Cracking & Polymerisation

Cracking in this case means breaking chemical bonds in molecules so they split apart. They are cracked into smaller molecules.

Cracking and Refining

Crude oil is made of long hydrocarbon chains which can be distilled or refined  into various products such as diesel and petrol.

Longer hydrocarbon chains (such as diesel) are  harder to ignite and slower to burn. Short hydrocarbon chains (for example petrol), ignite very easily and burn more quickly.

You might want more petrol. You can’t distill anymore from your crude oil but you can break up refined hydrocarbon chains to get shorter chains. You you  can crack  diesel into petrol.


So heavy hydrocarbon molecules are broken up into lighter molecules. This is done by means of heat, pressure, and sometimes catalysts.

  • Thermal cracking was invented in 1930 by William Meriam Burton.
  • Catalytic cracking process was invented by Eugene Houdry in 1937.

The end result is in smaller hydrocarbon molecules.

But you don’t just use cracking to transform one product into another. You can rebuild the hydrocarbon molecules into something else. You can use them as building blocks for an entirely new product. For example plastic.

Polymerisation & Plastic

These smaller hydrocarbon molecules can be mixed and matched then  stuck back together or chemically processed to make a whole load of new hydrocarbon monomers –  for example  products like styrene, vinyl chloride, acrylonitrile  used in plastics.

These new monomers can be joined together to create more complex substances called polymers. This process is called polymerisation. Plastics are an example of a manmade, synthetic polymer

Different polymers result in different types of plastic.


Find out more about plastic and how it is made here.

Don’t know your polymers form you Pollyannas? Here’s a list of definitions.


Plastic packed food & storage times

This post does not deal with using plastic to protect food in transit rather than the plastic used to pre-package food for sale in stores.

Plastic is used to pack food for a number of reasons. The most simple are

  • to contain it – to stop it falling about
  • protect it from bruising
  • wrapping products in plastic reduces moisture loss which helps to keep certain veg fresh for much longer and so prolongs shelf life. This type of packaging is used for root vegetables and cucumbers. 

However plastic packaging can be far more sophisticated then that.

Modified Atmosphere Packaging

Wikipedia defines this as  the “Re-balancing of gases inside the packaging can be achieved using active techniques such as gas flushing and compensated vacuum or passively by designing “breathable” films known as equilibrium modified atmosphere packaging (EMAP).”

Heres a bit more on these processes

Gas flushing and compensated vacuum techniques

This massively extends the shelf life of fresh food products. Here products are enclosed in a plastic container (the packaging), then the air inside the pack is changed (the modified atmosphere). Basically they actively suck out the oxygen and shove in a gas (you may need to look up those technical terms).
The modification process varies depending on the product. Different amounts of oxygen will be needed and the gas composition will change depending on the food being packed. Red meat needs high oxygen to maintain the red color, bread requires low oxygen to avoid mould and vegetables often need a three-gas mixture. Yum!
A wide variety of products are gas flushed including

  • Fresh meat /
    Processed meat /
    Cheese /
    Milk powder
    Fresh pasta / Fruit & Vegetables / Ready Meals
    Case ready meat / Fresh poultry / Fish & Seafood

Is it Safe? You might want to consider this

The Committee therefore concluded that there is no health concern associated with the use of 0.3%-0.5% CO in a gas mixture with CO2 and N2 as a modified atmosphere packaging gas for fresh meat provided the temperature during storage and transport does not exceed 4°C. However the Committee wishes to point out that, should products be stored under inappropriate conditions, the presence of CO may mask visual evidence of spoilage.

Specially Designed Films

Specially designed plastic films and bags can be used to modify the atmosphere round the product are used. One example is;
PrimePro® is a packaging technology designed to extend the shelf life of fresh fruits and vegetables. It extends shelf life by removing ethylene gas, a powerful plant hormone that triggers the process of ripening and decay.
PrimePro® is a polyethylene plastic film contains a proprietary additive that is specially designed to remove ethylene from the air around fresh produce.”

Breathable plastics

Unlike most food products, fresh fruits and vegetables continue to respire after they have been harvested. They need some oxygen and will continue to  produce carbon dioxide and water vapor. Packaging here has to allow for this. It has to be breathable. There are plastic films that can accommodate that process.

