Dominique Souchet

Laboratory bench for the characterization of triboelectric properties of polymers

The use of polymers as materials for sliding machine components is due to their low cost, ease of manufacturing, as well as appropriate mechanical and thermal properties. The aim of this paper is to present the experimental bench designed for the study of the triboelectric charge generated in sliding conformal contacts between flat polymer materials. The experiments were performed with 4-mm-thick samples of polystyrene and 5-mm-thick samples of poly-vinyl-chloride.The normal contact force can be adjusted using an appropriate control system and measured by a force sensor (± 50 N). The translational back-and-forth motion of the samples is produced by a crank-shaft system that generates a sinusoidal translational speed profile, with amplitudes between 12 and 50 mm/s, for strokes of 36 to 60 mm. The distribution of charge at the surface of the samples is measured by the capacitive probe of an electrostatic voltmeter (± 10 kV). The experiments pointed out that this bench enables the evaluation of the non-uniformity of the electric charge accumulated on the sliding bodies and the study of the correlations that might exists between this charge and the external forces applied to the contact.

Sliding Conformal Contact Tribocharging of Polystyrene and Polyvinyl Chloride

The electric double layer is known to affect thin-film lubrication. Other researchers have shown that tribocharging affects the breaking torque in a metal shaft-oil-lip seal system and that an external electric field may be employed to control this phenomenon. One main issue in all these studies is the characterization of the charging state of the bodies in contact. This is quite a difficult challenge when the contact occurs between two insulating materials. The ultimate aim of this paper is to validate an experimental procedure appropriate for ensuring the reproducibility of the tribocharging conditions in sliding contacts between polymeric materials. The experiments were performed with samples of polystyrene and polyvinyl chloride. Surface potential measurements were done to evaluate the tribocharging effects. The experiments pointed out that the amount of charge accumulated on the sliding bodies depends on the external force applied to the contact and the number of tribocharging cycles (i.e., back-and-forth relative motions). However, this charge is nonuniformly distributed on the surface of the samples. This means that it will be difficult to use the tribocharging effect for controlling the charging state and, hence, the lubrication of the contact between two insulating bodies.

Tribocharging phenomena in sliding contacts between polymeric materials

The electric double layer is known to affect thin film lubrication. Other researchers have shown that tribocharging affects the breaking torque in a metal shaft - oil-lip seal system and that an external electric field may be employed to control this phenomenon. One main issue in all these studies is the characterization of the charging state of the bodies in contact. This is quite a difficult challenge when the contact occurs between two insulating materials. The aim of the present work was to validate an experimental procedure appropriate for ensuring the reproducibility of the tribocharging conditions in sliding contacts between polymeric materials. The experiments were performed with samples of polystyrene and poly-vinyl-chloride. Surface potential measurements were done in order to evaluate the tribocharging effects. The experiments pointed out that the amount of charge accumulated on the sliding bodies depends on the external force applied to the contact and the number of tribocharging cycles (i.e., two back-and-forth relative motions). However, this charge is non-uniformly distributed on the surface of the samples. This means that it will be difficult to use tribocharging effect for controlling the charging state and hence the lubrication of the contact between two insulating bodies.