Abstract
Carbon black has been a key ingredient in high-performance composites, such as tire rubber, for over a hundred years. This reinforcing filler increases rubber rigidity and reduces tire wear, among many other useful effects. New nanomaterials, such as graphene and carbon nanotubes, may bring new performance improvements. However, their usefulness cannot be evaluated unless worker safety is assured by demonstrating that the nanoparticles are not released at harmful concentrations during manufacture and testing. Here, we present a flexible, general method for the quantitative evaluation of nanoparticle release from rubber nanocomposites. We evaluate manufacturing steps such as powder handling, uncured rubber milling, and curing. We also evaluate particle emission during cured rubber abrasion as an aggressive example of the testing rubber goods are subjected to. We quantify released nanoparticle concentrations for clay nanoparticles, graphene-like materials, and carbon nanotubes. We also describe a mechanistic framework based on the balance of adhesive and kinetic energies, which helps understand when nanoparticles are or are not released. This method contributes to the assessment of workers’ exposure to nanoparticles during the various stages of the industrial process, which is an essential step in managing the risk associated with the use of nanomaterials in manufacturing.
Highlights
Fillers, such as silica and carbon black, have been used in rubber composites for decades (Donnet and Voet 1976; Vilgis et al 2009) producing performance improvements such as reduced tire wear, reduced rolling resistance, and shorter vehicle braking distances. New nanomaterials, such as carbon nanotubes (CNTs) (Iijima 1991) and graphene (Novoselov et al 2005), have the potential to become the generation of rubber fillers, yet they have not found many commercial applications, in part due to unknown hazards which limit their industrial investigation
The following rubber mix components were obtained from standard rubber industry sources: styrene butadiene rubber (SBR, grades with Tg = − 65 °C and − °C); treated distillate aromatic extract oil (TDAE); aliphatic resin (Tg = °C), diphenyl guanidine (DPG); stearic acid, n-(1,3-dimethylbutyl)-n’-phenyl-pphenylenediamine (6PPD); ZnO, bis(triethoxysilylpropyl)tetrasulfide (Si69®); n-octyltriethoxysilane (Octeo); and sulfur (S) and ncyclohexyl-2-benzothiazole sulfenamide (CBS)
We explain the rarity of released nanoparticles by considering the balance of kinetic and adhesive forces during the most likely nanoparticle release route: kinetic energy transfer to a loose particle on the rubber surface
Summary
Fillers, such as silica and carbon black, have been used in rubber composites for decades (Donnet and Voet 1976; Vilgis et al 2009) producing performance improvements such as reduced tire wear, reduced rolling resistance, and shorter vehicle braking distances. Riediker recently summarized (Riediker et al 2019), toxicity depends on the “five Bs” of bioavailability, biopersistence, bioprocessing, biomodification, and bioclearance of nanoparticles. These factors in turn depend on key physical and chemical characteristics, such as particle shape, size (Chang et al 2011; Xiong et al 2011), and surface chemistry (Akhavan and Ghaderi 2010; Sasidharan et al 2011; Wohlleben et al 2016)
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
