Effect of mixing pressure in a high-pressure machine on morphological and physical properties of flexible polyurethane foams

Effect of mixing pressure in a high-pressure machine on the structure and physical properties of flexible polyurethane foams was investigated. The foams were produced under industrial conditions using the PLUSOL-F-201-05 polyurethane system and pressures ranging from 90 to 170 bar. Apparent density, cell structure (SEM), chemical composition (FT-IR), thermal properties (TGA), hardness, SAG (comfort index), resilience, and deformation stability were assessed. Samples taken from the lower and middle sections of the blocks differed in density, urea group content, and degree of phase separation, which influenced their thermal resistance and degradation. The key effect of mixing process parameters on the structure and properties of flexible foams was confirmed. As mixing pressure increased, hardness decreased and flexibility increased, while their cellular structure changed.