Effect of gamma irradiation on the optical properties of UHMWPE (Ultra-high-molecular-weight-polyethylene) polymer

doi:10.1016/j.nimb.2011.11.001

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Volume 271, 15 January 2012, Pages 44-47

https://doi.org/10.1016/j.nimb.2011.11.001 Get rights and content

Abstract

The UV–Visible absorption spectra of virgin and high dose gamma irradiated (up to 2000 kGy) UHMWPE polymer have been studied by using UV–Visible spectrophotometer (JASCO, V-570). The existence of the peaks, their shifting and broadening as a result of gamma irradiation has been observed. In the present work the Urbach energy is calculated by using Urbach edge method. Also the direct and indirect energy band gap in virgin and gamma irradiated UHMWPE polymer has been calculated. The values of indirect energy band gap have been found to be lower than the corresponding values of direct energy band gap. A decrease in the optical energy band gap with increasing gamma irradiation has been discussed on the basis of gamma-irradiation-induced modification in the UHMWPE polymer. The correlation between optical energy band gap and the number of carbon atoms in a cluster with modified Tauc’s equation has been discussed in this polymer. We have also observed the color formation which became more and more prominent with increasing dose and at the highest dose the fully transparent sample became completely opaque.

Looking at the trend of the absorption curve this polymer can be used as a very good dosimeter for the gamma ray irradiation.

Introduction

The importance of polymers having improved surface and bulk properties has increased very rapidly during the last few decades because of their low weight, low cost, easy processability and easy fabrication of thick and thin samples, etc. UHMWPE (Ultra-high-molecular weight-polyethylene) is one among those having monomer –CH₂–. The applications of UHMWPE lie in the field of medicine, microelectronics, engineering, chemistry and the food industry, etc. In fact, UHMWPE has excellent properties of biocompatibility, electrical insulation, high mechanical and chemical resistance. UHMWPE has special application in the gliding part of the mobile prosthesis, such as the hip and knee joints and the hydraulic tubes of different conductive fluids. These applications require high mechanical resistance in order to answer to high dynamical pressure loads and long-term mechanical performance [1].

Now a days the irradiation of polymers is one of the important fields for altering the polymer properties like electrical, optical, chemical, mechanical, etc. significantly [2], [3], [4]. The interaction of radiation with polymers destroys [5] the initial structure of the polymers and leads to chain scission, chain aggregation, formation of double bonds and molecular emission. As a consequence of this the polymer properties are modified [5], [6].

The knowledge of optical properties of polymers is needed in the fabrication of LEDs, optical sensors, antireflective coatings, etc. This justifies the need of studying the irradiation effects on the optical properties of the polymers such as optical energy band gap [7].

In the present work we have studied the behavior of optical energy band gap and Urbach energy with increasing gamma dose [8]. Also we have calculated the optical energy band gap of UHMWPE polymer with increasing gamma dose (0–2000 kGy) [9]. The simultaneous existence of direct and indirect energy band gap in UHMWPE polymer and the number of carbon atoms (N) in a cluster are also reported [8].

Section snippets

Experimental details

UHMWPE polymer sheets of thickness 1 mm were brought from Good Fellow UK (United Kingdom) and were used without any further treatment. The samples, of size (2 × 1) cm² each, were irradiated at UGC-DAEF CSR, Kolkata Center by using 1.25 MeV gamma radiation source of ⁶⁰Co in the high vacuum (2 × 10⁻⁶ Torr) radiation chamber (in the form of cylindrical chamber of 14 cm length and 10 cm diameter with dose rate 4 kGy/h and source strength 74 GBq). One sample was kept as virgin for reference and the other four

Study of optical behavior

The UV–Visible absorption spectra of virgin and gamma irradiated (500–2000 kGy) UHMWPE polymer samples are presented in Fig. 1. The recorded spectra show a shift of absorption edge towards longer wavelength with increasing gamma dose. The broadening of absorption peak with increasing gamma dose is observed in the spectra (Fig. 1). This behavior is generally interpreted as caused by the formation of extended systems of conjugate bonds i.e. possible formation of carbon clusters [8]. The absorption

Conclusion

In the present study of virgin and gamma irradiated UHMWPE polymer samples, the values of the optical band gap (E_g), and Urbach energy (E_u) were calculated using the UV–Visible spectroscopy analysis. The observed fact indicates that the values of indirect energy band gap are lower than the corresponding values of direct energy band gap in virgin as well as in gamma irradiated UHMWPE polymer. The analysis also indicates that the energy band gap (E_g) decreases with increasing gamma irradiation

Acknowledgements

The authors are thankful to Dr. A.K. Sinha, Director, UGC-DAEF Consortium for Scientific Research, Kolkata Center, for his help in getting the samples irradiated. We are also thankful to Dr. A.K. Saha for his kind help.

