Preparation of Polyurethane Adhesives from Crude and Purified Liquefied Wood Sawdust | JoVE Visualize

Preparation of Polyurethane Adhesives from Crude and Purified Liquefied Wood Sawdust

Wen Jiang¹, Reza Hosseinpourpia¹, Vladimirs Biziks²

¹Department of Forestry and Wood Technology, Linnaeus University, Lückligs Plats 1, 35195 Växjö, Sweden.

Polymers|October 13, 2021

View abstract on PubMed

Summary

This study developed sustainable polyurethane (PU) adhesives from wood sawdust bio-polyols and polymeric diphenylmethane diisocyanate (pMDI). The optimal 1.5:1 isocyanate to hydroxyl ratio yielded high shear strength, demonstrating potential for eco-friendly adhesives.

Area of Science:

Materials Science
Polymer Chemistry
Sustainable Materials

Background:

Growing demand for sustainable and eco-friendly adhesive solutions.
Need for utilizing wood waste streams in high-value applications.
Polyurethane adhesives offer versatile bonding properties.

Purpose of the Study:

To synthesize and characterize polyurethane (PU) adhesives using bio-polyols derived from wood sawdust.
To investigate the effect of varying isocyanate to hydroxyl (NCO:OH) molar ratios on adhesive properties.
To evaluate the performance of these bio-based PU adhesives through shear strength and thermal analysis.

Main Methods:

Acid-catalyzed liquefaction of wood sawdust to produce crude (CLW) and purified (PLW) bio-polyols.
Synthesis of PU adhesives (CLWPU and PLWPU) by reacting bio-polyols with polymeric diphenylmethane diisocyanate (pMDI) at different NCO:OH ratios (0.5:1 to 2:1).
Characterization using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA).
Performance evaluation via single-lap joint shear tests (EN 302-1:2003) and adhesive penetration tests.

Main Results:

High yield (99.7%) of bio-polyols achieved through liquefaction.
Optimal shear strength of 4.82 N/mm² (CLWPU) and 4.80 N/mm² (PLWPU) obtained at an NCO:OH ratio of 1.5:1.
NCO:OH molar ratio significantly influenced the chemical structure and thermal properties of the cured PU adhesives.

Conclusions:

Wood sawdust can be effectively converted into bio-polyols for synthesizing high-performance polyurethane adhesives.
The developed bio-based PU adhesives exhibit promising mechanical strength, comparable to conventional adhesives.
The study highlights a sustainable pathway for wood waste valorization in the adhesive industry.