Value addition to agricultural waste and byproducts is a key in increasing economic return to farmers and processing industries. Soy meal, canola meal and poultry feathers are some of the agricultural byproducts that require value added applications. North America alone, produces more than 4 billion pounds of poultry feathers which contain ~90% protein, called keratin. Wood adhesives are mainly produced using petroleum byproducts; however, environmental and human health concerns regarding emission of formaldehyde and other volatile organic compounds and non-renewability in synthetic adhesives are prompting the industry to seek alternative bio-based polymers such as proteins. However, protein based adhesives have poor water resistance and adhesion strength compared to traditional wood adhesives. Keratin contains ~7% cysteine in its amino acid composition, which creates strong disulfide bonds among protein molecules making most functional groups unavailable to react with wood surface. However, the same unique structure of keratin provides a potential to use chemical modification in improving its functionality. We hypothesise that chemical modification with reducing agents will improve water resistance and functionality of keratin based wood adhesives; therefore the objective of this study is to improve adhesion strength and water resistance of keratin adhesives using chemical modification. Extracted keratins were modified using optimized concentrations of dithiothreitol (DTT) and Na2SO3. Adhesion strength was measured using Instron tensile loading according to the ASTM standard methods and data were analyzed using ANOVA followed by Duncan's multiple range test to identify the effects of reducing agents. Adhesives were characterized using XRD, FTIR, SEM and DSC for compositional, structural and thermal properties. Adhesion strength of keratin was significantly improved up to ~6-7 MPa and ~4-4.5 MPa for dry and wet adhesion strengths respectively under optimized conditions for DTT, without any delamination which was observed in control samples and some of Na2SO3 modified adhesives. Decrease in β-sheets and α-helix, increase in unordered structures in keratin secondary structure, change in keratin crystallinity and shift in thermal transitions were observed with modification. Chemical modification proved to have the potential for developing value added adhesive products from feather keratin with significantly improved functionalities.

Chemical modification of poultry feather keratin for biobased wood adhesive applications

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.