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采用淬火法制备聚乳酸(PLA)非晶薄膜,并利用原位显微红外光谱在线研究PLA非晶薄膜在不同退火温度下的结构演化.结果表明,PLA非晶薄膜存在一个临界结晶温度,当退火温度高于临界结晶温度时,PLA非晶薄膜可以通过分子链的局部调整实现冷结晶,反之,不能发生冷结晶;在冷结晶过程中先出现中间相,随后发生中间相-晶体相的转变;中间相是通过分子链的构象调整和分子链间的堆砌调整产生的,退火温度越高,中间相出现得越早,最终得到的晶体结构越规整.
The polylactic acid (PLA) amorphous films were prepared by quenching method and the in - situ microstructures were used to study the structure evolution of PLA amorphous films at different annealing temperatures. The results show that there is a critical crystallization temperature for PLA amorphous films. When the annealing temperature is higher than the critical crystallization temperature, the PLA amorphous film can be cold-crystallized through partial adjustment of the molecular chain, and conversely, cold crystallization can not occur. In the cold crystallization, the mesophase appears first, followed by the transformation of the mesophase-crystalline phase ; The mesophase is generated by the conformational adjustment of the molecular chain and the stacking adjustment between the molecular chains. The higher the annealing temperature, the earlier the mesophase appears, and the more regular the crystal structure is obtained.