Are there alternatives to 6PPD as a rubber antioxidant?

Nevertheless, conclusive studies identifying superior alternatives to 6PPD as a rubber antioxidant remain scarce in the current literature. Urbanization has resulted in an increase in surface runoff, a phenomenon that plays a pivotal role in the transportation of chemicals originating from tire wear into aquatic environments.

Are p phenylenediamine (PPD) antioxidants in recycled tire rubber products toxic?

Recently, roadway releases of N, N ′-substituted p -phenylenediamine (PPD) antioxidants and their transformation products (TPs) received significant attention due to the highly toxic 6PPD-quinone. However, the occurrence of PPDs and TPs in recycled tire rubber products remains uncharacterized.

Which industrial rubber additives have higher chemical concentrations?

Furthermore, we quantified 15 other industrial rubber additives (including bonding agents, vulcanization accelerators, benzotriazole and benzothiazole derivatives, and diphenylamine antioxidants), observing that PPD-derived chemical concentrations were 0.5–6 times higher than these often-studied additives.

Do recycled tire rubber products contain PPDS and TPS?

However, the occurrence of PPDs and TPs in recycled tire rubber products remains uncharacterized. Here, we analyzed tire wear particles (TWPs), recycled rubber doormats, and turf-field crumb rubbers for seven PPD antioxidants, five PPD-quinones (PPDQs), and five other 6PPD TPs using liquid chromatography-tandem mass spectrometry.

Which PPD-Q compounds are found in tire rubber granules?

Among the various PPD-Q compounds identified in tire rubber granules (12 μg/g), rubber crumbles (0.3–25 μg/g), and recycled rubber door mats (11–26 μg/g), 6PPD-Q stands out as the most prevalent (Zhao et al., 2023b). Research indicates that sunlight not only catalyzes the formation of 6PPD-Q in TRWPs but also accelerates its breakdown.

Is crumb rubber toxic?

Various PPD antioxidants, PPD-quinones, and toxic transformation products are widely present in crumb rubber and other rubber consumer products, posing environmental and human exposure risks.