Observation of heterogeneities in elastocaloric natural/wastes rubber composites

The strain-induced crystallization and elastocaloric properties of various natural rubber (NR)/ground tire rubber (GTR) blends, comprising waste particles of diverse sizes and contents, were investigated. The decreasing inter-distance between particles in conjunction with their increasing content as studied by micro-computed tomography (mu CT) as well as the inter-melling between GTR and NR matrix were observed. It resulted in a strain localization in the NR matrix at the GTR and NR interface at the origin of mechanical reinforcement upon tensile deformation. In addition, GTR particles were found to show a nucleating ability on strain-induced crystallization (SIC) and elastocaloric properties independently of the particle size. The strain localization was found to relate to a localization of the temperature field, suggesting localization of the elastocaloric effect in NR/GTR blends. The evidence of such heterogeneities would be of interest for the proper design of elastocaloric waste-based rubber composites for heating/cooling applications.