A Slow Shape-Recovery Polymer Based On Polylactic Acid

Shape-recovery materials are expected to have numerous applications as ductile structural compounds which can recover their shape after significant deformations. We report a new type of shape-recovery polymer consisting of polylactic acid (PLA) derived from glucose compounded with a cinnamic acid ester derived from lignin. Unlike existing shape-memory polymers, this shape-recovery polymer exhibits a spontaneous but gradual recovery of its original dimensions, following elongation and release of stress, over a period ranging from several hours to days, without the requirement for external stimulus. In the case of a typical rubber or elastomer, shape-recovery takes place almost instantaneously after deformation due to the energy stored by the material. Although the slow shape-recovery polymer reported herein appears to exhibit plastic deformation as if the energy of elongation is lost, it eventually recovers from the deformation in the same manner as an elastic material. This material may have applicability to the energy-absorbing and shape restoration automotive parts. (C) 2014 Wiley Periodicals, Inc.