction, and resulted in better dispersion and higher loading of graphene in epoxy matrix. Rheological evaluation of different graphene-epoxy dispersions showed a rheological percolation threshold of 0.2 vol% which is an indication of highly dispersed nanosheets. Observation of the samples by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM), showed dispersion homogeneity of the sheets at micro and nano scales. Study of graphene-epoxy composites showed good bonding between graphene and epoxy. Mechanical properties of the samples were consistent with theoretical predictions for ideal composites indicating molecular level dispersion and good bonding between nanosheets and epoxy matrix.
Quality of injection molded parts of semi-crystalline polymers has been the subject of intense in... more Quality of injection molded parts of semi-crystalline polymers has been the subject of intense interest from both analytical and industrial points of view. Crystallinity profile plays an important role in determining mechanical properties of a part and its quality. Therefore it is important to analyze the effect of injection molding parameters on the crystallinity profile of the molded parts. In this study, finite element analysis has been used to solve the equations of mass, momentum, and energy conservation simultaneously with the equation of crystallization kinetics to predict melt front, its solidification and crystallinity profile. The results from our numerical analysis have been compared with the reported experimental results. Furthermore, progress of the crystallization is proposed to be a proper criterion for estimation of the eject time. Finally, the effects of mold and melt temperature on the eject time; part temperature and average degree of crystallinity, for a specific...
Processing graphene and graphene polymer nanocomposites in an aqueous medium has always been a bi... more Processing graphene and graphene polymer nanocomposites in an aqueous medium has always been a big challenge due to the hydrophobic nature of graphene (or reduced graphene oxide) nanosheets. In this work, a waterborne latex of polyurethane has been used both as the matrix material for embedding the graphene nanosheets and as a unique stabilizer to help produce an up to 5 wt% graphene/PU nanocomposites. The graphene oxide/polyurethane latex aqueous suspension is reduced in-situ using hydrazine, without any trace of aggregation/agglomeration upon completion of the reduction process, which would otherwise have occurred severely were PU not present. A highly aligned nanostructure is produced when graphene content is increased beyond 2 wt%, resulting in a remarkable improvement in electrical and mechanical properties of the nanocomposite. The exceptionally low electrical percolation threshold of 0.078%, as well as 21-fold and 14 fold increases in tensile modulus and strength, respectively, have been attained thanks to the alignment of graphene nanosheets in the polymeric matrix.
A new methodology to assess ion diffusion in side-chain modified AEMs reveals separate roles for ... more A new methodology to assess ion diffusion in side-chain modified AEMs reveals separate roles for functionality and side-chain length: the former determines hydrophilic pathway morphology and the latter regulates anion diffusion rate in the channels.
The use of catechol-containing comonomers as a general property enhancer to achieve unique proper... more The use of catechol-containing comonomers as a general property enhancer to achieve unique properties has received particular attention for designing bioinspired polymeric materials.
Polyaniline/graphene oxide composites of different morphologies were synthesized by oxidation pol... more Polyaniline/graphene oxide composites of different morphologies were synthesized by oxidation polymerization method without using conventional oxidants. By changing the type of acid (doping agent) and its concentration, two different morphologies including worm-like morphology and flaky- or scalelike morphology were obtained. Morphology of these composites was studied by scanning electron microscopy (SEM). In order to achieve a better characterization of the polyaniline/graphene oxide composite, they were also investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). XRD analysis showed that, unlike in worm-like composite, crystallization was induced in flaky- or scale-like composite and the graphene oxide sheets were well exfoliated. To study electrochemical properties of the composites, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used. The synthesized polyaniline/graphene oxide composites were evaluated by meas...
The significant breakthroughs of flexible gel electrolytes have attracted extensive attention in ... more The significant breakthroughs of flexible gel electrolytes have attracted extensive attention in modern wearable electronic gadgets. The lack of all-around high-performing gels limits the advantages of such devices for practical applications. To this end, developing a multi-functional gel architecture with superior ionic conductivity while enjoying good mechanical flexibility is a bottleneck to overcome. Herein, an architecturally engineered gel, based on PVA and H3PO4 with different molecular weights of PVA for various PVA/H3PO4 ratios, was developed. The results show the dependence of ionic conductivity on molecular weight and also charge carrier concentration. Consequently, fine-tuning of PVA-based gels through a simple yet systematic and well-regulated strategy to achieve highly ion-conducting gels, with the highest ionic conductivity of 14.75 ± 1.39 mS cm-1 have been made to fulfill the requirement of flexible devices. More importantly, gel electrolytes possess good mechanical ...
