Gamma Irradiation Effects on Poly (Vinylidene Fluoride) Films (original) (raw)
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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...
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. #
Changes in poly-vinylidene fluoride produced by electron irradiation
Radiation Physics and Chemistry, 1999
A study was made of the eects of electron irradiation of poly-vinylidene¯uoride, using the DSC, FTIR, and Xray techniques, as well as determining the percent cross-linking. Changes in crystallinity and melting point of the sample as a function of dose were found, the latter due to competition between cross-linking and crystallinity. The cross-linking was observed to increase with radiation dose. Chemical changes observed include the formation of carbonyl groups and double bonding, associated with the loss of HF. #
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.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2003
The effects of electron beam irradiation on two partially fluorinated polymer films i.e. poly(vinylidene fluoride) (PVDF) and poly(ethylene-tetrafluoroethylene) copolymer (ETFE) are studied at doses ranging from 100 to 1200 kGy in air at room temperature. Chemical structure, thermal and mechanical properties of irradiated films are investigated. FTIR show that both PVDF and ETFE films undergo similar changes in their chemical structures including the formation of carbonyl groups and double bonding. The changes in melting and crystallisation temperatures (T m and T c ) in both irradiated films are functions of irradiation dose and reflect the disorder in the chemical structure caused by the competition between crosslinking and chain scission. The heat of melting (DH m ) and the degree of crystallinity (X c ) of PVDF films show no significant changes with the dose increase, whereas those of ETFE films are reduced rapidly after the first 100 kGy. The tensile strength of PVDF films is improved by irradiation compared to its rapid deterioration in ETFE films, which stemmed from the degradation prompted by the presence of radiation sensitive tetrafluoroethylene (TFE) comonomer units. The elongation at break of both films drops gradually with the dose increase indicating the formation of predominant crosslinked structures at high doses. However, the response of each polymer to crosslinking and main chain scission at various irradiation doses varies from PVDF to ETFE films.
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.
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.
Indian Journal of Pure and Applied Physics
In the present paper, the physico-chemical changes induced by 70 MeV carbon ions (12C+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 11011 to 31012 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 ...
Polymer Degradation and Stability, 2003
Films of poly(vinylidene fluoride) (PVDF) were exposed to proton and electron beam irradiation at high doses, from 50 to 5000 kGy. Modifications induced in the samples were determined by electron paramagnetic resonance (EPR). Samples irradiated with electrons and protons showed similar behaviours, with the presence of several types of radicals. The number of radicals produced as a function of dose in the proton case is slightly below that of the electron case, indicating non-linear effects. The evolution of radical density and its decay in the dark and in normal light conditions at room temperature was studied, as well as its decay with increase in temperature. When kept in the dark for up to 180 days, no decay of radicals was observed. #