A high-performance bio-adhesive derived from soy protein isolate and condensed tannins. Issue 34 (18th April 2017)

• Record Type: Journal Article
• Authors: Liu, Chang; Zhang, Yi; Li, Xiaona; Luo, Jing; Gao, Qiang; Li, Jianzhang
• Is Part Of: RSC advances. Volume 7:Issue 34(2017)
• Page Start: 21226
• Page End: 21233
• Publication Date: 2017-04-18
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra01210a
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : We describe the formulation of an adhesive only from natural products: soy proteins and condensed tannins. The main achievement is a high crosslinking density, which was attributed to aminomethylene bridges and covalent interactions. Abstract : In this research, condensed tannins (CTs) were modified by hexamine and mixed with soy isolate protein (SPI) under pH 9.0 conditions to form a series of new high-performance bio-adhesives (HCT-SPI). The adhesives had a compact structure and stable thermal performance according to the results of FTIR, SEM and TGA measurements. Their high crosslinking density was attributed to the crosslinking reaction of CT molecules via the imine groups of the hexamine decomposition product; another reason was that the ortho -quinone obtained via pyrocatechol oxidation on the tannins B ring led to covalent interactions and a crosslinking reaction with SPI molecules. The hydrolytic stability of HCT-SPI 5 adhesive (SPI 15 g, CTs 5 g, hexamine 2.5 g) increased by 3.2% compared to the native SPI-based adhesive, and the wet shear strength of plywood bonded by the HCT-SPI 5 adhesive was enhanced by 90.7% compared to plywood bonded by native SPI-based resins, which is acceptable for industrial application in plywood fabrication according to the China National Standard (≥0.7 MPa).