Effect of heterogeneous catalysts on the mechanical and relaxometric behavior of lactic acid-cured epoxidized vegetable oil vitrimer

Biobased vitrimeric materials were obtained from epoxidized canola oil (ECO) and lactic acid (LA) where zinc acetate (ZnAc) and ZnAl-layered double hydrox- ide (ZnAl) were used as transesterification catalysts at concentrations of 1 and 2wt%. Incorporation of these catalysts into the vitrimers was confirmed by X- ray diffraction analysis where characteristic crystalline peaks of the catalysts appeared in the vitrimers. NMR Relaxometric showed that the addition of cat- alysts reduced the density of cross-links and promoted increased mobility of polymer chains in the vitrimers. Mechanical tests revealed that the addition of both catalysts promoted decrease in some mechanical properties with a variation in rupture stress in the range of 0.71 to 0.11 MPa, rupture strain in the range of 21.3 to 49.4% and in Young’s modulus from 0.24 to 3.04 MPa. SEM images revealed that the addition of the catalysts introduced defects in the polymer matrix and increased the brittleness of the material.