enhancement of materials

Question 1

polymer enhancement
additives to make less expensive

Answer 1

lubricants- addition of wax reduces viscosity making it less sticky, allowing more intricate shapes, lower moulding temp
thermal antioxidants- prevent polymer oxidising or discolouring

Question 2

polymer enhancement
additives to enhance aesthetics

Answer 2

pigments- gives colour

Question 3

polymer enhancement
additives to improve function

Answer 3

antistatics- due to being used for electrical products can build up electrical activity, improves surface conductivity with moisture reducing static charge
flame retardants- chlorine or metal when added to polymers reduce combustion or spread of fire
plasticisers- become less hard and brittle at normal temp (pvc), food wrap to be spread over food (ldpe)
fillers- bulk to the product, increase thermal conductivity

Question 4

polymer enhancement
additives to prolong life

Answer 4

antioxidants- help to reduce the environmental deterioration of the polymer from exposure to oxygen in the air
uv light stabilisers- prevent polymer chains from being broken and causing discolouration and brittleness

Question 5

polymer enhancement
additives to encourage degradation

Answer 5

biodegradable plasticisers- enhance processing making the polymer more flexible softer and easier to break down

biobatch additives- addded to polymer to help reduce the degradation time from hundreds of years to a few years or months
don’t comtribute to landfill

Question 6

wood enhancement
natural wood defects

Answer 6

strength reduce when wet
combustible
suceptible to fungal attack and rot
different properties in different directions

Question 7

wood enhancement
preservatives

Answer 7

pretreated with preservatives
penetrate wood
copper based

impregnated with a modified polysaccharide like cellulose in timber

Question 8

wood enhancement
resins and laminations

Answer 8

chipboard
compressing wood chips with a resin
stable not affected by temperature uniform strength

SCL LVL are engineered woods made by layering veneers with resins then curing them less prone to defects

Question 9

metal enhancement
work hardening

Answer 9

cold worked, bending rolling and hammering
lead to improve tensile strength
prevented from moving freely less ductility or damage in the worked area

removed by annealing

Question 10

metal enhancement
annealing

Answer 10

work hardened metal easier to work by making it less brittle and more ductile
metal is heated then very slowly cooled allowing the metal crystals to grow

Question 11

metal enhancement
case hardening

Answer 11

hardening the surface of steels with less than 0.4% carbon content
outer casting of greater hardness
resistance to surface indentation
inner core retains the softer properties

carburising- changed chemical combustion, absorbing more carbon to increase surface hardness
930-950 for certain time
carbon atoms diffuse into structure building surface, the longer the thicker
760 then quenched ( hot metal in water, fast cooling, seals the case not affecting properties

Question 12

metal enhancement
hardening and tempering

Answer 12

hardening- heating medium and high carbon steels to alter the crystalline structure, holding temp then quenching in water or oil increases hardening and brittleness

tempering- carried out after hardening to reduce some of the excess hardness and increase the toughness
heat below critical point