Transition in viscoelastic properties within successive annual rings of radiata pine (Pinus radiata)

Abstract

Dynamic mechanical analysis (DMA) measurements of water-saturated radiata pine wood in the temperature range from 0 ℃ to 100 ℃ were focused to clarify the transition in viscoelastic properties within successive annual rings. Four radially consecutive specimens were taken per annual ring and DMA measurements in the tangential direction were performed using these specimens. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in all samples. The temperature of peak tanδ tended to decrease from earlywood to latewood within an annual ring. The temperature of peak tanδ increased across annual ring boundary. The same trend was repeated within the next annual ring. It was found that the viscoelastic properties transitioned within successive annual rings.