There is a common knowledge that the dynamic and structural behavior of polymer chains in the vic... more There is a common knowledge that the dynamic and structural behavior of polymer chains in the vicinity of nano-fillers is rather different from the bulk. Despite the extensive literature on this topic, this phenomenon is not yet fully understood. Apart from several experimental methods to study it, molecular simulations, in particular molecular dynamics (MD) methods, are good candidates for such study. In other words, MD simulation techniques give us a remarkable ability for mechanistic studies of dynamic and structural properties of polymer chains in nano-scales and they are proved to be highly reliable methods for estimating such properties. Therefore, in this study, we developed a time and spatially-resolved molecular dynamic method by which the structural and dynamic properties of two polymers, i.e., polypropylene (PP) and polyvinyl alcohol (PVA), are studied as a function of distance from graphene (G) and graphene oxide (GO) nano-layers.
The present work explores a facile route to prepare a durable conductive fabric by using reduced ... more The present work explores a facile route to prepare a durable conductive fabric by using reduced graphene oxide and polypyrrole. Prior to coating of active materials, polyester surface experienced a modification which resulted in high uptake of materials. Then, dipcoating approach was used to deposit graphene oxide on the modified polyester. After reduction of graphene oxide, polypyrrole particles grew on the fabric surface through an in situ polymerization method. SEM, XRD, FTIR, and TGA were employed to investigate the morphology and chemical structure of the samples. A high electrical conductivity of 0.98 S.cm-1 was obtained which arises from establishing the numerous conduction routes in the structure. A mere decrease in conductivity after 20 laundry cycles confirms the excellent washing durability of the conductive fabric. Moreover, a high specific capacitance of 8.3 F.g-1 was recorded for this fabric by cyclic voltammetry in a three-electrode measurement system.
Any improvement in drilling technology is critical for developing the oil and gas industry. The s... more Any improvement in drilling technology is critical for developing the oil and gas industry. The success of drilling operations largely depends on drilling fluid characteristics. Drilling fluids require enough viscosity to suspend the particles and transport them to the surface and enough capability to control the fluid loss into the formation. Rheology and filtration characteristics of drilling fluids are crucial factors to consider while ensuring the effectiveness of a drilling operation. Graphene oxide (GO), xanthan gum (XG), and low-viscosity carboxymethyl cellulose (CMC LV) are being utilized in this research to produce high-performance, low-solid water-based drilling fluids (WDFs). Rheological and filtration behaviors of GO/XG/CMC LV-WDF were investigated as a function of GO, XG, and CMC LV at low concentrations (0.0−0.3% w/w) and atmospheric conditions. According to the findings, GO improved the rheological and filtration capabilities of the WDF. By adding 0.15 wt % GO, shear stress could be doubled, especially at a high shear rate of 1022 s −1. The plastic viscosity of the fluid could be expanded from 6 to 13 centipoise, and a fluid loss of 8.7 mL over 30 min was observed during the API fluid test, which would be lower than the suggested fluid loss value (15.0 mL) for water-based mud. At the same concentration of XG and CMC LV, XG had a more significant influence on rheological characteristics in the presence of GO. Adding 0.3 wt % XG could increase fluid shear stress from 20.21 to 30.21 Pa at a high shear rate of 1022 s −1. In contrast, CMC LV had more impact on filtration properties, acting as a filtration control agent by decreasing the API fluid loss of fluid from 21.4 to 14.2 mL over 30 min. The addition of XG and CMC LV to the GO solution may influence the microstructure of the filter cake, resulting in a treeroot morphology. Indeed, in the GO/CMC LV solution, the individual platelets may bind together, form a jellyfish shape, and block the micropores. The incorporation of CMC LV helped develop compact filter cakes, resulting in excellent filtration. Five rheological models were employed to match the fluid parameters quantitatively. The Herschel−Bulkley model outperformed the other models in simulating fluid rheological behavior. The findings of this study can be utilize to provide low-cost, stable, and environmentally compatible additives for drilling low-pressure, depleted, and fractured oil and gas reservoirs.
