3. (25pts) Gamma irradiation is one common method to sterilize orthopedic implan
ID: 951114 • Letter: 3
Question
3. (25pts) Gamma irradiation is one common method to sterilize orthopedic implants. In the late 1990s to early 2000s, researchers identified a potential issue with the standard sterilization and storage parameters for implants that contained ultra high molecular weight polyethylene (UHMWPE). Specifically, results indicated significant deterioration of mechanical properties if the impla oxygen for long periods of time. The graphs below depict the typical stress-strain curves for UHMWPE sterilized in oxygen or nitrogen then stored for either 0wks or 4wks. nts were irradiated in an oxyg en-enriched environment and further deteriorated if stored in 50 40 30 20 ..4wks 40 --4wks 30 20 10 0.01 0.02 0.03 0.04 0.05 0.01 0.02 0.03 0.04 0.05 Strain Strain a. (5pts) Based on your knowledge of polymer degradation, what type of degradation is most likely occurring when UHMWPE is sterilized in oxygen? b. (5pts) Explain the rationale for your answer in part b and describe the general steps for this type of degradation. c. (5pts) Explain why similar degradation does not occur when sterilized under nitrogen.Explanation / Answer
a ) Oxidative degradation occure.
b ) Gamma sterilization of polyethylene in oxygen has been shown to lead to long term degradation of the material’s mechanical properties as a result of continual chain scission stemming from entrapped free radicals.
c) The measured oxidation indices of the nitrogen sterilized components were substantially lower than those exhibited by the oxygen sterilized components of the approximately the same periode of time.The nitrogen sterilized components do not exhibit mechanical signs of oxidative chain scission.
e ) 1 ) Breaking down and dissolution of the intermetallic particles in alloys.11) Electrical corrosion.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.