Viscoelastic Polyurethane Foams From Unmodified Kraft Lignin Dispersed Into Methoxy Polyethylene Glycol and Palm Kernel Oil as Substitutes of Petroleum-Based Polyols

Abstract

Kraft lignin (KL) dispersions in methoxy polyethylene glycol (MPEG) and in a mixture of palm kernel oil (PKO) with MPEG (PKO/MPEG) were evaluated for viscoelastic polyurethane foams (VPFs) production with different contents of KL (0-3.9 pphp) and PKO (0 -15 pphp). The influence of the dispersed KL on the foam structure, foam growth profile, foaming reactivity, mechanical properties, and final properties of VPFs were studied. The appearance of the VPF produced with KL dispersion in MPEG/PKO was similar to the control VPF foam. The addition of KL dispersion (0 to 15 pphp), had a significant effect on the growth profile, foaming reactivity, density and consequently on the foam morphology. VPFs produced with 3.9 pphp of KL presented shrinkage values about 4 times when compared to the control. The presence of the KL and PKO did not improve the burning rate of the foam samples compared to the control foam, without KL and PKO. Thermal stability of the produced foams showed no relevant differences regardless of the contents of KL/MPEG/PKO used in comparison to the control. Mechanical properties of VPF can be adjusted by making changes to the standard formulation. It can be concluded that the dispersion of KL in a mixture of MPEG and PKO represents an alternative for incorporating fractions of KL and PKO into VPF. In addition, this study provides new insights for the production of VPF using renewable resources for packaging applications, as well as in the mattress industry.