Materials

Question 1

Compressive strength (mechanical properties)

Answer 1

the ability to withstand being crushed or shortened by pushing forces

Question 2

Tensile strength (mechanical properties)

Answer 2

the ability to resist stretching and pulling forces

Question 3

Bending strength (mechanical properties)

Answer 3

the ability to resist forces that may bend a material

Question 4

Shear strength (mechanical properties)

Answer 4

the ability to resist sliding forces parallel to it

Question 5

Torsional strength (mechanical properties)

Answer 5

the ability to resist twisting forces

Question 6

Hardness (mechanical properties)

Answer 6

the ability to resist abrasive wear like scratching

Question 7

Toughness (mechanical properties)

Answer 7

the ability to absorb impact without fracture

Question 8

Plasticity (mechanical properties)

Answer 8

the ability to be permanently deformed and retain the deformed shape

Question 9

Ductility (mechanical properties)

Answer 9

the ability to be drawn out under tension without cracking

Question 10

Malleability (mechanical properties)

Answer 10

the ability to withstand compression without cracking

Question 11

Elasticity (mechanical properties)

Answer 11

the ability to be deformed and then return to the original shape when the force is removed

Question 12

List three hardwoods and their properties

Answer 12

Oak - Hard, tough, aesthetic grain, good weather resistance. Contains tannic acid which is corrosive.

Ash - Tough, comparatively flexible, aesthetic open grain.

Mahogany - Interlocking grain makes difficult to work with, rich dark red colour.

Teak - Hard, tough, straight grain, natural oils make corrosive resistant.

Birch - Hard, straight close grain resists warping.

Beech - Tough, close grain, hard.

Question 13

List three soft woods and their properties

Answer 13

Pine - Straight grain, can contain resinous knots.

Spruce - Straight grain, resistant to splitting.

Douglas fir - Straight-ish grain, few knots, resistant to corrosion.

Larch - hard, tough, attractive grain.

Cedar - straight grain, has corrosive acids, low density, resistant to rot and insects.

Question 14

List three manufactured boards and their properties

Answer 14

Plywood - thin layers of wood are placed and glued at 90 degrees to one another and compressed to form the board. Strong in all directions, no grain weakness, always has an odd number of layers.

Marine plywood - plywood that uses WBP glue to resist moisture, and sometimes fungi.

Aeroply - plywood that uses high quality timber, available in lightweight thin sheets.

Flexible plywood - plywood with two outer layers of open grained timber which allows the board to flex.

Chipboard - wood chips compressed with a resin like urea formaldehyde.

MDF - compressed wood fibres, sometimes with additional resin, with two smooth faces.

Question 15

What are the three types of plastics?

Answer 15

Thermoplastics - can be reheated and reshaped repeatedly

Thermoset polymers - cannot be reheated and reshaped due to covalent bonds between polymer chains

Elastomers - a material that can be deformed at room temperature, and will return to its original shape.

Question 16

List three thermoplastics and their properties

Answer 16

PolyPropylene - tough, chemical resistant, good fatigue resistance. Safe working temp: 100 C

Acrylonitrile Butadiene Styrene - tough, hard, Safe working temp: 80 C

Rigid polyvinyl chloride - rigid, tough, hard, weather and chemical resistant, Safe working temp: 95 C

flexible PolyVinyl Chloride - tough flexible, weather and chemical resistant, Safe working temp: 95 C

Question 17

List three thermoset polymers and their properties

Answer 17

Urea Formaldehyde - hard, heat and electrical insulator, brittle, Safe working temp: 80 C

Melamine Formaldehyde - hard, tough, heat resistant, food safe, chemical resistant, Safe working temp: 130 C

Polyester resin - rigid, heat and chemical resistant, brittle, Safe working temp: 95 C

Epoxy resin - rigid, hard, tough, chemical resistant, Safe working temp: 80 - 200 C.

Question 18

List three elastomers and their properties

Answer 18

Natural rubber - high tensile strength, low elongation, good hardness, tough, electrical insulator, cold resistant.

Butadiene Rubber - tough, thermal and wear resistant, electrical insulator.

Neoprene - abrasion, weather, oil, thermal, and chemical resistant, electrical insulator.

Silicone - very flexible, temperature resistant, vulnerable to abrasion, good lubricant, electrical insulator.

Question 19

List three bio-polymers and their source

Answer 19

Corn starch - naturally occurring in potatoes, corn, and maize.

Potatopak - naturally occurring in potato starch

Biopol - naturally occurring in bacteria grown in cultures, acts as an additive to promote degradation in thermoplastics

PLA - synthetically occurring, made from fermented corn kernels or cane sugar

PHA - naturally occurring in bacteria cultures.

Lactide - synthetically occurring made from cellulose, fully compostable and water soluble.

Glycolide - synthetically occurring made from cellulose, fully compostable.

Question 20

describe the composition, features, and applications of glulam

Answer 20

layered timber and glue used to create various components
-eliminates timber defects
-easy to form parts 
-good strength/weight ratio
-sustainable
used in construction

Question 21

describe the composition, features, and applications of kevlar

Answer 21

fibre and resin
-very tough
-high tensile strength
used for bullet proof vests, puncture resistant tires and aircraft construction

Question 22

describe the composition, features, and applications of graphene

Answer 22

2D form of microscopic carbon particles with a honeycomb atomic structure
-can be rolled into very thin hollow tubes
-high tensile strength, hardness,
-heat resistant and electrically conductive
-not recycleable
used in medical treatment, nanoelectric devices, and battery furniture.

Question 23

describe the composition, features, and applications of Precious Metal Clay

Answer 23

microscopic particles of precious metals are bound together in a pliable medium
-easily hand shaped
-aesthetically pleasing
used in jewellery and decorative items