Wood Properties and Processing
Wood Properties and Processing

Author: Miha Humar

Publisher: MDPI

Published: 2020-05-23

Total Pages: 350

ISBN-13: 3039288210

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Wood-based materials are CO2-neutral, renewable, and considered to be environmentally friendly. The huge variety of wood species and wood-based composites allows a wide scope of creative and esthetic alternatives to materials with higher environmental impacts during production, use and disposal. Quality of wood is influenced by the genetic and environmental factors. One of the emerging uses of wood are building and construction applications. Modern building and construction practices would not be possible without use of wood or wood-based composites. The use of composites enables using wood of lower quality for the production of materials with engineered properties for specific target applications. Even more, the utilization of such reinforcing particles as carbon nanotubes and nanocellulose enables development of a new generation of composites with even better properties. The positive aspect of decomposability of waste wood can turn into the opposite when wood or wood-based materials are exposed to weathering, moisture oscillations, different discolorations, and degrading organisms. Protective measures are therefore unavoidable for many outdoor applications. Resistance of wood against different aging factors is always a combined effect of toxic or inhibiting ingredients on the one hand, and of structural, anatomical, or chemical ways of excluding moisture on the other.

Effect of Thinning and Fertilization on Wood Properties and Intra-ring Characteristics in Young Douglas-fir
Effect of Thinning and Fertilization on Wood Properties and Intra-ring Characteristics in Young Douglas-fir

Author: Josef Bodner

Publisher:

Published: 1983

Total Pages: 228

ISBN-13:

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The purpose of this study was to determine if thinning, fertilization or a combination of thinning and fertilization had an effect on overall average specific gravity, modulus of elasticity, modulus of rupture, fiber length and intra-ring characteristics. Material for this experiment consisted of 7 trees randomly selected from each of two thinning/fertilization treatments and a control (unthinned and not fertilized) stand. Thus a total of 21 trees were involved. The trees were cut in the summer of 1982. Static bending tests were done on juvenile and mature wood from trees of all plots at the butt and at a height of 18 feet. Specific gravity and fiber length were also determined. The intra-ring parameters (earlywood width, latewood width, ring width, earlywood density, latewood density, ring density, minimum earlywood density, maximum latewood density, density range and percentage latewood) were determined by X-ray studies. Statistical analyses showed significant differences between treatments (thinning, or thinning/fertilization) in modulus of elasticity, modulus of rupture, fiber lengths and all the intra-ring parameters. Overall average specific gravity did not differ significantly among treatments but did between butt and top (18-foot height) wood values. Ring width and ring density seemed most influential on mechanical properties. Average modulus of elasticity for the samples tested were 10.6% (for the thinning/fertilization experiment) and 17.3% (for the thinning experiment) less than comparable values in the control plot. Average modulus of rupture for the samples tested were 6.3% (for the thinning/fertilization experiment) and 12.4% (for the thinning experiment) less than comparable values in the control plot. Age seemed to have the most influence on fiber length. Thinning treatments within the tree age-range of juvenile wood affected intra-ring parameters less than did such treatments in the age-range of mature wood. Fertilization by itself did not significantly increase tree growth (annual ring width).

Age and Thinning Effects on Wood Properties of Red Spruce (Picea Rubens Sarg.)
Age and Thinning Effects on Wood Properties of Red Spruce (Picea Rubens Sarg.)

Author: Michael P. Wolcott

Publisher:

Published: 1987

Total Pages: 28

ISBN-13:

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Ten overstory red spruce were selected from a thinned stand and 10 from an unthinned stand. Average age of sample trees was approximately 80 years. Specific gravity reached a maximum at age 53 in the thinned stand and age 72 in the unthinned stand, after which it remained relatively constant. Stiffness reached a maximum at ages 35 and 50, and bending strength at ages 41 and 54; both remained relatively constant with further increases in age. Stiffness showed the largest relative difference between juvenile and mature wood, 22%, and specific gravity the smallest difference, 8%. Thinning did not adversely affect any of the properties, even though the width of some growth rings was increased by three to four times. These results suggest that (1) growth of mature red spruce stands can be increased by thinning without affecting wood physical properties, and (2) intensive management practices designed to shorten the rotation age may lead to stands that have not begun to produce mature wood before they are harvested. These short-rotation stands will contain a higher percentage of juvenile wood than stands presently being harvested, which means that pulp yields will decrease and the material will be less suitable for structural lumber.

Wood Quality and its Biological Basis
Wood Quality and its Biological Basis

Author: John Barnett

Publisher: John Wiley & Sons

Published: 2009-02-18

Total Pages: 240

ISBN-13: 1405147814

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Wood is the most versatile raw material available to man. It isburned as fuel, shaped into utensils, used as a structuralengineering material, converted into fibres for paper production,and put to newer uses as a source of industrial chemicals. Its quality results largely from the chemical and physicalstructure of the cell walls of its component fibres, which can bemodified in nature as the tree responds to physical environmentalstresses. Internal stresses can accumulate, which are releasedcatastrophically when the tree is felled, often rendering thetimber useless. The quality of timber as an engineering materialalso depends on the structure of the wood and the way in which ithas developed in the living tree. Tree improvement for quality cannot be carried out without anunderstanding of the biological basis underlying wood formation andstructure. This volume brings together the viewpoints of bothbiologists and physical scientists, covering the spectrum from theformation of wood to its structure and properties, and relatingthese properties to industrial use. This is a volume for researchers and professionals in plantphysiology, molecular biology and biochemistry.

Wood Variation
Wood Variation

Author: Bruce J. Zobel

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 376

ISBN-13: 3642740693

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Wood is the usual end product of a forestry operation. Because of its importance, numerous studies have been made relative to wood prop erties, the causes of wood variation, and how best to develop wood for desired products. There is voluminous literature related to these subjects, but it is neither well known nor appreciated by foresters because the publications are often not available or are not well understood by the forester or by those who use the wood. Frequently, the literature is confusing and contradictory, making it difficult for the nonspecialist to use what information is available. In order to produce and use wood efficiently, the variation pat terns within trees, among trees within species, and among species must be understood. This also requires some knowledge of the causes of variation and the effects of different wood properties upon utiliza tion. The information about variation patterns, their causes, and con trol and effect upon the product must be known by the tree grower, the tree breeder, and the tree harvester as well as by those who ultimately convert wood into a final, salable product.