Processing and characterization of bio-polyester reactive blends: From thermoplastic blends to cross-linked networks

The addition of ethyl ester L-lysine tri-isocyanate (LTI) to mixtures of poly(lactide)/poly(ε-caprolactone) has been reported to improve the compatibility of the resulting blends. In the present work, we have investigated the influence of adding increasing amounts of LTI to the mechanical and thermal properties of the blends. Torque trends, plate-plate rheology, differential scanning calorimetry, scanning electron microscopy, and uniaxial tensile characterization were conducted on samples with amounts of LTI comprised between 0.5 and 5 phr. Results suggests that by increasing the content of LTI over 0.5 phr the mechanical and thermal behaviour of the blends tend to change from that of a thermoplastic to that of a cross-linked, rubber-like material with outstanding mechanical properties. Morphological investigations show a very fine, well-dispersed morphology in all cases. Numerical models have been applied to rheological experiments to identify processes and phases in the studied blends, further supporting the hypothesis of a cross-linked phase formed for blends containing more than 0.5 phr of LTI.