Poly(<scp>L</scp>‐lactide)/C₆₀ nanocomposites: Effects of C₆₀ on crystallization of poly(<scp>L</scp>‐lactide)

Abstract

Abstract The effects of solvent type and concentration of C 60 on the crystallization of poly( L ‐lactide) (PLLA) during solvent evaporation, heating from room temperature, and cooling from the melt were investigated by polarized optical microscopy and differential scanning calorimetry. The addition of C 60 enhanced the PLLA crystallization during solvent evaporation, during heating of the melt‐quenched films, and during cooling from the melt of As‐cast films, except for heating and cooling of the PLLA film with 1 wt % of C 60 prepared with dichloromethane. In the case of solvent evaporation, the difference in crystallinity between the PLLA films with and without C 60 became higher for the solvent with a lower boiling point. In the case of heating of melt‐quenched films, the addition of C 60 had a small effect on the crystallinity of PLLA, whereas significantly lowered the peak top and ending temperatures of cold crystallization, except for melt‐quenched PLLA film with 1 wt % of C 60 prepared with dichloromethane. The crystallinity of PLLA was determined by the solvent type, rather than by the C 60 concentration. In the case of cooling from the melt of As‐cast films, the addition of C 60 elevated the crystallinity and cold crystallization temperature values of PLLA films, except for PLLA films prepared with dichloromethane. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2167–2176, 2007