Reducing the carbon footprint of hevea rubber carbon composites using surface-modified fly ash

Authors: BORDOLOI, SANANDAM - University Of Illinois; DEVNEY, ERIC - The Ohio State University; POLYAK, PETER - The Ohio State University; CORNISH, KATRINA - The Ohio State University; Sharma, Brajendra - Bk; RAJAGOPALAN, NANDAKISHORE - University Of Illinois; PUSKAS, JUDIT - The Ohio State University; BAROI, CHINMOI - University Of Illinois

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/2024
Publication Date: 7/16/2024
Citation: Bordoloi, S., Devney, E.P., Polyak, P., Cornish, K., Sharma, B.K., Rajagopalan, N., Puskas, J.E., Baroi, C. 2024. Reducing the carbon footprint of hevea rubber carbon composites using surface-modified fly ash. Industrial Crops and Products. https://doi.org/10.1016/j.indcrop.2024.119190.
DOI: https://doi.org/10.1016/j.indcrop.2024.119190

Interpretive Summary: The carbon black used as filler in natural rubber-based composites needs to be replaced by a suitable filler to reduce their greenhouse gas potential. A waste byproduct fly ash generated in coal power plants could have the potential to be used as a filler after suitable coating. As even the landfill disposal of fly ash poses environmental hazards due to the high leaching potential, suitable hydrophobic coating will be needed. This study evaluates a novel surface-modified fly ash prepared using polymer made from vegetable oils and sulfur followed by their characterization, leaching potential, and filler in rubber composites. This vegetable oil-based coating made fly ash hydrophobic, minimized the leaching of toxic heavy metals and was found to be morphologically ideal as a partial replacement filler of carbon black (up to 20%) in natural rubber-based composites without loss of mechanical properties and thermal stability. This work will add another application of waste cooking oil, thereby helping improve the economic value, utilization, and demand for farm products.

Technical Abstract: CO2 intensive carbon black (CB) as filler material in natural Hevea rubber-based composites needs to be partially replaced by suitable fillers. In this study, a novel surface modified filler (SuMo FA) was made by encapsulating fly ash (FA) with a polysulphide coating. This SuMo FA was hydrophobic, minimized leaching, and was morphologically ideal as partial replacement filler of CB in Hevea rubber-based composites. This SuMO fly ash and unmodified FA was compounded from 5, 10and 20 parts per hundred rubber (phr) accounting for partial substitution of CB at 5, 10, 20 and 40 wt%, respectively. The tensile properties and Shore A hardness were practically unchanged with unmodified FA at 5 wt% CB replacement. SuMo FA performed better, retaining tensile properties up to 10 wt% CB replacement. Major decreases were seen only at 40 wt% CB replacement. Chemical crosslink densities decreased somewhat with increasing ash content, while thermal stability remained constant. The encapsulation reduced the leachability of toxic heavy metals from SuMo FA to below United States-Environmental Protection Agency limits opening up the use of such composites in consumer markets in addition to industrial ones. Thus, SuMO FA is a promising waste-derived filler that can be used to partially replace carbon black in rubber composites without loss of mechanical properties or thermal stability.