Amendment the physicochemical properties of polycarbonate/polybutylene terephthalate blend by gamma-ray irradiation doses
TL;DR: In this article, a blend of polycarbonate (PC)/polybutylene terephthalate thin films was used to detect gamma-rays with different doses (55 −355 kGy).
Abstract: In this study, blend of polycarbonate (PC)/polybutylene terephthalate thin films was used. This blend belongs to the class of polymeric solid-state nuclear track detectors. Blend samples were exposed to gamma-rays with different doses (55–355 kGy). The compositional changes, the changes of optical properties, the electrical parameters changes and surface morphology in the gamma irradiated samples were studied. Different techniques were used to study improving the physicochemical properties of the irradiated samples, such as Fourier transform infrared spectroscopy, UV–Visible spectroscopy, LCR Meter Bridge and scanning electron microscope, as well as, the roughness testing. Fourier transform infrared measurements exhibit that the degradation in the polymer chain occurs after irradiation with gamma-rays. This means that some functional groups are the most sensible groups to gamma-rays. UV–Visible spectra of the gamma exposed samples exhibited a shift in the absorbance edge toward the region of higher wavelength. This trend reflects a decrease in the band gap energy, which leads to an increase in the electrical conductivity of the samples. The outcomes of dielectric loss and dielectric constant are sensible parameters for whole frequency range to the changes in the structural and optical behaviors as a result to gamma irradiation. Additionally, the surface changes were discussed.
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TL;DR: In this paper , structural and optical characterizations of gamma-irradiated poly allyl diglycol carbonate (PADC) have been analyzed using Gas Chromatography-Mass Spectrometry (GC-MS), X-ray diffraction (XRD) diffractometer, Fourier Transform Infrared (FTIR) spectra and UV/Vis Spectroscopy.
Abstract: The investigation of fragment products, structural and optical characterizations of gamma-irradiated Poly Allyl Diglycol Carbonate (PADC) has been analyzed. Gas Chromatography–Mass Spectrometry (GC–MS), X-ray diffraction (XRD) diffractometer, Fourier Transform Infrared (FTIR) Spectroscopy and UV/Vis Spectroscopy have been applied to analyze alterations of PADC polymeric solid state track detector for the understanding the mechanisms of produced alterations by gamma-irradiation. The obtained results show that the irradiated PADC samples contain induced fragment products by gamma radiation. The GC-MS analysis shows that the pristine sample has one compound product with a clear peak of ethylene glycol (EG), but for irradiated samples two compound fragmentation products appeared ethylene glycol (EG) and diethylene glycol (DEG) with different areas %. This is theoretically confirmed, by density functional theory (DFT) using Spartan’20 parallel suite for PADC in neutral and ionized states. The XRD results reveal that the molecules ordering/disordering of irradiated samples have been influenced by gamma exposure according to the values of exposure doses. This increase in disordering is due to the degradation of the polymer chains. An induced change in the band intensities have been observed in FTIR spectra, which indicate to the cleavage in the C–H bond after irradiation. The optical properties studies illustrate that significant modification in the band gap energies after irradiation.
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Book•
01 Jan 1940
TL;DR: The Fermi Glass and the Anderson Transition as discussed by the authorsermi glass and Anderson transition have been studied in the context of non-crystalline Semiconductors, such as tetrahedrally-bonded semiconductors.
Abstract: 1. Introduction 2. Theory of Electrons in a Non-Crystalline Medium 3. Phonons and Polarons 4. The Fermi Glass and the Anderson Transition 5. Liquid Metals and Semimetals 6. Non-Crystalline Semiconductors 7. Tetrahedrally-Bonded Semiconductors - Amorphous Germanium and Silicon 8. Aresnic and Other Three-Fold Co-ordinated Materials 9. Chalcogenide and Other Glasses 10. Selenium, Tellurium, and their Alloys
8,188 citations
"Amendment the physicochemical prope..." refers methods in this paper
...The relationship between the absorption coefficient (α) and the wavelength (λ) can be determined according to Davis and Mott model [39]:...
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TL;DR: It is shown that the 1.5-eV optical gap of a-C:H is unusually small and requires that both its valence and conduction band consist of \ensuremath{\pi} states on ${\mathrm{sp}}^{2}$ sites and that these sites must also be significantly clustered, such as in graphitic clusters containing four or more rings.
