FIBRES

Name two essential feature a papermaking fibre should have?
1. Good length and stiffness
2. Flexibility and good length
3. Stiffness and natural bonding
4. Natural bonding and stiffness
The extent of bonding in a whole sheet is a function of what?
1. Number of crossovers x area of crossover
2. Total length x number of crossovers
3. Total length x area of crossovers
4. Number of fibres x number of crossovers
In order to form a coherent sheet of paper, what is the minimum number of crossovers each fibre needs to have?
1. 1
2. 2
3. 3
4. 4
What is the main difference between chemical and mechanical fibres?
1. Chemical fibres are whiter
2. Chemical fibres contain no lignin
3. Mechanical fibres are shorter
4. Mechanical fibres are longer
What is the main difference between chemical and mechanical fibres?
1. Mechanical fibres are darker
2. Mechanical fibres cannot swell
3. Mechanical fibres are longer
4. Chemical fibres are stiffer
What is the advantage of long fibres?
1. Long fibres are stiffer
2. Long fibres are more flexible
3. Long fibres are stronger
4. Long fibres are capable of greater modification
What happens to the specific surface area of fibres as they are recycled?
1. It increases
2. It does not change
3. It decreases
4. It increases and then decreases
What happens to the crystallinity index of fibres as they are recycled?
1. It increases
2. It does not change
3. It decreases
4. It increases and then decreases
What happens to the swelling capacity of fibres as they are recycled?
1. It increases
2. It does not change
3. It decreases
4. It increases and then decreases
What proportion of the worlds trees are softwoods?
1. 25%
2. 35%
3. 45%
4. 55%
What percentage of the world's surface is under forestation?
1. 10%
2. 20%
3. 30%
4. 40%
Which of the following species is not generally used for Bioengineering purposes
1. Eucalyptus
2. Pine
3. Poplar
4. Oak
There are 5 stages in growth optimisation. What is their correct order?
1. province/family – hybridization – macro propagation – micro propagation - DNA manipulation
2. hybridization – macro propagation – micro propagation- DNA manipulation - province/family
3. hybridization – province/family –macro propagation – micro propagation - DNA manipulation
4. hybridization – macro propagation – province/family –micro propagation - DNA manipulation
What diameter wood is used for the pulping industry?
1. Less than 10cm
2. 10 - 14 cm
3. 14 - 18cm
4. Less than 22cm
Which tree is most renowned for its strength?
1. Ash
2. Dutch Elm
3. Scottish pine
4. Sitka spruce
There are 11 elements to a tree cross-section, which one is missing from this list?

Outer bark, inner bark, vascular cambium, juvenile wood, heartwood, pith, annular ring, earlywood fibres, latewood fibres, rays
1. tension wood
2. compression wood
3. pitwood
4. sapwood
There are six features of tension wood, which one is missing from the following list? Usually found in hardwoods, upper side, more dense than normal, highly crystalline cellulose, gives good chemical yield, poor bonding
1. Difficult to refine
2. Easy to refine
3. Lighter in colour
4. Darker in colour
There are six features of compression wood, which one is missing from the following list ?
Mainly soft woods, underside of leaning tree/branch, thick walled fibres, highly lignified, short fibres, poor refining
1. High density
2. Low density
3. Light colour
4. Dark colour
What time span is aimed for, from felling to pulping?
1. Less than 3 weeks
2. Less than 6 weeks
3. Less than 9 weks
4. Less than 12 weeks
What is considered to be the ideal chip size?
1. 20mm long 5mm thick
2. 10mm long 10mm thick
3. 5mm long 20mm thick
4. 20mm long 20mm thick
What forces hold fibres together?
1. Entanglement forces
2. Hydrogen bonding
3. Surface tension
4. Van der Waals forces
What chemical groups are responsible for the bonding between fibres?
1. Amide
2. carboxyl
3. Hydroxyl
4. Nitrile
What is the main building block of cellulose?
1. Carbohydrate unit
2. Cellobiose unit
3. Fibril units
4. Glucose unit
What do we mean by degree of polymerisation?
1. The number of repeat units in the chain
2. The number of links in the chain
3. The number of atoms in the chain
4. The number of molecules in the chain
What is a typical DP of native cellulose?
1. 3000-3500
2. 2000-2500
3. 1000-1500
4. Less than 1000
Apart from water, which are the four main categories of materials in wood
1. holocellulose, hemicellulose, lignin, extractives
2. cellulose, hemicellulose, lignin, extractives
3. cellulose, hemicellulose, lignin, bark
4. cellulose, hemicellulose, softwood, extractives
What are the two main differences between cellulose and hemicellulose?
1. Cellulose has a higher DP, hemicellulose is only one sugar type
2. Cellulose has a lower DP, cellulose is only one sugar type
3. Cellulose has a lower DP, hemicellulose is only one sugar type
4. Cellulose has a higher DP, cellulose is only one sugar type
What are two molecules of glucose joined together are known as?
1. Anhydroglucose
2. Bi-glucose
3. Cellotriose
4. Diglucose
What is alpha cellulose?
1. Alpha cellulose has a DP of less than 90
2. Alpha cellulose has a DP of less than 60
3. Alpha cellulose has a DP of more than 90
4. Alpha cellulose has a DP of more than 120
The fringe micelle theory indicates that there are two distinct regions. What are they?
1. Cellulose and hemicellulose
2. Crystalline and amorphous
3. Holocellulose and lignin
4. Holocellulose and lignin
Certain alcohol’s in lignin, may be used to differentiate between hardwoods, softwoods, and grasses. Which of these materials would be found to contain sinapyl alcohol?
1. Hardwoods and softwoods
2. Hardwoods and grasses
3. Softwoods and grasses
4. Hardwoods softwoods and grasses
What is the softening temperature of lignin?
1. 110-130
2. 130-150
3. 150-170
4. 170-190
What is the collective name for cellulose and hemicellulose?
1. Hemicellulose
2. Hetrocellulose
3. Holocellulose
4. Homocellulose
What pH region does wood ash lie?(1)
1. Acid
2. Neutral
3. Alkaline
4. Depends on the type of tree
A fibre is composed of how many walls?
1. 1
2. 2
3. 3
4. 4
Which is the thickest fibre wall?
1. P
2. S1
3. S2
4. S3
What dictates fibre strength?
1. The number of crossovers
2. Fibril angle in the S2 wall
3. Fibre length
4. The number of walls
Approximately how many lamella are there in the S2 wall?
1. 1-3
2. 4-6
3. 7-10
4. 11-14
What is the middle lamella?
1. The hole through the centre of the fibre
2. The S2 wall
3. The lignin between the fibres
4. The collective name given to the S1 S2 and S3 walls
Chemically how would you differentiate between hardwood and softwood?
1. Hardwoods contain more xylan
2. Softwoods contain more xylan
3. Hardwoods contain more extractives
4. Hardwoods contain galactoglucomannans
What three steps should be taken to produce a good strong interfibre bond?(3)
1. Expose as many OH groups as possible, create as much surface as possible, create as many crossovers as possible
2. Create as many OH groups as possible, create as much surface as possible, bring the surfaces as parallel as possible
3. Create as many OH groups as possible, create as much surface as possible, bring the surfaces as close as possible
4. Expose as many OH groups as possible, create as much surface as possible, bring the surfaces as close as possible

FIBRES

Quiz