On interacting with materials like HDPE, gamma radiation can
produce free radicals or chemical species with unpaired electrons
which can be extremely reactive, resulting in complex structures
and irreversibly broken covalent bonds [9]. Free radical reactions in
plastics cause crosslinking between polymer chains, chain scission
and oxidations of the carbon chains [10]. When crosslinking occurs,
new chemical bonds between the atoms of adjacent polymer
strands may be formed. These bonds can alter a polymer's mechanical
and chemical properties [11,12].