Abstract
The preparation method of a PMUF resin manufactured in a single synthesis procedure has been shown to have fundamental importance both at the molecular level and for the resin application performance. 13C NMR spectra of PMUF resins present excellent correspondence with applied tensile strength results of plywood prepared with the same resins. PMUF resins prepared by initial reaction of phenol with formaldehyde followed by standard MUF preparation procedures present better results than resins prepared with the phenol either added during the preparation or added at the end of the MUF resin preparation. The reason for this is the reaction procedure itself which ensures that the phenol is copolymerized with the main MUF chain to form a block copolymer and that both PF and MUF resin blocks still present consistent amounts of reactive methylol groups. Progressive deviation from these molecular level requirements during the course of PMUFs preparation also ensures a progressive deviation from their optimal performance, even leading to PMUF resins of worse performance than their corresponding MUF resin to which phenol has not been added.
Zusammenfassung
Die Präparationsmethode eines PMUF-Harzes hats eine grundlegende Bedeutung sowohl für die Molekülstruktur als auch das Klebeverhalten. 13C NMR Spektren der Harze stehen in ausgezeichneter Übereinstimmung mit der Festigkeit der damit hergestellten Sperrhölzer. Wenn vor der Standardpräparation des PMUF-Harzes zunächst eine Phenol/ Formaldehyd-Kondensation gestartet wird, erhält man bessere Ergebenisse als bei späterer Zugabe des Phenols. Auf diese Weise wird eine Kopolimerisation der MUF-Ketten mit Phenol schergestellt. In diesem Block-Kopolymer weisen beide Harzkomponenten noch genügend reaktive Methylolgruppen auf. Abweichungen von dieser Präparationsmethode führen zu entsprechenden Verschlechterungen der Klebereigenschaften, bis dahin, daß sogar minderwertigere PMUF-Harze entstehen können als ensprechende MUF-Harze ohne Phenolzusatz.
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References
Breitmaier, E.; Voelter, W. 1987: Carbon-13 NMR Spectroscopy, 3rd Edition, VCH, Weinheim
Cremonini, C.; Pizzi, A.; Tekely, P. 1996: Improvement of PMUF adhesives performance for fireproof plywood, Holz Roh Werkstoff, 54:
Dunky, M. 1995: private communication European Norm UNI EN314, pretreatment 5.1.3, Plywood bonding quality (1993)
Ferg, E. E.; Pizzi, A.; Levendis, D. 1993: A 13C NMR Analysis method for urea-formaldehyde resin strength and formaldehyde emission, J. Appl. Polymer Sci., 50: 907–915
Higuchi, M.; Roh, J.-K.; Tajima, S.; Irita, H.; Honda, T; Sakata, I. 1994: Polymeric structures of Melamine based composite adhesives, in Chapter 6, Adhesives and Bonded Wood Products (C.-Y. Hse, B. Tomita and S. J. Branham, Eds.), Forest Products Society, Madison, Wisconsin, 429–449
Pizzi, A.; 1983: Wood adhesives Chemistry and Technology, Vol. 1, Dekker, New York
Pizzi, A. 1994: Advanced Wood Adhesives Technology, Dekker, New York
Tomita, B.; Hatono, S. 1993: Urea-formaldehyde resins III: Constitutional characterization by 13C Fourier transform NMR spectroscopy, J. Polymer Sci., 16: 2509–2517
Van Niekerk, J.; Pizzi, A. 1994: Characteristic industrial technology for exterior Eucalyptus particleboard, Holz Roh Werkstoff, 52: 109–112
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Cremonini, C., Pizzi, A. & Tekely, P. Influence of PMUF resins preparation method on their molecular structure and performance as adhesives for plywood. Holz als Roh-und Werkstoff 54, 85–88 (1996). https://doi.org/10.1007/s001070050142
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DOI: https://doi.org/10.1007/s001070050142