Physico-chemical modification induced by 70 MeV carbon ions in alpha phased polyvinylidene fluoride (α-PVDF) polymer (original) (raw)
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In the present paper, the physico-chemical changes induced by 70 MeV carbon ions (12 C +5) have been investigated in PVDF using UV-Visible, FTIR, XRD and HFIA techniques. The induced changes have been studied with respect to their optical, chemical, structural and electrical response. The polymer samples have been irradiated in the ion fluence ranging from 1×10 11 to 3×10 12 ions cm −2. The UV-visible spectra show that the optical absorption increases with increasing ion fluence. Two new dips at 482 nm and 654 nm were appeared in the irradiated sample which may be due to the fluorinated defects created due to irradiation. In the FTIR spectra, it was found that transmittance intensity decreases with increasing ion fluence in the range 1500-4000 cm −1. The diffraction pattern of PVDF indicates that crystallinity decreases with increasing ion fluence but the crystallite size is found to increase due to carbon ion irradiation. The variation of dielectric constant and dielectric loss for virgin and irradiated films have been studied in the frequency range 10 mHz-10 MHz at ambient temperature. There is an exponential increase in ac conductivity with increasing frequency and the effect of irradiation is significant at higher fluence. The dielectric constant and dielectric loss changed significantly due to ion beam irradiation, meanwhile the frequency exponents decreased with increasing ion fluence. It was found that dielectric response in both virgin as well as irradiated samples obey the Jonscher's power law.
7 Abstract 8 Physical and chemical changes induced by 70 MeV carbon ions 12 C 5 have been investigated in bulk polyvinylidene 9¯uoride (PVDF) polymer. The induced changes have been studied with respect to their optical, chemical and structural 10 response using UV±visible, FTIR and XRD techniques. The ion¯uences ranging from 2:5 Â 10 11 to 9 Â 10 13 ions cm À2 11 have been used to study the irradiation eects. It has been observed that at the¯uence of 9 Â 10 13 ions cm À2 the PVDF 12 sample became brittle and practically it was not possible to handle it for any further measurements. The recorded UV± 13 visible spectra show that the optical absorption increases with increasing¯uence, indicating maximum absorption at 14 200 nm. An interesting feature of UV±visible spectra is that dips change into peaks and vice versa with increase of 15¯uence. In the FTIR spectra, development of new peaks at 1714 and 3692 cm À1 along with disappearance of peaks at 16 2363 and 3025 cm À1 and shifting of peak at 2984±2974 cm À1 have been observed due to high energy irradiation, in-17 dicating the chemical changes induced by 12 C 5 . The diraction pattern of PVDF indicates that this polymer is semi-18 crystalline in nature; a large decrease in the diraction intensity indicates decrease in crystallinity. Increase in crystallite 19 size has also been observed due to heavy ion irradiation. Ó
50 MeV lithium ion beam irradiation effects in poly vinylidene fluoride (PVDF) polymer
2000
Physical and chemical changes induced by 70 MeV carbon ions 12 C 5 have been investigated in bulk polyvinylidene 9¯uoride (PVDF) polymer. The induced changes have been studied with respect to their optical, chemical and structural response using UV±visible, FTIR and XRD techniques. The ion¯uences ranging from 2:5 Â 10 11 to 9 Â 10 13 ions cm À2 have been used to study the irradiation eects. It has been observed that at the¯uence of 9 Â 10 13 ions cm À2 the PVDF sample became brittle and practically it was not possible to handle it for any further measurements. The recorded UV± visible spectra show that the optical absorption increases with increasing¯uence, indicating maximum absorption at 200 nm. An interesting feature of UV±visible spectra is that dips change into peaks and vice versa with increase of 15¯uence. In the FTIR spectra, development of new peaks at 1714 and 3692 cm À1 along with disappearance of peaks at 2363 and 3025 cm À1 and shifting of peak at 2984±2974 cm À1 have been observed due to high energy irradiation, indicating the chemical changes induced by 12 C 5. The diraction pattern of PVDF indicates that this polymer is semicrystalline in nature; a large decrease in the diraction intensity indicates decrease in crystallinity. Increase in crystallite size has also been observed due to heavy ion irradiation.
Investigation of electron irradiation induced-changes in poly(vinylidene fluoride) films
Polymer Degradation and Stability, 2002
The radiation-induced changes taking place in poly(vinylidene fluoride) (PVDF) films exposed to electron irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by a universal electron beam accelerator to doses in the range of 100-1200 kGy. Various properties of the irradiated PVDF films were studied using FTIR, differential scanning calorimetry (DSC) and universal mechanical tester. Unirradiated PVDF film was used as a reference. Electron irradiation was found to induce changes in physical, chemical, thermal, structural and mechanical properties of PVDF films and such changes vary depending on the irradiation dose. #
Gamma Irradiation Effects on Poly (Vinylidene Fluoride) Films
2002
In this work, the properties of Poly(vinylidene fluoride) PVDF films after exposing to gamma radiation at different doses (5, 10 and 15 kGy) were investigated. PVDF is a semicrystalline polymer that shows good properties in terms of chemical, thermal and electrical stabilities. The gamma radiation is a convenient and effective way of modification perfluorinated and partially fluorinated polymers such as PVDF. The properties of the pristine and irradiated PVDF films were studied by infrared spectroscopy, thermal analysis (TGA and DSC) and mechanical measurements at room temperature and at melting temperature of the PVDF. The infrared spectra of the irradiated PVDF samples do not present significant alterations in the absorption bands at all irradiated doses. The results obtained by thermal analysis indicate that the radiation does not alter significantly the decomposition temperature of the pristine PVDF film. Tensile strength measurements at room temperature before and after exposition to gamma radiation showed decrease of elongation at rupture in relation of pristine PVDF, suggesting that the radiation caused the crosslinking or chain scission of the PVDF film.
