Coffee Grounds as Renewable Filler in NBR Biocomposites

Abstract

Using biological/renewable resources as filler or modifier in both thermoplastics and rubbers has been of a great interest in order to reduce negative effects of traditional petroleum/natural gas based fillers. In this study, the main goal was the use of spent (waste) coffee grounds as a natural alternative filler to carbon black in acrylonitrile butadiene rubber (NBR) based compounds. Stabilization effect of fresh coffee grounds was also investigated. Both fresh and spent coffee grounds were gradually replaced with CB in a reference (control) NBR compound formulation. Rheological, physico-mechanical, thermal, morphological, and dielectric properties of the biocomposites were tested and compared with the control. Processability has been affected positively in the case of using coffee grounds thanks to the presence of triacyl groups in coffee. Improved abrasion resistance and lower oil swelling could be obtained for coffee containing compounds. In conclusion, spent coffee grounds were found to be a good natural alternative filler for preparing NBR based biocomposites without a significant change in material properties.