Formation of cavities, when a polymer is stressed, which contain load-bearing fibrils spanning the gap between the surfaces of each cavity.
Source:
PAC, 1996, 68, 2313. 'Definitions of terms relating to degradation, aging, and related chemical transformations of polymers (IUPAC Recommendations 1996)' on page 2317 (https://doi.org/10.1351/pac199668122313)