Attempts have been made to use a rod specimen in place of any conventional type of specimens for estimating changes in mechanical properties of plastic materials consequent on various sorts of their degradation.
There are several advantages with rod specimens as follows:
(1) The specimens are available by utilizing common commercial rods simply by cutting off the required pieces.
(2) Their mechanical properties can be measured with a torsional apparatus made for trial by us.
(3) The rod specimens are better suitable to surface resistance measurement.
The rod specimens have proved to be efficient means for estimating durability in the experiments with polypropylene and polycarbonate for photo- and thermal degradation, for immersion in solvent and alkali, and for torsional fatigue.