Changes in the physical and chemical properties of PVDF irradiated by 4 MeV protons
Revista Mexicana De Fisica, 2003
The behavior of poly-vinylidene fluoride (PVDF) under bombardment of different kinds of radiation is of interest due to the polymer's unique piezo-electric properties and various crystalline forms. In this work, PVDF film samples of 0.3 mm thickness and density 1.76 g/cm 3 were irradiated with 4 MeV protons from the Instituto de Física 9SDH-2 Pelletron Accelerator. Changes in the physical and chemical properties were investigated using Fourier Transform Infrared Spectroscopy (FTIR) with ATR, X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and gel fraction measurements. The gel percent increases with fluence to almost 60% for a fluence of 10 13 cm −2 , and then more slowly up to 100% for a fluence of 3 × 10 14 cm −2. The DSC curve of the control sample shows a sharp band at 176 • C with a shoulder on the low temperature side. A well defined lower temperature peak, related to the relaxation of inter-crystalline regions appears at a fluence of 10 13 cm −2. At 3 × 10 14 cm −2 there are no melting peaks, due to complete destruction of the crystalline structure. This was confirmed at this high fluence by the FTIR spectra, and by x-ray diffraction, where an amorphous structure was observed.
Study of poly(vinylidene fluoride) radiative modification using core level spectroscopy
2014
Modification of poly(vinylidene fluoride) (PVDF) directly during radiation exposure was investigated using core level spectroscopy. The strongly non-equilibrium condition of PVDF was studied. The highresolved C K-edge NEXAFS spectra of poly(vinylidene fluoride) have been measured. The spectra modification due to the polymer degradation caused by monochromatic synchrotron radiation has been revealed. Residual fluorine content was monitored using x-ray photoelectron spectroscopy. The study has shown a significant modification of PVDF chemical content and electronic structure in the course of carbonization under synchrotron radiation. Gradual defluorination of the PVDF sample takes place during irradiation with enrichment of carbon skeleton with hydrogen. In the initial stages of radiative modification, defluorinated system is inhomogeneous and changes under the influence of two simultaneous processes: photochemical defluorination and diffusion of unbounded fluorine atoms to the sample surface.
Increase in crystallinity in poly(vinylidene fluoride) by electron beam radiation
Journal of Polymer Science Part B-polymer Physics, 1987
We examine the influence of high-energy radiation and subsequent aging and orientation on the degree of crystallinity of poly(vinylidene fluoride) (PVDF) films. In particular, PVDF films were exposed to electron beam radiation (doses up to 50 W a d) and aged a t room temperature for varying lengths of time followed by uniaxial orientation. The degree of crystallinity of these films was found to increase significantly with increasing radiation dase. In addition, a further substantial increase in the degree of crystallinity was observed upon subsequent aging of irradiated films a t room temperature. Upon orientation, in addition to a further rise in the degree of crystallinity, the crystallits were observed to undergo the a form + p form transformation, the latter phase being the polar phase effective for piezo-electric/pyroelectric activity.
Effect Of Gamma Irradiation On The Crystalline Structure Of Poly(Vinylidene Fluoride)
2016
The irradiation of polymeric materials has received<br> much attention because it can produce diverse changes in chemical<br> structure and physical properties. Thus, studying the chemical and<br> structural changes of polymers is important in practice to achieve<br> optimal conditions for the modification of polymers. The effect of<br> gamma irradiation on the crystalline structure of poly(vinylidene<br> fluoride) (PVDF) has been investigated using differential scanning<br> calorimetry (DSC) and X-ray diffraction techniques (XRD). Gamma<br> irradiation was carried out in atmosphere air with doses between 100<br> kGy at 3,000 kGy with a Co-60 source. In the melting thermogram of<br> the samples irradiated can be seen a bimodal melting endotherm is<br> detected with two melting temperature. The lower melting<br> temperature is attributed to melting of crystals originally present and<br> the higher melting p...
Advances in Polymer Technology, 2014
Polytetrafluoroethylene (PTFE) polymer samples were irradiated by 50 MeV Li 3+ ion beams to the fluences of 1 × 10 10 , 1 × 10 11 , and 1 × 10 12 ions/cm 2. The structural, optical, and chemical properties were studied by X-ray diffraction (XRD), UV-visible (UV-vis) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, respectively. The XRD analyses showed amorphization of the polymer sample at fluences of 1 × 10 10 and 1 × 10 11 ions/cm 2. Crystallite size (calculated by applying the Scherrer formula) decreased for irradiated samples at fluences of 1 × 10 10 and 1 × 10 11 ions/cm 2. The other factors like microstrain (ε), dislocation density (δ), and distortion parameters (g) showed variations at these fluences. However, there was no change in the interchain separation (R) and interplanar distance (d) for all irradiated samples. UV-vis showed a shift of the absorption edge of irradiated samples towards the visible region. The band gap energy (E g) was calculated using Tauc's relation, and its value decreased with an increase of ion fluence for all irradiated samples. The number of carbon atoms per conjugation length (N) increased for the irradiated samples. The FTIR results revealed the liberation of CF 2 groups and the appearance of some new bands after irradiation.