Effect of weight percent gain and experimental method on fiber saturation point of acetylated wood determined by differential scanning calorimetry

Abstract

This paper evaluates the effects of acetylation level and experimental method on the observed fber saturation point (FSP) of loblolly pine (Pinus taeda)woodmeasuredusing differential scanning calorimetry. To achieve this goal, 1-mm-thick latewood samples were tested overawiderange of equilibrium moisture content(EMC). In this work, the FSP was defined as the non-freezable portion of water of the samples.Two experimental methods were used: the extrapolation of the melting enthalpy to zero and the direct calculation of the non-freezable water amount. For both methods, the FSP decreased with increasing acetylation, varying from about 27% reduced EMC (EMC_R) for control to about 9% EMCR for the highest level of acetylation. For unmodifed samples, the measured FSP was higher with faster scan rates. Moreover, under a specifc range of EMCR, freezing curves revealed the occurrence of two water phase transitions for samples at the highest level of acetylation. Based onprevious studies andinpresent fndings, there is strong evidence that the lower temperature freezing peak may result from the homogenous nucleation of water, which is physically separated from water that freezes heterogeneously.

Citation

Passarini, Leandro; Zelinka, Samuel L.; Glass, Samuel V.; Hunt, Christopher G. 2017. Effect of weight percent gain and experimental method on fiber saturation point of acetylated wood determined by differential scanning calorimetry. Wood Science and Technology. 51(6): 1291-1305.