Recycled polyester filled with eggshells waste-based nano CaCO3: thermo-mechanical and flame-retardant features

Abstract

Substitution of primary resources by solid waste and natural alternatives is being targeted worldwide. In this regard, this work aims to prepare a new environmentally friendly polymer nanocomposite based on a recycled polyester matrix and waste CaCO₃. The novel aspect is filling the environmentally friendly polyester, obtained from natural biomass and natural oleic acid (BM-PES), with different concentrations of eggshell-waste-based calcium carbonate (ES-CaCO₃) nanofiller, for the first time. ES-CaCO₃, ∼ 80 nm, was extracted by milling and calcination of solid eggshell waste, then added to the BM-PES matrix at concentrations of 3%, 5%, 7% and 10% to give the ES-CaCO₃/BM-PES nanocomposites. The polymerized composites exhibited enhanced properties unlike those of the blank matrix. The microstructural investigations confirmed the successful preparation of the crystalline CaCO₃ nanofiller. The obtained nanocomposites have improved thermal properties, owing to the increased thermal decomposition temperatures. The 7% and 10% ES-CaCO₃/BM-PES nanocomposites achieved higher mechanical performance, where hardness and scratch resistance improved by 12.5% and 41.7%, respectively. The cone calorimetric parameters indicated the effective flame retardancy of the ES-CaCO₃ nanofiller, including the decreased peak heat release rate, specific extinction area, total smoke parameter and mass loss rate, as well the longer time to ignition, compared with the blank BM-PES matrix. The ES-CaCO₃ nanofiller protects the natural BM-PES polymer from thermal deformation, mechanical failure and ignition. The characterization confirmed the thermo-mechanical and fire-retardant properties of ES-CaCO₃/BM-PES nanocomposites with the successful exploitation of eggshell solid waste and recycled polyester as an environmentally friendly feature.