Synthesis and characterization of natural rubber/coal fly ash composites via latex aqueous microdispersion

Composite films composed of uncured natural rubber (NR) combined with coal fly ash (CFA) and CFA treated by acid washing (CFAT), both acting as fillers, were developed. The goal was to add value to the CFA (which is an industrial waste) while improving the mechanical properties of the NR. These NR-CFA and NR-CFAT composites were fabricated using the latex aqueous microdispersion method to ensure suitable dispersion of the filler. The mechanical properties of both composites, including tensile strength, elongation at break and Young's modulus, were improved considerably at a filler content of 20 phr compared to the original NR. Adding CFA and CFAT increased these values to 10.5MPa, 222% and 126 and 7.7MPa, 315% and 21.4MPa, respectively. NR-CFA and NR-CFAT composites also exhibited substantially higher structural stability in water with only minimal swelling, as well as better resistance to toluene. The NR-CFA composite film containing CFA at 20 phr was found to have the best structural stability, mechanical properties and resistance to solvents among the specimens tested.