Alkenes - Recent Advances, New Perspectives and Applications, 2021
Naphtha is one of the crude oil distillation products, bringing almost the lowest value-addition ... more Naphtha is one of the crude oil distillation products, bringing almost the lowest value-addition to crude oil, compared to other refinery products such as liquid petroleum gas, gasoline, and diesel. However, Naphtha can be converted to one of the highest value products at the end of the value chain, i.e., polyolefins. Although the production of conventional commodity polyolefins from crude oil, is considered as one of the final products in alkenes’ value chain, there are specialty polyolefins with higher values. Specialty polyolefins are small volume, high-performance thermoplastics with high-profit margins compared to traditional commodity polyolefins. Recently, some special purpose functionalized polyolefins have been developed as efficient substituents for high-performance engineering thermoplastics. Polyolefins are exploited as cost-effective platforms to produce these functionalized thermoplastics. They are promising candidates for replacing high-performance polymers with high-...
Electrochemical nonenzymatic biosensors with no immobilization and degradation problem, have rece... more Electrochemical nonenzymatic biosensors with no immobilization and degradation problem, have recently attracted growing attention due to stability and reproducibility. Here, a comparative study was conducted to precisely evaluate the nonenzymatic glucose sensing of pure/oxidized Ni, Co, and their bimetal nanostructures grown on electrospun carbon nanofibers (ECNFs). This method provides a low-cost free stand electrode. The prepared nanostructures with superb physiochemical features exhibited sensitivity (from 66.28 to 610.6 μA mM−1 cm−2), linear range of 2-10 mM, limit of detection in the range of 1 mM, and response time (<5 s), besides outstanding selectivity and applicability for glucose detection in the human serum. Regarding Co-C and Ni-C phase diagrams, solid-state diffusion phenomena, and rearrangement of dissolved C atoms after migration from metal particles was discussed. This study undoubtedly provides new prospects on nonenzymatic biosensing performance of mono-metal, b...
Abstract Manufacturing proper electrodes for supercapacitors including high capacitance is of gre... more Abstract Manufacturing proper electrodes for supercapacitors including high capacitance is of great importance for current increased demand for energy storage devices. In this paper, we evaluated metal nanoparticles infused in electrospun carbon nanofibers (ECNF) synthesized by electrospinning, followed by thermal treatment for supercapacitors’ electrode applications. The electrodes were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry. The characterization results indicated that the metal/ECNF samples have fibrous morphology, porous structure with a high specific surface area, including dispersed metal nanoparticles. The effect of embedding various transition metals, such as Co, Ni, and Cu on the electrochemical performance of ECNF has been investigated. The incorporation of Cu into ECNF resulted in the highest specific capacitance. At the scan rate of 5 mV s−1, the specific capacitance of the Cu/ECNF sample was 332 F g−1 while it was 4 F g−1 for the ECNF sample.
Abstract Conductive inks are considered very promising for device fabrication on flexible substra... more Abstract Conductive inks are considered very promising for device fabrication on flexible substrates and large areas. Silver (Ag)-graphene hybrid inks offer many opportunities, including cost/conductivity optimization for different applications. In this work, several conductive hybrid ink formulations containing Ag nanostructures and graphene derivatives were prepared using different processing strategies and thoroughly characterized. SEM and morphological studies were used to explore the probable reasons for the difference in electrical conductivity of various inks. Strong interaction between Ag nanoparticles and graphene layers prevented the formation of island structures in films, especially at high temperatures. While Ag nanowires and graphene layers formed a uniform, dense three-dimensional network, offering high electrical conductivity. Additionally, an improvement of electrical conductivity by using graphene quantum dots as a graphene component in hybrid inks was observed, which was related to creating new conductive bridges. The highest conductivity of prepared inks varied in the range of 2.67 × 102 S/cm to 4.0 × 104 S/cm. Finally, formulation guidelines were offered to be used for inks by several printing methods.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020
