Influence of Diethyl Phthalate (DEP) on Fluorescence Emission Quenching of Poly Vinyl Chloride (PVC) in Solid Films (original) (raw)
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Journal of Materials Science and Engineering B
The photodegradation of irradiated thin films of poly (para-ethoxystyrene) with 265 nm radiations in the presence of air and as a function of irradiation time has been studied using UV-VIS, fluorescence and FT-IR spectroscopic techniques. The increase in irradiation time caused an increase in the intensity of the absorption band of the polymer, thus indicating a possibility of photodegradation of polymeric chains. The influence of increase in irradiation times on pure poly (ethoxystyrene) films caused a decrease in the intensity of the fluorescence band and the appearance of new broad band at longer wavelength and to decrease with increase in irradiation time. The influence of added phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated, and found to increase the photodegradation processes in polymeric chains. The photo-quenching rate constant was found to increase with the increase of the molar mass and bulkiness of the used plasticizers and to increase with the increase in irradiation time. The rate constant of the photo quenching process was found to decrease with the increase in the amount of added plasticizers, indicating that the added plasticizers may act as UV-absorbers which inhibit the photodegradation process. The analysis of the FT-IR spectra of the irradiated and non-irradiated samples, showed a noticeable formation of new bands, and their intensity was found to increase with the increase in irradiation time and also with the increase in the amount of added plasticizer. In addition, the observed increase in the intensities of the carbonyl and hydroxyl absorption regions of the FT-IR spectra, provide evidence for the photodegradation as well as photo-oxidation of polymeric chains.
Effect of Temperature and Concentration on the Optical Properties of PVC Solutions
Engineering and Technology Journal
In this paper, effects of temperature and concentration on the absorption spectra for Polyvinyl chloride solutions are studied at wavelengths from 200 to 400 nm and with the range of temperature 20, 30, 40, 50, and 60 degrees (C o). Electronic absorption spectra were examined over the wavelength range 200-400 nm by different concentrations (1x10-3 , 8x10-4 , 6.5x10-4, 5x10-4 and 3x10-4)[M]. The UV spectra shifted slightly towards large wavelength with increasing the temperature. The values of the energy gap of polyvinyl chloride are decreasing as concentration and temperature increased. The data shows that the refractive index of the polymer decreases with increasing the wavelength and temperature. The relationship between the absorption coefficient and photon energy of the PVC solutions are calculated.
Optical properties of pure and modified poly(vinyl chloride)
International Journal of Industrial Chemistry, 2013
Background: In this study, poly(vinyl chloride) (PVC) is considered one of the most versatile plastics. It is the second largest manufactured resin by volume worldwide. Results: To study the optical properties of modified PVC containing 1,3,4-thiadiazole and phthalyl groups in the repeating units, thin films of the prepared polymers (P I, P II, P III, P IV, P V, and PVC) were casted from tetrahydrofuran solvent with a thickness of 30 μm. The optical properties were studied in the range of 200 to 600 nm, and the optical data were analyzed and interpreted in terms of the theory of phonon-assisted direct electronic transitions; the measured E g of pure and modified PVC increases in the following order:
Study of secondary relaxations in poly(vinyl chloride) by phosphorescence decay
Journal of Photochemistry and Photobiology A-chemistry, 2007
The phosphorescence emission of both naphthalene and pyridine can be used to detect the secondary () relaxation of PVC, as this relaxation manifests by a decrease in the emission from the grafted probe at the temperatures at which the local motion at the backbone begins. In this work, an extensive study of the kinetic and spectral features of the phosphorescence of 4-mercaptopyridine, 4-methoxybenzenethiol and 4-mercaptophenol groups as a function of temperature is presented. These three luminescent probes have been grafted onto PVC, with modification levels ranging from 3% up to 46%. The phosphorescence decay from −130 • C up to 30 • C has been followed and both the intensity of the emission and the spectral features have been studied as a function of temperature. The interaction between probes as the concentration increases leads in all cases to the emission from aggregates or excimers, which have features different to those of the isolated probe. Side reactions occur when grafting the hydroxyl containing probe, what also leads to surprising phosphorescence spectral and decay rate features. (P. Tiemblo).
