The present work investigates the friction coefficient of polymers filled by vegetables oils such as almond, camphor, castor, cress, flax seed, black seed, lettuce, olive, sesame and sun flower oils in content up to 10 wt. %. The polymers are polyamide 6 (PA), high density polyethylene(PE) and polyvinyl chloride(PVC). The friction coefficient displayed by the tested polymers is investigated at constant load and velocity when sliding against steel. Experiments showed that friction coefficient displayed by the tested polymers filled by the tested vegetables oils decreased with increasing oil content. The minimum values of friction coefficient were observed at 10 wt. % oil content for PA composites filled by camphor, castor, cress, flax seed, black seed, sesame and sun flower oils. PE composites filled by almond, lettuce and olive oils showed the lowest friction values. The friction decrease may be attributed to the oil stored in the pores inside the polymer matrix which experienced boundary lubricating film of low shear interfacial layer formed on the sliding surfaces and easily removed by the shear instead of the contacting asperities. Those pores were working as reservoirs feeding oil into the contact surface. The minimum friction values recommend using 10 wt. % oil filled PA as bearing material in dry sliding condition.
Ali et al. (Thu,) studied this question.