Electron irradiation of polyurethane: Some FTIR results and a comparison with a EGS4 simulation (original) (raw)
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Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2001
In this paper, investigation has been performed on thermoplastic and aromatic polyurethane (PU) irradiated by an electron beam with an energy of 200 keV. The changes in chemical structure resulting from the irradiation were determined using FTIR spectroscopy. This study has allowed us to highlight the polymer degradation versus depth, uence, electron¯ux and temperature by following the decrease in the NH band intensity. Results showed that degradation of the PU reached a maximum at a depth of about 200 lm, and that these eects are quanti®able up to 500 lm. Moreover, the results also showed that the¯uence, electron¯ux and temperature increase led to an increase in the degradation of the polymer. The oxidation was equally studied versus the same parameters by following the increase in the OH band intensity. This study produced the opposite results except for the temperature. When the temperature increased, the polymer oxidation seemed to decrease. Ó
Electron irradiation of polyurethane using UV spectroscopy, GPC and swelling analyses
Radiation Physics and Chemistry, 2002
Investigation has been performed on thermoplastic and aromatic polyetherurethane (ETPU) irradiated by an electron beam of 200 keV energy. The changes in chemical structure resulting from the irradiation and particularly the development of polyene sequences were studied using UV spectroscopy. Moreover, structural transformations have been characterized by GPC for soluble samples and by the swelling technique for insoluble samples. An increase in crosslinking rate of the polymer is observed and analyzed. The results of the chemical and structural modifications show that the development of polyene sequences and the crosslinking of the ETPU reached a maximum at about 200 mm, and that these effects increased with the fluence. Moreover, it also appeared that the increase in temperature has induced an increase in crosslinking, but the scission process has prevailed to the crosslinking with the increase in electron flux. r
European Polymer Journal, 2013
It is well known that polyurethane (PU) provides good irradiation resistance; however, extremely high irradiation doses can alter the structure and/or function of macromolecules, resulting in oxidation, chain scission and crosslinking. In this present study, modifications to the material characteristics resulting from irradiation were extensively examined through a broad array of analytical techniques. Fourier transform infrared spectroscopy (FTIR) revealed that there were a number of changes to the chemical structure after electron beam irradiation while dynamic frequency sweeps identified an occurrence of crosslinking particularly in the higher irradiation doses. The degree of crosslinking was further analysed by implementing the crosslink density experiment, which illustrated a high level of crosslinking at 200 kGy only. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) identified an increase in phase segregation and as a consequence it could lead to soft segment mobility. This increase in mobility could be responsible for an increase in the degree of chain orientation. Surface morphology of the electron beam irradiated material was determined using scanning electron microscope (SEM) imagery and this provided evidence that the surface of the material had clearly transformed with the development of additional ridges. The influence of such modifications initiated a significant reduction in the contact angle at the upper irradiation dose regime. Overall, this study demonstrated that the medical grade PU was highly affected by radiation exposure, particularly at high irradiation doses.
Structural modification in electron-irradiated polyetherurethane
Applied Surface Science, 2002
Doppler broadening spectroscopy (DBS) using a slow positron beam has been applied to investigate degradation induced by 200 keV electrons irradiation in polyetherurethane (PU). The low momentum fraction S (and respectively the high momentum fraction W) characteristic of the irradiated films is shown to decrease (and respectively to increase) when the electron deposited energy increases. The DBS results are compared to the mass loss measured by 'solvent swelling' of the films which shows that the cross-linking increases as the electron deposited energy increases. #
Electron Irradiated Effect in Polyurethanes Studied by Positron Annihilation Lifetime Spectroscopy
Khulna University Studies
The intensity variation of positronium as a result of electron irradiation has been studied on polyurethanes (PU) using positron annihilation lifetime spectroscopy (PALS). The PALS measurement was carried out at room temperature with a conventional fast-fast coincidence system. The lifetime spectra were analyzed into four components using melt program to extract the positron parameters such as lifetime and intensity. Due to irradiation a decrease of intensity about 2.7% was observed up to 10kGy. Free volume radius has been calculated for electron irradiated PU. PALS measurement has also been performed to study the effect of temperature variation in the range 30K to 310K. Analysis by melt program on the spectra shows that the fourth lifetime component increases significantly above glass transition temperature.
2020
The impact of electron beam irradiation on thermoplastic polyurethane material was studied for both an aliphatic and an aromatic polyurethane with equal amount of hard and soft segments. Irradiation doses up to 300 kGy at room temperature and at 100 °C were applied. Changes in chemical structure, molar mass and size were assessed using infrared spectroscopy, differential scanning calorimetry, size exclusion chromatography and thermal field flow fractionation. Material alterations were correlated with trends regarding to degradation, crosslinking or branching changes. Thereby, limits of characteri-zation by size exclusion chromatography are addressed and amended by thermal field-flow fractionation studies. In addition, a thermophoretic analysis has been carried out complementary to the portfolio of analytical methods applied in this work.
Study on the Microstructure of Polyester Polyurethane Irradiated in Air and Water
Polymers, 2015
The gamma irradiation induced aging of thermoplastic polymer Estane 5703 in air and water environments was studied by small-angle neutron scattering (SANS), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and X-ray diffraction (XRD). The degree of phase mixing was increased after irradiation, accompanied by the increase of domain distance and decrease of domain size. The hard domain distance increased from 9.8 to 11.2 nm and 14.4 nm for the samples irradiated in air and water with a dose up to 500 kGy, respectively. The GPC results indicated progressive formation of larger linked structures with very high molar mass with increasing absorbed doses. The samples irradiated in water exhibited a stronger aging effect than those irradiated in air. The FTIR results suggested that the cross-linking occurred among the secondary alkyl radicals, and the interactions in hard domains weakened because of the loss of inter-urethane H-bonds. The volume fraction of well-ordered soft segments in Estane increased upon irradiation.
Iraqi Journal of Physics (IJP)
Positron annihilation lifetime (PAL) technique has been employed tostudy the microstructural changes of polyurethane (PU), EUXIT 101and epoxy risen (EP), EUXIT 60 by Gamma-ray irradiation with thedose range (95.76 - 957.6) kGy. The size of the free volume hole andtheir fraction in PU and EP were determined from ortho-positroniumlifetime component and its intensity in the measured lifetime spectra.The results show that the irradiation causes significant changes in thefree volume hole size (Vh) and the fractional free volume (Fh), andthereby the microstructure of PU and EP. The results indicate thatthe γ-dose increases the crystallinity in the amorphous regions of PUand increase the cross-linking of EP.
EPR studies of gamma irradiated poly(ether-urethane)s
Radiation Physics and Chemistry, 2019
In this work the effect of gamma irradiation on two commercial poly(ether-urethane)s of different hard segments, namely Pellethane and Tecoflex was investigated. Electron Paramagnetic Resonance (EPR) spectroscopy was used because it is the only technique appropriate for direct detection and identification of paramagnetic intermediates in the irradiated substances. Thermal annealing was applied to compare the relative stability of the detected radicals. It was found that the dominant component of EPR spectra is a doublet which was assigned to diphenylmethyl radical in Pellethane and dihexylmethyl radical in Tecoflex, formed by the abstraction of hydrogen atom from-CH 2-group located between aromatic and cyclohexane rings, respectively. The other paramagnetic product present in the wide range of temperatures is alkyl radical-CH 2-CH 2 • localized in both segments of polyurethanes, presumably formed by scission of CO bond. The performed studies will allow to predict radiation susceptibility of polyurethanes designed in the future.