Effects of top confinement and diluent poly(ethylene oxide) (PEO) on poly(l-lactic acid) (PLLA) crystal morphology have been investigated. When crystallized at 120 °C, uncovered neat PLLA sample exhibits higher growth rate ringless spherulites; while the covered sample exhibits lower growth rate ring-banded spherulites. As PEO is introduced into PLLA, the morphology also undergoes significant changes. For the same Tc,PLLA=120 °C, the PEO/PLLA blend with PEO composition greater than 25% exhibits ring-banded patterns even in uncovered sample. However, in much greater PEO composition (>80 wt %), uncovered samples exhibit ring bands diverging into dendritic patterns, while top covered samples tend to maintain the spiral ring-band patterns. Both PEO inclusion in PLLA and top cover on films impose growth kinetic alterations. Additionally, the top glass cover tends to prevent the lower surface tension PLLA to be accumulated on the surface, resulting in the formation of ring-band pattern.
|頁（從 - 到）||1160-1170|
|期刊||Journal of Polymer Science, Part B: Polymer Physics|
|出版狀態||Published - 2015 八月 15|
All Science Journal Classification (ASJC) codes