| Summary: | 碩士 === 國立臺灣大學 === 高分子科學與工程學研究所 === 101 === This research focuses on the Stereocomplex addition how to affect crystal behavior and morphology of PLLA. PLLA polymer chains packed closely α form crystal structure at higher crystallization temperature, and loosely α’ form crystal structure at lower crystallization temperature. Two crystal structures can co-exist at moderate temperatue. It is investigated by POM, DSC and XRD to observe the crystal behavior changes of PLLA/Stereocomplex.
Due to the effect of Stereocomplex, the α and α’ coexistence zone of PLLA/ Stereocomplex system changes from 120℃~105℃ to 135℃~95℃. Because Stereocomplex can help PLLA nucleate, the α’ form crystal structure, which is nucleation control, can have more ability to nucleate at higher temperature. Furthermore, we add some impurity in PLLA, PLLA spherulite may encounter some obstacles, thus making growth rate decreases. On the other hand, the α and α’ kinetic competition model does not change when we add Stereocomplex into PLLA. As the above mentioned, the two factors make the coexistence zone change.
In POM, PLLA spherulite crystallizes between the Stereocomplex spherulite''s bundle; when we change the Stereocomplex amounts, internal - PLLA、SC - PLLA and amorphous - PLLA can be observed. Because of these three crystal, we can know the impurity-added effect is the main factor resulting in growth rate decreament, and Stereocomplex crystal is the main factor to assist PLLA to nucleate.
|
|---|
