  We present a general theory for the contribution from contact electrification
to the work necessary to separate two solid bodies. The theory depends on the
surface charge density correlation function, which we deduce from Kelvin Force
Microscopy (KFM) maps of the surface electrostatic potential. For silicon
rubber (polydimethylsiloxane, PDMS) we discuss in detail the relative
importance of the different contributions to the observed work of adhesion.
