Modification of soy proteins and their adhesive properties on woods

Abstract

Adhesive properties of trypsin‐modified soy proteins (TMSP) on woods were investigated. A simple method developed in our laboratory, consisting of measuring the force required to shear the bond between glued wood pieces in the Instron universal testing machine, was used to examine adhesive strength of modified soy proteins on wood. Adhesive strength of TMSP was measured for cold‐pressed (ambient temperature for 2 h) and hot‐pressed (60, 80, 100, and 120°C for times varying from 0.5 to 2.5 h) woods. Of the woods examined, soft maple gave the highest strength [743 Newtons (N) at a protein glue concentration of 2 mg/cm2]. For soft maple and cold‐pressing, TMSP at 2 mg/cm2 gave twice the adhesive strength of unmodified protein controls, 743 vs. 340 N. Also, the adhesive strength of TMSP increased from 284 to 743 N as glue concentration was increased from 1 to 2 mg/cm2. However, hot‐pressing of wood pieces beyond 1 h at 120°C and 30% relative humidity resulted in decreased adhesive strengths of TMSP compared to controls. Further, adhesive strengths of hot‐pressed glued wood samples decreased when the relative humidity at which they were kept for curing increased from 30 to 60%. This negative effect of increased humidity on adhesive strengths of glued wood pieces was not observed with cold‐pressed TMSP.

Adhesive Strength of Pilot-Scale-Produced Water-Washed Cottonseed Meal in Comparison with a Synthetic Glue for Non-Structural Interior Application

“…3;2017 were observed previously with protein-based wood adhesives (Kalapathy et al, 1995). Chemical reagents which denature protein's native structures could be used to improve the bonding ability at low temperatures whereas hot pressing is more effective way for higher bonding strength of the protein-based wood adhesives (Kalapathy et al, 1995;Zhong & Sun, 2001). It is reported that the adhesive strength of WCSM increased dramatically from press temperature at 40, 60, 80 o C to 100 o C (He et al, 2016a(He et al, , 2014a, and did not increased more between 110 and 130 o C of the tested range.…”

“…6, No. 3;2017 were observed previously with protein-based wood adhesives (Kalapathy et al, 1995). Chemical reagents which denature protein's native structures could be used to improve the bonding ability at low temperatures whereas hot pressing is more effective way for higher bonding strength of the protein-based wood adhesives (Kalapathy et al, 1995;Zhong & Sun, 2001).…”

Preparation and Testing of Plant Seed Meal-based Wood Adhesives

“…The adhesive slurries exampled in this protocol are simply the defatted seed meal product and water. Various adhesive formulations can be reached by addition of testing reagents (such as sodium dodecyl sulfate, sodium bisulfite or tung oil) 5,6,23 and/or changes in mixing conditions (such as pH, ratio of solid and water) 3,24,25 . Adjustment of the adhesive formulation is also needed if the rheological properties of the adhesive slurry are not suitable for appropriate application to the wood strips.…”

“…In the past two decades, this trend has reversed with renewed interest in the use of materials that are renewable, biodegradable, and more environmentally acceptable. These natural resources include, but are not limited to, soy protein [3][4][5] , cottonseed protein 6 , rice bran 7 , wheat gluten 8 , distillers grain protein 9 , canola protein and oil [10][11][12] , lignin from sorghum and sugar cane bagasse 13,14 , and polysaccharides derived from shrimp shells 15 .…”

Effect of Enzymatic Pretreatment on the Preparation and Properties of Soy-Based Adhesive for Plywood

“…Improved water resistance has also been observed in SBAs prepared from enzymatically treated soy protein. It has been demonstrated that SBAs developed from trypsin Kalapathy et al 1995), papain, and urease (Kumar et al 2004) resulted in treated soy protein with higher hydrophobicity, lower viscosity, and better water resistance compared with untreated soy protein. Moreover, several studies have reported that the water resistances of SBAs are also influenced by carbohydrates in DSF Hunt et al 2009;Chen et al 2013) because DSF is a complicated mixture consisting of approximately 50% protein, 40% carbohydrates, and other minor components (Bainy et al 2008;Chen et al 2013).…”