Differences in the Behaviour of Hardwood and Softwood Under Heat Treatment. Part 1. Strength Properties

Abstract

The differences in the mechanical behaviour of hardwood and softwood under heat treatment were investigated. There were 15.8% and 3.3% reduction in modulus of elasticity in the hardwood and softwood respectively while the loss in modulus of rupture is 32.9% and 15.6% in the hardwood and softwood respectively. The lower reductions in the strength properties in the softwood compared to the hardwood indicate that the former is less amenable to heat treatment than the latter. This is probably due to the higher acidity of the former, which could have resulted in higher degree of degradation, higher cellulose crystallinity and consequently higher strength reduction. From the results of this study, it is suggested that the effects of heat treatment on the strength properties of wood is more a function of the chemical composition of the material than its anatomical structure.

Keywords

HARDWOOD SOFTWOOD HEAT TREATMENT MODULUS OF ELASTICITY MODULUS OF RUPTURE

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References

BHUIYAN

M. T. R.

, HIRAI

and SOBUE

2000. Changes of crystallinity in wood cellulose by heat treatment under dried and moist conditions. Journal of Wood Science, 46(6): 431 —436.

DWIANTO

, MOROOKA

and NORIMOTO

. 1998. The compressive stress relaxation of albizia (Paraserienthes falcate Becker) wood during heat treatment. Journal of the Japan Wood Research Society, 44(6): 403 — 409.

GEIS SEN

and Du

Q. P

. 1995. Influence of heat treatment on the accuracy of wood moisture content determination by electrical resistance-type meters. Holz als Roh und Werkstoff. 53(5): 303 — 307.

HANGER

, HUBER

, LACKNER

, WIMMER

and FELLNER

. 2002. Improving the natural durability of heat-treated spruce, pine and beech. Holzforschung und Holzverwertung. 54(5): 92 — 93.

HODGIN

D. A.

and LEE

A. W. C

. 2002. Comparison of strength properties and failure characteristics between fire-retardant-treated and untreated roofing lumber after long-term exposure: A South Carolina case study. Forest Products Journal, 52(6): 91 — 94.

KAMDEM

D. P.

, PIZZI

and TRIBOULOT

M. C

. 2000. Heat-treated timber: potentially toxic byproducts presence and extent of wood cell wall degradation. Holz als Roh und Werkstoff, 58(4): 253 — 257.

KAMDEM

D. P.

, PIZZI

and JERMANNAUD

. 2002. Durability of heat-treated wood. Holz als Roh und Werkstoff, 60(1): 1 — 6.

KIM

G. H.

, YUN

K. E.

and KIM

J. J

. 1998. Effect of heat treatment on the decay resistance and the bending properties of radiata pine sapwood. Material und Organismen, 32(2): 101 — 108.

KUBOJIMA

, OKANO

and OHTA

. 2000. Bending strength and toughness of heat-treated wood. Journal of Wood Science, 46(1): 8 — 15.

10.

MANNINEN

A. M.

, PASANEN

and HOLOPAINEN

J. K

. 2002. Comparing the emissions between air-dried and heat-treated Scots pine wood. Atmospheric Environment, 36(11): 1763— 1768.

11.

OBATAYA

, TANAKA

, NORIMOTO

and TOMITA

. 2000. Hygroscopicity of heat-treated wood. I. Effects of after-treatments on the hygroscopicity of heat-treated wood. Journal of the Japan Wood Research Society, 46(2): 77 — 87.

12.

OBATAYA

and TOMITA

. 2002. Hygroscopicity of heat-treated wood. II. Reversible and irreversible reductions in the hygroscopicity of wood due to heating. Journal of the Japan Wood Research Society, 48(4): 288 — 295.

13.

RAPP

A. O.

and SAILER

. 2001. Oil-heat-treatment of wood-process and properties. Dryna Industrija. 52(2): 63 — 70.

14.

SAILER

, RAPP

A. O.

, LEITHOFF

and PEEK

R. D

. 2000. Upgrading of wood by application of an oil-heat treatment. Holz als Roh und Werkstoff. 58(1/2): 15 — 22.

15.

SANTOS

J. A

. 2000. Mechanical behavior of Eucalyptus wood modified by heat. Wood Science and Technology, 34(1): 39 —43.

16.

TEJADA

, OKUYAMA

, YAMAMOTO

, YOSHIDA

, IMAI

and ITOH

. 1998. Studies on the softening point of wood powder as a basis for understanding the release of residual stresses in logs. Forest Products Journal, 48(7-8): 84 — 90.