Structure and physical properties of poly(lactic acid) and cyclodextrin composite

The addition effects of cyclodextrin (CD) and methylated cyclodextrin (Me-CD) on the structure and mechanical properties of PLLA were investigated. Inclusion complexes (IC) of α, β and γ-CD and PLLA were prepared. The formation of IC was confirmed from 13C NMR chemical shifts and the number of peaks for α, β and γ-CD/PLLA IC. 10% of α, β and γ-CD/PLLA IC were mixed with PLLA and formed into films. The tensile test of the obtained films revealed the breaking strain is improved up to 350%. Me-CD was mixed with PLLA and prepared into films. The breaking strain of the films reached up to 250% and the addition effect was largest for Me-γ-CD10. From DSC measurements, one melting peak was observed and the peak moved to lower temperature as the amount of Me-CD increased. These results indicate Me-CD distributes homogeneously in PLLA. Solid state NMR of Me-α, β and γ-CD50 gave broad peaks and the molecular mobility of the mobile component increased. Therefore, Me-α, β and γ-CD do not form IC, but act as the plasticizer for PLLA.