Radiation-induced degradation and crosslinking of poly(ethylene oxide) in solid state

• Published in: Journal of radioanalytical and nuclear chemistry Vol. 253; no. 3; pp. 339 - 344
• Main Authors: Zainuddin, Albinska, J, Ulanski, P, Rosiak, J M
• Format: Journal Article
• Language: English
• Published: 01.09.2002
• ISSN: 0236-5731
• DOI: 10.1023/A:1020406930244

The effects of gamma -irradiation on solid poly(ethylene oxide) (PEO) of an initial weight-average molecular weight of 6.310 exp 5 Da were investigated by gel permeation chromatography and viscometry. The parameters studied were changes in number- and weight-average molecular weight, molecular weight distribution and viscosity of PEO in aqueous solution. Irradiation of poly(ethylene oxide) powder in the presence of oxygen leads to the dominance of chain scission reactions. Their high radiation-chemical yield [G(scission) approx = 2.510 exp -6 mol/J] indicates the occurrence of effective chain reactions. Upon irradiation in vacuum, crosslinking and scission occur side-by-side and the changes in molecular weight are less pronounced in the studied dose range (up to 20 kGy). Scission dominates for doses up to ca. 15 kGy, while for higher doses intermolecular crosslinking gains in importance. The competition between these processes seems to depend not only on the applied dose but also to be influenced by the inhomogeneity of the material (molecular weight and/or possibly the crystallinity). Parallel occurrence of scission and crosslinking leads to the broadening of the molecular weight distribution.