Replacing 100% of phenol in phenolic adhesive formulations with lignin

Abstract

Lignin, produced as a byproduct of pulp and paper and bioethanol industries, is a polyphenolic compound that has excellent potential to be used as phenol replacement in phenolic adhesive formulation. In this study, the phenol portion of phenol formaldehyde (PF) resin has been replaced by an agricultural-based lignin, which was produced as a byproduct of a cellulosic bioethanol process through dilute-acid pretreatment and enzymatic hydrolysis from corn stover. The PF resol resin was formulated using isolated lignin under alkaline condition. Chemical, physical, and thermal properties of the isolated lignin, PF resin and adhesive were measured using advanced analytical techniques such as Fourier transformed infrared spectroscopy (FTIR), size exclusion chromatography (SEC), phosphorous nuclear magnetic resonance spectroscopy ( 31 P NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The developed 100% lignin-based adhesive and a commercially formulated phenol resorcinol formaldehyde (PRF, as reference) were used to prepare single-lap-joint samples for mechanical testing. The plywood samples were pressed under exactly the same conditions (time, temperature, and pressure) as what recommended for the commercial PRF formulation. According to two-way ANOVA results, statistically there was no significant difference between the shear strengths of plywood samples made with 100% lignin-based adhesive and those made with the commercial PRF resin.

Techno-economic assessment for the large-scale production of colloidal lignin particles

“…Based on a preliminary assessment carried out to evaluate the economic potential of colloidal lignin particles, it was found that with a selling price of 1.10 €/kg, CLPs offer a great potential to be used in large-scale applications. These include PF resins 36 where CLPs can be used as a replacement for petroleum-based phenol. In addition, CLPs have potential applications in foams, anti-bacterial products such as bactericides, carbon fillers and nanocomposite manufacture.…”

The current and emerging sources of technical lignins and their applications

“…It was found 20% of the PF resin could be substituted with pine kraft lignin without changing the mechanical properties of the plywood samples. The corn stover lignin from POET cellulosic ethanol process was also evaluated for the PF application . The POET lignin was purified by dissolution and acid precipitation.…”

“…The corn stover lignin from POET cellulosic ethanol process was also evaluated for the PF application. 148 The POET lignin was purified with polydispersity of 8.1. Apparently, Alcell lignin was purer in composition, underwent less structural change in the process, was smaller in size, and was more homogeneous.…”

Green Binders for Wood Adhesives

“…The mechanical strength of the evaluated adhesive system was similar to a commercial phenol-resorcinol-formaldehyde (PRF) adhesive reference [113]. Different industrial lignins, such as softwood Kraft lignins, have been evaluated in selfbinding high-density fibreboards, of which some were found to perform well in dry conditions [114].…”