A strategy to prepare high‐robust and ultra‐tough polylactic acid/polycaprolactone/talc composites with thermo‐resistance.

Blending with ductile polycaprolactone (PCL) is one of the common toughening methods for polylactic acid (PLA). However, it seems inevitable to experience a trade‐off in mechanical strength and thermal stability of PLA. Therefore, this study aimed to improve the mechanical and thermal properties of PLA/PCL blends by adding different contents of talc (0–10 wt%) and conducting annealing treatments. Interestingly, the maximum tensile strength (52.04 MPa), elongation at break (83.51%), and impact strength (6.05 kJ/m2) were achieved by incorporating 2.5 wt% talc into the blends without annealing. Meanwhile, the addition of just 1 wt% talc shortened the semi‐crystallization time of PLA to one‐third of the neat PLA at 100°C. Particularly, after annealing treatment, the crystallinity of PLA increased to 32.1%, and the Vicat softening temperature reached as high as 133.3°C with 2.5 wt% talc. Importantly, the increase in crystallinity did not compromise the toughness of PLA composites but significantly enhanced the impact strength to 8.91 kJ/m2. This study provides an updated understanding of the relationship between toughness and crystallinity in PLA composites. Highlights: Thermo‐resistance of polylactic acid (PLA) composite increases to 133.3°C.Talc aids nucleation and promotes PLA crystallization.Increased crystallinity and high toughness are simultaneously realized.Adding 1 wt% talc reduced PLA semi‐crystallization time by one‐third.Crystal transformation and sea‐islands structure are vital for reinforcements. [ABSTRACT FROM AUTHOR]