Nanoparticles/surfactant interplays can robustly manipulate interfacial properties, while it is s... more Nanoparticles/surfactant interplays can robustly manipulate interfacial properties, while it is still unclear how their interactions affect interface behavior. This research recap unprecedented research for determination of dynamics of adsorption and dynamic surface properties of amphiphilic sheet-like nanoparticles in anionic surfactant mixtures and generalizing their characteristics in industrial and macroscopic applications by controlling microscopic active mechanism, particularly tuning foam properties and controlling its behavior. Amphiphilic nanosheets are surface-active particles which tend to self-assemble at the air-water interface. In this study, a system of an anionic surfactant (sodium dodecylsulfate (SDS)) and an amphiphilic nanoparticle (Graphene oxide (GO)) is studied at different ratios. It appears that there is a critical value for the minimum number of surfactants per nanosheets (> 160) to make the amphiphilic nanoparticle more hydrophilic. The results set out that below this critical ratio, the amphiphilic nanoparticles are partially hydrophobic and they are surface-active enough to be adsorbed considerably at the air-water interface. The nanoparticle adsorption causes an increase in surface elasticity and a decrease in surface tension (ST). As SDS/GO ratio increases, GO particles are heavily surrounded by SDS molecules rendering them hydrophilic particles. The hydrophilic GO particles start traveling back into the bulk, drastically decreasing elasticity and increasing the ST. When SDS concentration approaches the pure SDS critical micelle concentration (CMC), there appears that some of GO/SDS complexes are still on the airwater interface to slow down the dynamics of ST. The presence of GO/SDS complexes at the interface also
Abstract In this research, the fabrication of a hybrid structure of polyaniline hollow fibers (PA... more Abstract In this research, the fabrication of a hybrid structure of polyaniline hollow fibers (PANI-HF) and reduced graphene oxide (rGO) has been reported and the hierarchical structure and electrochemical performance of the system has also been studied. The formation of the hierarchical hybrid structure has been proved by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR), and X-ray diffraction (XRD). Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cyclic stability were employed to evaluate the electrochemical performance of the composites. PANI-HF has provided a superior structure for enhanced electrocapacitance due to its higher specific surface area. Decorating the PANI-HF by rGO sheets has resulted in better specific capacitance (Cs) at high scan rates. At the scan rate of 20 mV s−1, the specific capacitance of PANI-HF/rGO hybrid was found to be 449 F g−1 while it was 425 F g−1 for PANI-HF. Furthermore, rGO has provided a solid network in hybrid sustaining PANI-HF during the long-term charge-discharge cycles and improved the cyclic stability. In addition, only 16% of the initial capacitance of PANI-HF/rGO hybrid has been lost after 2000 cycles.
Engineered cementitious composites containing polymeric fibers such as poly(vinyl alcohol) show h... more Engineered cementitious composites containing polymeric fibers such as poly(vinyl alcohol) show high tensile ductility and toughness. The aim of the current study was to evaluate the effect of crystallinity degree of poly(vinyl alcohol) fibers on fiber debonding from cementitious matrix in the bending test. In this work, two types of poly(vinyl alcohol) fibers and one grade of polypropylene fiber were separately incorporated in cementitious composites. The chemical structure, surface chemistry, roughness, and microstructure of fibers were examined by Fourier transform infrared, attenuated total reflection, atomic force microscopy, and wide-angle X-ray diffraction tests, respectively. The compression and flexural behaviors of cementitious composites were also assessed. Attenuated total reflection results were indicative of similar surface chemistry for both poly(vinyl alcohol) fibers, while the main difference was observed in the case of degree of crystallinity, which plays an import...
In this research, an attempt was made to stabilize reduced graphene oxide (rGO) in all pH ranges,... more In this research, an attempt was made to stabilize reduced graphene oxide (rGO) in all pH ranges, incorporating both chitosan (CS) and hydroxyethyl cellulose (HEC) to make a proper drug carrier with suitable stability and drug release behavior. The stability of rGO-CS-HEC nanohybrid was assessed using field emission scanning electron microscopy (FE-SEM), ultraviolet-visible spectroscopy (UV-VIS) and Zeta potential measurements. Results depicted that the novel synthesized nanohybrid was stable in all pH ranges, due to the utilization of HEC, while without incorporation of this material, the rGO-CS nanohybrid aggregated at neutral and alkaline media, due to the ionic nature of chitosan. In addition, drug loading and release behaviour of folic acid (FA), as a model drug, was investigated to assess the role of chitosan on the release behavior of FA from the rGO-CS-HEC nanohybrid in comparison with rGO-HEC and rGO-CS nanohybrids. It was proved that the resultant nanohybrid could release nearly 27% more FA than the rGO-HEC nanohybrid and only 9% lower than the rGO-CS nanohybrid during 120 hours. Moreover, the biocompatibility of the resultant nanohybrid was also checked to introduce the novel rGO-CS-HEC nanohybrid as a suitable candidate for drug delivery application.