Vacuum packing

This process removes all the oxygen before sealing the plastic container. Here the non breathable impermeable plastic is shrink fitted to the product thereby allowing no contact with the oxygen in the air around it.

Reduction In Food Waste

Plastic packed food means that food can be stored for longer which should reduce food waste. This is often used to justify plastic packaging.

Plastic wrapped food certainly benefits the retailer as it lasts considerably longer on the supermarket shelves giving them a longer sales time. The producers and importers of pre packaged food also benefit from this increased timescale to sell their food.

And yet somehow it hasn’t cut food waste. In fact as a food waste preventive measure it seems remarkably ineffective. For example

“UK retailers and wholesalers are still wasting around 200,000 tonnes of food each year, and when their supply chains are factored in this figure rises to over 4,000,000 tonnes annually.”


“Supermarket giant Tesco has revealed it generated almost 30,000 tonnes of food waste in the first six months of 2013. Using its own data and industry-wide figures, it also estimated that across the UK food industry as a whole, 68% of salad to be sold in bags was wasted – 35% of it thrown out by customers.

Plastic Waste

Of course it rather depends on what you do with food waste and how you define it. If you compost it you return those nutrients to the soil and they are then used to sustain more plants. If you feed it to animals it can be used to make bacon. In fact calling it waste is really rather misleading. It is a resource and is often used as such.

Food waste is biodegradable, plastic waste is not. Food waste can be dealt with locally and if dealt with properly is a resource rather than a waste product. At worst if littered round the environment it will rot away. Plastic waste has to be specially disposed of at proper facilities. If not it will end up as permanent litter.

And thanks to food packaging there is an awful lot of it.

11% of household waste is plastic, 40% of which is plastic bottles, during 2002 plastic bottles worth around £27 million were disposed of at a cost of £45 million

In the UK  Waste on line, another government agency, are keen to tell us that we generate 3 million tonnes of plastic waste annually 56% of which is used packaging, three-quarters of which is from households. They estimated that only 7% of total plastic waste is currently being recycled. How Big Is Your Pile

Just A Different Kind Of Waste

Creating a huge pile of plastic waste to prevent food waste does not resolve the waste problem.. It merely shifts it to a different sector.

Packaging & Pre-Portioning

One response to the salad fiasco was to suggest making smaller bags of salad. This is of course another issue with prepackaged food. You can only buy what is there not what you want. Over purchasing obviously leads to increased food waste but is sometimes almost unavoidable. If you only want one pepper buying a three pack is unnecessary and despite good intentions often leads to food waste

Waste & The Consumer

Waste in the home is the responsibility of the purchaser. For sure a wrapped sealed product will last longer but one assumes fresh food was bought to be eaten within a fairly short time scale so the benefits of packaging, in that sense at least, are not so great.

A WRAP report into the subject claims that consumers do not understand how to use packaging specially designed to reduce waste any way. However more education on the subject could help. They also have some interesting observations on consumer attitudes to packaging. See their report Consumer attitudes to food waste and packaging

And we are still throwing away huge amounts and food plus huge amounts of plastic packaging.

Food Safety

Packed food is safer food. Yes, but food can still be stored and kept safely without plastic packaging. Plus There is a considerable body of evidence that chemicals leach from the plastic packaging into the food. Some claim the chemicals in plastic can have adverse effects on health.

There is a consensus of opinion, (though sadly not so much in the way of hard facts), that fruit and vegetables start to loose nutrients once harvested. Plastic packaging certainly slows down the aging process wether it slows down nutrient loss is less clear. But all advice seems to be eat your fruit and veg as fresh as possible. Plastic packaging means you don’t know how old that cucumber is. Wether that is relevant or not I cannot say but s the Committee points out when discussing gas flushing for meat, that unless the meat is stored properly, the presence of CO may mask visual evidence of spoilage.


The issues of food waste, the convenience of pre-packaged, longer-lasting food have to be weighed against environmental costs of plastic; the savings made by being able to store food for longer against the clean up costs for plastic. Bearing in mind that much of the latter is not paid for by the producers  but by the end consumer. The supermarket/producer does not pay for the disposal of the plastic wrapper, street cleaning or for the environmental damage it causes when it flies into the canal.

