Plastic a definition
Plastics – the key points
Links to related posts
Plastics are used to make everything from varnish to stockings, bottles to car parts by way of crisp packets and computers. They have revolutionized the world for the better but are now a major environmental pollutant. We use them everyday, for everything, even inserting it into our bodies. And yet we know very little about them.
This blog explores plastic the product, examines its impact and considers what we should and shouldn’t be using plastic for.
What is plastic?
Definition of plastic
If you look in the Oxford dictionary you will find plastic can be used to describe
substances or materials that “are easily shaped or moulded: ‘rendering the material more plastic’
1. 2.1 Offering scope for creativity:‘the writer is drawn to words as a plastic medium’
2. 2.2 Relating to moulding or modelling in three dimensions, or to produce three-dimensional effects:‘the plastic arts’
3. 2.3 (in science and technology) relating to the permanent deformation of a solid without fracture by the temporary application of force.
4. Artificial or unnatural: ‘a holiday rep with huge white teeth and a plastic smile’
But more commonly today it is used as a noun to refer to a “synthetic material made from a wide range of organic polymers such as polyethylene, PVC, nylon, etc., that can be moulded into shape while soft, and then set into a rigid or slightly elastic form: Oxford.
or Any of various organic compounds produced by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments used as textile fibres. Your Dictionary
So the term plastic was originally used to describe anything fluid, responsive capable of being molded or modelled; Clay could be plastic; sculpture could be described as plastic.
But more recently it has come to mean a certain type of product – a fluid, synthetic material that can be molded to make almost anything.
Are All Plastics The Same?
Plastic (when used to describe a product and not a quality) can be applied to a huge range synthetic polymers with massively different qualities. They look different, they act different and the general application of the term plastic to all plastic materials soon leads to confusion. Products such as varnish for example are not usually thought of as plastic. But some are.
But are all these different products basically made from the same stuff? No, even the base material can be a different product.
Plastic was used to describe the early first plastics derived from cellulose which were biodegradable. Later the same name was given the oil derived product. This was made in a very different way and did not biodegrade. It is now applied to corn starch plastic which is made differently again, from plant starch and is certified compostable.
plastics can be made in a variety of ways from a variety of materials; shale gas, oil, plants even chicken feathers;
different plastics have very different qualities.
Currently non- biodegradable, oil derived plastics are the most commonly used and so we tend to ascribe their qualities to all types of plastic.
Which is of course incorrect not least because most oil derived plastics do not biodegrade and last for centuries possibly for ever, while there are other plastics that are truly compostable with a lifespan of months.
It is important to know your different plastic types and their massively varied characteristics.
The sheer versatility of plastics make this a big task.
Check out A List Of Plastics for information on the individual kinds of plastic.
Lets get to know plastic! Key Points
Despite being lumped under the one, all-embracing name, not all plastics are the same..
Non-biodegradable and biodegradable plastics
Some plastics are compostable, (they biodegrade within a certain amount of time).
Most are not biodegradable and last if not for ever, for a very long time. Read the Plastic Lifespan to find out why and how.
N.B. Plastics can be described as compostable, degradable and or biodegradable. Which may seem clear but can be misleading. Some “biodegradable plastics” are oil derived plastics with a degrading initiator added to make them fall apart (degrade) more quickly. Unlike compostable plastics they don’t always break down into harmless substances and may leave behind a toxic residue. Read more here
Thermoplastics or Thermoset?
You might also hear plastic being described as a thermoplastics or thermoset plastic.
Thermoplastics can be heated and shaped many times.
Thermoset plastics can only be heated and shaped once.
Plastic can be made from pretty much anything from oil to chicken feathers….
How is plastic made?
Plastics are created from single units, monomers, combined in a variety of ways. This process is called polymerisation. This is why plastics are also called polymers. And you often find the word poly used in the name i.e. polystyrene.
Building Blocks – Polymers & Monomers
A polymer is a chain ( poly= many, mer = part) of single units called monomers.
Natural polymers occur in nature and can be extracted. They include silk, wool, DNA, cellulose, starch and proteins.
Synthetic polymers such as plastic are made by scientists and engineers. They too are extracted from natural resources BUT…. though the base material may be a natural product such as oil, the polymers derived from it are not.
To make synthetic polymers, the monomors are joined together in new ways, using heat and/or pressure and sometimes a catalyst.
Different combination of monomors result in different products and there are hundreds of different kinds of plastic.
Read more here – monomers and polymers.
Don’t know your PETS from your hamster. Think Polymer is a girl’s name? Check out this collection of definitions essential for understanding plastic!
What Is Plastic Made From?
Obviously given the different products, there is no one answer – it would depend on the plastic type.
Plastic can be made from just about anything but the two main feed materials are oil and plants (bioplastics)
Currently nearly all plastics (and we are talking millions of tons each year) are made from ethane.
Most ethane is derived from oil but it can also be got from coal, gas and plants.
Oil Derived Plastic
.. are cheap, so cheap they can be used to make one use throwaway products like plates and nappies in huge amounts.
Most oil derived plastics are resistant to chemicals, microrganisms and water. They don’t rot. They last for centuries possibly forever. Find out why most plastics don’t biodegrade here.
More are being made everyday.
How are oil derived polymers are made? You can see the process here.
Bioplastics or organic plastics are derived from renewable sources such as starch, vegetable oil and even chicken feathers.
Some bioplastics are compostable and biodegradable. SOME ARE NOT.
Bioplastics can be made from ethane derived from plants. This is the same as ethane derived from oil. Both are used to make PET plastic. PET plastic does not biodegrade.
PLA is a plastic derived from poly lactic acid that is a certified compostable plastic.
Different processes are used to make the various types of bioplastic. You can find links to technical information here.
There are thousands of different types of plastic product with different qualities. Some of those differences are down to the polymers, a lot are a result of later addatives.
The first stage in plastic production is the polymerization of raw material. Then substances such as fillers and chemicals are added to give color, texture and a whole range of other qualities. Reinforcing fibers for example make the base polymer stronger while man-made organic chemicals, such as phthalates are added to make plastic flexible, resilient and easier to handle.
While the polymers used in base plastics are considered harmless, the potential toxicity of the many additives is often unknown and some are thought to be dangerous.
Find out more about additives fillers and plasticizers here.
Perhaps the most amazing thing about most plastics is that they don’t rot. While every other thing on the planet is decomposing, plastic remains unchanged. Find out why most plastics don’t biodegrade here.
The most common types of plastics, what they are used for and links to technical data sheets.
Problems with plastic – Whats not to like?
List Of Links
Quick Plastic Facts
List Of Plastics – the most common types of plastics, what they are used for and links to technical data sheets.
Plastic Lifespan why most plastic don’t biodegrade
Compostable plastics that biodegrade within a certain amount of time).
Compostable, degradable and or biodegradable plastic – find out here.
Thermoplastics and thermoset plastics – plastics that melt & plastics that don’t
monomers and polymers
Oil Derived polymers – how they are made see the process here.
Bio Plastics derived from plants see the process here
Additives – Fillers and chemicals are added to the base plastic to give color, texture and other qualities. Read up on them here
Reports & statistics links to the latest reports on plastic
Welcome a quick introduction to everything
About Plastic everything you need to know about plastic and somethings you wish you didn’t
Bad Plastic – why you need to cut your plastic consumption
Cut plastic – how to cut unnecessary plastic out of your life & meet the other people doing it.
Links & Projects –links to other plastic free people, the U.K. directory and out other projects
Us & The Boycott –About us the blog and the boycott rules