Structural properties of ?-irradiated poly(vinyl alcohol)/poly(ethylene glycol) polymer blends

Effect of Al2O3 on Nanostructure and Ion Transport Properties of PVA/PEG/SSA Polymer Electrolyte Membrane

Polymer electrolyte membrane (PEM) fuel cells have the potential to reduce our energy consumption, pollutant emissions, and dependence on fossil fuels. To achieve a wide range of commercial PEMs, many efforts have been made to create novel polymer-based materials that can transport protons under anhydrous conditions. In this study, cross-linked poly(vinyl) alcohol (PVA)/poly(ethylene) glycol (PEG) membranes with varying alumina (Al₂O₃) content were synthesized using the solvent solution method. Wide-angle X-ray diffraction (XRD), water uptake, ion exchange capacity (IEC), and proton conductivity were then used to characterize the membranes. XRD results showed that the concentration of Al₂O₃ affected the degree of crystallinity of the membranes, with 0.7 wt.% Al₂O₃ providing the lowest crystallinity. Water uptake was discovered to be dependent not only on the Al₂O₃ group concentration (SSA content) but also on SSA, which influenced the hole volume size in the membranes. The ionic conductivity measurements provided that the samples were increased by SSA to a high value (0.13 S/m) at 0.7 wt.% Al₂O₃. Furthermore, the ionic conductivity of polymers devoid of SSA tended to increase as the Al₂O₃ concentration increased. The positron annihilation lifetimes revealed that as the Al₂O₃ concentration increased, the hole volume content of the polymer without SSA also increased. However, it was densified with SSA for the membrane. According to the findings of the study, PVA/PEG/SSA/0.7 wt.% Al₂O₃ might be employed as a PEM with high proton conductivity for fuel cell applications.

Obtaining of Mesoporous Aluminosilicates with High Hydrothermal Stability by Composite Organic Templates: Utility and Mechanism

We have reported the synthesis of mesoporous aluminosilicates (MAs) with high hydrothermal stability via assembly of basic characteristic structure units of typical microporous zeolite Y. In spite of this, high consumption of organic template and H₂O remains a major obstacle to its industrial application. Herein, a facile and effective strategy called "composite templates" was employed to decrease significantly the amount of P123 and H₂O. In this method, composite micelles of P123/poly(vinyl alcohol) (PVA) could be more easily dispersed in the solution due to the lowering of water's surface tension caused by the free hydroxyl groups of PVA. Moreover, the improved assembly ability of composite micelles in high concentration solution leads to the synthesis of hydrothermally stable MAs with 45% decrease of organic template P123 and 81% that of water amount. It was found that by the introduction of composite templates, the textural properties such as the surface area of materials, volume of pore, size of pore, and thickness were enlarged simultaneously. Meanwhile, this article presented an understanding into the assembly of composite micelles in the process of synthesis of MAs.

Exploring polyvinyl alcohol – nickel sulphate composite film for absorbed dose monitoring

In the current study, we employ the polyvinyl alcohol doped with nickel sulphate (PVA-Ni+2) as a new film for monitoring the absorbed dose in radiation processing facility. The effect of irradiation doses on the structure of PVA-Ni+2 composite films was analyzed through Fourier transform infrared and X-ray diffraction techniques. The PVA-Ni+2 composite films have a response curve that extends from 5 to 60 kGy and labeling character figured through color change from pale green to intense purple color on exposing to gamma photons. Although the films are dose rate dependent, the films have excellent post stability.

Preparation of Miscible PVA/PEG Blends and Effect of Graphene Concentration on Thermal, Crystallization, Morphological, and Mechanical Properties of PVA/PEG (10 wt%) Blend

Water-soluble polymers such as poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) and their nanocomposites with graphene were prepared by using a solution mixing and casting technique. The effect of different PEG loadings was investigated to determine the optimum blend ratio. The films were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA) methods. Also, the mechanical properties including tensile strength and elongation at break were measured using a universal tensile testing machine. FTIR results confirmed the formation of the H-bond between PEG and PVA. DSC studies revealed that PEG has a significant plasticization effect on PVA as seen by the drop in the glass transition temperature (Tg). The blend with 10 wt% PEG loading was found to be the optimum blend because of good compatibility as shown by FTIR and SEM results and improved thermal properties. PVA/PEG (10%) nanocomposites were prepared using graphene as a nanofiller. It was found that the elongation at break increased by 62% from 147% for the PVA/PEG (10%) blend to 209% for the nanocomposite with graphene loading of 0.2 wt%. The experimental values of tensile strength were compared using the predictive model of Nicolais and Narkis.

Frequency and temperature-dependent impedance spectroscopy of PVA/PEG polymer blend film

In this work, polymer blend films based on polyvinyl alcohol (PVA)/poly(ethylene glycol) (PEG) were prepared by solution casting technique. X-ray diffraction (XRD) analysis was performed to investigate the structural details of the polymer blend. XRD pattern confirms the polycrystalline nature of the films. Sandwich structures of the type Ag-PVA/PEG-Ag were formed to study the dielectric and conduction properties in the frequency range 300 Hz–3 MHz and at different temperatures varying from 298 K to 420 K. Experimental results show that both dielectric constant ( ε′) and dielectric loss ( ε″) values were strong functions of frequency and temperature. The AC conductivity ( σAC) was found to obey the power law Aωs and correlated barrier hopping as the conduction mechanism. The imaginary part of electric modulus shows peak shifting corresponding to relaxation mechanisms. Electric modulus study was also found to support the dielectric permittivity data.