Nanofibrous poly(ethylene oxide)‐based structures incorporated with multi‐walled carbon nanotube and graphene oxide as all‐solid‐state electrolytes for lithium ion batteries

Nanofibrous solid polymer electrolytes were prepared using the electrospinning method. These nanofibres were constructed from poly(ethylene oxide), lithium perchlorate and ethylene carbonate, which were incorporated with multi‐walled carbon nanotube (MWCNT) and graphene oxide (GO). The morphological properties of the as‐prepared electrolytes and the interaction between the components of the composites were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. X‐ray spectra and differential scanning calorimetry indicated an increase in amorphous regions of the nanofibrous electrolytes on addition of the fillers. However, the crystalline regions were increased on incorporation of fillers into polymeric film electrolytes. The conductivity values of the nanofibrous electrolytes reached 0.048 and 0.057 mS cm^?1 when 0.35 wt% MWCNT and 0.21 wt % GO were introduced into the nanofibrous structures, respectively. The capacity and cycling stability of the nanofibrous electrolytes were improved by incorporation of MWCNT filler. Furthermore, stress and elongation modulus were improved at low MWCNT and GO filler contents. Results revealed that the nanofibrous structures could be promising candidates as solvent‐free electrolytes applicable in lithium ion batteries. © 2019 Society of Chemical Industry     

Morphology and electrochemical and mechanical properties of polyethylene‐oxide‐based nanofibrous electrolytes applicable in lithium ion batteries

We report the synthesis of all‐solid‐state polymeric electrolytes based on electrospun nanofibers. These nanofibers are composed of polyethylene oxide (PEO) as the matrix, lithium perchlorate (LiClO₄) as the lithium salt and propylene carbonate (PC) as the plasticizer. The effects of the PEO, LiClO₄ and PC ratios on the morphological, mechanical and electrochemical characteristics were investigated using the response surface method (RSM) and analysis of variance test. The prepared nanofibrous electrolytes were characterized using SEM, Fourier transform infrared, XRD and DSC analyses. Conductivity measurements and tensile tests were conducted on the prepared electrolytes. The results show that the average diameter of the nanofibers decreased on reduction of the PEO concentration and addition of PC and LiClO₄. Fourier transport infrared analysis confirmed the complexation between PEO and the additives. The highest conductivity was 0.05 mS cm^?1 at room temperature for the nanofibrous electrolyte with the lowest PEO concentration and the highest ratio of LiClO₄. The optimum nanofibrous electrolyte showed stable cycling over 30 cycles. The conductivity of a polymer film electrolyte was 29 times lower than that of the prepared nanofibrous electrolyte with similar chemical composition. Furthermore, significant fading in mechanical properties was observed on addition of the PC plasticizer. The results obtained imply that further optimization might lead to practical uses of nanofibrous electrolytes in lithium ion batteries. © 2019 Society of Chemical Industry     

PVDF/TiO2/graphene oxide composite nanofiber membranes serving as separators in lithium-ion batteries

Improving the electrochemical properties of membranes in lithium-ion batteries (LIBs) is very important. Many attempts have been made to optimize ionic conductivity of membranes. The aim of this study was fabricating composite nanofiber membranes of poly(vinylidene fluoride) (PVDF), containing titanium dioxide (TiO₂) and graphene oxide (GO) nanoparticles to use in LIBs as separators. The morphology, crystallinity, porosity, pore size, electrolyte uptake, ionic conductivity, and electrochemical stability of the membranes were investigated using scanning electron microscopy, wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, and linear sweep voltammetry. The electrolyte uptake and ionic conductivity of the PVDF/TiO₂/GO composite nanofiber membranes containing 2 wt % GO were 494% and 4.87 mS cm⁻¹, respectively, which were higher than those of the other fabricated membranes as well as the commercial Celgard membrane. This could be attributed to the increased porosity, larger surface area, and higher amorphous regions of the PVDF/TiO₂/GO composite nanofiber membranes as a result of the synergistic effects of the nanoparticles. In this work, suitable optimized membranes with greater electrochemical stability compared with the other membranes were presented. Also, it was demonstrated that the incorporation of the TiO₂ and GO nanoparticles into the PVDF nanofiber membranes led to a porous structure where the electrolyte uptake enhanced. These properties made these membranes promising candidates for being used as separators in LIBs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48775.     

