Development of Self-Healing Coatings

2017-03-29T01:25:14Z (GMT) by Karan Thanawala
Epoxy based self-healing coatings were developed using two independent approaches. In the first approach, self-healing coatings were developed by incorporating microcapsules containing Linseed Oil and Tung Oil as self-healing constituents. The healing mechanism of such coatings is the restoration of the physical barrier function. The microcapsules retain the self-healing constituents, i.e. Linseed Oil and Tung Oil in the liquid form until rupture triggers their flow through the damaged area, facilitating self-repair of the coatings. In the second approach, self-healing coatings were formulated by employing halloysite nanotubes as host for entrapment of benzotriazole (BTA) and yttrium nitrate tetra hydrate (YNT) corrosion inhibitors. Halloysite nanotubes possess a unique functionality of selectively adsorbing and releasing the corrosion inhibitors on demand, facilitated by changes in the pH of the surrounding of the damaged region of the coating, forming a passive film, facilitating self-healing of the modified coatings.
   Challenges pertaining to the process parameters governing the encapsulation of drying oils to form microcapsules and loading/release of corrosion inhibitor from the halloysite nanotubes have been optimized. The micro/nano-containers prepared at optimized conditions were incorporated in an existing epoxy primer coating to investigate their effectiveness in achieving self-healing function. The mechanical properties and corrosion protection properties of the modified coatings were investigated to demonstrate the negative effect of the incorporation of such micro/nano-containers, if any.
   The synthesis of process of microcapsules and loading process of halloysite nanotubes with corrosion inhibitors were performed at 5x and 30x batch sizes, to investigate the probability of synthesising such micro/nano-containers at commercial scale. Smart measures to overcome challenges associated with synthesis of micro/nano-containers at commercial scale have been demonstrated. Additionally, studies related to the storage and service life of such micro/nano-containers have been performed to investigate their commercial competitiveness.