Synthesis, optimization, and evaluation of polyurethane from underutilized vegetable oils

Abstract

Biodegradable polyurethane can be produced from sustainable feedstocks such as waste sunflower cooking oil, which is often used for biodiesel production. This work describes the synthesis, characterization, and optimization of sustainable, mixed petroleum-sunflower polyol alongside their optimization. Polyol production was studied at a fixed sodium hydroxide catalyst concentration (1.0% w/w), reaction times of 40, 60, and 80 min, and oil-to-glycerol molar ratios of 3:1 and 4:1. Fourier transform infrared (FTIR) spectroscopy was used for polyol characterization. Polyurethane synthesis used a fixed amount of toluene diisocyanate (TDI), variable mixed-polyol ratios, and stannous octoate catalyst (2.0% w/w). The polyurethanes were evaluated for physical properties, mechanical and structural performance, chemical resistance, and stress--strain behavior. The highest polyol yield was 60.1% at an oil-to-glycerol molar ratio of 4:1, a reaction time of 80 min, a fixed sodium hydroxide catalyst concentration of 1.0% w/w, and 250 oC. SuPU-30:20 showed the best overall balance, with a tensile strength of 14 kPa, elevation of 52 mm, porosity of 16, weight of 14.9 g, 40% compression of 36.5, and good resistance to chemical attack. These results suggest that waste sunflower cooking oil is a promising sustainable feedstock for polyurethane, with SuPU-30:20 approaching the performance range of commercial flexible foams in tensile strength and density, although porosity and elevation remain below typical values.