Novel whey protein‐based aqueous polymer‐isocyanate adhesive for glulam

Abstract

Whey, a by-product of cheese making, contains whey proteins, lactose, vitamins, and minerals. Whey and whey proteins are still not fully used. In this study, whey protein-based aqueous polymer-isocyanate (API) adhesives were developed and characterized by bond test, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscope (SEM) for bond strength, chemical structures, and morphology. The optimized whey protein-based API adhesive for Glulam had a 28-h boilingdry-boiling wet strength of 6.81 MPa and a dry strength of 14.34 MPa. Results indicated that the addition of polyvinyl acetate emulsion can prolong the work life of the API adhesive. Addition of crosslinker polymeric methylene bisphenyl diisocyanate (P-MDI) not only increased the cohesive strength of the cured adhesive by crosslinking whey proteins but also resulted in strong chemical bonds via urethane linkage in wood bondlines. Addition of polyvinyl alcohol (PVA) further increased the crosslinking density of the cured adhesive due to its capability of crosslinking whey proteins through the reaction with P-MDI. Nanoscale CaCO 3 powder (3.5 wt %) as filler significantly improved bond strength due to its mechanical interlock with the polymers in the adhesive. SEM examinations confirmed that both PVA and nanoscale CaCO 3 improved the compatibilities of the components in the optimized whey protein-based API adhesive. FTIR results revealed that P-MDI reacts mainly with the residual amino groups rather than the hydroxyl groups of whey proteins. V C 2010Wiley Periodicals, Inc. J Appl Polym Sci 120: [220][221][222][223][224][225] 2011

Formulation of a novel soybean protein‐based wood adhesive with desired water resistance and technological applicability

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The Effect of Carboxymethyl Cellulose Addition on the Properties of Starch-based Wood Adhesive

“…With increasing consumption of fossil resources, the contradiction between energy supply and demand is becoming more and more prominent. The raw materials of wood adhesive may gradually need to be replaced by renewable biobased polymers, such as soy protein, natural tannins, and starch (Moubarik et al 2009;Gao et al 2011;Wang et al 2012).…”

The effects of thermal-acid treatment and crosslinking on the water resistance of soybean protein

“…7. It has been confirmed that in a polyisocyanate-protein system, the isocyano groups of polyisocyanate mainly react with residual amino groups rather than the hydroxyl groups of proteins, which is attributed to the much higher reactivity of the isocyano-amino reaction than the isocyano-hydroxyl one (Gao et al, 2011). Some unreacted isocyano groups were detected at 2267 cm −1 , and these could react with the hydroxyl groups of wood to form strong interfacial adhesion via a chemical urethane bridge.…”