Abstract
Although carbon black has been the dominant filler material for rubber composites for over a century, it is a finite, fossil fuel-based product that is sensitive to geopolitical issues and economics. Renewable sources of carbon need to be developed to replace carbon black in order to reduce dependence on petroleum. Biochar is the solid material left over after the anaerobic treatment of biomass at high temperature. In this work, two biochars made from coppiced hardwoods, Paulownia elongata and Populus tremuloides were used to partially replace carbon black in rubber composites using a 50/50 blend of butadiene rubber and natural rubber. Rubber composite samples using these biochars were able to replace 30% of the carbon black with virtually no loss in tensile strength, and improved elongation and toughness compared to the reference sample containing 100% carbon black.
Highlights
Polybutadiene rubber (BR) is a synthetic rubber that is a primary ingredient in automobile tires
We demonstrate substituting Carbon black (CB) with silica-milled biochar from two coppiced hardwood feedstocks, Paulownia and poplar, into a rubber matrix featuring BR to make rubber composites
Biochars made from Paulownia elongata (PAUL) and Populus tremuloides (POP) using a proprietary method were supplied by Biochar Options (Whitewater, WI, USA) and used as delivered
Summary
Polybutadiene rubber (BR) is a synthetic rubber that is a primary ingredient in automobile tires. Paulownia is currently being studied as potential feedstock for bioethanol production [13], filler for wood plastic composites [14], and biochar made from it has been studied as a horticultural amendment to soil [15] Hybrid poplar is another excellent candidate as a coppiced hardwood feedstock. With previous studies [22,23], milled biochar would have a small fraction of particles ranging from 10–100 μm, and these particles were problematic because they cause localized stresses in the rubber composite that weakened it and caused it to fracture [24] To help with this issue, we have used small amounts of industrial silica during our milling processes to help reduce biochar particle size. We demonstrate substituting CB with silica-milled biochar from two coppiced hardwood feedstocks, Paulownia and poplar, into a rubber matrix featuring BR to make rubber composites. This work along with previous studies [26,27] demonstrates that renewable biochar can partially replace carbon black in all three of these rubber matrices with virtually no loss in tensile strength, plus improved elongation and toughness properties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
