Optimisation of bio-based viscoelastic polyurethane foam production using high-pressure machine technology: Impact of isocyanate indices

This study examines the impact of varying isocyanate indices on the morphology and properties of bio-based viscoelastic polyurethane (VE PU) foams produced using high-pressure processing and moulding technology. Palm-based polyol, referred to herein as Pioneer E-135, was used as a sustainable alternative to petroleum-based polyol. VE PU foams were formulated with different isocyanate indices (71%, 75%, 79% and 83%) and their physical, mechanical and morphological characteristics were evaluated. Results indicated that the VE PU foam containing 10% Pioneer-E135 polyol and an isocyanate index of 83% exhibited superior mechanical properties compared to the VE PU foam with 100% petroleum-based polyol. The incorporation of 10% Pioneer-E135 polyol significantly enhanced the mechanical properties, including surface texture, morphology and load-bearing capacity, as indicated by indentation force deflection and sag factor measurements. Higher NCO indices contributed to increased tensile strength, tear strength, and ageing resistance, but resulted in lower density and reduced elongation at break. Overall, the optimised processing parameters enabled the successful production of high-quality, bio-based VE PU foams using high-pressure machine technology.