| The objective of this thesis is to compare the results of an instrumented PENT test procedure carried out at Fina Oil and Chemical Company on polyethylene, to the results of the three-point bend (TPB) test carried out at Texas A&M University-Kingsville.;The TPB and PENT tests were used to measure the slow crack growth in polyethylene. A constant load was applied on the specimen and the tests were carried out at temperatures of 80°C, 60°C and 40°C.;The plastic zone size and crack growth was observed and recorded using a camera setup, a video recorder and player. The plots of crack growth rate (a˙) and stress intensity factor (KI) were made for the tested specimens.;When TPB test results were compared to PENT test results, it was observed that the plots of crack growth rate versus stress intensity factor for TPB and PENT follows a power law expression. The value of Q, which is the activation energy for slow crack growth, calculated for PENT test was found to be closer to the published value than TPB test. Also the comparison of TPB and PENT tests results showed that TPB test is better for slow crack growth than PENT test. The video recording data for the TPB test suggested a correction factor to be added to values obtained from analytical method of TPB test. |