The Application of Heavy Alkyl Benzene in Engine Oil and Hydraulic Fluid Formulations

Heavy alkyl benzene (HAB) is a byproduct in the process of linear alkyl benzene (LAB) production. It is used as heat transfer oil and lubricating greases. In this article the potential of the usage of HAB in the formulation of gasoline and diesel engine oils as well as hydraulic fluid is indicated. With the aim of passing 5W30, 5W40, 10W40, and 15W40 standards, different engine oils have been formulated. The formulations contain various amounts of HAB as minor component, and miscellaneous quantities of solvent neutral 100 (SN-100), SN-150, and SN-650 as major component. The measurement of typical properties of obtained oils indicates that some of them do have the intended criteria. Test field of the recent oils designate that they have good performance. In the next step, different blends of HAB as major component and polyisobutene (PIB) as minor component have successfully been employed in the formulation of several ISO grade hydraulic fluids. The achieved materials do have suitable air release and demulsibility.     

Evaluation of PCL/chitosan electrospun nanofibers for liver tissue engineering

In this investigation, a nanofibrous scaffold was fabricated through electrospinning of polycaprolactone (PCL) and chitosan (CS) using a novel collector to make better orientation and pore size for cell infiltration. PCL/CS nanofibers with 90-rpm collector speed and 40° angle between collector wires of the new collector have fewer diameters with better pore, size and nanofibers orientation. Mechanical properties, roughness parameters, topology, structure, hydrophilicity, and cell growing were considered for liver tissue engineering. The cell culture was done using epithelial liver mouse cells. The developed electrospun PCL/CS scaffold using novel collector would be an excellent matrix for biomedical applications especially liver tissue engineering.     

A novel model of optimum nanofibre distribution in nanofibre scaffold structure by genetic algorithm method

Recently, nanofibre scaffolds have been used in prosthesis such as blood vessels, ligaments and skin. The optimum nanofibre distribution in the scaffold leads to uniform spreading in the tissue structure, regularity and smoothness on the tissue surface and in suitable tensile properties of prosthesis. This study presents a novel optimum model of nanofibre distribution in the scaffold structure by using the genetic algorithm method. The optimised model was considered in nanofibre scaffold samples prepared from polycaprolactone. Surface characteristics and tensile tests were performed to tissue samples. All of the experimental results strongly confirmed the results of optimised structural model of nanofibre scaffolds.     

Optimization of acrylic dry spinning production line by using artificial neural network and genetic algorithm

Acrylic fibers are synthetic fibers with wide applications. A couple of methods can be utilized in their manufacture, one of which is the dry spinning process. The parameters in this method have nonlinear relationships, making the process very complex. To the best of the authors' knowledge, no comprehensive study has yet been conducted on the optimization of acrylic dry spinning production using computer algorithms. In this study, such parameters as extruder temperature in and around the head, solution viscosity, water content in the solution, formic acid content of the solution, and the retention time of the solution in the reactor were measured in an attempt to predict the behavior of the dry spinning process. The color index of the manufactured fibers was used as an indicator of production quality and statistical methods were employed to determine the parameters affecting the process. An artificial neural network (ANN) using the back propagation training algorithm was then designed to predict the color index. ANN parameters including the number of hidden layers, number of neurons in each layer, adaptive learning rate, activation functions, number of max fail epochs, validation and test data were optimized using a genetic algorithm (GA). The trial and error method was used to optimize the GA parameters like population size, number of generations, crossover or mutation rates, and various selection functions. Finally, an ANN with a high accuracy was designed to predict the behavior of the dry spinning process. This method is capable of preventing the manufacturing of undesired fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel method for treatment of hollow fiber membranes using hypochlorite

A novel hypochlorite treatment method that enhances hydraulic permeability of hollow fiber membranes used in ultra-filtration was successfully devised and tested. Dope containing polysulfone/poly vinyl pyrrolidon (PVP-K90)/N-methyl-2-pyrrolidone (NMP) in mass ratio of 15:5:80, respectively, were used to produce hollow fibers via dry-jet wet spinning process. NMP in 1:1 ratio and distilled water were used as bore fluid. Hollow fiber membrane samples were post-treated using the novel, 95°C water and traditional hypochlorite treatments. State of membranes before and after post-treatment were morphologically compared using SEM microphotographs of fiber cross-section in conjuncton with image proceesing techniques. It was observed that in general both the novel and the traditional methods results in elimination of PVP swelling alone with alteration of pore size and pore distribution. This was confirmed by an increase in water flux of the hollow fibers that were subjected to these two post-treatment methods. Atomic force microscopy analysis vividly pointed to an intense increase in the roughness of the inner and outer surfaces of the membranes. This was attributed to the effect of post-treatment methods. It was found that in general post-treatments involving hypochlorite, increases the surface roughness of the membranes. However, increase in rate of the roughness of inner surface of traditionally hypochlorite treated hollow fiber membrane was found to be much higher than those subjected to the novel treatment method. It was established that the developed novel hypochlorite treatment method can be successfully used for production of high permeable hollow fiber membranes which have vast potential in therapeutic applications.