Abstract
Phenol-urea-formaldehyde-tannin (PUFT) adhesives were prepared by co-polymerization of Pinus pinaster bark tannins with phenol-urea-formaldehyde (PUF) prepolymers at room temperature. A detailed analysis by 13C-NMR spectroscopy of the resins together with an evaluation of their properties was performed in order to find suitable preparation conditions for prepolymers prior to their co-polymerization with tannins. 13C-NMR spectroscopy allowed identification of the different linkages formed and quantification of the main functional groups in the PUF prepolymers, which were greatly influenced by the preparation conditions. The decrease in the free formaldehyde content in the PUFT adhesives with respect to the original prepolymers was attributed to tannin methylolation at room temperature. The fast increase in the apparent viscosity of the PUFT adhesives after the blending suggested the possibility of a co-polymerization reaction between tannins and the PUF prepolymers; however, the occurrence of this reaction could not be confirmed by 13C-NMR.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
