Effect of Kraft lignin and palm kernel oil as substitutes of petroleum-based polyols on the properties of viscoelastic polyurethane foams

Viscoelastic polyurethane (VE-PU), also known as memory foams are petroleum-based materials widely used in industry due to their specific properties, such as, comfort and low resilience. In this study, VE-PU foams were produced using different contents of Kraft lignin (KL) and palm kernel oil (PKO) additives, as partial substitutes of petroleum-based polyols. The study intends to replace methoxy-poly(ethylene glycol) (mPEG) with KL and PKO in the VE-PU formulation and to investigate the consequent effects on the foam growth profile, foaming reactivity and final properties of VE-PU foams (e.g., cell morphology, indentation strength, resilience, recovery time, deformation and sensory effect). The results indicate that it is possible to produce VE-PU foams by adding KL and PKO as additive to replace petroleum-based polyols. The addition of PKO and KL dispersed in petroleum-based polyol from 0 to 15wt%, had a significant effect on the growth profile, foaming reactivity and consequently on the foam morphology. The appearance of the VE-PU foams produced with PKO was similar to the control VE-PU foam sample. The foams with larger cells, induced densification and changes in the indentation strength, resilience and compression set test. Thermal properties of VE-PU foams showed a direct relationship to the content of KL used. The VE-PU foam with different PKO contents did not necessarily result in obtaining a foam with tactile sensory attributes. Mechanical properties of VE-foams can be adjusted by making changes to the standard formulation. In addition, these results point to a new approach for the application of VE-PU foams for packaging applications, as well as in the mattress industry.