@Article{jrm.2021.015066,
AUTHOR = {Xinyi Chen, Antonio Pizzi, Xuedong Xi, Xiaojian Zhou, Emmanuel Fredon, Christine Gerardin},
TITLE = {Soy Protein Isolate Non-Isocyanates Polyurethanes (NIPU) Wood Adhesives},
JOURNAL = {Journal of Renewable Materials},
VOLUME = {9},
YEAR = {2021},
NUMBER = {6},
PAGES = {1045--1057},
URL = {http://www.techscience.com/jrm/v9n6/41722},
ISSN = {2164-6341},
ABSTRACT = {Soy-protein isolate (SPI) was used to prepare non-isocyanate polyurethane (NIPU) thermosetting adhesives for
wood panels by reacting it with dimethyl carbonate (DMC) and hexamethylene diamine. Both linear as well
as branched oligomers were obtained and identified, indicating how such oligomer structures could further
cross-link to form a hardened network. Unusual structures were observed, namely carbamic acid-derived
urethane linkages coupled with lactam structures. The curing of the adhesive was followed by thermomechanical
analysis (TMA). It appeared to follow a two stages process: First, at a lower temperature (maximum 130°C), the
growth of linear oligomers occurred, finally forming a physically entangled network. This appeared to collapse
and disentangle, causing a decrease of MOE, as the temperature increases. This appears to be due to the ever more
marked Brownian movements of the linear oligomer chains with the increase of the temperature. Second, chemical cross-linking of the chains appeared to ensue, forming a hardened network. This was shown by the thermomechanical analysis (TMA) showing two distinct MOE maxima peaks, one around 130°C and the other around
220°C, with a very marked MOE decrease between the two. Plywood panels were prepared and bonded with the
SPI-NIPU wood adhesive and the results obtained are presented. The adhesive appeared to pass comfortably the
requirements for dry strength of relevant standards, showing to be suitable for interior grade plywood panels. It
did not pass the requirements for wet tests. However, addition of 15% of glycerol diglycidyl ether improved the
wet tests results but still not enough to satisfy the standards requirements.},
DOI = {10.32604/jrm.2021.015066}
}