The mesophase in the as-stretched poly(L-lactide) (PLLA) exhibits low thermal stability and undergoes melting around T-g. As a consequence, without constraints as-stretched PLLA can recover to its original (unstretched) length while being held above T-g. Upon constrained annealing at 70 degrees C mesophase is transformed into highly oriented crystals, responsible for little free shrinkage and superior dimensional stability. At the same time, molecular orientation in the amorphous phase first decreases significantly due to thermodynamic relaxation, and then increases moderately with the advent of cold crystallization. It correlates well with the change of yield strength with respect to annealing time. (c) 2013 Society of Plastics Engineers