  • It uses a lot of resources to plastic wrap food.
  • While it might reduce food waste (debateable), it means a huge increase in plastic waste.
  • Food waste is biodegradable. Plastic waste is not.
  • Plastic rubbish goes on to pollute the environment in many ways.
  • It costs a lot of money to treat plastic waste and a lot of plastic waste is food packaging.
  • Pre-portioning can actually increase food waste
  • There are many hundreds of different plastic used to package food. Many of them are difficult to recycle.
  • There is a considerable body of evidence that chemicals leach from the plastic packaging into the food. Some claim the chemicals in plastic can have adverse effects on health.
  • You don’t know how old that fruit is. Gas flushing might disguise food rot.

I feel that plastic packing benefits the producers and retailers more than the consumer and the environment. Personally I prefer buying seasonally grown, unpacked food  from local suppliers, only buying what you need and eating it as quickly as possible.

Why package produce




Whats your food wrapped in…..

Long ago I bought myself some lentils from a major retailer of whole foods. They came in a clear, crinkly, sharp kind of plastic bag with colorful, crisp images.  The bag had no plastic code so I  set about researching the packaging. I phoned and asked the producer/ retailer but they couldn’t help me. So I had the packaging analyzed. I can now tell them that it was in fact a film consisting of a series of bonded layers including a 70 micron thick polypropylene and ethylene layer, laminated and printed. Or to put it more simply several layers of plastic each with different properties stuck together.

This method of making plastic films leads to a very versatile product that looks good and has a wide range of uses.

On the down side these films are difficult to recycle. Because they consist of different plastics bonded together it is difficult to know what they are and how to treat them and separating the films is tricky and so very expensive. Films therefore often don’t get recycled but burnt or landfilled.

Just to remind you

Another barrier to [plastic] recycling is the widespread use of dyesfillers, and other additives in plastics. The polymer is generally too viscous to economically remove fillers, and would be damaged by many of the processes that could cheaply remove the added dyes. Additives are less widely used in beverage containers and plastic bags, allowing them to be recycled more often. . Yet another barrier to removing large quantities of plastic from the waste stream and landfills is the fact that many common but small plastic items lack the universal triangle recycling symbol and accompanying number. From  Wikipedia on plastic recycling

So if you need to buy something in plastic, try avoid the film and go for easily recycled polythene. You can find some suppliers here….

Plastics used to package food include the following. Copied from practical action 


Film Type


Barriers to Moisture




Normal Thickness Micrometers






21 – 40







19 – 42






21 – 42


Nitro- cellulose




21 – 24

Polythene (low density)





25 – 200

Polythene (high density)





350 – 1000






20 – 40







18 – 34






20 – 30






12 -23










20 -30

Table 1: Properties of selected packaging materials
* = low ** = medium *** = high. Thicker films of each type have better barrier properties than thinner films. PVDC = polyvinylidene chloride.

Laminated films

Lamination of two or more films improves the appearance, barrier properties or mechanical strength of a package.

Coextruded films

This is the simultaneous extrusion of two or more layers of different polymers. Coextruded films have three main advantages over other types of film:

  • They have very high barrier properties, similar to laminates but produced at a lower cost.
  • They are thinner than laminates and are therefore easier to use on filling equipment.
  • The layers do not separate.
    Examples of the use of laminated and coextruded films are as follows:

Type of laminate

Typical food application

Polyvinylidene chloride coated polypropylene (2 layers)

Crisps, snackfoods, confectionery, ice cream, biscuits, chocolate

Polyvinylidene chloride coated polypropylene- polyethylene

Bakery products, cheese, confectionery, dried fruit, frozen vegetables


Pies, crusty bread, bacon, coffee, cooked meats, cheese

Cellulose-acetate-paper-foil- polyethylene

Dried soups

Metallised polyester-polyethylene

Coffee, dried milk


Dried soup, dried vegetables, chocolate

Type of coextrusion


High impact polystyrene- polyethylene terephthalate

Margarine, butter tubs

Polystyrene-polystyrene- polyvinylidene chloride-polystyrene

Juices, milk bottles

Polystyrene-polystyrene- polyvinylidene chloride-polyethylene

Butter, cheese, margarine, coffee, mayonnaise, sauce tubs and bottles


Thermoplastics and Thermoset Plastics

Plastics are divided into thermoplastics and thermoset plastics.

Thermoplastics can be heated and shaped many times.

