Phase Morphology, Mechanical, and Thermal Properties of Calcium Carbonate-Reinforced Poly(L-lactide)- b -poly(ethylene glycol)- b -poly(L-lactide) Bioplastics.

Poly(L-lactide) (PLLA) is a promising candidate as a bioplastic because of its non-toxicity and biodegradability. However, the low flexibility of PLLA limits its use in many applications. Poly(L-lactide)- b -poly(ethylene glycol)- b -poly(L-lactide) (PLLA- b -PEG- b -PLLA) block copolymer is of interest for bioplastic applications due to its superior flexibility compared to PLLA. The aim of this work is to modify PLLA- b -PEG- b -PLLA using a low-cost calcium carbonate (CaCO 3 ) filler to improve material properties compared to PLLA/CaCO 3 composites. The addition of CaCO 3 enhanced the crystallinity and thermal stability for the PLLA- b -PEG- b -PLLA matrix but not for the PLLA matrix, as determined by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). Phase morphology investigation using scanning electron microscopy (SEM) revealed that the interfacial adhesion between PLLA- b -PEG- b -PLLA and CaCO 3 was stronger than between PLLA and CaCO 3 . Additionally, tensile testing was carried out to determine the mechanical properties of the composites. With the addition of CaCO 3 , the tensile stress and Young's modulus of the PLLA- b -PEG- b -PLLA matrix were increased, whereas these properties of the PLLA matrix were significantly decreased. Thus, CaCO 3 shows great promise as an inexpensive filler that can induce nucleation and reinforcing effects for PLLA- b -PEG- b -PLLA bioplastics.