Investigation of the Shape Memory Effect in Shape memory Springs of Poly Lactic Acid Alloy Type

In order to obtain a blend with noticeable shape memoryproperty, thermoplastic polyurethane was melt-blended withbiodegradable polylactic acid. This blend possesses a greatpotential in medical applications such as actuators in form ofspring, compression springs of this blend were prepared bythe compression molding process. The shape memorybehaviors were examined to determine the shape recoveryproperties by altering the weight ratios and recoverytemperatures (Tr). Besides, dynamic mechanical analysiswas used to determine the glass transition temperatures andmiscibility of blend. Scanning electron microscopy was usedto investigate the dispersion of two phases in the blends. Theresults showed that the spring made of 70/30 PLA/TPU havebetter shape memory properties than 50/50, the highestrecovery ratio (Rr=99%) was obtained at the Tr of 90℃.However, the Rr value for this spring recovered near bodytemperature was 50%.