Viscoelastic polyurethane foams from unmodified kraft lignin dispersed into methoxy polyethylene glycol and palm kernel oil as partial 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 v iscoelastic 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.

Lignin-Based Low-Density Rigid Polyurethane/Polyisocyanurate Foams

“…The closed-cell content of the foam is crucial in maintaining low thermal conductivity. , Additionally, closed and more homogenous cells create foams with better mechanical strength and thermal conductivity properties. ,, The industry-accepted method to measure foam closed cell content uses a gas pycnometer . For lignin-based rigid PUR foams, most researchers have utilized a combination of digital, light, or scanning electron microscopy to estimate closed cell content. , To yield more accurate results, we used a gas pycnometer for closed-cell content analysis (Table ). All control and lignin-based foams met the minimum 90% closed cell content requirement for thermal insulation, with foams up to 50% lignin loading meeting stricter 95% closed cell content requirements .…”

“…63 For lignin-based rigid PUR foams, most researchers have utilized a combination of digital, light, or scanning electron microscopy to estimate closed cell content. 8,64 To yield more accurate results, we used a gas pycnometer for closed-cell content analysis (Table 4). All control and lignin-based foams met the minimum 90% closed cell content requirement for thermal insulation, 58 with foams up to 50% lignin loading meeting stricter 95% closed cell content requirements.…”