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

Dynamic mechanical analysis (DMA) measurements of water-saturated radiata pine wood in the temperature range from 0 degrees C to 100 degrees C 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 tan delta caused by micro-Brownian motion of lignin was observed in all samples. The temperature of peak tan delta tended to decrease from earlywood to latewood within an annual ring. The temperature of peak tan delta 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.

Automated summary

This study utilized dynamic mechanical analysis (DMA) to measure the viscoelastic properties of water-saturated radiata pine wood in the temperature range of 0 to 100 degrees Celsius, aiming to understand the transitional behavior within successive annual rings. The results showed that the peak tan delta temperature caused by micro-Brownian motion of lignin varied between different annual rings and within the same ring.