Elastocaloric effect: Impact of heat transfer on strain-induced crystallization kinetics of natural rubber

When natural rubber is rapidly loaded and unloaded there occurs a variation of its temperature called the elastocaloric effect. The objective of this work was to determine whether this temperature variation could be responsible for a delay in strain-induced crystallization (SIC) kinetics and stress relaxation. To this end, the SIC kinetics of cross-linked natural rubber samples with different thicknesses was studied at constant elongation after adiabatic stretching using thermal, mechanical and in-situ WAXS characterizations. The coupling of these tech-niques revealed that, at a fixed elongation lambda (between 5 and 6), the crystallization kinetics and stress relaxation were faster in the thinner sample (with a short heat exchange time constant), thus providing evidence that heat transfer affected the SIC kinetics and should be considered when interpreting experimental results.