| 초록 |
The following are observations of changes in the trends in the slow crack growth behavior of HDPE materials according to different cooling rates. Slow crack growth was observed under three different cooling conditions: slow cooling (at room temperature), intermediate cooling (13℃), and quenching (0℃), with Full notched creep test (FNCT) specimens. Using the CAS AI 1600 system, the temperature of molding plates (300×300mm) exposed to different cooling conditions during HDPE compression molding was taken at various spots, and dog-bone specimens were made for each spot tested. Results showed that the faster the cooling rate, the lower the tensile strength of the resulting piece, while tensile strength increased in proportion with time taken to cool. Also, the values for tensile strength collected from the middle of the molding plate tended to be higher than values collected from either of the ends of the molding plate. This was understood to be due to the probability of polymer chain mobility rising as cooling rate dropped. |
