Polymers Flashcards
What is a Thermosetting plastic
Thermosetting plastics are plastics that can not be reformed after being manufactured
What is Thermoforming plastics
Thermoforming plastics are plastics that can be re-set many times so it is better for recycling
What is acrylic
Acrylic is a brittle plastic that can be transparent e.g car lights
What is high impact polysterene (HIPS)
It is a durable and flexible plastic that can withstand high impact e.g yoghurt pots
What is high density polythene (HDPE)
It is a very durable plastic with a slight bit of flexibility e.g bucket
What is polypropylene (PP)
Polypropylene is a very strong plastic that has a slight bit of flex and is heat resistant e.g chairs or anything that needs strength
What is polyvinyl chloride (PVC)
It is a very strong and durable plastic that has good resistance to UV rays e.g window sills
What is a polyethylene terephthalate (PET)
It is a very flexible plastic that can be easily recycled e.g plastic bottles
What is epoxy resin?
Epoxy resin is a substance made up of resin and hardener, it is used as an adhesive
What is melamine formaldehyde (MF)
It is a heat resistant plastic covering (over wooden board) that is smooth and finishes nicely e.g kitchen top
What is phenol formaldehyde
A very heat resistant plastic that is used for pan handles
What is a polyester resin
It is a very hard and brittle plastic than can withstand harsh conditions and is very durable e.g boat
What is urea formaldehyde
Urea formaldehyde is an extremely hard and brittle plastic that is heat and electricity resistant so it is good for sockets
What is an elastomer
A polymer which can be bent and deformed at room temperature but when the pressure is released it will go back
Name 6 polymer additives
Antistatics
Flame retardants
Plasticisers
Fillers
Thermal antioxidants
Pigments
Lubricants
Name 3 proliferation polymer additives
Antioxidants
UV light stabilisers
Biodegradable plasticisers
Bio-batch additives
What is vacuum forming
Vacuum forming is a process in which a polymer sheet is heated
and the mould which is on the ‘platen’ is raised up and pushes it into shape from the bottom
then a vacuum pump sucks it into shape from underneath and the excess is trimmed off.
It can usually be identified from a ‘shell’ like structure and thin material
What is thermoforming
Thermoforming is a process in which polymers are heated up and
a positive mould presses it into the negative mould while a vacuum pump is sucking.
Unlike vacuum forming, thermoforming can provide a high level of detail.
What is calendaring
Calendaring is a process in which heated granules in a dough like state are fed into a series of heated rollers.
The rollers then get progressively closer together making the output sheet thinner
until the end were a set of cooling rollers cool the plastic again
What is line bending
Line bending is when a line of the plastic is heated to make it malleable
then a corner is bent along this line and it is left to cool in a jig
What is lamination (lay up)
Lamination is the process by which fibre based composites such as carbon fibre are made into 3D objects e.g. yacht.
It works by preparing a mould of the product and then adding a layer of release agent such as parcel tape so you can take off the finished piece
Then a gel coat of resin mixed with pigment is applied and a matting is applied
then a roller is passed over the layers to make them bond in the desired shape
What is injection moulding
Injection moulding is the process by which detailed plastic products are made.
It works via pouring plastic granules into a hopper where they will be fed into a chamber
where they will then be heated up into molten plastic.
Then an archimedes screw forces it into the mould where it is left to cool in the final product shape
What is blow moulding
Blow moulding is a process in which a polymer is fed into a hopper where it is heated and stretched into a ‘parison’ which is a tube.
The tube of thermoplastic is lowered into a mould and then has high pressure air blowed in to blow it up like a balloon.
The plastic then takes the shape of the mould and cools. (Commonly used for bottles)
What is rotational moulding
Rotational moulding is a process in which a plastic powder is poured into a mould
and then the mould is clamped shut and rotated around two axes while being heated.
The polymer is then cooled which makes it shrink slightly so it can be taken out of the mould.
This creates a hollow product which is usually thicker than a blow moulded product.
What is extrusion
Extrusion is the process which produces long shapes of a consistent profile.
This is done by a similar process to injection moulding except there is no mould at the end and instead the plastic is pushed through the die onto a conveyor belt.
Extrusion can produce a solid rod, hollow tubes, or I and T sections
What is compression moulding
Compression moulding is a process in which a blob of hot polymer is placed in a lower mould
and then an upper mould is forced down by a hydraulic press which squeezes the plastic
this forces the plastic to cover the whole mould
How are polymers sourced
Fractional distillation of crude oil
What are pigments
Tiny particles mixed into a polymer that gives it a desired colour
What are antistatics
An additive that reduces static charge by improving surface conductivity and attracting moisture from the surroundings
What are flame retardants
An additive which reduces the chance of combustion by adding elements such as bromine, chorine or phosphorus
What are plasticisers
An additive which makes the polymer more stretchy and less brittle and hard
What are fillers
An additive which provides bulk to a product and also makes the properties better depending on the filler e.g. mineral fillers help increase thermal conductivity
What are antioxidants
An additive which helps to reduce deterioration of the polymer from oxygen exposure
What are UV light stabilisers
An additive that prevents polymer chain breakdown from ultra violet light
Name five polymer based sheets
Foam board
Fluted PP sheet
Translucent PP sheet
Styrofoam
LDPE sheet
Plastazote foam
Cellulose acetate
Polyactide
What are acrylic spray paints
A fast drying and protective coating to water, UV and weathering
What is an overmoulding and give an example
Overmoulding is when a second layer of polymer is moulded over specific parts of a product e.g. a toothbrush would have an elastomer overmoulding for the grips
What are the two ways of producing an overmoulding and briefly explain
Using two injection moulding moulds-one mould is for the main body of the product, then the second mould includes that main body and is for the overmoulding
Twin shot injection moulding-a single mould with separate component cavities is used, first the main body is injected into the first mould cavity, then the mould opens slightly and reorients to the secondary position where the overmould can be injected into the second cavity
