Dynamic Sorption and Hygroexpansion of Wood Subjected to Cyclic Relative Humidity Changes. II. Effect of Temperature

Tiantian Yang, Erni Ma


To investigate the effect of temperature on the dynamic sorptive and hygroexpansive behavior of wood, poplar (Populus euramericana cv.) specimens, 20 mm in radial (R) and tangential (T) directions with two thicknesses of 4 mm and 10 mm along the grain, were exposed to a sinusoidally varying relative humidity between 45 and 75% for 1, 6, and 24 h at 25 and 40 °C. Moisture changes, as well as radial and tangential dimensional changes measured during cycling, produced the following results: moisture and dimensional changes in the specimens were generally sinusoidal, and an increase in temperature led to decreased moisture contents and transverse dimensions, accordingly. The amplitude of moisture and dimensional changes was in positive correlation with temperature, while the phase lag was inversely related to temperature. Sorption hysteresis and swelling hysteresis decreased as temperature increased. Both moisture sorption coefficient (MSC) and humidity expansion coefficient (HEC) were supposed to share the approximate value for different thick specimens if cyclic period is sufficiently long. Transverse anisotropy could be found under dynamic conditions, and the T/R was about 1.65 to 1.75, varying sinusoidally with a phase difference of about a half cycle to the imposed relative humidity.


Dynamic sorption; Hygroexpansion; Nonequilibrium state; Temperature; Wood

Full Text: PDF

Welcome to BioResources! This online, peer-reviewed journal is devoted to the science and engineering of biomaterials and chemicals from lignocellulosic sources for new end uses and new capabilities. The editors of BioResources would be very happy to assist you during the process of submitting or reviewing articles. Please note that logging in is required in order to submit or review articles. Martin A. Hubbe, (919) 513-3022, hubbe@ncsu.edu; Lucian A. Lucia, (919) 515-7707, lucian.lucia@gmail.com URLs: bioresourcesjournal.com; http://ncsu.edu/bioresources ISSN: 1930-2126