Nanostructure evolution mechanisms during slow load-cycling of oriented HDPE/PA microfibrillar blends as a function of composition

Abstract

Oriented precursors of MFCs consisting of HDPE and PA6 or PA12 are studied during strain-controlled slow load-cycling. In the PA6-containing blends a strongly retarded nanostrain response is detected. Compatibilization induces nanostrain heterogenization. Stress fatigue is lower in the PA12 blends, but hardly decreased by the compatibilizer. Selective migration of the compatibilizer into a disordered semi-crystalline fraction of the HDPE matrix can explain the findings. The semi-crystalline HDPE entities in PA6 blends appear more disordered than in PA12-blends. An analysis of the HDPE nanostructure evolution during cycling reveals epitaxial strain crystallization. Uncompatibilized PA6 blends cycled about high pre-strain show plastic flow but nanoscopic shrinkage in the semi-crystalline stacks.