Miscibility, thermal properties and polymorphism of stereocomplexation of high-molecular-weight polylactide/poly(D,L-lactide) blends

• High-molecular-weight sc-PLA and PDLLA blends were prepared.
• The Tgs of the blends fit Gordon–Taylor equation.
• Dynamic and isothermal crystallization of blends were assessed.
• Full stereocomplexation was formed with 70 wt% PDLLA.
• Nucleation mechanism of sc-PLA was unaffected.

High-molecular-weight stereocomplex-poly(L- and D-lactide) (sc-PLA) and poly(D, L-lactide) (PDLLA) blends were prepared by solution blending. The miscibility, crystallization kinetics, melting behavior and crystal structure of sc-PLA/PDLLA blends were investigated. The single composition-dependent Tgs of the blends indicated the miscible characteristic of the blend system at all compositions. The interesting aspect of this research is that the polymorphic crystallization of high-molecular-weight sc-PLA could be tailored by incorporation of miscible PDLLA with different dynamic and isothermal crystallization conditions. Full stereocomplexation can be formed with 70 wt% PDLLA, irregardless of the crystallization conditions. The possible mechanism of the polymorphic crystallization of high-molecular-weight sc-PLA by incorporation of miscible PDLLA has been tried to propose.