Abstract
Abstract 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 ( Veriflex 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 pre-strain. 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.
Published Version
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