Dr.Elders stupid products class

Juvenile Wood

Produced in the first year of growth.

Properties of Juvenile Wood

Generally lower quality, More hemicellulose and lignin.

Reaction Wood

Formed in response to non-vertical growth.

Compression Wood

formed in soft wood. Stem shape is eccentric. higher lignin and hemicellulose count

Opposite wood

Occurs opposite to compression wood, high fibril angle. lower lignin than compression wood

Tension wood

Occurs in hardwoods. paper made of tension wood is weak. sawing and machining is difficult with this type of wood.

Branchwood

small diameter, large proportion of bark.

Rootwood

Large amounts of fiber. large amounts of dirt that can cause excessive tool wear

Drying of Wood

removes water from the cell lumens

Greenwood

Moisture in greenwood is important because it adds weight and to the transportation costs

Fiber Saturation Point

Point at which all water is removed from the lumens but the cell wall is still completely saturated

Free Water

Liquid water present in the lumens, removed first in the drying process

Bound Water

Water in the cell wall, as moisture content decreases below the FSP the removal of water becomes more difficult

Moisture Content Calculations- Dry Basis MC

Dry basis MC = (green wt-OD wt/OD wt)*100

Moisture Content Calculations- Wet basis

Wet basis MC = (green wt-OD wt/ green wt) * 100

Measurement of Moisture Content- Oven Drying

Weigh in the wet sample, dry in the oven at 105. weigh dry sample, calc moisture content

Electronic Moisture Content

Fast, but only work below FSP

Resistance moisture meters

Electrical resistance between the pins is measures

Capcitance moisture meters

Capacitance varies with density

Does wood shrink above or below FSP

Below FSP

does wood swell when FSP changes, or when RH and MC change

RH and MC

Shrinkage % formula

(decrease on dimension/original dimension) * 100

Swelling % formula

(increase in dimension/original dimension) * 100

Veneer

Thinner than lumber, moves through a heated chamber

Particles and fibers

because of the volumes needed, these are fast.

Hardwood Structure

More complex than softwood, has multiple different kinds of longitudenal cells

Vessels or Pores

Found in almost all hardwoods, larger in diameter than tracheids but shorter in length

Tyloses

cell membranes from parenchyma,

• make wood difficult to dry and treat

• impede flow of gases and liquids

Tracheids

two Types

• Vasicentric tracheids

• Vascular tracheids

Vasicentric tracheids

shorter than fibers but have a larger diameter

Vascular tracheids

these look like latewood vessels

Longitudinal parenchyma

Function in storage

Can have distinct patterns helpful for identification

Rays

Horizontally oriented tissue with variable width

Different Patterns

• Upright

• Procumbent

• Homocellular

• Heterocellular

Softwood Anatomy

Relatively simple, Longitudinal cells and Horizontal cells

Longitudinal Cells in a softwood

Tracheids

Parechyma

Epithelial cells

Horizontal cells in a softwood

Ray tracheids

Ray parenchyma

Ray epithelial cells

Longitudinal Tracheids

long and slender

radially arranged

function in support and conduction

Longitudinal parenchyma

Only occurs in certain species

Funciton as a storage site for nutrients

Longitudinal epithelial cells

Function in secretion

Occur in certain genera

• Pinus,picea,Larix,Pseudotsuya

Horizontal cells

Only occur in tissues called rays

Ray tissue

Consist of Tracheids, Parenchyma, and Epithial cells

Cross field pits

A semi-bordered pit with connecting ray parenchyma with longitudinal tracheids

Polysaccharides

polymers of sugars

Hexose sugars

Glucose, galactose, and mannose

Pentose sugars

Xylose and arabinose

Cellulose

a polymer of glucose

Linear

cotton is almost entirely made of it

Hemi cellulose

Lower Dp than cellulose

composed of more than just glucose

Lignin

stiffens the cell wall, Hydrophobic, protects against UV light

Crystalline regions

hgihly order parallel arangements

difficult to penetrate with chemicals

Amorphous regions

Less well ordered

Parallel arrangement breaks down

more accessible to chemicals

Pits

Openings in the side of the cell wall

allow liquids to flow between the cells

Earlywood

produced in the early part of the growing season

pale in color

Latewood

Produced in the late growing season

darker in color

smaller cell lumen diameter

Ring porous

Diffuse Porous

Semi-rig porous

Discontinous Rings

Ring is not complete in cross-section

• can cause problems in aging trees

False Growth rings

caused by environmental changes that caused latewood formation

Heartwood

occurs at the center of the tree

darker in color

functions only in support

Sapwood

Lighter in color

retains living cells

Different types of grain orientation

Wood is made up of

Xylem and Phloem

Wood is

Anisotropic

Hygroscopic

Biodegradable

Combustible

Variable

What sugar is not found in wood

Lyxose

what is cellulose a polymer of

Glucose

what is the function of sapwood

Conduction and support

the darker color of heart wood is due to

the accumulation of extractives

what grain pattern is categorized by fibers twisting around the stem?

spiral grain

wood generally shrinks less in the

Longitudinal direction

the precursor for softwood lignin is

Coniferyl alcohol

The objective of chemical pulping is

the dissolution of lignin

the highest amount of lignin by percentage is found in

the compound middle lamela

The anisotropy of wood is largely influenced by the

S2 layer of the secondary cell wall

what do simple pits do

connect parenchyma cells to parenchyma cells

The flow of liquid through pits is precluded by

Aspirated pits

Diffuse porous hardwood lacks visible growth rings

False

Heartwood contains living cells that actively transport water

False

Sapwood is usually lighter than heartwood

True