Effect of a cold helium plasma at -180 degrees C on polyolefin films - I. Plasma induced luminescence features of polyethylene and polypropylene

Plasma induced luminescence (PIL) recorded from LDPE films 25 m thick and f rom oxidised 50 m PP films is compared to earlier observations on PIL of 20 m unoxidised PP films. It is found that PIL features, decay kinetics and l uminescence spectrum are very similar in both PP samples and in LDPE. As in the unoxidised PP sample, PIL is found to be composed of phosphorescence a t about 450 mn, chemiluminescence near 400 nm and an emission due to radiat ive recombination of charges implanted on the surface which appears around 500 nm. The decrease in the PIL chemiluminescence component as consecutive plasma treatments are performed on the same sample, which had been found in unoxidised PP samples, is again found both in LDPE and in oxidised PP. (C) 1999 Elsevier Science Ltd. All rights reserved.