Unit 2 (CP) Flashcards
What are the 4 mechanical properties
Toughness , Flexibility, Elasticity, Mouldability
What is toughness
Toughness of polymers determines ability to absorb energy and deform plasticically without cracking
What is elasticity
Materials resistance to distortion and ability to return to original shape
Polyurethane used to produce fabrics with good elasticity
What is Flexibility and folding
Flexibility is the ability of a material to be bent or folded without breaking
Stiffness is how rigid a material is
Thermoplastics tend to be stiff and rigid when set
What is mouldability
A polymer ability to be shaped into a form or mould will dictate type of product used for
What is physical properties and some examples
Physical properties are the measurable characteristic a material displays
Example - insulation , self finishing , uv resistance , melting points , transparency
What is thermal insulation
Thermal insulators reduce heat transfer,
especially between objects and people
Some polymer materials are formed with
air trapped inside them to create foams
that are used as insulation in packaging
and in the construction industry
What is electrical insulation
An electrical insulator is a material that does not allow electricity to flow freely through it
Polymers are very good electrical insulators, making them especially useful for electrical product casings and shielding
What is UV resistance
UV ‘bleaches’ the colour from polymers like ABS, which is commonly used for products such as garden furniture
What polymer is resistant to chemicals
HDPE
What is polymer films and moulded polymer usually used for
Food packaging
what is transparency
Transparency dictates how permeable a material
is to light radiation – how see-through it is
What is self finishing
Polymers are widely regarded as self-finishing which means no additional surface finishing is required
Why are additives useful in polymers
Additives are sometimes used to make polymers easier and more efficient to process
What is recycling
Recycling is the process of recovering waste polymers and reprocessing them into
useful materials and products
What does recycling reduce and prevent
Prevents waste being sent to landfill or dumped
Reduces reliance on the production
of new material from finite resources
What are the two main polymers and characteristics
Thermoplastics and Thermosets
React to heat in different ways and have different molecular structures
What are synthetic polymers
Synthetic polymers are produced
from finite resources such as
coal, gas and oil
What are natural polymers
Natural polymers come from a
variety of sources such as
rubber and amber, which
come from trees
When does fractional distillation occur
when crude oil is heated in the crude oil distillation unit
What is cracking
This is the process of converting the large hydrocarbon molecules found in the separated fuel types into smaller, more useful versions
Polymerisation
Molecules of single compounds known as monomers join together
These atoms are joined end to end to form long chains
The long chains of molecules are called polymers MONO (one) 🡪 🡪 🡪 POLY ( Many)
Thermoplastics characteristics
They have long chains of molecules, tangled together with no fixed structure or pattern
They are generally soft and flexible with some shape memory
What is LDPE and characteristics
Low density polyethylene (LDPE) is derived from ethylene – it is quite flexible, but also tough. Has excellent resistance to chemicals
What is HDPE and characteristics
High-density polyethylene HDPE is tough and has a higher strength to weight ratio than LDPE. HDPE is harder than LDPE but
also has good chemical resistance
commonly used for bottles
What is Polypropylene and characteristics
is a tough, flexible polymer with excellent fatigue resistance. It is available in translucent form and in a range of colours
PP is resistant to chemicals and solvents
What is HIPS and characteristics
High Impact Polystyrene (HIPS) is a rigid lightweight polymer with high impact strength. It has the ability to retain heat
without deformation
It has a glossy appearance
What is ABS and characteristics
Acrylonitrile Butadiene Styrene (ABS) is hard and tough with excellent impact strength. ABS has very good resistance to
acids, alkalis, oils and grease
It is easily moulded with a high quality
surface finish which can be painted
What is PMMA (acrylic) and characteristics
Polymethyl methacrylate (PMMA) is more commonly known as acrylic and is a tough lightweight material
It can be a clear plastic but is available
in a very wide range of colours
It has relatively poor resistance
to chemicals compared to
many polymers
Nylon characteristics
Nylon has a low coefficient of friction , It’s durable and resistant to abrasion , It is heat resistant