The effect of free radical reactions onto structure and properties of poly(lactic acid) (PLA) based blends

The blending of PLA with poly(butylene-adipate-co-terephthalate) (PBAT) is a promising strategy to
achieve a toughened multiphase material. The blends ductility could be further improved through
reactive compatibilization, i.e. inducing the formation of comb PLA-PBAT copolymers during the melt
blending. In the present work a non-selective strategy was adopted which consisted in the use of
a peroxide, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane. The phase morphology development and the
final properties (torque, fluidity in the melt, tensile behaviour, thermal and dynamicalemechanical
features) of the blends were studied as a function of the peroxide concentration. The elongation at break
was improved up to a maximum value thanks to this approach and a corresponding minimum was
observed in the value of the dispersed phase diameter. A structural characterization of the macromolecules
formed during the reactive process was attempted by using size exclusion chromatography of the
blends and comparison with the pure polymers obtained by processing in the presence of the peroxide.