Lesson 1-3 Flashcards by Docayag Angelica S.

a hard substance that forms the branches and trunks of trees that can be used as a building material, for making things, or as a fuel.

Wood

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an area of land covered with
a thick growth of trees with a less shade compared to a true forest

Woods

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A branch of wood science which deals with the non mechanical properties of wood.

Wood Physics

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Theory of the physical and mechanical properties of wood and wood-based materials

Wood Physics

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What determines the non-mechanical properties of wood or the factors inherent in the structural organization of wood?

1.Amount of water in the cell wall
2. Amount of water substances
3. Amount of extractives
4. Arrangement of cell wall materials
5. Kind and size of woody tissues

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The ability of wood to absorb and lose water.

Hygroscopicity

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Non-hygroscopic

0-0.12

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Slightly hygroscopic

0.2-2

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Moderately hygroscopic

2.0-15

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Types of water in wood

Bound water
Free water
Water of constitution

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Very hygroscopic

> 15

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Water found associated in the cell wall

Bound water

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Water in the cell lumen, cavities and intercellular spaces.

Free water

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Water found associated with the chemical structure which is part of the molecular built-up of wood.

Water of constitution

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The amount of water in wood expressed as the percentage of its oven dry weight.

Moisture Content

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What are the factors affecting MC of wood?

Dependent on the relative humidity and temp. of its surrounding air.
MC rises and falls irregularly with variations in the atmospheric conditions around

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A point when all water is evaporated from the cell cavities but the cell walls are still fully saturated with moisture.

Fiber Saturation Point

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A condition by which the moisture content of the wood is balanced with that of the atmospheric moisture condition and wherein the wood is neither gaining nor losing moisture

Equilibrium Moisture Content

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The ratio of the amount of water or moisture that is present in the air compared to the greatest amount it would be possible for the air to hold at that temperature

Relative Humidity

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Computing the dimensional and volumetric changes in wood.

Anisotropy

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What is one of the areas where the attribute of shrinkage anisotropy is evidently seen?

Dimensional Shrinkage

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One of the areas where this attribute is most evidently seen is in the dimensional shrinkage.

Shrinkage Anisotropy

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The quality of having different properties along different directions.

Anisotropy

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The wood has different properties depending on its 3 grain directions or sections which are the Tangential, Radial, and Longitudinal Directions.

Anisotropy

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Why do we need to know anisotropy?

It is used in determining properties of various directions and wise utilization of wood.

Urban Wood Utilization: Top Branches? Bottom Branches? Trunk

Mulch Firewood, Fuel wood Lumber, veneer, others

Reduction in wood dimension and volume as it losses moisture below FSP expressed in percent.

Shrinkage

Bound water is removed from the cell wall

Shrinkage

Wood Shrinkage occurs in:

RS, TS, LS

the amount the wood moves perpendicular to the growth rings or along the radial or medullary rays that transport nutrients into the interior of the tree.

Radial Shrinkage

This is a small amount of movement but still should be accounted for.

Radial Shrinkage

THE AMOUNT THE WOOD MOVES ALONG THE GROWTH RINGS.

Tangential Shrinkage

The greatest amount of movement a lumber experiences.

Tangential Shrinkage

What are the reasons for higher tangential shrinkage?

1. Restricting effect of ray on radial plane 2. Cell wall on T direction is thicker than radial 3. Increased thickness of middle lamella in Tan. wall compared to Rad. wall 4. Early wood and latewood relationship. Orientation of the Microfibril angle

Grain that is parallel, or tangent, to the growth rings.

Tangential Plane

Grain that is perpendicular to growth rings.

Radial plane

The amount a piece of wood will shrink lengthwise that is usually inconsequential to volumetric change.

Longitudinal Shrinkage

Increase in wood dimension and volume as it gains moisture below FSP expressed in percent.

Swelling

This continues until the cell wall become completely saturated.

Swelling

Density is how much space an object or substance takes up (__ _____) in relation to the amount of matter in that object or substance (__ ____).

its volume, its mass

It is how much space an object or substance takes up (volume) in relation to the amount of matter in that object or substance (mass).

Density

The amount of mass per unit of volume

Density

Materials that are _____ are most likely to ‘feel’ ______ or ___

dense, heavy or hard.

Solid wood substance in a given volume of wood – but they are expressed somewhat differently.

Wood density

Density differs depending on the _______ __ ______(cell wall) and______ (cell lumen) ______ in the certain volume of wood

extent of material , voids present

Important physical properties of all wood resources both for softwoods and hardwoods

Wood Density

Used to measure the amount of these wood substances (dead cell, cell walls and cell cavities

Wood Density

Types of Density

APPARENT DENSITY CONVENTIONAL DENSITY

▪the ratio, expressed in g / cm³, between the apparent mass and volume of wood

APPARENT DENSITY

ρc) represents the ratio of wood mass a.u. (anhydrous) and the maximum volume of the same sample (the maximum volume is the wood with saturated moisture fiber)

CONVENTIONAL DENSITY

g/cc

centimeter-gram-second system (CGS)

kg/m3

international system (SI)

lb/ft3

inch-pound system (I-P)

What are the units to measure the density of wood?

1. centimeter-gram-second system (CGS) 2. international system (SI) 3.inch-pound system (I-P)

density is calculated using the weight and volume of a certain wood at the _____ __

same %MC

Every time the density values are provided, the ___ at which the density is computed should be _____.

%MC, specified

1 kg= __g

1000g

1 cm = __ ft

0.032 ft

1 m= __ cm

100 cm

1 lb= __ kg

0.45 kg

1 in= __ cm

2.54 cm

1 ft= __ m

0.30 m

1 bdft= __ cu. m

0.0023597 cu.m

Strongest direction

Longitudinal

High density is equal to high specific gravity because the substance is = to the _____ ___ __ ___.

specific density of water

Fast growing species have ____ _____.

Lower density or less dense

It is the important physical properties of all wood resources

Density

Higher the ration of density -

the denser the wood

Latewood have _____ _____.

Higher density

It is made of cells which have denser walls and smaller voids as compared to early wood.

Late wood

Greater growth rings and Higher latewood

Hardwood

Fast growing but lower thinner/lower latewood

Softwood

______ _______ is prone to splitting and have the greatest amount of movement.

Tangential shrinkage

Weakest direction

Tangential