The thermoresponsive shape memory characteristics of polyurethane foam

摘要

The purpose of this study is to develop a protective and thermally intelligent filler by optimizing the preparing conditions and the thermoresponsive property of PU foam. The specimens were polyurethane synthesized by a one step process with 4,4′-diphenylmethane diisocyanate, polycaprolactone and 1,4-butanediol. After dissolving the polyurethane in tetrahydrofuran, the poly-urethane foam was manufactured by the salt leaching method. The appearance, compressive property, and thermal property of the manufactured foam as well as the shape memory effects were evaluated. In addition, air and water vapor permeabilities and the thermal insulation property were measured to examine the basic properties of the foam. The cell sizes of the completed foam were distributed in the range of 400-1,000 μm. The compressive stress of the foam was low in the initial compressive strain but increased dramatically above a compressive strain of 70. However, the foam showed a very low capacity for compressive stress compared with an electrospun web or a film manufactured by using the identical shape memory polyurethane. The transition temperature of the foam was 30°C. The shape recovery and shape retention were 98 or higher. The foam, with a porous structure, was found to be generally good in both air and water vapor permeability. In the case of the foam that maintained its compressed shape below the transition temperature, these permeabilities of the foam decreased slightly, but not significantly. Because of the porous structure of the foam, the shape memory effect did not noticeably influence the permeability change with a change in temperature.