Nanoscale Insights into Strain-Induced Crystallization: Revealing Self-Reinforcement Mechanisms in Filled Elastomers

Strain-induced crystallization (SIC) in elastomers significantly enhances their elastic moduli and rupture resistance. However, the self-reinforcement mechanisms in filled elastomers remain unclear due to their nanoscale nature. We stretched isoprene rubber with/without silica nanoparticles to strains >5 while performing in situ transmission electron microscopy. Nanoscale electron diffraction mapping revealed that, while unfilled isoprene rubber exhibited spatially homogeneous crystallization that dramatically enhanced elastic moduli above the crystallization onset strain, silica-filled isoprene rubber showed preferential crystallite formation in highly stressed regions along silica aggregates aligned in the stretching direction. This reinforces stress propagation pathways, resulting in lower crystallization onset strain and higher rupture strength in filled systems [1]. These insights into the role of fillers in SIC support better elastomer design and development.