References (19)

M. Mujahid et al.
Radiat. Phys. Chem.
(2005)
A.F. Saad et al.
Radiat. Measu.
(2005)
S. Singh et al.
Nucl. Instr. Meth. Phys. Res. B
(2004)
A.M. Abdul-Kader
Appl. Surf. Sci.
(2009)
M.D. Migahed et al.
Curr. Appl. Phys.
(2006)
A.V. Kokate et al.
Solar Energy
(2006)
G. Hirankumar et al.
J. Power Sources
(2005)
S.C. Scholes et al.
A frictional study of total hip join replacement
Phys. Med. Biol.
(2000)
L. Calcagno et al.
Nucl. Instr. Meth. Phys. Res. B
(1992)

There are more references available in the full text version of this article.

Cited by (41)

Investigation on discoloration mechanism of cyclic olefin copolymer under ionizing irradiation sterilization
2024, Polymer Degradation and Stability
Cyclic olefin copolymer (COC) is a material used in various aspects of medical and health fields due to its excellent comprehensive properties. When sterilized by ionizing irradiation, COC is typically exposed to an absorbed dose <25 kGy, yet noticeable discoloration still occurs. In this study, the COC with norbornene content of 52 mol.% was taken as the research subject to investigate the discoloration mechanism of the COC upon irradiation. After γ-ray irradiation, the transparent and colorless COC changed to varying degrees of yellowish-green. However, after 24 days of storage at room temperature, this color significantly diminished. The color change in COC after gamma irradiation primarily results from the presence of free radicals, which gradually fade through recombination. By employing time-dependent density functional theory simulations to analyze the UV–vis absorption spectrum of free radicals, the cause for the color change was illustrated. Additionally, it is worth noting that the faded sample can be recolored through re-irradiation, indicating a ``reversible change'' in coloration caused by gamma irradiation.
Electric production of high-quality fuels: Via electron beam irradiation under ambient conditions
2022, Green Chemistry
The production of high-quality fuels and petrochemicals is both energy and emission intensive with traditional methods. The thermal activation of reactions by catalysts or high temperature and pressure or both is very costly, and emits a vast amount of greenhouse gases (GHG). Electric conversion methods using renewable electricity to minimize GHG emissions become more and more necessary. We have now investigated a greener method that uses electron beam irradiation to produce the desired products without any CO₂ emissions. Chemical reactions are initiated by collisions between molecules and high energy electrons under ambient conditions. High energy electrons could penetrate the material and effectively deposit energy inside, achieving uniform chemical conversion. Taking advantage of this, new and desirable compounds could be synthesized. Oligomers are the most important product from irradiating liquid hydrocarbons. Straight alkane molecules break down randomly upon irradiation, resulting in broadly distributed iso-paraffins which serve as high-quality fuels. This technology could also effectively convert gaseous hydrocarbons such as propane and isobutane to liquid fuel products with a high concentration of iso-paraffins in a gas to liquid process. This method is electrical and easily adaptable to renewable energy sources with potentially zero GHG emissions.
Loss of chemical bonds induced by high doses of γ-radiation in a PADC polymer film: The influence of dose and dose rate on radiation chemical yields
2021, Radiation Physics and Chemistry
The effects of gamma rays on molecular properties of a poly allyl diglycol carbonate (PADC) polymer, commercially named as CR-39, have been studied. PADC films were exposed to gamma rays at doses ranging from 0.5 to 3 MGy. Gamma exposure induces considerable molecular modifications in PADC films. These modifications were analyzed using Fourier transform infrared (FT-IR) spectroscopy. FT-IR absorption spectra of the gamma irradiated samples show a change in the intensity and the shape of the absorption bands of the chemical groups forming the PADC polymer relative to the pristine one. We have determined G-values for the loss of carbonate ester and ether chemical moieties within PADC. By comparing our G-values with those from other studies, we show that dose rate and dose significantly affect the radiation chemical yields and play an important role of molecular bond kinematics.
Optical response of a thermally treated polyallyl diglycol carbonate (PADC) polymer to gamma ray exposure: Prospects of a new approach in gamma ray dose estimation
2020, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Citation Excerpt :
Notably, the optical spectra also show an enhancement and a shift of the absorption edge towards longer wavelengths with increasing gamma ray dose in the non-annealed CR-39 detectors up to 600 kGy, and no shift after that up to the end of the exposure dose at 1000 kGy as seen in Figs. 1–3(a). This shift has been observed at doses higher or lower than 1000 kGy (the highest dose considered in the current study) in polymeric nuclear track detectors by several research groups [22–26]. Meanwhile, the UV spectra of the annealed-gamma-irradiated detectors showed a strong enhancement and a significant systematic gradual shift, within the overall gamma ray dose range, with increasing annealing time, as seen in the same figures from (b) to (f).
