THE CHEMISTRY OF GAMMA-IRRADIATED BISPHENOL-A POLYCARBONATE

On exposure to sterilizing doses of Co-60 gamma-rays, bisphenol-A poiy carbonate (BPA-PC) turns a moderately intense yellow color. Product st udies of gamma-ray irradiated BPA-PC and a model compound, BPA-PC cycl ic tetramer, were undertaken to define the major degradative process i nvolved, and to try to identify the chemical species responsible for t he color. The major irradiation products were isolated and identified using base hydrolysis followed by HPLC/MS analysis. These studies show that the principal degradative process induced by gamma-ray irradiati on involves Fries type free radical reactions leading to the destructi on of the carbonate linkages and formation of a number of phenol coupl ing products and salicylate esters. Chromatographic/spectroscopic stud ies indicated that the yellow color was mainly due to the formation of two labile products having a broad lambda(max) at similar to 360 nm. However, numerous attempts to isolate and identify these compounds usi ng HPLC/MS and GC/MS were unsuccessful.