Dielectric spectroscopy of Scots pine
2009
Tomppo, Laura | Tiitta, Markku | Laakso, Tapio | Harju, Anni | Venäläinen, Martti | Lappalainen, Reijo
Dielectric properties of Scots pine (42 trees) were compared with density, moisture content (MC), and resin acid content (RAC) (of heartwood). The samples were measured in frozen, green, conditioned and non-conditioned dry moisture states to evaluate the potential of dielectric spectroscopy in determining the wood characteristics at different stages of wood processing. Heartwood and sapwood parts of each sample were measured separately, and through-transmission measurement was conducted in longitudinal and tangential direction at frequencies from 1 MHz to 1 GHz. The MC and density correlated significantly with the dielectric parameters in both measurement directions but especially in longitudinal direction. The RAC of the heartwood correlated significantly with tanδ and ε″/(ε′ − 1) of the green samples measured in the tangential direction at frequencies above 200 MHz. The correlation at 1 GHz was −0.56 for green samples, −0.66 for conditioned samples and −0.61 for non-conditioned samples (P < 0.001, for all). The study suggests that the extractives also affect radio-frequency dielectric responses, which might be used for extractive analyses of pine heartwood.
显示更多 [+] 显示较少 [-]