S. A. Nouh

Stabilization of poly(vinyl chloride) against laser radiation with ethyl-N-phenylmaleimide-4-carboxylate

Abstract Ethyl- N -phenylmaleimide-4-carboxylate (ENPMC), has been studied as a stabilizer for poly (vinyl chloride), (PVC) against laser radiation. The effects of ENPMC concentration and laser radiation dose on the thermal properties of the polymer have been studied. The results reveal a great improvement in the thermal stability of the polymer in the presence of the organic material. This thermal stability is shown by both thermal gravimetric analysis and the rate of dehydrochlorination of the polymer. The effective concentration for the protection of the polymer against thermal degradation was found to be 10 mmol ENPMC per 100 g PVC. The effect of laser pulses on the polymer stabilized with this concentration of ENPMC have been studied using UV spectroscopy, infra red spectroscopy and thermal gravimetric analysis

Structural and optical modifications in gamma-irradiated polyimide/silica nanocomposite

The structural and optical properties of thin films of polyimide composites with nanosilica particle content of 15 wt%, prepared via sol–gel process, were studied as a function of the gamma dose. The resultant effect of gamma irradiation on the properties of polyimide/silica nanocomposite has been investigated using X-ray diffraction and UV spectroscopy. Absorption and reflectance spectra were collected by a spectrophotometer giving UV-radiation of wavelength range 200–800 nm. The optical data obtained were analyzed and the calculated values of the optical energy gap exhibited gamma dose dependence. The direct optical energy gap for the nonirradiated polyimide/silica nanocomposite is about 2.41 eV, and increases to a value of 2.65 eV when irradiated with gamma doses up to 300 kGy. It was found that the calculated refractive index of the polyamide/silica increases with the gamma dose in the range 50–300 kGy.

Gamma-induced changes in some of the structural and optical properties of Makrofol polycarbonate/silver nanocomposites films

ABSTRACT Nano-sized silver (Ag) was prepared and mixed with Makrofol polycarbonate (PC) (5 wt%) to produce nanocomposites films. Samples from the PC/Ag nanocomposite films have been exposed to gamma radiation in the dose range of 20–300 kGy. The consequential effect of gamma radiation has been studied using X-ray diffraction, fourier transform infrared spectroscopy and UV spectroscopies and color difference measurements. The results indicate that the gamma irradiation up to ∼150 kGy increases the intermolecular interaction of PC chains and Ag that could be attributed to crosslinking that destroys the ordering structure, giving the polymer more resilience. This was accompanied with a reduction of the optical energy gap and an increase in refractive index. In addition, the color intensity, which is the color difference between the irradiated samples and the non-irradiated one, increases with increasing the gamma dose at the range of 20–150 kGy, accompanied with an increase in the blue and green color components.

Effect of electron beam irradiation on the structural, thermal and optical properties of poly(vinyl alcohol) thin film

Poly(vinyl alcohol) (PVA) polymer was prepared using the casting technique. The obtained PVA thin films have been irradiated with electron beam doses ranging from 20 to 300 kGy. The resultant effect of electron beam irradiation on the structural properties of PVA has been investigated using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), while the thermal properties have been investigated using thermo-gravimetric analysis and differential thermal analysis (DTA). The onset temperature of decomposition T 0 and activation energy of thermal decomposition E a were calculated, results indicate that the PVA thin film decomposes in one main weight loss stage. Also, the electron beam irradiation in dose range 95–210 kGy led to a more compact structure of the PVA polymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The variation of transition temperatures with electron beam dose has been determined using DTA. The PVA thermograms were characterized by the appearance of an endothermic peak due to melting. In addition, the transmission of the PVA samples and any color changes were studied. The color intensity Δ E was greatly increased with increasing electron beam dose, and was accompanied by a significant increase in the blue color component.

Optical properties and spectroscopy of gamma-irradiated Rosin/Polycarbonate blends

ABSTRACT Blending of polymers is a useful technique to develop materials with enhanced properties better than those of the single polymer equivalents. The effect of blend concentration of Abietic acid (Rosin) on the optical properties and spectroscopy of Polycarbonates PC has been investigated. Ultraviolet–visible (UV–VIS) spectroscopy was applied to investigate the major process that is induced due to blend concentration. Moreover, using UV–vis spectroscopy, optical energy gap, Urbach energy, refractive index and color changes were evaluated. The results reveal that the Urbach energy increases with increasing the Rosin concentration up to 80% associated with a reduction in the optical energy gap that could be attributed to the morphological changes associated with an increase in disorder character. Also, the PC samples show color changes due to Rosin blends. Samples from the 50%Rosin/50%PC blend were irradiated with gamma at the dose range 20–300 kGy. The resultant effect of gamma radiation on the optical properties and spectroscopy of the blended samples has been investigated using UV and Fourier Transform Infrared FTIR spectroscopy. The results indicate that the gamma irradiation leads to the formation of shorter molecules as a result of degradation, which causes both a random breaking of bonds and the formation of stable molecules with a lower molecular weight. Also, the blended samples do not have a high resistance to degradation, and its tendency to crosslinking is low.

