Polymers Flashcards
How do thermoplastics return to there original shape?
They have a ‘plastic memory’ that is when they are heated they soften and return to their original shape.
Why are thermoplastics bad for products at high temperatures?
The soften at low temperatures (as low as 100°C). However they are the most commonly used.
How do thermosetting plastics form?
When they are being formed a chemical reaction occurs causing them to create strong links or cross chains in their structure, which means that when they are permanently formed, they cannot be softened by reheating.
What are elastomers?
These are polymers that have good elasticity I.e. they can be distorted under pressure but will return to its original shape when the pressure is removed.
What about the long-chain molecules in elastomers that make them have good elasticity?
They have long-chain molecules considered to be coils (similar to springs); when the material is distorted (compressed or stretched) the molecules distort, and then released they return to their original shape.
What are the two types of elastomers?
Thermosetting elastomer
Thermoplastic elastomer
What are thermosetting elastomers?
Natural or synthetic rubbers, cannot be recycled or reshaped
What are thermoplastic elastomers?
It can be reheated and reshaped therefore recycled, can be manufactured using conventional equipment such as injection moulding or blow moulding.
What are the thermoplastics?
Low-density polyethylene (LDPE)
Acrylonitrile Butafine Styrene (ABS)
Nylon
High Impact Polystyrene (HIPS)
UPVC
Polyvinyl chloride PVC, Polypropylene
PMMA (Acrylic)
High-density polyethylene HDPE
What are examples of thermosetting plastics?
Polyester resin, Melamine formaldehyde, Epoxy resin, Urea Formaldehyde
What are examples of elastomers?
Natural rubber (polyisoprene), Buradiene rubber (BR), Silicone, Neoprene (Polychloroprene rubber)
What polymer can an inflatable pool be made out of?
Flexible Polyvinyl Chloride (PVC)
What polymer can a car headlight be made out of?
Acrylic (PMMA)
What can an electric socket be made out of?
Urea Formaldehyde (UF)
What polymer can a plastic folder be made out of?
Polypropylene (PP)
What polymer can a car fuller object (what you use to put fuel in a car) be made of?
High-density polyethylene (HDPE)
How do you enhance polymers?
Enhancing a polymers properties is done by using additives.
Why do we enhance polymers?
It is a way of improving a materials properties to better suit the requirements of the final product.
Name all the polymer enhancements
- Lubricants
- Thermal antioxidants
- Pigments
- Antistatics
- Flame retardants
- Plasticiser
- Biodegradable plasticisers
- Antioxidants
- UV light stabilisers
What are pigments?
Tiny particles that are mixed into the polymer in its molten state to give colour to the final processed product.
What are Biodegradable plasticisers
These make the polymer more flexible, softer and easier to break down which means faster degradation time.
What are polymer characteristics?
- Toughness
- Elasticity
- Insulation (thermal and electrical)
- UV resistance
- Ability to be moulded
- Resistance to chemicals and liquids
- High/low melting points
- Suitability for food packaging applications
- Biodegradability
- Recyclability
- Self finishing
- Ability to be combined with other polymers and/or polymers
What can bio-polymers designed for?
It can be designed to degrade in as little time as a few months to a couple of years
Degradation occurs in the presence of?
- Light (photodegradable)
- Oxygen (oxy-degradable)
- Water (hydro-degradable)
What is a natural bio-polymer?
It is made from natural materials such as cellulose starch and polysaccharides
What is a synthetic bio-polymer?
It is made from the renewable resources but chemically engineered (synthesised) to break down more quickly
What are examples of biodegradable polymers?
- Corn starch polymer
- Potatopak
- Biopol
- PLA
- PHA
- Lactide
- Eco Film
What are the stock forms of polymers?
- Sheet
- Film
- Granules
- Rod and other extruded forms
- Foam
- Powder
Low density polyethylene (LDPE) properties and uses
Thermoplastic
Properties: Very tough, good chemical resistance, weatherproof, available in translucent, low level of rigidity.
Safe working temperature 65 °C
Uses: Squeezy detergent bottles, toys, carrier bags, bin liners, general packaging, food wrap film, food trays
High density polyethylene (HDPE) properties and uses
Thermoplastic
Properties: Available in translucent form, weatherproof, tough, good chemical resistance.
Safe working temperature 65 °C.
Uses: Chemical drums, jerry cans, toys, household and kitchenware, long life carrier bags, buckets, bowls
Polypropylene (PP) properties and uses
Thermoplastic
Properties: Available in translucent, good chemical resistance, tough, good fatigue resistance (hinge property).
Safe working temperature 100 °C.
Uses: Rope, folders, folio cases, food containers, medical equipment, hinged containers lids
High impact polystyrene (HIPS) properties and uses
Thermoplastic
Properties: Hard, rigid, available in translucent, tough. Safe working temperature 70 °C.
Uses: Yoghurt pots, refrigerator linings, single use drink cups, toilet seats, instrument control knobs
Acrylonitrile butadiene styrene (ABS) properties and uses
Thermoplastic
Properties: Extremely tough, hard, available in opaque. Safe working temperature 80 °C.
