New Composites from Waste Polypropylene/Eggshell Characterized by High Flame Retardant and Mechanical Properties

This manuscript aimed to enhance the mechanical, ignition properties of polypropylene (PP). To reduce waste pollution of the environment, recycled waste polypropylene (WPP), and waste chicken eggshell (WCES) were used. WCES was used as a bio-filler to form new WPP composites. The effect of the addition of magnesium hydroxide (MOH) and monoammonium phosphate (MAP) on the properties of WPP/WCES composites has been studied. The structure of the composites was characterized by Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The mechanical and dynamic mechanical properties of the composites were investigated. The morphology and the thermal properties of the composites were investigated using a scanning electron microscope (SEM), thermal shrinkage %, and thermal analysis (TGA, DTA). The flame retardancy of the composites was assessed using limiting oxygen index (LOI) and flame chamber (UL/94) according to standard test methods. The results indicated that the 10 phr of the WCES enhanced the tensile strength and flexural strength of WPP/WCES composites by 15 and 8 % compared to the neat WPP composite, respectively. In the case of MAP and MOH fillers, the 5 and 10 phr of MOH enhanced the tensile strength and flexural strength of WPP/WCES composites by 8.3, 25, 51.1, and 65.0 % compared to the WPP/WCES composite containing 30 phr of WCES, respectively. The organic matter of WCES is a natural antioxidant for WPP/WCES composites. The limiting oxygen index (LOI) for a composition containing 30 parts per hundred resin (phr) of WCES is 20.8, slightly greater than that for neat WPP (17.9 %). While the LOI value of WPP composite containing 30 phr of mono-ammonium phosphate is 26 %.

Automated summary

This study aimed to enhance the mechanical and flame retardant properties of polypropylene by using recycled waste polypropylene and waste chicken eggshell as fillers. The addition of magnesium hydroxide and monoammonium phosphate significantly improved the tensile and flexural strength of the composites. Overall, the organic matter in waste chicken eggshell acted as a natural antioxidant for the composites.