The following Timeline was put together by the British Plastics Federation with the backing of their Sponsors. This timeline milestone shows the history of plastics dating back to 1284 and through the years up until the current day and beyond.
The History of Plastics
People do not always realise how plastics are absolutely essential in modern day life being used in such diverse sectors as construction, manufacturing, packaging, aerospace and medicine.
Plastics applications are all around us, used in everything from our homes to our hospitals – plastic’s adaptability allows it to be extremely useful. Polymers have many different functional properties, from being light and strong, to being chemical resistant, flexible, transparent and taking an infinite amount of shapes and sizes.
Most plastics you have heard of are called thermoplastics, which means they can be re-melted after they are hardened. Thermosets in contrast, remain in their permanent solid state.
Plastic can either be ‘synthetic’ or ‘biobased’. Synthetic plastics are derived from crude oil, natural gas or coal. Whilst biobased plastics come from renewable products such as carbohydrates, starch, vegetable fats and oils, bacteria and other biological substances.
The vast majority of plastic in use today is synthetic because of the ease of manufacturing methods involved in the processing of crude oil. However, the growing demand for limited oil-reserves is driving a need for newer plastics from renewable resources such as waste biomass or animal-waste products from the industry.
In Europe, only a small proportion (about 4 – 6%) of our oil and gas reserves goes towards the production of plastics, with the rest used for transport, electricity, heating and other applications.
Plastic Manufacture Process
Most of the plastic in use today is derived by the following steps:
Extraction of raw materials (largely crude oil and natural gas, but also coal) – these are a complex mixture of thousands of compounds that then need to be processed.
Refining process transforms crude oil into different petroleum products – these are converted to yield useful chemicals including “monomers” (a molecule that is the basic building blocks of polymers). In the refining process, crude oil is heated in a furnace, which is then sent to the distillation unit, where heavy crude oil separates into lighter components called fractions. One of these, called naphtha, is the crucial compound to make a large amount of plastic. However, there are other means, such as using gas.
Polymerisation is a process in the petroleum industry where light olefin gases (gasoline) such as ethylene, propylene, butylene (i.e., monomers) are converted into higher molecular weight hydrocarbons (polymers). This happens when monomers are chemically bonded into chains. There are two different mechanisms for polymerisation:
The addition polymerisation reaction is when one monomer connects to the next one (dimer) and dimer to the next one (trimer) and so on. This is achieved by introducing a catalyst, typically a peroxide. This process is known as chain growth polymers – as it adds one monomer unit at a time. Common examples of addition polymers are polyethylene, polystyrene and polyvinyl chloride.
Condensation polymerisation includes joining two or more different monomers, by the removal of small molecules such as water. It also requires a catalyst for the reaction to occur between adjacent monomers.
This is known as step growth, because you may for example add an existing chain to another chain. Common examples of condensation polymers are polyester and nylon.
In Compounding/processing, various blends of materials are melt blended (mixed by melting) to make formulations for plastics. Generally, an extruder of some type is used for this purpose which is followed by pelletising the mixture.
Extrusion or a different moulding process then transforms these pellets into a finished or semi-finished product. Compounding often occurs on a twin-screw extruder where the pellets are then processed into plastic objects of unique design, various size, shape, colour with accurate properties according to the predetermined conditions set in the processing machine.
Plastic Manufacture Machinery
Our years of working in the plastic sector, has enabled us to build up a full understanding of the types of complex machinery used. The types of applications we have monitored over our company growth are as follows:-
- Single and Twin screw extruders
- Rewind drums
- Twin blowers
- Cooling fans
- Roller drives
- Water pumps
- Additive feeders
- Injection moulding machine
- Hydraulic powerpacks
- Cooling towers