Design of Self-Healing Microcapsules Containing Bituminous Rejuvenator With Nano-CaCO3/Organic Composite Shell: Mechanical Properties, Thermal Stability, and Compactability

Microencapsulated rejuvenator powder has been used to repair microcracks and improve self-healing ability of aged bitumen. These microcapsules must retain their integrity in bitumen matrix with necessary special characters such as excellent mechanical properties, thermal stability, and compactability. Herein, novel self-healing microcapsules containing bituminous rejuvenator with nano-CaCO3/organic composite shells were developed by in situ polymerization using methanol-modified melamine-formaldehyde as organic shell material. The effect of nano-CaCO3 particle contents on the mechanical properties, thermal stability, and compactability of microcapsules were examined utilizing nanoindentation, thermogravimetric analysis, and visible spectrophotometer. Nano-CaCO3 particles had greatly enhanced the thermal stability and mechanical properties of the microcapsule because of the higher thermal resistance of nano-inorganic/organic composite shells. These microcapsules could survive in melting bitumen without destruction. The release curves of microcapsules in ethyl alcohol, relationship between time and logarithmic residual weight of rejuvenator, showed that the nano-CaCO3/organic composite shell structure led to a higher compactability of microcapsules. (C) 2017 Society of Plastics Engineers