Abstract PBI: PVPA (Poly (benzimidazole): poly (vinylphosphonic acid)) polymer electrolyte membranes were fabricated with several molar ratios and number-average molecular weights (M? n) of PVPA. Inter-polymer interactions and cross-section morphology of membranes were analyzed using FT-IR and scanning electron microscopy, respectively. Water uptake, proton conductivity, and methanol permeability of the membranes were characterized at several operating conditions. In addition, the influence of doping level of phosphoric acid (H 3 PO 4) on the membranes proton conductivity was investigated. The membranes proton conductivities were enhanced with PVPA molar ratio and M? n. The highest proton conductivity at 150? C, 79.6 mS. cm− 1, was obtain

To predict the novel poly (benzimidazole): poly (acrylic acid)(PBI: PAA) blend membranes proton conductivity, an ionic conductivity equation combined with thermodynamic model is proposed where different proton transport mechanisms including Grotthuss, vehicle and surface hopping mechanisms are considered in calculations. Based on the PAA titration behavior, by increasing the number-average molecular weight (Mn), apparent acidity of PAA decreases. Hence, to calculate the concentration of protons involved in different mechanisms, a new modification in the predictive model is suggested by considering acidity and its relation with Mn. Effect of temperature, PAA molar ratio and Mn on the membranes proton conductivity is investigated theoreticall

The interfacial region has a critical role in determining the gas separation properties of nanofiller-containing membranes. However, the effects of surface chemistry of nanofillers on gas separation performance of thin film nanocomposite (TFN) membranes, prepared by the interfacial polymerization method, have been rarely studied in depth. In this work, pristine and three differently surface-modified halloysite nanotubes (HNTs), by non- (SHNT), moderately (ASHNT), or highly CO2-philic (SFHNT) agents, are embedded in the polyamide top layer of thin film nanocomposite (TFN) membranes for CO2/N2 and CO2/CH4 separations. Trimethoxyoctyl silane, 3-(2-aminoethylaminopropyl)trimethoxysilane, and poly(styrenesulfonic acid) are used as modifying agen

The current paper investigated the halloysite nanotube (HNT) effects on workability, mechanical properties, permeability and microstructure of cementitious mortar. Results indicated that HNT has significant effects on improving the properties of cementitious mortar. It increased the hydration rate of cementitious composites. Moreover, incorporation of 3?wt% HNT enhanced the compressive and flexural strength of plain mortar up to 25 and 20%, respectively. DTA-TGA test results indicated that the incorporation of HNT into mortar leads to more calcium hydroxide consumption and denser microstructure. Permeability tests results demonstrated that loading 3?wt% HNT into cementitious mortar reduces the capillary water absorption by 25% and electrica

Abstract Poly (benzimidazole)(PBI): poly (acrylic acid)(PAA) blend membranes were prepared with different number-average molecular weights (M? n) and molar ratios of PAA as novel proton exchange membranes. PAA titration behavior showed that by increasing the M? n, apparent acidity of PAA decreases. The interaction between PBI and PAA was confirmed by FTIR and DSC. The cross-section SEM photographs showed that pore structure can be formed in the membrane by increasing M? n and molar ratio of PAA. The membranes showed lower methanol permeability (1.06–1.91? 10− 9 cm 2. s− 1) in comparison to the Nafion and mechanical properties were comparable with phosphoric acid (PA)-doped PBI membranes. An increasing trend in proton conductivity of t

In this study, the effect of chemical modification on adsorption behavior of scleroglucan polymer on carbonate rock of oil reservoir was studied. The chemical modification was performed to increase hydrophobicity of scleroglucan while substituting ionic and hydrophobic groups on its structure simultaneously. Investigation of adsorption behavior of the samples on carbonate rock surfaces revealed an increase in uptake of the modified samples compared to the original one. Evaluation of various factors affecting the adsorption process showed that the Langmuir isotherm can describe the adsorption behavior of primary and hydrophobic scleroglucan samples better that Freundlich & Temkin isotherms. However, the adsorption behavior of the ionic-hydro

In this work Poly (hexamethylene isophthalamide) (PA 6I) was synthesized via interface step polymerization at room temperature for the first time, here. Layered silicates were used in order to fabricate PA 6I nanocomposites by in-situ polymerization. Thermal, mechanical and morphological of obtained nanocomposites were examined. The dispersion effect of silicate layers in the matrix was studied by means of XRD and FE-SEM. The incorporation of layered silicates in PA 6I leads to a significant improvement in the mechanical properties of the resulting nanocomposites. The thermogravimetric analysis results showed that layered silicate incorporation enhances the thermal resistance of PA 6I nanocomposites. Improvements in thermal deg

Acyl chlorides with different alkyl lengths (C6, C10 or C18) are grafted onto scleroglucan (Sclg) and aqueous/brine solutions viscosities of modified samples are studied at 25/90 ?C. All modified Sclgs solutions show lower viscosities than those of the unmodified Sclg solutions, due to the helix-coil transition caused by the modification. The viscosity of the samples aqueous solutions at 25 ?C is increased by increasing the grafted alkyl length. However, the viscosity profiles of the aqueous solutions of modified Sclgs are superimposable at 90 ?C. The modified Sclg by C10 moieties exhibits the highest viscosity in the brine solution at 90 ?C. The results are interpreted by a model depicting the effects of the alkyl lengths on the di

