Fourier Transform Infrared (FT-IR) spectroscopy is widely used in characterization of bio-based wood adhesives. This technique is frequently used to detect the relevant FTIR features of dried powders of adhesive slurries, not cured adhesives under the bonding conditions. It is a challenge by using FT-IR to evaluate the impacts of bonding conditions (e.g., temperature, pressure, and time) on the adhesive performance. Attenuated total reflection (ATR) a sampling technique used in conjunction with FT-IR which enables samples to be examined directly in the solid or liquid state without further preparation. Thus, in this work, we directly placed the cohesively-broken bonding surface of the wood pairs glued by cottonseed protein on the ATR probe for FT-IR spectroscopic analysis.  This status quo” ATR FT-IR characterization shed light on the interaction of protein adhesive and wood substrate. Especially, ATR FT-IR spectra revealed the difference in the band shape around 2926 cm<sup>-1</sup> between different adhesive formations as well as between different bonding conditions. As the band features at 2926 cm<sup>-1</sup> are related to wettability (or hydrophobicity), the observation suggested the wettability of cured adhesives is an important factor to determine the interaction on the adhesive-wood bondlines. The data of the contact angle of a water drop on these strips were further confirmed the FT-IR observations.

“Status quo” ATR FT-IR spectroscopic characterization of the bonding interface of cottonseed protein adhesives with wood veneers

ACS Fall 2020 Virtual Meeting

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