Tactile property of surfaces controls the safety of materials handling. Operators need gloves to keep their hands safe and enhance their ability to handle materials. This ability can be developed by controlling the friction property of the gloves. Sometimes, operators rub their hands so that the gloves may get charged by triboelectrification. Electrostatic charges (ESC) generated from friction of the gloves has a negative effect friction coefficient. The present work aims to investigate the influence of pre-triboelectrification on friction coefficient displayed by polymeric materials by sliding of polyethylene (PE) on polyurethane (PU) at dry sliding. PU in form of 0.5 mm coating was adhered into polypropylene (PP) as well as copper substrates. The experiments showed thatthe intensity of ESC generated on the sliding surfaces depends on their ranking of material in the triboelectric series. As the gap between the two rubbing materials increases, the intensity of the ESC increases. The influence of the gap on friction coefficient and intensity of ESC is found to be higher than that observed for the pre-triboelectrification process of the two contacting surfaces. Besides, friction coefficient for surfaces without pre-triboelectrification displayed the highest values. It is concluded that adhesion depends on the double layer of ESC of equal intensity, where excess of ESC on one surface does not affect the adhesion, where the adhesion between the two contact surfaces will be relatively weaker than that observed in condition of absence of pre-triboelectrification. In addition to that, it was found that metallic substrate of polymeric coatings leak some of the ESC outside the sliding surface causing drastic decrease in friction coefficient. Finally, pre-triboelectrification of surfaces before sliding by rubbing each other reduces the values of friction coefficient.
Ali et al. (Mon,) studied this question.