Abstract: The electronic structure of amorphous carbon and hydrogenated amorphous carbon (a-C:H) has been investigated through calculations on a number of model structures containing different configurations of ${\mathrm{sp}}^{2}$ and ${\mathrm{sp}}^{3}$ sites. We find that the most stable arrangement of ${\mathrm{sp}}^{2}$ sites is in compact clusters of fused sixfold rings, i.e., graphitic layers. The width of the optical gap is found to vary inversely with the ${\mathrm{sp}}^{2}$ cluster size, and the \ensuremath{\sim}0.5-eV optical gap of evaporated amorphous carbon is found to be consistent with a model of disordered graphitic layers of about 15 A\r{} in diameter, bounded by ${\mathrm{sp}}^{3}$ sites. It is argued that a-C forms such finite clusters in order to relieve strain. It is then shown that the 1.5--2.5-eV optical gap of a-C:H is unusually small and requires that both its valence and conduction band consist of \ensuremath{\pi} states on ${\mathrm{sp}}^{2}$ sites and that these sites must also be significantly clustered, such as in graphitic clusters containing four or more rings. In other words, the optical gap of both a-C and a-C:H depends on their degree of medium-range order, rather than just on their short-range order as is the case in most amorphous semiconductors. We have also studied the nature of states away from the gap in order to interpret the photoemission data and the carbon 1s core-level absorption spectra. The nature of defects and midgap states is discussed, and it is predicted that the defect density decreases with increasing band gap. Finally it is argued that the doping of a-C:H by group-III and -V elements proceeds via a substitution mechanism, as in a-Si:H, in spite of the coordination disorder present in a-C:H. Doping is also expected to be accompanied by an increase in gap states, as in a-Si:H.
1,227 citations
01 Jan 1974
TL;DR: The sharp structure observed in the fundamental optical spectra of crystals, both vibrational and electronic, can be classified and interpreted by symmetry arguments based explicitly on the existence of long-range order as mentioned in this paper.
Abstract: The sharp structure observed in the fundamental optical spectra of crystals, both vibrational and electronic, can be classified and interpreted by symmetry arguments based explicitly on the existence of long-range order. Indeed, this is one of the few properties of crystals which cannot be accounted for on the basis of short-range order alone: If the long-range order is destroyed, the sharp structural detail, which is typical for crystals, disappears. However, the broad features of the spectra are similar if the short-range order is similar.
579 citations
TL;DR: In this paper, the initial phase of carbonaceous cluster growth is studied in detail and it is shown that the increase in cluster growth with energy density is much slower than the one of radical formation and conductivity.
Abstract: Carbonaceous clusters-supposed to be the carriers of electric conductivity-are formed along latent tracks of energetic ions in polymers. The different experimental techniques for cluster determination are summarized. Here we present some new results which have been derived from UV-Vis spectrometric examinations. Especially the initial phase of cluster growth is studied in detail. There are hints that a threshold energy density has to be deposited in the polymer before cluster growth sets in. This threshold is similar to the one for producing radicals (as seen by EPR studies), and to the one for the onset of strong polymeric conductivity. The cluster growth is shown to scale rather well with the mean transferred electronic energy density. The increase in cluster growth with energy density is much slower than the one of radical formation and conductivity.
167 citations
Journal Article•
TL;DR: In this article, the authors present a review of the field of ion implantation of polymers, focusing on low-energy implantations of metal ions causing the nucleation and growth of nanoparticles in the shallow polymer layers.
Abstract: The current paper presents a state-of-the-art review in the field of ion implantation of polymers. Numerous published studies of polymers modified by ion beams are analysed. General aspects of ion stopping, latent track formation and changes of structure and composition of organic materials are discussed. Related to that, the effects of radiothermolysis, degassing and carbonisation are considered. Specificity of depth distributions of implanted into polymers impurities is analysed and the case of high-fluence implantation is emphasised. Within rather broad topic of ion bombardment, the focus is put on the low-energy implantation of metal ions causing the nucleation and growth of nanoparticles in the shallow polymer layers. Electrical, optical and magnetic properties of metal/polymer composites are under the discussion and the approaches towards practical applications are overviewed.
149 citations