Influence of γ‐irradiation on poly(methyl methacrylate)

Abstract

Poly(methyl methacrylate) (PMMA) was ␥-irradiated (5-20 kGy) by a 137 Cs source at room temperature in air. The changes in the molecular structure attributed to ␥-irradiation were studied by mechanical testing (flexure and hardness), size-exclusion chromatography, differential scanning calorimetry, thermal gravimetric analysis, and both Fourier transform infrared and solution 13 C-NMR spectroscopy. Scanning electron microscopy was used to investigate the influence of the dose of ␥ rays on the fracture behavior of PMMA. The experimental results confirm that the PMMA degradation process involves chain scission. It was also observed that PMMA presents a brittle fracture mechanism and modifications in the color, becoming yellowish. The mechanical property curves show a similar pattern when the ␥-radiation dose increases.

Use of Lead (II) Sulfide Nanoparticles as Stabilizer for PMMA Exposed to Gamma Irradiation

“…This result agrees with literature reports on the effect of gamma radiation on PMMA matrix 12,17 . During PMMA irradiation, both electronic excitation and ionization processes produces excited atoms and ions which lead to the release of side groups like CH 3 OOC• and main chain scissions 12,14 .…”

“…This result agrees with literature reports on the effect of gamma radiation on PMMA matrix 12,17 . During PMMA irradiation, both electronic excitation and ionization processes produces excited atoms and ions which lead to the release of side groups like CH 3 OOC• and main chain scissions 12,14 . It was reported that initial side-chain scissions generate macro radicals that further undergo main chain scissions 12,19 and is the basic reason for the radiation-induced degradation of PMMA.…”

“…In particular, Poly (methyl methacrylate) (PMMA) is commonly used to determine the effects of various additives on polymer radiation stability. The PMMA is produced and formed in rigid bodies showing excellent transparency, good mechanical properties and high resistance to weathering 12 . This polymer is also used in manufacturing of radio-sterilizable medical supplies 13 or in dosimeters for intense radiation fields…”

“…, and the behavior of this polymer under radiation has been extensively studied 12,14 , including ours previous studies 15 . PMMA is known to undergo main chain scission when exposed to ionizing radiation.…”

“…In general, polymer radicals are responsible for changes in physical properties of PMMA 16 . In particular, gamma irradiation of PMMA, causes main chain scission and hydrogen abstraction from an alpha-methyl or methylene 12,13,14 .…”