Monitoramento do teor de umidade de madeiras de Pinus elliottii Engelm. E Eucalyptus grandis W. Hill ex Maiden, sob diferentes temperaturas de secagem, através do ultra-som

• Main Authors: Leandro Calegari, Diego Martins Stangerlin, Elio José Santini, Clovis Roberto Haselein, Solon Jonas Longhi, Paulo Inácio Obregon do Carmo, Luiz Carlos Pinto da Silva, Darci Alberto Gatto
• Format: Article
• Language: Portuguese
• Published: Universidade Federal de Santa Maria 2007-01-01
• Series: Ciência Florestal
• Online Access: http://www.redalyc.org/articulo.oa?id=53417411

With the purpose of evaluating the viability of use of ultrasonic technique to estimate the wood moisture content during the drying process, samples of Pinus elliottii Engelm. and Eucalyptus grandis W. Hill ex Maiden with dimensions of 3.5 cm thick, 10 cm width and 25 cm long were submitted to drying temperatures of 20, 40 and 70ºC. A PUNDIT ultrasonic equipment with plane face transducers by 50 KHz was used to measure sound velocity in the longitudinal direction of the wood. Results indicated increase of estimated ultrasonic speed with reduction of moisture content. This relationship showed to be valid for the wood from green to the end of the drying process, and the best determination coefficients were found in the eucalypt wood (R² = 81%). Although no influence of the species in the ultrasonic speed has been observed, this one was influenced by the wood specific gravity and by the drying temperature. The effect of the specific mass was directly proportional for the pinus wood. Opposite effect was observed in eucalypt wood. The ultrasonic speed tended to decrease as drying temperature increased for both species. Results suggest that this method presents good potential for the control of the drying process.