A biomimic shape memory polymer based self-healing particulate composite

In a previous study, a biomimic two-step self-healing scheme (close-then-heal (CTH)) by mimicking human skin has been proposed for self-healing structural-length scale damage [Li and Uppu. Composites Science and Technology 2010; 70: 1419-1427]. The purpose of this study is to validate this idea by fabricating a composite with thermoplastic particles (Copolyster) dispersed in a shape memory polymer matrix (Veirflex Polystyrene). In this particulate composite, the confined shape recovery of the shape memory matrix is utilized for sealing (closing) cracks and the thermoplastic particles are used for molecular-length scale healing. In this study, 6% by volume of thermoplastic particles was used. Beam specimens were prepared and programmed by compression in the longitudinal direction to 6.7% of prestrain. Structural-length scale damage was then created by producing a notch in the programmed beam specimens per ASTM D 5045. The notched beam specimens were then tested to fracture. The fractured specimens were healed per the close-then-heal mechanism and tested again to fracture. This fracture-healing test lasted for 5 cycles. The healing efficiency was evaluated per the peak-bending load. SEM was used to examine healed cracks at micro-length scale while EDS was used to evaluate molecular-length scale healing. It is found that over 65% of the peak bending load can be repeatedly recovered and the structural-length scale damage (notch) is healed at molecular-length scale. (C) 2010 Elsevier Ltd. All rights reserved.