Shape-Memory Behavior of Poly(L-lactide)/Poly(ε-caprolactone) Blends

Poly(L-lactide) and poly(epsilon-caprolactone) (PLLA/PCL) blends with various weight ratios were compounded by melt mixing and their shape memory properties were investigated. The thermal properties, surface morphology and dynamic mechanical properties of the blends were characterized. The results demonstrate that the introduction of PCL improves the process of crystallization of PLLA whereas the reverse situation is for PCL. PLLA/PCL blends were found to exhibit an immiscible behavior from the characterizations of surface morphology. DMA tests show the blends with different weight ratios have different transition temperatures. The properties of blends provide the basis of owning shape memory behavior. The strain recovery ratio (R-r) of PLLA/PCL blend with the weight ratio of 1:3 was about 95% within 22s, whereas the R-r of other blends were less than 75% within 23 similar to 30s. It was found that lower transition temperature combined with increased crystallization of PLLA with the increasing PCL content contribute to such a good shape memory effect.