The UV–visible absorption spectra of virgin and gamma ray-irradiated thermally treated and non-thermally treated CR-39 polymeric track detectors are measured using a UV–visiblespectrometer. Annealing experiments are carried out on CR-39 polymer films exposed to ⁶⁰Co. The prime aim of this research is to find a relationship between the gamma ray dose and the corresponding changes in the optical properties of thermally treated CR-39 after being irradiated by gamma rays. These results will be of use for the optical representation of CR-39, as well as for investigations of the alterations of polymers caused by thermal annealing after exposure to gamma rays. From our analysis of the dependence of the absorbance on the annealing time and exposure dose, we find that the obtained results are consistent and systematic across all samples. The optical absorbance in the UV–visible range (190–450 nm) has a linear dependence on the gamma ray dose, as shown using thermally treated CR-39 detectors. Consequently, a semi-empirical relation between the wavelengths of UV–visible light and gamma ray dose at certain absorbance is established for the gamma ray dose estimation. This new technique is particularly very useful in measuring medium doses ranging from 200 to 1,000 kGy, where optical absorbance in non-annealed CR-39 is not well resolved because of superimposed absorbance. We also provide evidence that there is a considerable interaction effect between the gamma ray dose and temperature, which causes the CR-39 material to respond quite differently than when it is subjected to temperature alone. In this paper, the results provide a new approach to measuring the specific property changes induced by both thermal annealing and exposure to gamma rays, allowing a unique detection of gamma ray doses over the range 200 to 1000 kGy.
High dose rate electron beam irradiation of heavy alkanes in a multi-phase flow system
2020, Fuel
A high energy electron beam (10 MeV, LINAC) was used to irradiate mineral oils in a continuous flow system to study radiation effect on large alkane hydrocarbons at constant temperatures (80 and 150 °C). Oil flows down an open channel with methane or helium bubbling from the bottom. The gas mixes with the oil but also may be reactive. Oil was irradiated with about 300–500 kGy by passing 20–30 times down the channel at 18–24 kGy per pass. Analysis by GC-FID showed 7–12% conversion in treated samples and about 60–70% product selectivity to light hydrocarbons right after the irradiation experiment. Stability of products was tested after two years and showed reduced conversion to light products. Selectivity to light products was nearly 100% and dropped to 72% after two years in sample treated with methane. Initially 63%, after aging product selectivity to lights became 46% in sample irradiated at higher temperature and reduced from 62% to 18% in sample irradiated at lower temperature. Overall conversion yields in the flow system are 4–7 molecules/100 eV higher than typical literature values for batch processing of alkanes and cycloalkanes. Irradiation with methane had higher yields and higher selectivity to lighter products compared to helium. Product selectivity to light products is 72% after two years and total yield to lights is 4.4 molecules/100 eV. Methane gas led to higher yield with no viscosity change. Product instability may cause significant economics loss in irradiation upgrading of heavy oils and needs to be addressed.
Gamma rays irradiation effects in thin film polyethylene terephthalate polymer
2019, Radiation Physics and Chemistry
The effect of gamma rays irradiation on structural properties of polyethylene terephthalate (PET) has been studied using Fourier Transform Infrared Spectroscopy (FTIR), X-rays diffraction (XRD) and UV–Visible spectrophotometry techniques. The gamma rays irradiations were performed, using ⁶⁰Co source with mean energy of 1.25 MeV, at Nuclear Research Centre of Algiers, Algeria. The gamma absorbed dose rate was about 1.3 kGy/h as measured using the Frick dosimeter. Several PET samples with a thickness of 6 μm were irradiated at room temperature with the presence of air atmosphere at different doses (0.05–5 MGy). The FTIR analysis reveals that the intensities of the different absorption bands decrease with increasing gamma rays dose. This is attributed to the chain scission induced by gamma rays irradiation. It is found from XRD analysis that the crystallinity is reduced after irradiation. The variation in crystallite size is also observed. The UV–vis spectra show a large absorption band extended from 310 to 355 nm assigned to the formation of extended systems of conjugate bonds with the creation of carbon clusters. The optical absorbance in this range increases linearly with the gamma rays dose. An empirical relation is established to estimate gamma dose from this correlation. Both direct and indirect energy gaps are found to decrease with increasing gamma rays dose indicating the appearance of new electronic transitions. Moreover, it is also observed that the Urbach energy increases with the gamma rays dose. This indicates the disorganization of the PET structure after irradiation.

View all citing articles on Scopus

View full text

Effect of gamma irradiation on the optical properties of UHMWPE (Ultra-high-molecular-weight-polyethylene) polymer

Abstract

Introduction

Section snippets

Experimental details

Study of optical behavior

Conclusion

Acknowledgements

Radiat. Phys. Chem.

Radiat. Measu.

Nucl. Instr. Meth. Phys. Res. B

Appl. Surf. Sci.

Curr. Appl. Phys.

Solar Energy

J. Power Sources

A frictional study of total hip join replacement

Phys. Med. Biol.

Nucl. Instr. Meth. Phys. Res. B