Biodiesel has several drawbacks, such as being prone to oxidation, having reduced stability, and having limited storage time. Antioxidants compatible with biodiesel are being used to address its drawbacks. Utilizing antioxidants effectively improves the quality of biodiesel. Enhancing the quality of biodiesel for use as a clean energy source benefits both the global economy and ecology. Therefore, we believe that our work will contribute to the advancement of the biodiesel industry worldwide. This study used blends consisting of 20% biodiesel and 80% diesel fuel. Isatin-thiosemicarbazones were tested as additives in blends at a concentration of 3000 parts per million (ppm) using an oxifast device and were compared with the chemical antioxidant Trolox. FT-IR, DSC, and TGA were used to characterize these samples. DSC measured sample crystallization temperatures (Tc). Samples with antioxidants showed decreased values compared to the non-antioxidant diesel sample D100. Several DSC tests were conducted to determine the antioxidant strengths of various samples. The results show that the FT-IR spectrum’s antioxidant effect regions grow clearer with antioxidants. The extra antioxidant is effective. Biodiesel’s oxidative stability improves with isatin-thiosemicarbazones at varying concentrations. The kinetics of thermal decomposition of isatin-thiosemicarbazones under non-isothermal conditions were determined using the Kissinger, Ozawa, and Boswell techniques. The activation energies of compounds 1 and 2 were calculated as 137–147 kJ mol⁻¹ and 173–183 kJ mol⁻¹, respectively.

Thermoplastic polyurethane (TPU) is widely used in engineering and industrial applications due to its excellent mechanical properties and versatility; however, its inherent flammability and thermal degradation behavior limit its use in fire‐sensitive environments. In this study, flame‐retardant TPU composites containing red phosphorus (RP) and zinc borate (ZnB) were prepared via melt compounding to investigate their combined effects on thermal stability, fire performance, and mechanical properties. Thermogravimetric analysis demonstrated that RP significantly increased char yield and altered the degradation pathway, whereas ZnB further enhanced condensed‐phase stability by forming boron‐rich protective layers. Non‐isothermal degradation kinetics, evaluated using model‐free methods, revealed conversion‐dependent activation energies, indicating a complex multi‐step degradation mechanism. RP‐containing composites exhibited higher activation energies at advanced conversion levels, suggesting improved resistance to thermal degradation. Mechanical testing showed that RP increased tensile strength and modulus, whereas the incorporation of ZnB into hybrid systems reduced tensile strength and elongation at break. Overall, the RP/ZnB hybrid system offers a promising approach to achieving a balance among flame retardancy, thermal stability, mechanical performance, and processability in TPU composites.

Biodiesel has several drawbacks, such as being prone to oxidation, having reduced stability, and having limited storage time. Antioxidants compatible with biodiesel are being used to address its drawbacks. Utilizing antioxidants effectively improves the quality of biodiesel. Enhancing the quality of biodiesel for use as a clean energy source benefits both the global economy and ecology. Therefore, we believe that our work will contribute to the advancement of the worldwide industry. The study used blends consisting of 20% biodiesel and 80% diesel fuel. Isatin-thiosemicarbazones were tested as additives in blends at a concentration of 3000 parts per million (ppm) using an oxifast device. Comparing them to the chemical antioxidant Trolox. FT-IR, DSC, and TGA were used to characterize these samples. DSC measured sample crystallization temperatures (Tc). Samples with antioxidants showed decreased values compared to the non-antioxidant diesel sample D100. Several DSC tests were conducted to determine the antioxidant strengths of various samples. The results showed that the FT-IR spectrum's antioxidant effect regions grow clearer with antioxidants. The extra antioxidant is effective. Biodiesel's oxidative stability improves with isatin-thiosemicarbazones at varying concentrations. The kinetics of thermal decomposition of isatin-thiosemicarbazones under non-isothermal conditions have been determined using the Kissinger, Ozawa, and Boswell techniques. The activation energies of compounds 1 and 2 were calculated 137–147 kJ mol^-1 and 173–183 kJ mol^-1, respectively.

This study investigated the influence of synthetic sulfenimides on biodiesel–diesel fuel blends. Three previously synthesized sulfenimide derivatives were structurally characterized using spectroscopic techniques. We evaluated their antioxidant properties through phosphomolybdenum activity and reducing power capacity assays. The tested fuel samples were designated as D100, B10D90, B10D90_AA (ascorbic acid), B10D90_3, B10D90_2, and B10D90_1. The effect of adding 2000 ppm of the additive was measured using an Oxifast instrument following the ASTM D7545 standard, and the results were compared to those of the chemical antioxidant ascorbic acid. Inhibition time values were derived from the oxidation stability results. The starting temperatures for crystallization (Tc) of the mixtures were found using differential scanning calorimetry (DSC), and the measured temperatures were –7.24, –7.64, –7.89, –8.06, –8.39, and –8.52 °C. FT-IR spectra exhibited characteristic absorption bands associated with antioxidant functional groups, which means the sulfenimide compounds were successfully added. The addition of sulfenimides improved the oxidative stability of biodiesel blends. Furthermore, we conducted thermogravimetric analysis (TGA) at multiple heating rates to investigate the thermal decomposition kinetics of the sulfenimides. The activation energies for compounds 1, 2, and 3 were calculated using the Kissinger–Akahira–Sunose (KAS) method and were found to be 125.28, 111.34, and 88.11 kJ mol– ¹, respectively.