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 memory property, thermoplastic polyurethane was melt-blended with biodegradable polylactic acid. This blend possesses a great potential in medical applications such as actuators in form of spring, compression springs of this blend were prepared by the compression molding process. The shape memory behaviors were examined to determine the shape recovery properties by altering the weight ratios and recovery temperatures (Tr). Besides, dynamic mechanical analysis was used to determine the glass transition temperatures and miscibility of blend. Scanning electron microscopy was used to investigate the dispersion of two phases in the blends. The results showed that the spring made of 70/30 PLA/TPU have better shape memory properties than 50/50, the highest recovery ratio (Rr=99%) was obtained at the Tr of 90℃. However, the Rr value for this spring recovered near body temperature was 50%. .