Lignin effect in castor oil-based elastomers: Reaching new limits in rheological and cushioning behaviors

Lignin is demonstrated as an unprecedented reinforcing material that tailors the rheological and cushioning properties of castor oil-based polyurethane elastomers, expanding their viscoelastic moduli by four orders of magnitude. The tensile strain at break was triplicated in the presence of lignin while the Young modulus and the stress at break were enhanced 17- and 7-fold, respectively. Remarkably, in compression tests, lignin addition increased the stresses at break by more than 88-fold, whereas the strain at failure shifted from 50 to 93%. Dynamic mechanical compression tests indicated outstanding cushioning and resistance performance. Overall, the results demonstrate a performance not reached before for biosourced elastomeric materials, fitting the demands of a wide range of applications.