scholarly journals Wood and Wood Based Materials. Effects of Moisture Content on Bending Properties and Creep Behavior of Phenolic-Resin-Treated Particleboards.

1998 ◽  
Vol 47 (4) ◽  
pp. 339-343
Author(s):  
Hiromu KAJITA ◽  
Hiroyuki YANO
Holzforschung ◽  
2008 ◽  
Vol 62 (5) ◽  
Author(s):  
John F. Hunt ◽  
Jane O'Dell ◽  
Chris Turk

Abstract Fibers from treetop residues of lodgepole pine (Pinus contorta) and recycled old corrugated containers were used to fabricate wet-formed fiberboard panels over a range of densities from 300 to 1100 kg m-3, a thickness range from 1.3 to 4.8 mm, and phenolic resin contents from 0% to 4.5%. The panels were then tested after conditioning in 50% and 90% relative humidity (RH) environments. Density, thickness, equilibrium moisture content, bending modulus of elasticity (MOE), and modulus of rupture (MOR) were measured for each panel. Panel apparent-density increased with thickness, but this may be due to surface effects rather than true density values. The equilibrium moisture content approximately doubled for the panels in the 90% RH environment, compared to 50% RH. At 50% and 90% RH conditions, equilibrium moisture contents decreased significantly when only 0.5% resin was added and remained essentially the same with increasing resin levels. In this study, both MOE and MOR increased with approximately the square of density. MOE increased, whereas MOR showed no clear effects as thickness and resin amount increased. This research is part of a larger program for developing an understanding of panel properties for engineered three-dimensional fiberboard products.


1995 ◽  
Vol 34 (12) ◽  
pp. 4520-4523 ◽  
Author(s):  
Linda F. Lorenz ◽  
Alfred W. Christiansen

Bauingenieur ◽  
2018 ◽  
Vol 93 (03) ◽  
pp. 95-102 ◽  
Author(s):  
M. Drexel ◽  
Y. Theiner ◽  
G. Hofstetter

Im vorliegenden Beitrag wird ein umfangreiches Versuchsprogramm zum Schwinden und Kriechen unter Druckbeanspruchung eines Betons der Festigkeitsklasse C 30/37 vorgestellt. An versiegelten und unversiegelten zylindrischen Probekörpern wurde die zeitliche Entwicklung (i) der autogenen Schwinddehnungen, (ii) der kombinierten autogenen Schwind- und Trocknungsschwinddehnungen, (iii) der totalen Dehnungen von im Alter von zwei, sieben und 28 Tagen mit 30 % der jeweiligen Druckfestigkeit belasteten Probekörpern und (iv) des Feuchtegehalts der Schwind- und Kriechprobekörper ermittelt. Dadurch konnte der Einfluss der Druckbelastung auf den Feuchtegehalt in Abhängigkeit des Betonalters bei Belastungsbeginn sowie der Einfluss des Feuchteaustausches zwischen Probekörper und trockenerer Umgebungsluft auf das Kriechen (Pickett-Effekt) und Schwinden von Beton untersucht werden. Zusätzlich wurde die Desorptionsisotherme für fünf verschiedene Werte der relativen Luftfeuchtigkeit ermittelt sowie die zeitliche Entwicklung der Druckfestigkeit und des Elastizitätsmoduls jeweils an bis zur Prüfung versiegelten Probekörpern bestimmt.


Author(s):  
Ying-dan Zhu ◽  
Nan Fu ◽  
Dong Li ◽  
Li-jun Wang ◽  
Xiao Dong Chen

Abstract:The study is conducted to investigate the physical and viscoelastic properties of the highland barley kernels in different moisture content range from 10.1 %% to 20.5 %% (w.b.). Highland barley kernel samples were selected with physical properties in terms of length, width, thickness, 1000-kernel weight, volume, geometric and arithmetic mean diameter changing in linear trends. By using a dynamic mechanical analyzer, the 4-element Burgers model was found to adequately represent the creep behavior of the highland barley kernels (R2> 0.977). The creep behavior of the ventral groove and dorsal side was also matched perfectly with Burgers model (R2> 0.946). The creep behavior of these kernels at long-time frame was studied applying time-temperature superposition (TTS). TTS method was successfully used to predict the creep behavior of these kernels at longer frame of time. TheTgvalues for the kernels decreased with increasing moisture content. TheTgvalues for the kernels at the moisture contents of 10.1 %%and 20.5 %% were 114.33 °C and 67.95 °C, respectively. The magnitude of the storage modulus, loss tangent and their change rates with frequency were maximum at 10.1 %% and minimum at 20.5 %% moisture contents.


2010 ◽  
Vol 69 (4) ◽  
pp. 633-639 ◽  
Author(s):  
Satoshi Fukuta ◽  
Atsushi Watanabe ◽  
Yuichi Akahori ◽  
Akira Makita ◽  
Yuji Imamura ◽  
...  

Holzforschung ◽  
2006 ◽  
Vol 60 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Chika Takahashi ◽  
Yutaka Ishimaru ◽  
Ikuho Iida ◽  
Yuzo Furuta

Abstract The creep of wood increases remarkably during moisture changes, a phenomenon called mechano-sorptive creep. The microstructure in cell walls of wood is destabilized by changes in temperature and/or moisture content. The mechanical properties of destabilized wood change over long periods of time. In the present study, the influence of moisture conditioning history on bending creep was examined. During changes in moisture, greater creep occurred in wood subjected to the first moisture change after long-term moisture conditioning than immediately after desorption or adsorption. This result indicates a kind of memory effect immediately after moisture change. During desorption processes, greater creep occurred immediately after slow adsorption than immediately after rapid adsorption. In the course of adsorption, the reverse was observed: the creep was greater immediately after rapid desorption than immediately after slow desorption. Accordingly, greater instability immediately after a change in moisture does not always cause greater creep during the next moisture change. The size of the moisture change and the load level affect the recovery of creep during adsorption processes.


CATENA ◽  
2020 ◽  
Vol 187 ◽  
pp. 104371 ◽  
Author(s):  
Xingang Wang ◽  
Jiading Wang ◽  
Hongbin Zhan ◽  
Ping Li ◽  
Haijun Qiu ◽  
...  

2006 ◽  
Vol 100 (7) ◽  
pp. 074911 ◽  
Author(s):  
J. Fortineau ◽  
F. Vander Meulen ◽  
L. Haumesser ◽  
G. Feuillard ◽  
S. Barré ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document