Investigation on Effectiveness and Shape Recovery Ratio of Shape Recovery Self-Healing Plastic

Abstract

Shape recovery fiber reinforced self-healing plastic which achieves full strength recovery is developed. In this system, microcapsules containing dicyclopentadiene (DCPD) as healing agent are dispersed in epoxy resin matrix. Moreover, thermal shrinkage fibers coated by weak interlayer with Grubbs catalysts are uniaxially oriented. When a crack is introduced to the material, it propagates through the matrix and branches along the interlayer while breaking the microcapsules. Then DCPD flows from microcapsules into the cracks and polymerizes. At the same time, the fibers thermally shrink due to the polymerization heat, and the cracks are completely healed and closed. Furthermore, shape recovery ratio is defined as ratio of closed crack width with respect to initial crack width , and can be rewrote as ratio of loads. Tensile tests were carried out using flat plates with a notch, and they were pulled in the fiber direction. After the crack introduction, the displacement was kept constant. The specimen was heated to about 70°C, and temperature and load change were measured until the stress reduction was done. As a result, the shape recovery ratio was calculated to be 7.89% due to the temperature rose caused by polymerization. Therefore, the full strength recovery can be expected by demonstrating the shape recovery effect of this material.