REACTIONS OF POLYETHYLENE SURFACES WITH THE DOWNSTREAM PRODUCTS OF ANAIR PLASMA - GAS-PHASE AND SURFACE SPECTROSCOPIC STUDIES

The gas phase downstream products of an air glow discharge have been m easured, using absorption and emission spectroscopies, as a function o f plasma power, air flow rate, and distance from the plasma. In additi on, the reaction of these products with a linear low density polyethyl ene (LLDPE) polymer surface has been followed using x-ray photoelectro n spectroscopy (XPS). At higher air flow rates (>300 seem), the primar y reactive species is confirmed to be O(P-3) atomic oxygen. Some O(P-3 ) is generated in the plasma itself, but more appears to be formed in the downstream region, because of dissociation of molecules in their e xcited states. At low flow rates, the concentration of O(P-3) is stron gly depleted at the sample position, but other atomic oxygen states be come more prominent. O(S-5) and O(S-3) are two states which are identi fied. XPS studies of the polyethylene surface reacted at high flow rat es shows oxygen functionalities that are likely the result; of an init iation by hydrogen abstraction. At low flow rates, the products sugges t initiation by oxygen insertion. Thus, changes in flow rate can resul t in major changes to the polymer surface chemistry. (C) 1996 John Wil ey & Sons, Inc.