Research article

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In this research, poly(lactic acid) (PLA) was toughened and improved the crystallinity by rubber particles and inorganic filler. CaCO₃ was employed as a filler and nucleating agent while poly(methyl methacrylate)-poly(butadiene-styrene) (MBS) core-shell impact modifier was added as a toughening agent. Overall, the enhancements of both the toughness and crystallization of PLA with CaCO₃ and MBS were successfully achieved. The tensile modulus and strength of PLA increased with increasing CaCO₃ content from 10 to 30wt%. However, they decreased slightly when CaCO₃ loading reached 40 wt% due to particles agglomerations. With the addition of MBS rubber, the tensile modulus and strength of the PLA/CaCO₃ composites became lower than those observed for PLA/CaCO₃ composites due to the softening effect. Furthermore, the compositions with MBS showed superior toughness in terms of the tensile elongation at break and impact strength. CaCO₃ nucleated the PLA crystal which reflected as the increase in the degree of crystallinity (X_c) by at least 2 times for all formulations studied. The crystallization half-time (t_1/2) of PLA with 40 wt% CaCO₃ was dramatically reduced, from 26 min, in neat PLA, to 0.9 min. With the addition of MBS, it did at 2.7 min for the same CaCO₃ content. The maximum increment of heat distortion temperature (HDT), around 8 °C, was found for the PLA with 20 wt% CaCO₃.