Optimizing synthesis factors of polyamide top layers is an important requirement in the design of thin film composite (TFC) membranes. In this research, the top layer fabrication method (conventional, heat curing, and spin coating), type of acid acceptor (sodium carbonate, sodium hydroxide, and triethylamine), type of organic phase solvent (hexane, heptane, and mixed hexane/heptane), and concentration of surfactant sodium dodecyl sulfate (0, 0.5, and 1 wt %) are selected as the control parameters of this synthesis and optimized using the Taguchi approach. The analysis of variance shows that the layer fabrication method is the most influential parameter on water flux and salt (NaCl) rejection of TFCs. Furthermore, although the type of org

Si-based phase component was incorporated in carbon aerogel using the sol-gel polymerization. The results of non-isothermal kinetic study in the temperature range of 500–1200 ?C confirm the determinant role of the diffusion process in the global oxidation kinetic due to the highly porous character of the hybrid aerogel. This leads to the effect of the reaction condition on the reaction pathway; so that, a shift is observable from the reaction-control to diffusion-control regimes of the oxidation process by increasing the heating rate. The rate constants corresponding to these two different regimes were differentiated by applying the non-parametric kinetic analysis.

A. Sharif/Journal of Membrane Science and Research 4 (2018) 2-3 structure of the precursor hydroxyl− polyimide and by applying different thermal treatment protocols [16]. It is believed that the excellent upper bound performance (ie, both high permeability and selectivity) of currently available TR polymers is due to a combination of higher diffusion selectivity, high diffusion coefficients, and high solubility coefficients, relative to other glassy polymers [15].Despite all the above-mentioned advantages, polymers with extra high gas permeability are relatively expensive and prone to physical aging, which can severely affect the performances of the glassy polymer membranes. Thus, research efforts still need to be directed toward decreasi

In the last decades, the development of nanotechnology has been rising and nanomaterials have been widely used in combination with many traditional materials. The prominent chemical and physical properties of nanomaterials enable them to play an important role in various applications such as modifying the structure of materials, improving the properties of composites, and manufacturing new multifunctional products. The building industry has not been exempted from this rule. Many studies have been carried out on the effect of nanoparticles on concrete performance and most of them demonstrated the improvement of concrete properties. There are a lot of studies on the effect of nanoclay on cement composites. However, there are little researches

Storage, transformation, and absorption of energy play effective roles in application and performance of heat and thermal energy beneficiary. Phase change materials (PCMs) are substances with high heat of fusion which can be utilized to design thermal protective and thermal energy storage systems. However, PCM leakage in phase changing process is a well-known disadvantage of the PCM containing systems. One of the approaches to avoid PCM leakage is to prepare shape-stabilized PCM in polymeric composites. In this study, polyethylene glycol (PEG), as a PCM, was shape-stabilized with low leakage in the novolac colloidal structure with no solvent and through a sol–gel in situ polymerization process. Supercooling is a negative asso

Nanocomposites consisting of semi‐aromatic polyamide (PA) and pristine or alkali activated halloysite nanotubes (HNT or mHNT, respectively) were synthesized by the in‐situ interfacial polymerization method. The condensation reactions were carried out between isophthaloyl dichloride in hexane and triethylenetetramine in water containing different amounts of HNT or mHNT. The interactions and crystallinity of the nanocomposites were studied by Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) analysis, respectively. Development of hydrogen bonds between the functional groups of PA and hydroxyl groups of nanotubes was indicated by FTIR spectroscopy. According to the XRD analysis, the addition of HNT and mHNT nanot

In this work, the interfacial mass balance relations combined with the non-parametric kinetic (NPK) analysis results were used for evaluating the thermo-chemical ablation process and oxidation mechanism of carbon aerogels with various porous structure. It was found that the two-parameter model of Nomen–Sempereis was able to describe the kinetics of the oxidation reaction and to reveal the structure-dependent contribution of two main processes with chemical and physical nature. The porosity of the carbon aerogel, rather than the other microstructural features, was realized more effective on the rate of ablation.

In-situ interfacial polymerization method was employed to synthesize nanocomposites based on a semi-aromatic polyamide (PA) and pristine or sulfonated graphene oxides (GO or SGO, respectively). The PA chains were produced at the interface of a nonaqueous solution of isophthaloyl dichloride and an aqueous triethylenetetramine solution containing different amounts of GO or SGO dispersed nanosheets. The effects of SGO and pristine GO on the structure, thermal stability and dynamic mechanical and electrical properties of PA were studied. Favorable interfacial interactions between SGO and PA were confirmed using Fourier transform infrared spectroscopy and X-ray diffractometry. Consequently, SGO significantly increased the thermal

The present study describes the successful fabrication of bio-polymeric nanocomposite bead (NCB) of alginate caged magnetic graphene oxide (Alg-MGO). NCB was obtained by crosslinking of sodium alginate and calcium ions in the presence of MGO. Analytical techniques Fourier transform infra-red (FT-IR), field emission scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the Alg-MGO. Analytical application is conducted with magnetic solid phase extraction (MSPE) method for determination of Cu(II) and Pb(II) in urine, saliva and river water sample. The linear concentration range obtained were 0.33–25.00??g?L− 1 with appropriate coefficient of determination (R2 = 0.9

Poly(vinylphosphonic acid) (PVPA) was synthesized by free radical polymerization of vinylphosphonic acid (VPA) in different solvents. Bromotrichloromethane as a chain transfer agent (CTA) was used in some experiments to control molecular weight of the PVPA. The effects of solvent type and initiator and CTA concentrations on the microstructure, molecular weight and stereoregularity of the resulting PVPA was extensively investigated by FTIR, 1HNMR, 31PNMR and elemental analysis. Polymers with a number-average molecular weight (Mn) in the range of 1550 to 42,190?gmol−1 were prepared. High molecular weight PVPA with Mn of 42,190?gmol−1 was obtained from aqueous solution polymerization of VPA with initiator/monomer molar ratio