Influence of α-Fe2O3, CuO and GO 2D nano-fillers on the structure, physical properties and antifungal activity of Na-CMC-PAAm blend

The present work aims to improve the uses of the carboxymethyl cellulose-polyacrylamide (Na-CMC-PAAm) blend for energy storage, optoelectronic applications, biological control, and plant disease management. Nano-sized materials (α-Fe₂O₃ nanoplates (NP), CuO NP, and GO nanosheets (NS), were synthesized and incorporated into the blend. The phase purity and morphologies of the used fillers were studied by XRD and HR-TEM. The interactions and complexation between the nano-fillers and the blend chains were investigated using XRD and FTIR spectra. The chemical composition and surface morphology of the nanocomposites were studied using EDS and FE-SEM analysis. UV-vis-NIR spectra revealed that the blend shows about 95% transmittance, reduced by 10-30% after doping. The absorption and refractive indices, as well as the optical gaps of the blend, were greatly affected by the doping. The dielectric constant and loss depend on the type of filler and the applied frequency. The maximum ac conductivity of the blend at 303 K and 4.0 MHz is 21.5 × 10^-4 S/m and increased to 23.5 × 10^-4 S/m after doping with CuO NP. The thermal stability, activation energy, stress-strain curves, and tensile strength are dependent on the filler type. All nanocomposite solutions except the blend exhibited a wide range of antifungal properties against pre- and post-harvest phytopathogenic fungi. Aspergillus niger among the examined fungi showed high sensitivity to the tested nanocomposite solutions. Furthermore, the CuO/blend nanocomposite had the highest antifungal activity against all tested fungi. Based on that, we suggest the use of CuO/blend and GO/blend nanocomposites to control and combat pre- and post-harvest fungal plant diseases.

MODIFICATION INDUCED BY PROTON IRRADIATION IN BAYFOL UV1 7-2 NUCLEAR TRACK DETECTOR

Bayfol is a class of polymeric solid state nuclear track detector which has many applications in various radiation detection fields. It is a Makrofol polycarbonate/polyester blend. Samples from Bayfol film have been irradiated with different fluences (1011-1014 p/cm2) of 1 MeV protons at the University of Surrey Ion Beam Center, UK. The resultant effect of proton irradiation on the structural and optical properties of the Bayfol samples has been investigated using X-ray diffraction, Fourier Transform Infrared and UV spectroscopy. The optical energy gap was decreased from 4.24 to 4.03 eV with increasing the proton fluence from 1011 to 1013 p/cm2, and was accompanied by an increase in the Urbach energy from 0.79 to 1.29 eV. This could be correlated to the results obtained from XRD and FTIR spectroscopy. Further, the non-irradiated Bayfol is nearly colorless. It showed significant sensitivity to color by proton irradiation, associated with an increase in the red and yellow color components. The variation of optical and color parameters with the proton fluence indicate that the dynamic range of Bayfol UV1 7-2 is in the fluence range from 1011 to 1013 p/cm2.

Structural and Optical Characteristics of Laser Irradiated CdSe/PVA Nanocomposites

Nanocomposites of polyvinyl alcohol (PVA) and Cadmium selenide (CdSe) were fabricated by ex-situ casting technique. CdSe nanoparticles were prepared by thermolysis under the flow of nitrogen. Rietveld refinement of x-ray data showed that the prepared CdSe adapts cubic zinc blend structure with a lattice parameter 6.057 Å and a mean grain size of 2 nm. Samples from CdSe/PVA nanocomposite have been exposed to infrared (IR) laser fluences in the range 0–19.6 J/cm2. The effect of IR laser radiation on the structural and optical properties of CdSe/PVA has been investigated using XRD and UV-vis spectroscopy. UV/VIS absorption spectra confirm the formation of hybridized film CdSe/PVA nanocomposite with refractive index in the range of 1.4119–1.8621 (at 700 nm). Also, the laser radiation reduces the optical energy gap from 4.1 to 3.43 eV which could be attributed to the increase in structural disorder of the irradiated CdSe/PVA nanocomposites due to the formation of coordination reaction between OH of PVA and CdSe nanoparticles. This means that the laser radiation led to a more compact structure of CdSe/PVA nanocomposite and causes proper dispersion of CdSe nanoparticles in the PVA matrix. Further, the Commission Internationale de E'Claire (CIE units x, y and z) methodology was applied in this work for the description of colored samples. The color intensity ΔE, which is the color difference between the non irradiated sample and the irradiated ones, was increased from 11.40 to 30.57 with increasing the laser fluence up to 19.6 J/cm2.

Modification Induced by Gamma Irradiation in Polystyrene/Poly(methyl methacrylate) Blends

The influence of gamma irradiation on the structural and optical properties of polystyrene/poly(methyl methacrylate) (PS/PMMA = 50/50 w/w %) blend films have been investigated. A dose range of 20 kGy to 400 kGy is covered. Applying the viscometry technique, the dose dependence of the intrinsic viscosity was investigated. In addition, the variation of refractive index with gamma dose was studied. The observed increase in the intrinsic viscosity from 0.45 up to 0.69 and the refractive index in the high dose range indicates that the predominant induced process by gamma irradiation is crosslinking, which reduces the free volume and increases the average molecular weight leading to a more compact structure of PS/PMMA samples. Fourier Transform Infrared (FTIR) and ultraviolet-visible (UV-VIS) spectroscopies were applied to identify the chemical structure and to investigate the major process that is induced by irradiation. Moreover, using UV-vis spectroscopy, optical energy gap, Urbach energy and color changes were evaluated. The results reveal that the optical energy gap has arisen from direct transitions. The color intensity ΔE was significantly decreased with increasing the dose up to 400 kGy.