Composites based on high-density polyethylene, polylactide and calcium carbonate: effect of calcium carbonate nanoparticles as co-compatibilizers

Investigating the compatibility mechanism of hybrid composites based on two polymers and one mineral nanofiller is a challenge that needs to be better understood. This study evaluates the effect of calcium carbonate (nCaCO₃) nanoparticles as co-compatibilizers in a blend based on poly(lactic acid) (PLA), polyethylene from renewable sources (HDPE) and maleic anhydride grafting polyethylene (HDPE-g-MA or MA) using rheological and morphological analyses. Morphological assessment by scanning electron microscopy showed the formation of co-continuous-like phase morphology when nCaCO₃ was added to the PLA/MA/HDPE blend, indicating that nCaCO₃ affected the dispersion of PLA domains in the HDPE matrix. Rheological characterization carried out by stress relaxation and sweep frequency response analysis demonstrated that the addition of nCaCO₃ improved the solid-like behavior of the blend, corroborating the morphological results. Additionally, an interaction mechanism of nCaCO₃ as a co-compatibilizer was also proposed.