X-ray irradiation-induced changes in (PVA–PEG–Ag) polymer nanocomposites films

ABSTRACT The effects of X-ray irradiation on the structural, thermal and optical properties of polyvinyl alcohol–polyethylene glycol–silver (PVA–PEG–Ag) nanocomposites have been investigated. The samples of nanocomposites were prepared by adding Ag nanoparticles with 5 wt% to the (PVA–PEG) blend. The films of 0.05 mm thickness were prepared by the casting method. These films were irradiated with X-ray doses ranging from 20 to 200 kGy. The resultant effect of X-ray irradiation on the structural properties of PVA–PEG–Ag has been investigated using X-ray diffraction and Fourier transform infrared spectroscopy. Also, thermal property studies were carried out using thermogravimetric analysis. Further, the transmission of the PVA–PEG–Ag samples and any color changes were studied. Fourier transform infrared spectroscopy measurements showed that the crosslinking is the dominant mechanism at the dose range 50–200 kGy. This led to a more compact structure of PVA–PEG–Ag samples, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. Moreover, the color intensity ΔE was greatly increased with an increase in the dose, and was accompanied by a significant increase in the yellow color component.

Modification of structural and optical properties of polyvinyl alcohol/polyethylene glycol thin film by laser irradiation

ABSTRACT The effect of infrared laser irradiation on the structural and the optical properties of polyvinyl alcohol/polyethylene glycol (PVA/PEG) co-polymer has been investigated. Thin films of PVA/PEG (nearly 50 µm thickness) were irradiated up to 15 J/cm2 of Ga-As laser pulses of 904 nm, 5 W power, and 200-ns pulse duration. The resultant effect of laser irradiation on the structural properties of PVA/PEG has been investigated using X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). Further, the refractive index and the color difference between the exposed samples and the pristine have been studied. FTIR spectroscopy showed that the PVA/PEG samples exhibited degradation under the effect of laser irradiation up to 9 J/cm2, where crosslinking started and continued until 15 J/cm2. The refractive index had a minimum value of 1.5020 at 9 J/cm2, accompanied by a high degree of ordering and maximum value of 1.5640 at 15 J/cm2, with an increase in disordering character due to the degradation and crosslinking formation inside the sample, respectively. Moreover, the color intensity ΔE was greatly increased with increasing the laser fluence, accompanied by a significant increase in the yellow color component.

X-ray irradiation-induced structural modifications in PM-355 polymeric nuclear track detector film

Samples from sheets of the polymeric material PM-355 have been exposed to X-rays from a 50 kV X-ray tube in the dose range of 10–300 kGy. The resultant effect of X-ray irradiation on the structural properties of PM-355 has been investigated using different techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Vickers hardness and refractive index measurements. The results indicate that the X-ray irradiation of PM-355 in the dose range of 10–20 kGy causes initially chain scission. Above 20 and up to 100 kGy, the active free radicals produced from scission contribute to chemical reactions that lead to the crosslinking. Thus, the X-ray irradiation in the dose range of 20–100 kGy leads to a more compact structure of the PM-355 polymer, resulting in an enhancement of its Vickers hardness and refractive index. Moreover, the irradiation in the dose range of 100–300 kGy leads to the predominance of the degradation. This degradation is reported by FTIR spectroscopy and enhances the degree of ordering in the degraded samples as revealed by XRD technique. Additionally, it decreases both the Vickers hardness and refractive index of the PM-355 samples.

X-ray irradiation-induced changes in cellulose triacetate

Samples from sheets of the polymeric material cellulose triacetate (CTA) have been exposed to X-ray radiation in the dose range 50–260 kGy. The modifications induced in the molecular and optical properties of CTA samples due to X-ray irradiation have been studied through different characterization techniques such as intrinsic viscosity, refractive index and color change studies. The results indicated that the cross-linking is the dominant mechanism at the dose range 100–260 kGy. This cross-linking led to an increase in the value of intrinsic viscosity from 1.28 for the non-irradiated sample to 1.41 for the sample irradiated with 260 kGy at 35°C, indicating an increase in the average molecular mass. This was associated with an increase in the refractive index. Additionally, the non-irradiated CTA samples showed significant color sensitivity toward X-ray irradiation. This sensitivity appeared by the change in the blue color component of the non-irradiated CTA film to yellow after exposure to X-ray up to 260 kGy. This is accompanied by a net increase in the darkness of the samples.

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

Abstract 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.