Mechanical strength of microcapsules made of different wall materials

The mechanical strength of microcapsules made of three different wall materials, including melamine-formaldehyde resin, urea-formaldehyde resin and gelatin-gum arabic coacervate, were measured by a micromanipulation technique. Single microcapsules were compressed to large deformations or rupture and the force being imposed on them were measured simultaneously. Melamine-formaldehyde and urea-formaldehyde microcapsules showed clear bursting under compression, and their bursting force, deformation at bursting and deformation at a pesudo yield point were determined. Gelatin microcapsules did not show clear bursting under compression, and their mechanical strength was characterized by the force required to cause their deformation to 50%. The mechanical strengths of these three types of microcapsules are compared in this paper.