Development and properties of bio-based rice oil microcapsule and its dispersibility in emulsified asphalt

To develop a new bio-based rice oil microcapsule for the self-healing of emulsified asphalt, rice oil and melamine formaldehyde (MF) resin were utilized as core and wall materials, respectively, preparing rice oil-melamine formaldehyde resin (ROMF) microcapsule. Then its morphology, particle size distribution, encapsulating status, thermal stability, micromechanical properties and dispersity in emulsified asphalt was studied. The results show that the prepared microcapsules show regular 2-10 mu m spherical shapes, following a normal distribution. The microcapsule surface has a large roughness, promoting a close combination with emulsified asphalt. Also, during the synthesis of microcapsules, the methylene is generated and the condensation reaction occurs on rice oil droplet surface, proving that core material of rice oil is successfully encapsulated by MF resin. The micro capsules exhibit excellent thermal stability. Further, the distribution regularities of adhesion force and Young's modulus on microcapsule surface are closely correlated with the particle sizes and thickness of MF resin. The Young's modulus of microcapsule surface is improved with the thickness increase of wall material. Finally, the microcapsule at the dosage of 5 % exhibits the best dispersibility in emulsified asphalt and a clear core-shell structure is observed. The proposed dosage of ROMF microcapsules used in emulsified asphalt is 5 %.