Many consumer goods are made of polymeric materials whose appearance or performance can be altered by impact, scratches or cracks. Driven by manufacturers and consumers, research has increased to extend the life of products.
Self-repairing polymers can provide a satisfactory solution to repair unsightly fractures or damage to specific parts.
There are two different technologies regarding self-healing polymers:
Assisted healing
Assisted wound healing involves encapsulated healing agents, released during the propagation of a crack and reconstituting the material. Because the amount of these agents is limited, the material can only be repaired a certain number of times.
Self-healing
Self-healing (or self-healing) is an inherent healing ability of the material that can heal an infinite number of times. It can involve the movement of polymer chains within the material or allow for the reversible formation of chemical or physical bonds between material constituents.
Chain creep – Molecular interdiffusion: the case of thermoplastics
In a polymeric material, chain entanglements prevent lateral diffusion of the chains, which then diffuse by creep. The material then behaves like a solid at short times but flutes at longer times. Healing takes place on freshly damaged surfaces, by re-contacting at a temperature above the glass transition (Tg). Gradually, the interface disappears and the mechanical properties at the polymer-polymer interface increase as the crack repairs itself through molecular diffusion at the interface. Increasing the temperature above Tg, as well as increasing the healing time, improves the quality of healing.