Development of High‐Strength Soy Protein Adhesives Modified with Sodium Montmorillonite Clay

Abstract

This study investigated the high strength of a soy protein adhesive system with good flowability at high protein concentration. Sodium montmorillonite (Na MMT), the most widely used silicate clay, was incorporated into viscous, cohesive soy protein adhesives at concentrations ranging from 1 to 11 % (dry basis, w/w). Hydroxyethyl cellulose was used as a suspension agent to stabilize the soy protein and nano clay to be the dispersion system. The interaction between soy protein and Na MMT was characterized by XRD, FTIR, Zeta potential and DSC. Results indicated that soy protein molecules were adsorbed on the surface of the interlayer of Na MMT through hydrogen bonding and electrostatic interaction. The soy protein/Na MMT adhesives had the intercalation structure with Na MMT contents ranging from 1 to 11 %. Adhesion strength, specifically wet adhesion strength, of soy protein adhesives at isoelectric point (pI) was significantly improved by the addition of Na MMT. It is believed that the physical cross‐linking reactions between soy protein and Na MMT mainly contribute to the improved adhesion performance of soy protein adhesives. Wet adhesion strength increased from 2.9 MPa of control soy protein adhesive to 4.3 MPa at 8 % Na MMT. An increase of pH beyond pI value resulted in decreased adhesion strength due to increased surface charges of soy protein and slightly reduced affinity of soy protein on the nano clay surface.

Soy protein isolate nanocomposite film enriched with eugenol, an antimicrobial agent: Interactions and properties

“…have also observed some shifts of characteristic diffraction peak indicating the existence of structures with protein chains intercalated into the clay layers in nanocomposites SPI films containing 15 wt % MMT. As previously observed, the soy protein chains can be adsorbed on the surfaces of the interlayer of MMT and at their extremities through hydrogen bonding and electrostatic interaction …”

“…Chen and Zhang 11 have shown that highly exfoliated MMT layers were randomly dispersed in the protein matrix containing As previously observed, the soy protein chains can be adsorbed on the surfaces of the interlayer of MMT and at their extremities through hydrogen bonding and electrostatic interaction. 33 In the presence of eugenol (30% w/w SPI dry mater) and with 5 wt % clay content, the basal peak shifted down to 2u 5 4.28, corresponding to a slightly wider interlayer distance (21.0 Å ), which indicated that some SPI chains were intercalated between the clay platelets but full exfoliation was not achieved. In contrast, for a higher MMT content (7.5%), and the same eugenol concentration, the d 001 diffraction peak disappeared, suggesting that eugenol was well intercalated in the interlayer as demonstrated for other systems.…”

Exfoliating nanomaterials in canola protein derived adhesive improves strength and water resistance

“…20 Li et al (2016) recently studied the effect of modied sepiolite-based united crosslinked network in improving adhesion of soybean meal-based wood adhesive and reported an improvement of wet strength from 0.81 MPa to 1.18 MPa. 3 Another recent study by Qi et al (2016) reported an improvement of wet adhesion from 2.9 MPa to 4.3 MPa by exfoliating sodium montmorillonite at 8% w/w addition rate into soy protein isolate. 21 Both studies suggest that "physical lling effect" of sepiolite, 3 and nanomaterial induced crosslinking of protein network as the key factors contributing towards improving adhesion.…”

“…3 Another recent study by Qi et al (2016) reported an improvement of wet adhesion from 2.9 MPa to 4.3 MPa by exfoliating sodium montmorillonite at 8% w/w addition rate into soy protein isolate. 21 Both studies suggest that "physical lling effect" of sepiolite, 3 and nanomaterial induced crosslinking of protein network as the key factors contributing towards improving adhesion. 3,21 It is well recognized that proper dispersion and exfoliation of nanomaterials is a critical factor in their applications.…”

Properties of a new renewable sesame protein adhesive modified by urea in the absence and presence of zinc oxide

“…Many researchers have investigated plant protein-based adhesives such as soy protein-based adhesive, peanut protein-based adhesive, and cotton protein-based adhesive. [5][6][7][8][9][10][11] However, the low-water resistance and solid content of the plant protein-based adhesives have limited their application in the wood adhesive industry. 12 It is essential to improve water resistance of plant protein-based adhesives to expand their application.…”