Synergistic toughening of polypropylene random copolymer at low temperature: β-Modification and annealing

► The synergistic effect of β-modification and annealing on the impact toughness of a commercially available polypropylene random copolymer (PPR) was investigated. ► The impact toughness of β-nucleated PPR after annealing at low temperature (0 °C) was almost five times as high as that of the virgin PPR without annealing. ► Annealing improved the mobility of chain segments in amorphous phase as well as the strength of ligament of PPR matrix. ► This work provides a possible method to toughen semi-crystalline polymers at low temperature by combination of β modification and suitable annealing.