Lignosulfonate-Based Polyurethane Adhesives

Abstract

The feasibility of using lignosulfonate (LS) from acid sulphite pulping of eucalyptus wood as an unmodified polyol in the formulation of polyurethane (PU) adhesives was evaluated. Purified LS was dissolved in water to simulate its concentration in sulphite spent liquor and then reacted with 4,4′-diphenylmethane diisocyanate (pMDI) in the presence or absence of poly(ethylene glycol) with Mw 200 (PEG200) as soft crosslinking segment. The ensuing LS-based PU adhesives were characterized by infrared spectroscopy and thermal analysis techniques. The adhesion strength of new adhesives was assessed using Automated Bonding Evaluation System (ABES) employing wood strips as a testing material. The results showed that the addition of PEG200 contributed positively both to the homogenization of the reaction mixture and better crosslinking of the polymeric network, as well as to the interface interactions and adhesive strength. The latter was comparable to the adhesive strength recorded for a commercial white glue with shear stress values of almost 3 MPa. The optimized LS-based PU adhesive formulation was examined for the curing kinetics following the Kissinger and the Ozawa methods by non-isothermal differential scanning calorimetry, which revealed the curing activation energy of about 70 kJ·mol−1.

Incorporating Phenolated Lignin into Polyurethane Materials: Impact on Mechanical, Thermal, and Adhesion Performance

“…In light of this, we conducted a comparative analysis between the maximum lap shear stress strengths of the PhL-based PU adhesives developed in this study and those previously reported in scientific literature for similar lignin-based PU adhesives. It is worth noting that the lignin used in these previous studies was either functionalized using various methods, such by acetylation, alkylation, amination, depolymerization, solvent extraction, or used directly without any prior chemical modification. ,− Our results, as depicted in Figure , demonstrates that the adhesion performance achieved in the present study is comparable to, or even surpasses, that reported in earlier work in this area.…”

Lignin as a Renewable Building Block for Sustainable Polyurethanes

“…In addition to PUF, different types of lignins and LBPs have also been used to prepare other forms of Pus, such as adhesives [ 121 , 127 , 128 ], elastomers [ 129 , 130 , 131 ], coatings [ 132 , 133 ], and films [ 125 ]. Elastomeric PUs are a class of PU materials that have the characteristics of rubber, and their application has increased in recent years due to the high demand for advanced applications such as in biomedicine, shape memory materials, self-healing materials, and gel materials.…”

Getting Value from Pulp and Paper Industry Wastes: On the Way to Sustainability and Circular Economy

“…The valorization of SSL has a well-established market for decades, using lignosulfonates as binders (pelletizing of animal feed, ceramics, dust control, fertilizers), dispersants (ceramics, dyes, pigments), emulsifiers (asphalt, inks, waxes), concrete plasticizing agents or adhesives [18,[78][79][80][81]. Most of these applications rely on the good water-solubility of lignosulfonates [81].…”