Extraction of Jatropha curcas proteins and application in polyketone-based wood adhesives

Jatropha proteins were successfully extracted from the corresponding seeds using the principle of isoelectric precipitation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), elemental analysis and Fourier transform infrared spectroscopy (FTIR) were used to analyze the obtained proteins. The proteins were used at different contents as a reactive component in polyketone-based wood adhesive formulations. The stability, structure, pot-life and performance of the emulsions as wood adhesive were studied at room temperature by using rheology analysis, confocal fluorescence microscopy and shear strength tests. Emulsions containing proteins were prepared at 45% solids content, a composition which results in phase separation when using only the reference polyketone-based adhesive. Several factors, such as the particle size (100, 250 μm) of the Jatropha proteins and the overall chemical composition of the emulsion, were systematically studied regarding their influence on the product performance. The present study shows that introducing Jatropha proteins into the basic recipe of a polyketone-based adhesive constitute a successful strategy for improving the performance as wood adhesives while at the same time significantly improving the economical attractiveness of these adhesive formulations. All emulsions presented in this work fulfill the requirements for the application of the final product as wood adhesives according to the European EN-314 Standard.