XPS and surface resistivity measurements of plasma-treated LDPE and ageingeffects

Low-density polyethylene (LDPE) film containing a polydimethylsiloxane (PDM S) additive has been investigated using x-ray photoelectron. spectroscopy ( XPS) and surface resistivity measurements. The samples measured were: as-re ceived; plasma-treated; washed with ethyl acetate; aged in air; and combina tions of these treatments. Analysis by XPS has been used to characterize su rface species concurrently with resistivity in the surface region to assist in understanding the relationship between charge transport and surface ele ctronic structure. Radiofrequency plasma treatment causes major oxidation e ffects and lowering of resistivity in the first 4 s. With the same treatmen t time, in the case of washed samples, surface segregation of PDMS is enhan ced, causing an initial increase of surface region resistivity. Plasma trea tment beyond 4 s causes saturation of the O:C ratio in the surface and a lo ss of charged bonds. These points also allow a description of resistivity c hange with ageing, which includes hydration effects on exposure to air. Cop yright (C) 2001 John Wiley & Sons, Ltd.