Abstract
Viscoelastic Thermal Compression (VTC) of wood is a treatment which greatly improves material properties by means of densification with mechanical compression perpendicular to the grain. VTC is similar to other wood densification processes, but is designed for thin lamina and employs dynamic temperature and steam pressure conditions. A device was constructed that is capable of producing VTC wood. Details of the construction and operation of the VTC device are presented. The device consists of a pressurized chamber with variable volume. Wood density may be modified from the initial density of the virgin wood up to approximately 1400 kg/m3. Control of steam pressure and temperature insures that the wood cell walls are not fractured during the process. The device is designed for batch operation and may be adapted to a conventional laboratory hot-press. An example operating schedule is described, but other procedures are possible within the design parameters of the device.
Zusammenfassung
Viskoelastische thermische Verdichtung (Viscoelastic Thermal Compression – VTC) ist ein Verfahren, das die Materialeigenschaften von Holz mittels Verdichtung quer zur Faserrichtung stark verbessert. Das VTC Verfahren ähnelt anderen Holzverdichtungsverfahren, wurde jedoch für dünne Holzbrettchen entwickelt und nutzt wechselnde Temperatur- und Druckbedingungen. Entwickelt wurde ein Gerät zur Produktion von VTC Holz, dessen Einzelheiten der Konstruktion und des Betriebes hier vorgestellt werden. Das Gerät besteht aus einem Druckbehälter mit veränderbarem Volumen. Dieses Gerät kann Holz ausgehend von der Ausgangsdichte bis zu einer Dichte von 1400 kg/m3 verdichten. Die Steuerung des Dampfdruckes und der Temperatur gewährleistet, dass die Zellwände des Holzes während der Behandlung nicht zerstört werden. Das VTC Gerät wurde für den diskontinuierlichen Betrieb entwickelt und kann in eine Laborheißpresse eingebaut werden. Ein Beispiel eines Betriebsplanes ist hier beschrieben. Das Gerät kann jedoch auch unter Nutzung anderer Systemgrößen betrieben werden, solange die Maximalwerte des Gerätes nicht überschritten werden.
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Acknowledgements
Funding for this work was provided by USDA Cooperative State Research, Education and Extension Service, National Research Initiative Grant # 2006-35504-17444, and the JELD-WEN Foundation.
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Kamke, F.A., Rathi, V.M. Apparatus for viscoelastic thermal compression of wood. Eur. J. Wood Prod. 69, 483–487 (2011). https://doi.org/10.1007/s00107-010-0461-7
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DOI: https://doi.org/10.1007/s00107-010-0461-7