FRICTION AND WEAR BEHAVIOR OF IRRADIATED POLYETHYLENE SLIDING AGAINST ROUGH STEEL SURFACE

TUCKART WALTER; MOLINARI ERICA; ROSSIT DANIEL; FAILLA M.

TRIBOLOGY LETTERS

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 2014 vol. 54 p. 165 - 176

1023-8883

The aim of this study was to evaluate the tribological behavior of polyethylene crosslinked by gamma radiation sliding against steel surface. Two high density polyethylenes were irradiated under vacuum at room temperature to total doses in the range from 2 to 20 Mrad. After irradiation, the materials were annealed at 423 K for 5 minutes and then cooled slowly to room temperature. The same treatment was applied to the non-irradiated polymer. The wear behavior was determined at controlled ambient temperature of 298 K and 333 K using a homemade tribometer. Sheet-shaped test pieces were placed in contact with a surface of a steel disc by applying different normal loads between 2.5 and 15 N. The tests were performed under dry conditions using a disc rotational speed of 375 rpm for 30 minutes. The wear rate was obtained as the mass loss of the sample divided by the sliding distance and the friction coefficient was determined by measuring the force of friction. The results indicate that the wear rate increases with load in the case of non-irradiated polyethylene and low-dose irradiated polymers, while the wear rate reaches a maximum value with the load in the case of the irradiated samples with high dose. The samples irradiated with a dose of 10 Mrad showed the lowest wear. The coefficient of friction increases slightly with the load in all the cases. Most irradiated polymers have higher coefficient of friction than the non-irradiated material when compared to a particular load, although it was not possible to determine a relationship between the coefficient of friction with the dose in irradiated materials.