title: Shape recovery and irrecoverable strain control in polyurethane shape-memory polymer.
abstract: In shape-memory polymers, large strain can be fixed at a low temperature and thereafter recovered at a high temperature. If the shape-memory polymer is held at a high temperature for a long time, the irrecoverable strain can attain a new intermediate shape between the shape under the maximum stress and the primary shape. Irrecoverable strain control can be applied to the fabrication of a shape-memory polymer element with a complex shape in a simple method. In the present study, the influence of the strain-holding conditions on the shape recovery and the irrecoverable strain control in polyurethane shape-memory polymer is investigated by tension test of a film and three-point bending test of a sheet. The higher the shape-holding temperature and the longer the shape-holding time, the higher the irrecoverable strain rate. The equation that expresses the characteristics of the irrecoverable strain control is formulated.
authors.affiliation: Department of Mechanical Engineering, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan.
authors.forename: Hisaaki
authors.initials: H
authors.lastname: Tobushi
authors.affiliation: DiAPLEX Co. Ltd, Ebisu-minami 1-5-2, Shibuya-ku, Tokyo 150-0022, Japan.
authors.forename: Syunichi
authors.initials: S
authors.lastname: Hayashi
authors.affiliation: Churyo Engineering Co, Ltd, 60-1 Kutanjo, Iwatsuka-cho, Nakamura-ku, Nagoya 453-0862, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Hoshio
authors.affiliation: Department of Mechanical Engineering, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ejiri
keywords: irrecoverable strain; polyurethane; shape fixity; shape recovery; shape-memory polymer; strain-holding condition