Improved Water Resistance of Soybean Meal-based Adhesive with SDS and PAM

Abstract

In a previous study, a soybean meal-based adhesive was developed by mixing soybean meal flour with a self-made cross-linking agent. The objective of this study was to investigate the effects of retention agents on the properties of the adhesive. Soybean meal flour (together with a cross-linking agent) and two kinds of additives (SDS and cationic PAM) were used to develop the soybean meal-based adhesive. The water resistance of the adhesive was measured by testing the wet shear strength of the resulting three-ply plywood samples and the residual rate of the different adhesives themselves. The apparent viscosities of the adhesives were also measured. Cross sections of the cured adhesives were imaged with a scanning electron microscope (SEM). Results showed that adding 0.5% SDS to the adhesive formulation improved its wet shear strength by 38.6%, from 0.83 to 1.15 MPa, and increased the residual rate by 1.3%, from 76.5 to 77.5%. Adding 0.01% PAM improved the water resistance of the adhesive by 38.6%, from 0.83 to 1.15 MPa, and increased the residual rate by 2.2%, from 76.5 to 78.2%. Adding 0.2% SDS and 0.01% PAM together improved the water resistance of the adhesive by 55.4%, from 0.83 to 1.29 MPa. The plywood bonded with the soybean meal/SDS/PAM adhesive met interior plywood requirements. SEM results showed fewer holes and cracks on the cross section of the cured adhesive with the addition of SDS and PAM.

Future opportunities for bio-based adhesives – advantages beyond renewability

“…Decrease susceptibility to hydrolytic degradation 111,[113][114][115][116] Statistical design, 117 enzyme layer deposition, 119 amphiphilic battery binder, 121 seaweed 120,122 Lignin Increase reactivity to condensation reactions, 123,124 improve reproducibility and definition of structure 125 Vitrimer with reversible bonding 126…”

“…22, by Cuesta-Garrote et al, which resulted in an increase of the molecular weight from 32 kDa to up to 250 kDa, the crosslinking of a soy protein with a bisphenol-A-epoxy resin by Xu et al, which resulted in an increase of the wet shear strength by 55%, as well as the incorporation of L-DOPA into a soy protein for plywood bonding by Liu et al, which increased the wet shear strength from below 1 MPa to above 3 MPa. 111,113,114 An interesting solution was recently proposed by Paiva et al, who oxidised xanthan gum using sodium metaperiodate (NaIO 4 ) before testing it as an adhesive for cork. 115 The oxidation was observed to increase the tensile strength of a cork joint glued with 6% adhesive from around 1 MPa to 1.8 MPa.…”

Preparation and characterization of a soy protein based bio-adhesive crosslinked by waterborne epoxy resin and polyacrylamide

“…PAM is a water-soluble polymer including many amino groups, therefore, degree of crosslinking can be further increased by the multiple reaction of epoxy resin, PAM, and soybean protein. 32 This reason was mainly responsible for signicant improvement applications. Furthermore, since all raw materials used in the waterborne-epoxy resin crosslinked soy protein adhesive were water-solubility, it would be non-toxic and environmentally safe.…”

Use of additives to enhance the properties of cottonseed protein as wood adhesives

“…Modification of protein formulations with alkali, guanidine hydrochloride, sodium dodecyl sulfonate, and urea has also been shown to affect the adhesive properties of soy protein [11,15,[17][18][19] and cottonseed protein [11]. Other modifiers previously studied with soy proteins included various plasticizers [20], ethylene glycol and its polymers [21], cationic polyacrylamide [22], clay [23], calcium carbonate [24], and combinations of acid, base, and salt [25]. In this work we examined several new protein modifiers, and some were found to exhibit improved adhesive strength when incorporated into cottonseed protein.…”