Semicarbazide and thiosemicarbazide containing butylated hydroxytoluene moiety: new potential antioxidant additives for synthetic lubricating oil
Syabilah Sazeli, Amit Nath, Mohd Hafiz Ahmad, Nurin Wahidah Mohd Zulkifli, Mohd Rafie Johan, Wageeh A. Yehye, Hwei Voon Lee
Abstract
of 25.47 ± 0.42 μM) showed the best antioxidant activity against DPPH radicals compared to standard antioxidant butylated hydroxytoluene (BHT). Based on DPPH results, compound 5f' and its corresponding semicarbazide 5f were blended into trimethylolpropane trioleate (TMPTO) and isothermal differential scanning calorimetry (DSC) was carried out for the investigation of oxidative stability. At 125 °C isothermal DSC, TMPTO with 0.25 wt% of 5f' showed 1.5 times higher oxidation stability than its corresponding semicarbazide 5f and was 2 times better than BHT. It was anticipated that due to the strong auto-synergistic effect, compound 5f' showed promising oxidative stability to TMPTO by protecting from pre-mature oxidative degradation.