Self-repairing systems based on ionomers and epoxidized natural rubber blends.

The development of materials with the ability of intrinsic self-repairing after damage in a fashion resembling that of living tissues has important scientific and technological implications, particularly in relation to cost-effective approaches toward damage management of materials. Natural rubbers with epoxy functional groups in the macromolecular chain (ENR) and ethylene-methacrylic acid ionomers having acid groups partially neutralized with metal ions possess self-repairing behavior following high energy impacts. This research investigates the self-repairing behavior of both ENR and ionomers during ballistic puncture test on the basis of their thermal and mechanical properties. Heterogeneous blending of ionomers and ENR have also been used here as a strategy to tune the thermal and mechanical properties of the materials. Interestingly, blends of sodium ion containing ionomer exhibit complete self-repairing behavior, whereas blends of zinc ion containing ionomer show limited mending. The chemical structure studied by FTIR and thermal analysis shows that both ion content of ionomer and functionality of ENR have significant influence on the self-repairing behavior of blends. The mobility of rubbery phases along with its interaction to ionomer phase in the blends significantly changes the mending capability of materials. The healing behavior of the materials has been discussed on the basis of their thermal, mechanical, and rheological tests for each materials.