| 초록 |
Recently, we have reported the observation of the endotherm concurrent with shrinkage just above the glass transition for drawn and amorphous poly(lactic acid) (PLA) films. It was confirmed that this endotherm is a recovery of enthalpy decreased by stretching the amorphous PLA chains, which phenomenon, for the first time, is named as “strain-induced enthalpy relaxation”. In addition, the origin of strain-induced enthalpy relaxation was proved to be an increase in population of gt conformer with the lowest energy level due to the chain stretching. In this study, the influence of D-isomer content on strain-induced enthalpy relaxation is investigated for both crystalline and amorphous PLAs with various D-isomer content. |
