Evaluation of the probability of reaction of fast oxygen atoms with polymers and graphite

Abstract

On the basis of analysis of published data on the reaction efficiency of various polymer materials and graphite in their interaction with fast oxygen atoms (energy of about 4.5 eV) as obtained in flight tests of materials in low-Earth orbits of the International Space Station and ground tests, probability P_r of chemical oxidation reactions accompanied by ablation has been evaluated. Estimates have been made for 33 polymers consisting of carbon, hydrogen, oxygen, and nitrogen and graphite for two extreme cases when the carboncontaining oxidation products are either CO or CO₂ alone. The average probability values found are P_r(CO)(av) = 0.184 and P_r(CO₂)(av) = 0.317. The probability values range from P_r(CO) = 0.604 and P_r(CO₂) = 0.963 for allyl diglycol carbonate to P_r(CO) = 0.038 and P_r(CO₂) = 0.075 for pyrolytic graphite.