Thermoplastics pellets soften when heated and become more fluid as additional heat is applied. The curing process is completely reversible as no chemical bonding takes place. This characteristic allows thermoplastics to be remolded and recycled without negatively affecting the material’s physical properties.

Thermoset plastics can only be heated and shaped once.

Thermoset materials are usually liquid or malleable prior to curing and designed to be molded into their end form, or used as adhesives. Others are solids like that of the molding compound used in semiconductors and integrated circuits (IC

Thermoset plastics contain polymers that cross-link together during the curing process to form an irreversible chemical bond. The cross-linking process eliminates the risk of the product remelting when heat is applied, making thermosets ideal for high-heat applications such as electronics and appliances.

These polymers are highly cross-linked, which means the molecules have extremely strong chemical bonds. Once you’ve initially heated them up to set them into the shape you want – hence the name “thermoset” – they’re irreversibly bound. That means they’re much stronger than thermoplastics, but also that heating them up again won’t break down the bonds in a way that enables you to usefully reshape them, as with thermoplastics. It’ll just char them and crack them instead.

Thermoset plastics that can be remoulded and recycled several times over when heated to about 100ºC are possible, claim researchers in The Netherlands. 

The self-healing polymers make use of the Diels-Alder and Retro-Diels-Alder reactions between thermosetting polyketones and bis-maleimide, allowing the strong covalent bonds of the thermoset materials to be broken and reformed.

Examples of some thermoplastics.

Name Properties Principal uses
Polyamide (Nylon) Creamy colour, tough, fairly hard, resists wear, self-lubricating, good resistance to chemicals and machines Bearings, gear wheels, casings for power tools, hinges for small cupboards, curtain rail fittings and clothing
Polymethyl methacrylate (Acrylic) Stiff, hard but scratches easily, durable, brittle in small sections, good electrical insulator, machines and polishes well Signs, covers of storage boxes, aircraft canopies and windows, covers for car lights, wash basins and baths
Polypropylene Light, hard but scratches easily, tough, good resistance to chemicals, resists work fatigue Medical equipment, laboratory equipment, containers with built-in hinges, ‘plastic’ seats, string, rope, kitchen equipment
Polystyrene Light, hard, stiff, transparent, brittle, with good water resistance Toys, especially model kits, packaging, ‘plastic’ boxes and containers
Low density polythene (LDPE) Tough, good resistance to chemicals, flexible, fairly soft, good electrical insulator Packaging, especially bottles, toys, packaging film and bags
High density polythene (HDPE) Hard, stiff, able to be sterilised Plastic bottles, tubing, household equipment

Properties and uses of the thermoset plastics.

Name Properties Principal uses
Epoxy resin Good electrical insulator, hard, brittle unless reinforced, resists chemicals well Casting and encapsulation, adhesives, bonding of other materials
Melamine formaldehyde Stiff, hard, strong, resists some chemicals and stains Laminates for work surfaces, electrical insulation, tableware
Polyester resin Stiff, hard, brittle unless laminated, good electrical insulator, resists chemicals well Casting and encapsulation, bonding of other materials
Urea formaldehyde Stiff, hard, strong, brittle, good electrical insulator Electrical fittings, handles and control knobs, adhesives

Find out more about the above plastics and many others here .

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!


Plastic, an introduction

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.

To conclude;
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.

Made from?
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.

For example:

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. 

Plastic Types

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.

Plastic Lifespan
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.

A List Of Plastics 

The most common types of plastics, what they are used for and links to technical data sheets.

Bad Plastic

Problems with plastic Whats not to like?

Interesting  Check out this  great post by Chris Woodford

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
Making Plastics
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
Site Map


Non Biodegradable Plastics – some considerations…

Plastic is everywhere and possibly closer than you think. You might be wearing cotton but I will bet you anything the thread used to sew your clothes is man-made. As for the elastic, buttons and velcro – all synthetic. Your table is wood but the varnish is plastic, your water from plastic pipes, your food from plastic wrappers, even your tin cans are lined with plastic.

In addition to being incredibly versatile, synthetic plastics are cheap. Products that would be extremely expensive if made from natural materials are affordable when made from synthetics. Computers, waterproof jackets, shoes and even furniture are all much more available to very many more people.

All plastics can be recycled. Because they are man-made they can be broken down and remade into new items.

