Polyurethane foams (PUFs) are widely used as insulation materials for houses, cold warehouses, and pipelines due to the advantages such as low density, excellent corrosion resistibility, and low thermal conductivity. PUFs are synthesized by the polymerization between isocyanates and polyols under mild conditions, in which both two main components are petroleum products. Recently, the department of energy (DOE), the European Union (EU), and industrial interests are significantly advancing the use of bio-derived materials for PUF synthesis as petroleum production becomes volatile due to environmental and political issues.<br/>Lignin, a biopolymer of phenylpropane subunits, is the second most abundant natural biopolymer after cellulose but has been under-utilized. Lignin presents several reactive points of hydroxyl groups that make it attractive in the synthesis of PUFs directly as macromonomers. One of the biggest challenges of lignin polyurethane foam (LPUF) is that the intrinsic stiffness of lignin particles and low dispersity of lignin and diisocyanate system hinder the polymerization process, and the prepared LPUFs are brittle due to the low molecular mobility of lignin and diisocyanate.<br/>Herein, we selected specific lignin types including tetrahydrofuran (THF)-soluble lignin, 4-phenolsulfonic acid (PSA) extracted lignin, and hot water extracted lignin to substitute polyols. Small amounts (less than 10 wt.%) of organic solvents including THF and dimethylformamide (DMF) were used to improve the lignin dispersity. The LPUF was successfully prepared with up to 75 wt.% polyols replaced by THF-soluble lignin. The brittleness was controlled by adjusting polyethylene glycol (PEG) content to mix soft chains in PUFs. The prepared LPUFs were characterized using dynamic mechanical analysis (DMA), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). The LPUF with high lignin replacement content (70 wt.%) showed a comparable mechanical strength to commercial PUFs. A setup with an IR camera and hot stage was used to study the applications as insulation materials. The prepared LPUFs showed a similar thermal insulation ability compared with commercial PUFs. This study showed the possibility of a carbon-neutral process of insulation PU foams production.

Lignin-derived polyurethane foam for eco-friendly insulation material applications

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.