Facile method to improve toughness and biodegradability of polylactide by modified CaCO₃

In this study, an aluminate coupling agent (ACA) was utilized to modify calcium carbonate (CaCO₃) particles, producing modified CaCO₃ (Al-CaCO₃) particles, which were subsequently employed as inorganic fillers to enhance the toughness of polylactide (PLA). PLA/Al-CaCO₃ composites were prepared through melt mixing, with the reaction between ACA and CaCO₃ confirmed by Fourier transform infrared (FTIR) spectroscopy. The mechanical, thermal, and biodegradation properties of these composites were thoroughly investigated. The addition of Al-CaCO₃ significantly enhanced the mechanical properties, with impact strength reaching approximately 9.7 kJ/m², a 143% increase compared to neat PLA. The elongation at break also improved dramatically, rising from 7.5 to 34%, representing a 350% increase over neat PLA. Al-CaCO₃ particles demonstrated good dispersibility and strong interfacial interaction within the PLA matrix. Differential scanning calorimetry (DSC) results showed that Al-CaCO₃ enhanced the crystallization behavior of PLA, promoting the formation of more perfect crystals. Additionally, biodegradation tests revealed that the PLA/Al-CaCO₃ composites exhibited excellent biodegradation properties. The combined toughening and biodegradation properties of PLA/Al-CaCO₃ broaden the potential applications of PLA.