  Electrical charges generation occurring during contact and friction of
insulating materials has been identified for a long time. However the
contribution of these electrical charges to the friction behaviour is usually
neglected in the energetical balances. Based on published results and on our
own experimental results on the ability of the dielectric materials to trap
charges, we show in this study that the interaction energy during friction
depends markedly on these trapped charges. Eventually, we propose the
complementary use of the "mirror " method and of surface forces measurements to
obtain a quantitative evaluation of this contribution. dielectric behaviour /
friction / triboelectrification / interfacial interactions / surface free
energy / space charge / surface forces
