DIFFUSE-REFLECTANCE SPECTROPHOTOMETRY IN POLYPROPYLENE RADIOLYSIS STUDY

Application of diffuse reflectance spectrophotometry (DRS) in the inve stigation of stable and semi-stable products of radiolysis in solid st ate radiation chemistry creates the possibility of spectrophotometric measurements in the case of opaque objects of investigation, e.g. virg in polypropylene in powder. The main advantages of the method are: (1) the object of investigation may be used in any physical shape (hardly transpartent films, opaque powders); (2) The measurement is non destr uctive; (3) No solvents which could influence transients and final pro ducts of radiolysis are necessary; (4) Only optical spectra (200-1000 nm) of intermediate species and final products created during irradiat ion are observed, since unirradiated sample is used as the reference; (5) the method is complementary to EPR, because it shows spectra of no t paramagnetic species, which do not give EPR signals. Numerous spectr a of irradiated polypropylene have been recorded, some of them have be en identified as due to peroxides. Other remain to be identified or ar e waiting to be subject of working hypotheses. The new approach is in the phase of beginnings, and collected material is not equivalent in v olume to the information gained by other methods. Discussion draws att ention to the fact of variety of transient and final products of polyp ropylene radiolysis, caused by complicated nature of the irradiation o bject and heterogeneity of ionizing energy dissipation in the shape of ca 30% of energy deposited in multi-ionization spurs. Copyright (C) 1 996 Published by Elsevier Science Ltd