Date of Award
Master of Science
Muhammad Shah Jahan
PEEK (polyether ether ketone) is a biocompatible, semicrystalline thermoplastic that is mechanically strong and thermally stable; it is also generally considered to be radiation resistant. Interactions of PEEK with radiation, such as X-ray and UV, may bring chemical changes such as from the simultaneous occurrence of crosslinking and chain scission, which may also impact on the macroscopic properties of material. Past research work on PEEK is concentrated mostly on the study of the effect of energetic radiations like gamma-irradiation and electron beam radiation. In a recent study, Awaja et al. detected free radicals in plasma-treated PEEK at room temperature. The lifetimes of the radicals were found to be approximately 24 hours. In another study, Li et al. observed radiation-induced radicals at liquid nitrogen (77 K), and at room temperature, for UV-, gamma- and e-beam-irradiated PEEK; the gamma- and e-beam-induced radicals decayed in less than 20 minutes at room temperature, and the UV-induced radicals decayed in about 24 hours. While no structural information about the radicals was provided, these authors suggested that the residual radicals (present in as-received PEEK before irradiation) and the UV-induced radicals were similar or identical. Awaja et al., however, noted that the residual radicals could be produced during the manufacturing process. In this research work, we have used electron spin resonance to find the effects of UV- and X-irradiation on four types of PEEK. UV-and X-radiation appear to produce the same type of induced free radicals, which are observable for longer times than previously reported. In essence, we have found that radiation-induced radical formation may be more significant than previously thought for PEEK materials. Additional work is needed to further characterize the radiation-induced free radicals and their long- term consequences.
dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.
Riahinasab, Tayebeh, "Electron Spin Resonance Studies of UV-And X-Ray Irradiated Poly (ether ether ketone)" (2013). Electronic Theses and Dissertations. 793.