SHAPE MEMORY POLYURETHANES BASED ON RECYCLED POLYVINYL BUTYRAL II. MECHANICAL AND SHAPE MEMORY PROPERTIES

Shape memory polyurethanes (SMPUs) based on recycled polyvinyl butyral and 4,4′-diphenylmethane diisocyanate, hexane-1,6-diol, and polypropylene glycol of varying hard segment content were investigated. Their mechanical properties and shape memory effect in particular were examined defining the amorphous soft segment domain as a reversible phase, while the crystalline hard segment domain as a frozen phase. Effects of hard segment content (30 - 45 %) and maximum strain on the cyclic tensile and mechanical properties below (25°C) and above (70°C) material glass transition temperatures were studied. The properties reversibility observed on repeated deformation was improved by decrease of the deformation magnitude and the increase of the hard segment content.