Mechanical Properties of a Water-Based Acrylic Coating Containing Microcapsules of Rapeseed Oil- Ethyl Cellulose

Rapeseed oil-filled ethyl cellulose microcapsules were prepared using a two-step solvent evaporation method. The prepared oil-filled microcapsules were characterized by; optical microscopy, scanning electron microscopy and particle size analyzer. The mechanical properties of carboxylated styrene/butadiene copolymer latex films containing various levels of microcapsules were studied using DMTA and tensile strength measurements. The characterization test results showed that rapeseed oil-contained microcapsules with a regular spherical shape, diameter range of 10-45 μm, and a relatively rough porous shell were successfully prepared. The results also revealed that the overall mechanical properties of the latex films containing oil-filled microcapsules improved, due to reinforcing effect of capsules within the latex films; with the best results using 1-2 wt% of oil-filled microcapsules. The improved results were obtained in reinforcing the samples before tests such as tensile tension, capsule rupturing and the oil release within the polymeric network by maintaining the integrity of the films by plasticization of the surrounding polymeric network, increased elongation-at-break, and enhanced resistance against tear or break. With further increasing of microcapsules content up to 3 wt%, there was a drop in overall mechanical properties of latex films, due to possible aggregation of microcapsules, presence of free rapeseed oil within the latex film and weak polymer/microcapsules interface. A proper distribution and dispersion of oil-filled microcapsules within the latex film, and rupture of sufficiently large microcapsules under stress, oil release within the polymeric network and easy movement of the chains were the main requirements for achieving latex film with good mechanical properties.