The glass transition temperature of polyurethane shape memory polymer reinforced withtreated/non-treated attapulgite (playgorskite) clay in dry and wet conditions

Abstract

Attapulgite (playgorskite), a kind of nanosized fibrous clay mineral, may provide a simpleand cheap alternative to improve the stiffness and actuation stress of shape memorypolymers (SMPs). As a first step, in this paper, we investigate the glass transitiontemperature of a polyurethane SMP reinforced with treated/non-treated attapulgite in wetand dry conditions. In addition to confirming the strong influence of moisture, the resultsreveal that non-treated clay significantly reduces the glass transition temperature(Tg) of the composites, while the influence of treated clay onTg is limited. However, for composites mixed with non-treated clay,after drying, the well pre-wetted samples have a much higherTg than that of the dry ones. A partial detachment mechanism is proposed to explain thisinteresting phenomenon.