Vibroacoustic properties as a function of crystallinity changes in heat-treated Pinus radiata D. Don wood

In this work, the relationship between relative crystallinity with mechanical and vibroacoustic properties of Pinus radiata wood, before and after heat treatment, was studied. Heat treatment was applied using a laboratory oven with a tray of liquid nitrogen inside to generate an oxygen-depleted atmosphere. To determine the vibrational properties, a free beam measurement system was used, and by means of an FTIR infrared imaging system, the relative crystallinity in the wood was determined. There were differences in properties between untreated and treated wood depending on the treatment conditions. In treated samples, the higher temperature and time produce an increase in the coefficient of sound radiation, a decrease in specific acoustic impedance and a non-significant change in the speed of sound. Moreover, the best degree of association between crystallinity and mechanical and vibrational properties was achieved at higher temperature and time, coinciding in turn with the conditions that allow an improvement in the vibrational properties of Pinus radiata wood. In general, the relationships described in this work contribute to the consideration that fast-growing species can have a more noble use through heat treatments.