Self-healed Materials from Elastomeric Composites: Concepts, Strategies and Developments

Self-healing materials have been inspired by the ability of human/animal skins and plant tissues to self-repair their minor damages. Self-healing polymers and fibre-reinforced polymer composites acquire the ability to heal small ruptures and cracks during their service life. Presence of microscopic cracks and other types of damage depletes thermal, electrical, mechanical and acoustical properties, and seriously impairs performance of the material. This can ultimately lead to complete failure. Self-healing materials are imbibed with huge quantities of inorganic conducting fillers to trigger self-healing behaviours which are influenced by external forces, such as temperature, change in light intensity and spectrum, pH, or ambient chemistry. Three conceptual approaches of healing system exists which are based upon encapsulation, arterial network and intrinsic capabilities. Self-healing can be generated intrinsically by auto-response mode without manual intervention or requiring external stimulus. Primarily self-healing mechanisms entail resuming mechanical integration lost during cracking and crazing. As polymers are critical products used in coatings, electronics, transportation and energy industries, it is important to induce them with self-repairing mechanisms. Self-healing materials possess remarkable potential in enhancing the longevity of load bearing and tribological materials. Consequently, a large number of academic and industrial research organizations have come forward to explore new concepts in design and synthesis of such materials like thermosets, thermoplastic, elastomers, polymer composites, supramolecular gels, nanostructure conductive hydrogels. These materials can be easily processed, re-used and recycled. Their unique self-repairing properties, the simplicity of their synthesis, their availability from renewable resources and the low cost of raw ingredients augur well for futuristic applications.