Bioenveloping Inorganic Filler-Based Eggshell Wastes for Enhancing the Properties of Natural Rubber Biocomposites

In this study, eggshell (ES) wastes were used as a renewable reinforcing material in natural rubber (NR) composite to limit carbon production. Long bio-alkyd resin (LAR) was also used to envelope the inorganic ES particles and to aid in dispersing the filler in the NR matrix. The effect of the coated ES filler (ESR) in the rubber mix on the morphology, mechanical properties, and swelling was investigated. The ES filler and its biocomposites were characterized by X-ray fluorescence, scanning electron microscopy, Fourier transform infrared imaging microscope (FT-IR-IM), differential scanning calorimetry (DSC), and thermogravimetric analysis. The morphological data reveal that the resin enhances the dispersion of the ES filler in the NR matrix. These data were confirmed by the results obtained from FT-IR-IM. The swelling and mechanical properties were significantly improved when the coated filler was used in NR matrix, especially at 20 wt.% ESR. DSC thermograms revealed that the increase in the resin caused the glass transition temperature (Tg) to be shifted to a lower temperature. The obtained results show that the bioenveloping ESR can be used as potential alternative for green tire and vehicle applications rather than conventional petroleum-based filler.