The use of crude carbon dots as novel antioxidants for natural rubber

Natural rubber (NR) is acknowledged to be a strategically important material, which spans multiple applications from tires to shock absorbers, generally, the antioxidant is indispensable for NR to prolong the service life and improve the long-term reliability. Recent reports demonstrated that the purified carbon dots with the capability of scavenging oxy radicals can be effective antioxidants for rubbers. However, the application of purified CDs is greatly restricted by the multiple tedious, complicated, time-consuming, and expensive post-purification processes. Herein, we first synthesize the amine-passivated crude carbon dots (CCDs) by a facile microwave-assisted pyrolysis method, and we attempt to directly use the CCDs (without any purifications) as a novel and inexpensive antioxidant for NR. To achieve a fine CCDs dispersion within NR matrix, we disperse the CCDs into the NR matrix by the liquid feeding and in-situ compatibilizing. The CCDs fluid was firstly prepared by mixing the CCDs with water, then the CCDs fluid together with the compatibilizer was melt-compounded with NR. The results showed that the well-dispersed CCDs endowed NR with the impressive antioxidative property. Overall, this work extends application scope of CCDs and provides unique inspiration to develop novel and effective antioxidants for elastomers. (C) 2021 Elsevier Ltd. All rights reserved.