Soy and cottonseed protein blends as wood adhesives

Published Date
July 2016, Vol.85:324–330, doi:10.1016/j.indcrop.2015.12.024

Title 
Soy and cottonseed protein blends as wood adhesives ☆

• Author 

• H.N. Cheng ^,
• Catrina Ford
• Michael K. Dowd
• Zhongqi He

• Southern Regional Research Center, USDA Agricultural Research Service, 1100 Robert E. Lee Blvd., New Orleans, LA 70124, USA

Received 3 July 2015. Revised 8 December 2015. Accepted 11 December 2015. Available online 5 February 2016.

Highlights

• •
  Cottonseed protein exhibits better wood adhesive properties than soy protein.
• •
  In protein blends, the adhesive properties increase with increased cottonseed/soy protein ratio.
• •
  Use of polysaccharide filler can decrease the usage of protein in wood adhesives.
• •
  Adhesive properties tested include dry adhesive strength and hot water resistance.

Abstract

As an environmentally friendlier alternative to adhesives from petroleum feedstock, soy proteins are currently being formulated as wood adhesives. Cottonseed proteins have also been found to provide good adhesive properties. In at least some cases, cottonseed proteins appear to form greater shear strength and improved hot water resistance compared with soy proteins. In the present study, blends of soy and cottonseed proteins were prepared, and their adhesive properties were found to decrease steadily with increased levels of soy protein in the formulations. In addition, cottonseed- and soy-protein based adhesives were also formulated with xylan, starch, or celluloses to determine the influence of polysaccharide fillers on protein-based adhesive properties. In some cases, adhesive shear strength was retained even when the cottonseed or soy protein was mixed with up to 75% polysaccharide. For cottonseed protein/polysaccharide formulations, hot water adhesive resistance was retained when the blend contains about 50% polysaccharides. Soy protein formulations and its polysaccharide blends generally exhibited somewhat lower hot water resistance. In view of the ability of cottonseed protein/polysaccharide blends to retain shear strength and hot water resistance properties, these blends may provide an opportunity to decrease the amount of protein used in adhesive formulations, thereby decreasing cost.

Graphical abstract

Keywords

• Cottonseed protein
• Soy protein
• Protein blends
• Polysaccharide filler
• Adhesion
• Wood veneer

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• ☆
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