Doping Effect on Optical Constants of Poly-Vinyl Chloride (PVC)
Academic Research International
In the present work, the effect of silver acetic ((CH3COO) Ag) addition on some optical properties of poly-vinyl chloride has been studied. For that purpose, many samples has been prepared by adding ((CH 3COO) Ag) to the poly-vinyl chloride with different weight percentages from ((CH 3COO) Ag) with polymer and by different thickness .The absorption and transmission spectra has been recorded in the wavelength range (190-890) nm. The absorption coefficient, refractive index, extinction coefficient, real and imaginary dielectric constant and optical conductivity have been determined.
Features of Fluorescence Spectra of Polyethylene Terephthalate Films
Japanese Journal of Applied Physics, 2004
The characteristics of the fluorescence spectra of polyethylene 2,6-naphthalate (PEN) films were compared with those of poly(ethylene terephthalate) (PET). The fluorescence spectra of PEN films were found, by photoselection, to consist of two components, one peaking at 425 nm and the other at 445 nm, with their emission transition moments perpendicular to each other. The integrated excitation spectra of the PEN films were much more intense than those of PET. After the resolution of the integrated excitation spectra of PEN, most, but not all, of their component peaks corresponded to those of the absorption spectra. On the basis of this fact together with previous data on photodegradation, the spectral component peaking at 445 nm originated, at least partly, from traces of photochemical products generated by exposure during the measurements.
Optical properties and structural features of UV-C irradiated polyvinylidene chloride films
The modifications caused in polyvinylidene chloride (PVDC) polymer films on exposure to ultra-violet light (UV-C light of wavelength 254 nm) in air for different exposure times varying from one hour up to six hours have been investigated by using ultraviolet - visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopic techniques, as well as powder X-ray diffraction (XRD) technique. XRD scans reveal that the degree of crystallinity (Xc) increased from 4.7% up to 28.6% on increasing the UV exposure time of PVDC from 1 hour up to 4 hours, and a further increase in the exposure time causes a decrease in the value of Xc. The FTIR scans reveal the formation of hydrogen bonded hydroxyl groups as well as conjugated alkene structures in the PVDC sample on exposure to UV-C radiation. For the study of modification in band structure of the UV irradiated PVDC films, the UV-Vis spectroscopy was used; it was found that the optical band gap decreases from 4.70 eV down to 3.92 eV, as obtai...
Controlling the absorption and emission properties of polyparaphenylenevinylene films
Journal of Non-Crystalline Solids, 2008
In this work we used the conversion process of a precursor polymer into polyparaphenylenevinylene (PPV) at low temperatures in order to control the effective conjugation degree of spin-casted PPV films. The absorption and emission spectra of the films were studied by following a partial substitution of chloride counterions from poly(xylylidene tetrahydrothiophenium chloride) (PTHT), used as a precursor, by sodium acid dodecylbenzenesulfonate (DBS), added as a surfactant salt. Upon controlling the DBS amount and conversion temperature (T c) of PTHT/DBS to PPV films, the band gap of PPV changed from 409 to 506 nm, and 505 to 532 nm, values obtained from absorbance and emission measurements, respectively. Based on these experimental data, we proposed a physical model which represents the chemical structure of PPV as a distribution of conjugated chain segments (like oligomers) alternated by non-conjugated segments (structural defects and/or from the precursor polymer).
Optical studies of phthalocyanine molecules in PVA film
Materials Letters, 2000
Optical absorption and emission spectral studies of various phthalocyanine Pc molecules in PVA matrix have been reported for the first time. The recorded spectra are analyzed to get the important spectral parameters, such as optical Ž . Ž . Ž . Ž . absorption cross-section s , emission cross-section s , oscillator strength f , fluorescence bandwidth D l , emission a e Ž . Ž . Ž . wavelength l , radiative decay time t and optical gain G . Analysis shows that the emission cross-section and optical gain are maximum in the NdHPc -doped PVA matrix. However, a comparison of the calculated emission parameters with 2 that of borate glass matrix show that they are many times smaller in the present matrix. q
Journal of Non-Crystalline Solids, 2006
In this work, we studied the absorption and emission spectra of spin-coated poly(p-phenylene vinylene) (PPV)-dodecylbenzenesulfonic counter-ion (DBS) films. The PPV-DBS films were obtained from a soluble precursor polymer thermally converted to PPV over a comparatively short time interval (30 min), and at low temperature (110°C), conditions that yielded films with few structural defects. The line shape of the absorption spectra of the films deposited on glass substrates was analyzed by assuming a Gaussian distribution of segments along the main chain of PPV, and a conjugation degree between 3 and 15 units. For emission studies, only PPV segments with a high conjugation degree or a lower energy gap (HOMO-LUMO transition) contributed to the feature of the spectra.