Uses: Telephone handsets, rigid luggage, domestic appliances (food mixers), handles, computer housings, remote control casings, calculator casings
Acrylic (PMMA) properties and uses
Thermoplastic
Properties: Tough, hard, good chemical resistance, available in translucent. Safe working temperature 95 °C
Uses: Car light casings, computer numerically controlled (CNC) laser cut items, lighting units, lighting covers, baths
Nylon properties and uses
Thermoplastic
Properties: Tough, corrosion resistant, good temperature resistance, low coefficient of friction.
Safe working temperature 150 °C
Uses: Bearings, gears, curtain rails, textiles, boil-in-the-bag food packaging, car engine manifolds, cable ties
Rigid polyvinyl chloride (uPVC) properties and uses
Thermoplastic
Properties: Rigid, opaque, tough, hard, good weathering resistance, good chemical resistance, fire retardant.
Safe working temperature 95 °C.
Uses: Window frames, external doors, guttering and downpipes for buildings, water service pipes, bank cards
Flexible polyvinyl chloride (PVC) properties and uses
Thermoplastic
Properties: Available in translucent, tough, flexible, good weathering resistance, good chemical resistance.
Safe working temperature 95 °C.
Uses: Hose pipes, cable insulation, medical grade tubing, inflatable products, imitation leather, seat coverings
Urea Formaldehyde (UF) properties and uses
Thermoset polymers
Properties: Hard, heat resistant, good electrical insulator, brittle.
Safe working temperature 80 °C
Uses: Electrical fittings, adhesives
Melamine formaldehyde properties and uses
Thermoset polymers
Properties: Hard, opaque, tough, heat resistant food safe, chemical resistant. Safe working temperature 130 °C.
Uses: Decorative laminates, picnic ware, buttons
Polyester resin properties and uses
Thermoset polymers
Properties: Rigid, heat resistant, chemical resistant, brittle. Safe working temperature 95 °C.
Uses: Castings, used in lay-up process for glass reinforced plastic (GRP) for boat hulls, car parts, chair seats
Epoxy resin properties and uses
Thermoset polymers
Properties: Rigid, clear, hard, tough, chemical resistant. Safe working temperature 80–200 °C
Uses: Rigid, clear, hard, tough, chemical resistant. Safe working temperature 80–200 °C
What ability do elastomers have?
All elastomers have the ability to be stretched to many times their original length and then, upon the removal of the tension, return to their original shape.
Natural rubber properties and uses
Elastomer
Properties: High tensile strength, low elongation, good hardness compared to other elastomers, tough, electrical insulator, good cold resistance.
Uses: Automotive industry such as tyres, tubes, hoses, gaskets, belts, balloons, toys, footwear
Butadine rubber properties and uses
Elastomer
Properties: Tough, excellent wear resistance against friction, good thermal resistance against friction, electrical insulator.
Uses: Vehicle tyres, shoe soles, toys, conveyor belts, water and pneumatic hoses
Neoprene properties and uses
Elastomer
Properties: Good thermal resistance, toughness, good oil and chemical resistance, excellent weather resistance, good abrasion resistance and electrical insulator
Uses: Wetsuits, laptop cases, industrial wire insulation, automotive applications such as shock absorber seals, hose covers, transmission belts, gaskets and door seals
Silicone properties and uses
Elastomer
Properties: Good flexibility at low temperatures, poor abrasion resistance, good thermal resistance and resistance to temperature extremes, good weather resistance, good lubricating qualities, electrical insulator
Uses: Flexible ice cube trays, bakeware, cooking utensils, seals for refrigerators, machinery lubricant, sealants, mould making, medical uses such as lubricants for prosthetics, tubing for drug delivery systems
Corn starch polymer source and uses
Biodegradable polymer
Source: Bio-polymer (natural). Made from high starch vegetables such as corn, potatoes and maize.
Uses: Packaging products, straws, vending cups, disposable cutlery, bags, take-away food containers
Potatopak source and uses
Biodegradable polymer
Source: Bio-polymer (natural). Made from potato starch.
Uses: Single use food items such as bowls, cutlery, food trays, serviettes, packaging beads or ‘peanuts’, bin bags
Biopol source and uses
Biodegradable polymer
Source: Bio-polymer (natural).
Made from bacteria grown in cultures.
Additive to promote degradation. Usually 1 per cent added to thermoplastics.
Uses: Packaging products such as film, carrier bags, vending cups, nappies, surgical stitches, pill coverings
Polylactide acid (PLA) source and uses
Biodegradable polymer
Source: Bio-polymer (synthetic).
Made from corn kernels or cane sugar, fermented to produce lactic acid, then synthesised to produce polylactic acid.
Uses: Packaging, single use bottles, carrier bags, plant pots, disposable nappies, medical sutures, 3D printing
Polyhydroxyalkanoate (PHA) source and uses
Biodegradable polymer
Source: Bio-polymer (natural). Made from bacteria grown in cultures. Fully compostable.
Uses: Packaging, medical uses such as slow release medication patches, films, screws and bone plates
Lactide source and uses
Biodegradable polymer
Source: Bio-polymer (synthetic). Fully compostable, water soluble. PLA and cellulose based.
Uses: Biomedical applications, slow release medication, bone repair fixings, detergent washing sachets
Glycolide source and uses
Biodegradable polymer
Source: Bio-polymer (synthetic). Fully compostable. PLA and cellulose based.
Uses: Food film, bags, packaging wrap, bin bags, agricultural ground sheet, flower wrap
