Crystallization improvement of PLA by the talc with “grafting from” method of polymerization of lactide

As an inorganic filler, the fine particle talcum powder exhibits the poor compatibility when blended with polymers. By the "grafting from" method, a modified talcum powder (Talc-g-pla) was synthesized by the ring-opening polymerization (ROP) of lactide in bulk. The polymer chains grew in situ and chemically grafted on the talc surface, which was tightly connected even after washing with dichloromethane for 24 h. The Fourier transform infrared spectroscopy (FTIR), atomic force microscope (AFM), and the thermogravimetric analysis (TGA) of Talc-g-pla confirmed the successful modification of talc with PLA, which was about 2 wt%. Due to the good compatibility by the grafted PLA as a bridge between PLA and talc, the Talc-g-pla was well dispersed and served as an efficient nucleating agent of commercial PLA at low loadings. For the PLA/Talc-g-pla composite by the blend of Talc-g-pla with PLA in the proportions between 0.5–3.0 wt%, the differential scanning calorimeter (DSC) and polarized optical microscope (POM) showed that the improvement of thermodynamic properties and crystallization of PLA/Talc-g-pla composites were more obvious than those of the PLA/Talc physical composites. The DSC results suggested that the 1 wt% Talc-g-pla increased the crystallinity of PLA by over 3% than talc.