1.13 Enhancement of Materials Flashcards

1
Q

Define material enhancement

A

A way of improving a material’s properties to better suit the requirement of the final product

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2
Q

Polymer Enhancement

State the reason for adding lubricants

A

Adding wax or calcium stearate reduces the viscosity of the molten polymer, making it less ‘sticky’ and allowing more intricate shapes to be formed.

Lubricants also allow the moulding temperature to be lowered, saving energy

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3
Q

Polymer Enhancement

State the reason for adding thermal antioxidants

A

Prevent the polymer oxidising or discolouring due to excessive heat during processing.

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4
Q

Polymer Enhancement

State the reason for adding pigments

A

Tiny particles that are mixed into the polymer in its molten state to give colour to the final processed product

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5
Q

Polymer Enhancement

State the reason for adding antistatics

A

Reduce the likelihood of the polymer building up a static charge

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6
Q

Polymer Enhancement

State the reason for adding flame retardants

A

Reduce the likelihood of combustion or the spread of fire (care engine components) or potential electrical fires such as plug sockets.

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7
Q

Polymer Enhancement

State the reason for adding plasticiser

A

Allow plastics to become less hard and brittle at normal temperature use, e.g. added to LDPE food wrap, allowing the wrap to be stretched over the food product.

Plasticisers also help in processing because they allow polymers to be easily formed at higher temperatures

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8
Q

Polymer Enhancement

State the reason for adding fillers

A

Sawdust and wood flour provide bulk to the product, meaning that less polymer is required.

Mineral fillers such as chalk, clay and calcium carbonate help increase the thermal conductivity of the polymer, meaning it will heat up and cool down more quickly, which gives shorter mould cycle times.

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9
Q

Polymer Enhancement

State the reason for adding biodegradable plasticisers

A

These make the polymer more flexible, softer and easier to break down, which means faster degradation time.

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10
Q

Polymer Enhancement

State the reason for adding bio-batch additives

A

Oxy-degradable, photodegradable and hydro-degradable additives help reduce the degradable time from hundreds of years to a few years or even months.

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11
Q

Polymer Enhancement

State the reason for adding antioxidants

A

Help reduce the environment of the polymer from exposure to oxygen in the air

Also help prevent increased brittleness, surface cracks and pigment discolouration. Often used in polymer garden furniture.

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12
Q

Polymer Enhancement

State the reason for adding UV light stabilisers

A

Prevent the polymer chains being broken down by sunlight. UV attack causes colour loss and brittleness. Used in outdoor toys and play equipment, garden furniture, sports stadium seats and synthetic grass playing surfaces.

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13
Q

Wood Enhancement

State the use of resins and laminations

A

Used in engineered wood (e.g. manufacture boards) to enchance the properties of the useable parts of trees such as sawdust, wood chips and fibres.

Chipboard is made from compressing wood chip with a resin (urea formaldehydel).

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14
Q

Wood Enhancement

State the use of resins with fire retardants

A

Resin is impregnated with fire-retardant cladding (e.g. for indoor flooring).

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15
Q

Wood Enhancement

State the use of laminations

A

Veneers such as natural wood are laminated on to the board surface to enhance aesthetics.

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16
Q

Wood Enhancement

State the use of preservatives

A

Protect wood (especially for outdoor use) form fungal and insect attack.

Wood can be pre-treated with a copper-based preservative, which penetrates the wood to protect the whole plank.

Copper has excellent fungicidal properties.

17
Q

Wood Enhancement

State the use of pigments

A

Added to the preservative to give different coloured shades to enhance the aesthetics, e.g. outdoor decking.

Can also be used on cheaper softwoods to make them look like hardwoods.

18
Q

Wood Enhancement

State the use of fire-retardant preservatives

A

Used to pressure treat wood for roof joists, cladding etc. and exhibition stands.

Wood can also be treated to make it harder and more resistant in high-wear situations such as flooring.

19
Q

Wood Enhancement

State the use of modified natural polysaccharides

A

Wood is impregnated to cure within wood cell structure. Results in increased hardness, toughness and stability (often added to hardwood floor panels)

20
Q

Wood Enhancement

State the use of structural composite lumber (SCL) and laminated veneer lumber (LVL)

A

Made by layering strands (SCL) or veneers (LVL) of wood with resins such as urea formaldehyde, pressing and heat curing them to produce a stable wood billet.

SCL and LVL are less prone to defects such as warping, splitting or shrinking.

Used in structural applications including beams, joists and rafters.

21
Q

Metal Enhancement

Define work hardening

A

Improves tensile strength and hardness in the localised area when a metal is cold worked.

22
Q

Metal Enhancement

Define annealing

A

Heating work-hardened metal and very slowly cooling it, making it easier to work (less brittle and more ductile).

23
Q

Metal Enhancement

Define case hardening

A

Hardens the surface of steel with less than 0.4 per cent carbon content.

24
Q

Metal Enhancement

Define carburising

A

Changes the chemical composition of the surface of low carbon steel so it absorbs more carbon and increases surface hardness.

25
Q

Metal Enhancement

Define quenching

A

Rapid cooling of a heat-treated metal.

26
Q

Metal Enhancement

Define Hardening and tempering

A

Heating medium and high carbon steels to a given temperature, rapidly cooling via quenching and then heating to a set temperature to remove the excess to hardness.

27
Q

Metal Enhancement

Define tempering colour

A

The colour seen on metal that indicates the temperature at which brittleness is removed