Effect of the Temperature on the Sliding Wear Behavior of γ-Irradiated HDPE

WALTER R. TUCKART; MICHELLE L. ROSEVEAR; ERICA C. MOLINARI; DANIEL ROSSIT; MARCELO D. FAILLA

Conferencia; Gordon Research Conferece on Tribology; 2012

The objective of this study was to determine the influence of temperature on sliding wear behavior of a linear high density polyethylene irradiated with gamma rays. The polymer were irradiated under vacuum at room temperature to total doses of 2, 5, 10 and 20 Mrad. After irradiation, the materials were annealed at 140°C 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 25°C and 40° C using a homemade tribometer type pin on disk. Sample having a size of 10 x 10 mm and 1.5 mm thick is put into contact with a surface of a steel disc of 40 mm diameter by applying normal loads between 2.5 and 15N. The tests were performed using a disc rotational speed of 375 rpm for 30 minutes to produce a sliding distance of 1884 m. The wear rate was determined by measuring the weight loss of the samples and divided by the sliding distance. In addition, the frictional force was registered to determine the friction coefficient and the temperature in the sample near the contact zone was recorded by insertion of a thermocouple on the probe near the sliding surface. This temperature rise about 15°C during the test. The results found indicates that the wear rate increases with the applied load in the case of the nonirradiated materials and those samples irradiated with the lowest doses, while the wear rate displays a maximum with the applied load in the samples irradiated with the highest dose. The lowest wear was observed in the samples irradiated with 10Mrad.The friction coefficient of irradiated samples took values of ~ 0.12 that increases slightly with the load regardless of the dose.