中文摘要：

为使PLA薄膜的结晶速度进一步加快,提高PLA薄膜的结晶度,提高薄膜的耐热性和力学强度,研究了成核剂对应力诱导PLA薄膜结晶的影响.利用XRD、DSC、FTIR等表征手段,对PLA薄膜拉伸前后的结晶状态进行了表征.研究表明,简单的引入成核剂,并不能实现成核剂和应力诱导促进PLA结晶的协同作用.相反,成核剂的引入会在很大程度上阻碍应力诱导结晶.即使成核剂在与拉伸温度相同的等温冷结晶过程中能够显著的提高PLA结晶速率,但在应力诱导结晶过程中,成核剂的引入使得拉伸后薄膜结晶度较纯PLA体系拉伸后薄膜明显更低.在相对较低的拉伸温度进行实验,成核剂同样起到阻碍应力诱导结晶进行的作用.同时,实验发现相对较低的拉伸温度,更有利于应力诱导结晶的进行,薄膜在较低温度拉伸后结晶度更高且更稳定.

英文摘要：

To make the nucleating agent and the strain-induced crystallization work synergistically, the effect of nucleating agent on the strain-induced crystallization of poly （lactic acid） （PLA） films is investigated. Amorphous film samples of pure PLA （T0） and PLA/TMC328 （specialized nucleating agent） blends with different contents of TMC328 （0.5 wt% ,1 wt% denoted as TO. 5 ,T1 ） are prepared and characterized by Xray diffraction （XDR） and differential scanning calorimetry （DSC）. Then they are drawn at temperatures of 80 and 90 ~C , about 24 - 34 K above Ts. And the erystallinity of drawn samples is measured by DSC and Fourier transform infrared spectroscopy （FTIR）. Unexpected, at 80 and 90 ℃ the crystallinity of TO is much higher than those of TO. 5 and T1, even though the nucleating agent can improve the cold crystallization of PLA significantly at 90 ℃. Moreover,the strain-induced crystallization works better and more stably at Td of 80 ℃ than at Ta of 90 ℃. Then a new crystallization mechanism can be presented,which is independent of nucleation density even nucleation, but dominated by the formation and retention of strain-induced regular conformation. And the strain-induced crystallization works better with lower Td, at which the intensity of the chain thermal motion is weaker and the formation of regular conformation can be easier. Therefore, during the process of strain-induced crystallization,the nucleating agent diffusing between the PLA chains plays a role of impurity which impedes the formation of regular conformation of PLA chains. So the synergy of improving crystallization cannot be achieved by the addition of nucleating agent.