Abstract
AbstractPoly(L‐lactic acid) (PLLA) and poly(D‐lactic acid) (PDLA) with very different weight‐average molecular weights (Mw) of 4.0 × 103 and 7.0 × 105 g mol−1 (Mw(PDLA)/Mw(PLLA) = 175) were blended at different PDLA weight ratios (XD = PDLA weight/blend weight) and their crystallization from the melt was investigated. The presence of low molecular weight PLLA facilitated the stereocomplexation and thereby lowered the cold crystallization temperature (Tcc) for non‐isothermal crystallization during heating and elevated the radial growth rate of spherulites (G) for isothermal crystallization, irrespective of XD. The orientation of lamellae in the spherulites was higher for the neat PLLA, PDLA and an equimolar blend than for the non‐equimolar blends. It was found that the orientation of lamellae in the blends was maintained by the stereocomplex (SC) crystallites. Although the G values are expected to decrease with an increase in XD or the content of high‐molecular‐weight PDLA with lower chain mobility compared with that of low‐molecular‐weight PLLA, G was highest at XD = 0.5 where the maximum amount of SC crystallites was formed and the G values were very similar for XD = 0.4 and XD = 0.6 with the same enantiomeric excess. This means that the effect of SC crystallites overwhelmed that of chain mobility. The nucleating mechanisms of SC crystallites were identical for XD = 0.1–0.5 in the Tc range 130–180 °C. Copyright © 2011 Society of Chemical Industry
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.