Modification of reactive PB‐g‐SAG core–shell particles to achieve higher toughening ability for brittle polylactide.

Core–shell structured particles have been used to toughen brittle polylactide (PLA) extensively. In this research, reactive core–shell (RCS) particles with polybutadiene (PB) as core and the terpolymer styrene–acrylonitrile‐glycidyl methacrylate as shell were prepared to improve the toughening ability of RCS for PLA. The tert‐dodecyl mercaptan (TDDM) content was varied during polymerization and higher TDDM concentrations induced lower grafting and cross‐linking of the PB phase, which significantly influenced the dispersed phase morphology and toughness of RCS toughened PLA blends. With the increase of TDDM content, the phase morphology of RCS changed from uniform dispersion, net‐like structure to an agglomeration pattern. The impact strength of PLA blends increased with TDDM content and reached 922 J/m for the PLA/RCS‐T5 (TDDM: 1.18 wt%), which was 30 times higher than pristine PLA and ~3 times than PLA/RCS‐T0 blend. Higher TDDM contents decreased toughening efficiency. Appropriate TDDM contents decreased the glass transition temperature (Tg) and cross‐linking degree of RCS particles which enhanced the cavitation ability of the PB core phase and promoted the shear yielding of PLA matrix. The modification effect of TDDM solves the problem of insufficient toughening ability of core–shell particles. Under the same toughener content, the modified RCS particles make the PLA blend achieve super toughness. [ABSTRACT FROM AUTHOR]