Compatibilized polylactide/poly(pentamethylene furanoate) blends for fully bioderived packaging films with enhanced fracture toughness and UV- and O2-barrier properties

Abstract

Polylactide (PLA) is a promising biopolymer from renewable resources but its brittleness and poor gas barrier properties limit flexible packaging applications. Therefore, in this work PLA was blended with a biobased rubbery poly(pentamethylene furanoate) (PPeF), acting as a toughening agent, and a commercial epoxy-functionalized compatibilizer (i.e., Joncryl® ADR-4468) was added to improve the interfacial interaction. The effect of PPeF loading (1–30 wt %) on phase morphology, mechanical properties, oxygen permeability, and degradability in compost was characterized. All blends displayed a sea-island morphology with refined PPeF domains upon compatibilization. Incorporating PPeF induced major tensile ductility enhancements from 5 % strain at break for neat PLA up to 200 % for the blend with 30 wt % PPeF, accompanied by progressive stiffness and strength declines. Through the application of the essential work of fracture (EWF) approach on the prepared films, the specific essential work of fracture (w_e) was seen climbing from 6.2 to 40.0 kJ/m² with rising PPeF content, confirming its effectiveness as a toughness enhancer. PPeF contributed to increase the UV- and gas barrier properties of PLA. For example, the oxygen permeability dropped by 37 % for the blend with 30 wt % PPeF. Moreover, compost burial tests also revealed 26 % weight loss of PPeF after 60 days, proving its biodegradability. Hence, finely dispersed PPeF domains induced synergistic property improvements, making PLA/PPeF blends a promising sustainable option for flexible and biodegradable packaging.