In this paper, convective heat transfer coefficient of Grapheneewater nanofluid in a laminar flow... more In this paper, convective heat transfer coefficient of Grapheneewater nanofluid in a laminar flow through a circular pipe with uniform wall heat flux is investigated experimentally. To achieve this aim, the nanofluid is synthesized chemically in various concentrations, and a testbed is constructed. The effective thermal conductivity and viscosity of the Grapheneewater nanofluids are measured via hot wire method and an Ubbelohde viscometer, respectively. Results show that addition of low amounts (up to 0.02% volume fraction) of Graphene nanoparticles to water considerably increases the thermal conductivity and the convective heat transfer coefficient of the working fluid. Maximum enhancements are observed at 0.02% concentration. These enhancements are 10.3% for thermal conductivity and 14.2% for heat transfer coefficient at Re ¼ 1850. Moreover, the stability of the prepared nanofluids is examined by using the UVevis spectroscopy and is proved to be acceptably high. Finally, the results of the taken AFM images implied no agglomeration of nanoparticles.
Journal of Thermoplastic Composite Materials, 2016
Early stage crystallization kinetics of polypropylene (PP)/clay composites is studied using rheom... more Early stage crystallization kinetics of polypropylene (PP)/clay composites is studied using rheometery. Relaxation modulus of composites is measured at low frequencies near liquid–solid transition. Small amplitude oscillating shear flow is applied at low frequencies to obtain relaxation modulus. Relaxation modulus of polymeric materials at the liquid–solid transition follows [Formula: see text], at long times ( λ < t < ∞), where λ is the time to crossover to a different relaxation regime, s is the gel stiffness, and n is the relaxation exponent. Inverse quenching technique is then employed to retain degree of crystallization while rheological measurements are made. Lower gel time is observed as clay concentration increased, indicating the formation of more nuclei. An improvement to Avrami’s equation is proposed to predict crystallization kinetics for PP/clay composites. There is a good agreement between predicted relative crystallinity values and empirical values.
Dispersion of nanomaterials in polymeric matrices plays an important role in determining the fina... more Dispersion of nanomaterials in polymeric matrices plays an important role in determining the final properties of the composites. Dispersion in nano scale, and especially in single layers, provides best opportunity for bonding. In this study, we propose that by proper functionalization and mixing strategy of graphene its dispersion, and bonding to the polymeric matrix can be improved. We then apply this strategy to graphene-epoxy system by amino functionalization of graphene oxide (GO). The process included two phase extraction, and resulted in better dispersion and higher loading of graphene in epoxy matrix. Rheological evaluation of different graphene-epoxy dispersions showed a rheological percolation threshold of 0.2 vol% which is an indication of highly dispersed nanosheets. Observation of the samples by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM), showed dispersion homogeneity of the sheets at micro and nano scales. Study of graphene-epoxy composites showed good bonding between graphene and epoxy. Mechanical properties of the samples were consistent with theoretical predictions for ideal composites indicating molecular level dispersion and good bonding between nanosheets and epoxy matrix.
Quality of injection molded parts of semi-crystalline polymers has been the subject of intense in... more Quality of injection molded parts of semi-crystalline polymers has been the subject of intense interest from both analytical and industrial points of view. Crystallinity profile plays an important role in determining mechanical properties of a part and its quality. Therefore it is important to analyze the effect of injection molding parameters on the crystallinity profile of the molded parts. In this study, finite element analysis has been used to solve the equations of mass, momentum, and energy conservation simultaneously with the equation of crystallization kinetics to predict melt front, its solidification and crystallinity profile. The results from our numerical analysis have been compared with the reported experimental results. Furthermore, progress of the crystallization is proposed to be a proper criterion for estimation of the eject time. Finally, the effects of mold and melt temperature on the eject time; part temperature and average degree of crystallinity, for a specific...
Processing graphene and graphene polymer nanocomposites in an aqueous medium has always been a bi... more Processing graphene and graphene polymer nanocomposites in an aqueous medium has always been a big challenge due to the hydrophobic nature of graphene (or reduced graphene oxide) nanosheets. In this work, a waterborne latex of polyurethane has been used both as the matrix material for embedding the graphene nanosheets and as a unique stabilizer to help produce an up to 5 wt% graphene/PU nanocomposites. The graphene oxide/polyurethane latex aqueous suspension is reduced in-situ using hydrazine, without any trace of aggregation/agglomeration upon completion of the reduction process, which would otherwise have occurred severely were PU not present. A highly aligned nanostructure is produced when graphene content is increased beyond 2 wt%, resulting in a remarkable improvement in electrical and mechanical properties of the nanocomposite. The exceptionally low electrical percolation threshold of 0.078%, as well as 21-fold and 14 fold increases in tensile modulus and strength, respectively, have been attained thanks to the alignment of graphene nanosheets in the polymeric matrix.
Uploads
Papers by Farhad Sharif