| Popis: |
The durability of isotactic PP films with drawing ratios in the range 850–900 has been investigated at 130°, under a constant load, varying the oxygen pressures, as well as at 130° with the oxygen pressure at 600 torr, with differences in the stress levels. It was found that in oxygen there are no “safe” stress levels, and a rise in the oxygen pressure is reflected in lower durability. The durability of the film specimens in vacuo is higher by several orders than in oxygen. Under constant pressure conditions, durability is practically unrelated to stress within a particular stress interval, but at higher stress levels markedly reduced durability is observed. |
