Water Vapor Permeability of Poly(L‐lactide)/Poly(D‐lactide) Stereocomplexes

PLLA/PDLA blend films with only stereocomplex crystallites as a crystalline species together with pure PLLA and PDLA films with only homo‐crystallites as a crystalline species were prepared, and the effects of enantiomeric polymer blending, crystalline species, and crystallinity on the water vapor permeability were investigated. The WVT coefficient P of PLLA/PDLA blend films was 14–23% lower than that of pure PLLA and PDLA films in the crystallinity X c range of 0–30%. Amorphous PLLA/PDLA blend films have a much lower P than pure PLLA and PDLA films. The dependence of P on X c for blend films was stronger for X c = 0–30% than for X c = 30–100%. This dependence is discussed using the Nielsen model and the concept of “restricted” (or “restrained”) and “free” amorphous regions. magnified image