Compressive shape memory behavior of spring-shaped polylactic acid alloy type

This article presents an experimental study on the shape memory behavior of blends of thermoplastic polyurethane (TPU) and biodegradable polylactic acid (PLA) at the PLA/TPU weight ratios of 70/30 (PT7030) and 50/50 (PT5050). The manufactured springs were studied comprehensively based on their morphological and thermal properties. Scanning electron microscopy micrographs were captured, which verified that TPU was compatible with PLA. The wide-angle X-ray diffraction suggested that the crystallinity of PLA was enhanced in the presence of TPU. In order to determine the shape recovery properties [shape recovery ratio (R-r), shape fixing ratio (R-f), and shape recovery force (F-r)], the samples programmed at three different temperatures (T-p) of 70, 80, and 90 degrees C and at various recovery temperatures (T-r) over 40 to 90 degrees C, were studied. In general, the spring made with PT7030 showed higher R-r, R-f, and F-r values. The highest R-r (99%) was obtained at programmed temperature (T-p) of 70 degrees C and recovery temperature (T-r) of 90 degrees C. However, the R-r value for this spring programmed at 70 degrees C and recovered near body temperature was 50% with F-r of 1.4 N. Furthermore, the highest F-r (15.6 N) was observed in the spring made of PT7030 programmed at 80 degrees C and recovered at T-r of 78 degrees C. (C) 2017 Wiley Periodicals, Inc.