Lesson 1-3 Flashcards
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
an area of land covered with
a thick growth of trees with a less shade compared to a true forest
Woods
A branch of wood science which deals with the non mechanical properties of wood.
Wood Physics
Theory of the physical and mechanical properties of wood and wood-based materials
Wood Physics
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
The ability of wood to absorb and lose water.
Hygroscopicity
Non-hygroscopic
0-0.12
Slightly hygroscopic
0.2-2
Moderately hygroscopic
2.0-15
Types of water in wood
Bound water
Free water
Water of constitution
Very hygroscopic
> 15
Water found associated in the cell wall
Bound water
Water in the cell lumen, cavities and intercellular spaces.
Free water
Water found associated with the chemical structure which is part of the molecular built-up of wood.
Water of constitution
The amount of water in wood expressed as the percentage of its oven dry weight.
Moisture Content
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
A point when all water is evaporated from the cell cavities but the cell walls are still fully saturated with moisture.
Fiber Saturation Point
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
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
Computing the dimensional and volumetric changes in wood.
Anisotropy
What is one of the areas where the attribute of shrinkage anisotropy is evidently seen?
Dimensional Shrinkage
One of the areas where this attribute is most evidently seen is in the dimensional shrinkage.
Shrinkage Anisotropy
The quality of having different properties along different directions.
Anisotropy
The wood has different properties depending on its 3 grain directions or sections which are the Tangential, Radial, and Longitudinal Directions.
Anisotropy
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?
- Restricting effect of ray on radial plane
- Cell wall on T direction is thicker than radial
- Increased thickness of middle lamella in Tan. wall compared to Rad. wall
- 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?
- centimeter-gram-second system (CGS)
- 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
