Cardoon biolubricant through double transesterification: Assessment of its oxidative, thermal and storage stability

Biolubricants could be a suitable replacement for industrial lubricants, due to their good performance and environmental-friendly quality, showing better flash and combustion points. However, depending on the raw material, the quality of biolubricants can vary, especially concerning oxidative and storage stability. The aim of this research work was to assess the stability of cardoon biolubricant, paying attention to oxidation and thermal and storage stability (by using the Rancimat method, thermogravimetry and viscosity during storage, respectively). The high linoleic acid content in cardoon oil (exceeding 25 %) could influence the low oxidative stability of cardoon biolubricant (3 h), implying changes in quality parameters during storage (viscosity increased above 15 % and viscosity index decreased about 23 %). Thus, the use of antioxidants is advisable to keep its properties over time.