Dielectric properties of silicon dioxide/wood composite

For a better understanding of the binding between silicon dioxide and wood as well as the dielectric properties of silicon dioxide/wood composite, dielectric relaxation was measured for untreated wood [Cunninghamia lanceolata (Lamb.) Hook] and for silicon dioxide/wood composite with different weight percentage gain (WPG). Cole-Cole's circular arc law, distribution spectrum of relaxation time and relation model were applied to the results of relaxation due to motions of the methylol groups. The results were as follows. The generalized relaxation time and ε s - ε [infinity] decreased with increasing WPG. The distribution spectrum of relaxation time decreased more and more and broadened with increasing WPG. The methylol group in the amorphous region of the wood cell wall participated in hydrolysis reaction and condensation reaction caused by tetraethylorthosilicate (TEOS), and there is a cross-link between silicon dioxide and wood. The value of apparent activation energy (ΔE) increased for silicon dioxide/wood composite, and increased with increasing WPG. Activation enthalpy (ΔH) and activation entropy (ΔS) increased, while activation free energy (ΔG) decreased with increasing WPG. The number of hydroxyl groups cut in dielectric relaxation increased with increasing WPG.