Because they are (mostly) made from oil, and because they can be recycled, they obviously reduce the pressure on other natural resources. They can replace wood and steel and fibres so less land has to be farmed or mined, less forests cut down, less water diverted to irrigation and of course less pesticide pollution. All of which means less pressure on what is left of our wild habitats.

It is a wonderful product and it is easy to just how fantastic it seemed when it was first appeared – but 50 years on and the love affair is turning extremely sour.

Because most plastics are non biodegradable.

Non biodegradable oil based plastics the good, the bad and the ugly

The following points apply to non biodegradable oil based plastics – the commonest forms of plastic. Find out more about other kinds of plastic here.

So versatile… the many kinds of plastic

Plastic is made up single units, monomors of combined in a variety of ways. This process is called polymerisation. Different combinations result in different products. Products as dissimilar as hard machine parts to stuffed toys to glue are all made from plastics. Some products can be easily recognised as “plastic” others are not so obvious. Carrier bags? Plastic! Gel ink – what?? Find out how oil derived plastic is made here…

Then there are the additives….

Different chemicals are added to the base plastic increasing the range of properties.

While the polymers used in base plastics are generally harmless, the potential toxicity of the additives is often unknown and much more research needs to be done on the safe handling and ultimate disposal of these products.

Plastic Applications

What are plastics used for? just about everything. Have a look at this huge list of products made from synthetic polymers

Plastic Lifespan

Perhaps the most amazing thing about plastic is that it doesn’t rot. While every other thing on the planet is decomposing plastic remains unchanged. Find out why here

Problem Plastic

About 100 million tons of plastic are produced each year and much of it is used to make one-use, disposable items. Because plastic doesn’t biodegrade these items, though only used for moments, last for decades, centuries, possibly forever. We are creating ever lasting rubbish in huge and unsustainable amounts.

Not surprisingly plastic waste is increasing exponentially.It is now polluting the environment,maiming and killing the animals who come in contact with it,and destroying the resources accessed by the poorest.

Dirty, difficult to dispose of, kills animals and possibly carcinogenic and these are just some of the problems. You can find many more here.


Chemicals & Additives In Plastic

The first stage in plastic production, the polymerisation of raw material.

Then substances such as fillers and chemicals (sometimes called monomeric ingredients), 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.

These give the plastic an additional range of qualities. There are thousands of addatives used in making plastic.

Plastic additives

Reinforcing fibers to make the base polymer stronger.  For example baron, carbon, fibrous minerals, glass, Kevlar all Increases tensile strength. Others increase flexibility, heat-deflection temperature (HDT) or help resists shrinkage and warpage.
Extender fillers such as calcium carbonate and silica, clay reduces material cost.
Conductive fillers means electromagnetic shielding property can be built into plastics, which are normally poor electrical conductors include  aluminum powders, carbon fiber, graphite Improves electrical and thermal conductivity.
Coupling agents such as Silanes, titanates  improve the bonding of the plastic matrix and the reinforcing fibres.
Plasticizers – man-made organic chemicals, such as phthalates added to make plastic flexible, resilient and easier to handle. Some are considered unsafe – read more here.
Stabilizers (halogen stabilizers, antioxidants, ultraviolet absorbers, and biological preservatives) to stop it breaking down over time>Protects from thermal and UV degradation (with carbon blacks).
Processing aids (ie lubricants to reduce the viscosity of the molten plastic and others)
Flame retardants Chlorine, bromine, phosphorous, metallic salts Reduces the occurrence and spread of combustion.
Anti-static agents can be used to attract moisture, reducing the build-up of static charge.
Colorants (pigments and dyes) Metal oxides, chromates, carbon blacks.
Blowing agents Gas, azo compounds, hydrazine derivatives Generates a cellular form to obtain a low-density


As you can see that is a lot of additives. So many that  we do not know what they all are. Also manufacturers are not obliged to reveal what they use in their plastic mixes. So while the polymers used in base plastics are mostly considered to be harmless, the potential toxicity of the additives is often unknown.

It is claimed that many of the additives used have not been passed as fit for human consumption and that more research needs to be done on the safe handling and ultimate disposal of these plastics.

Rather worryingly, some of the chemicals used in plastic seem to be mobile and can leach from the plastic product into the contents. For example from the plastic packaging wrapped round your cheese or the epoxy resin lining of your can of beans into your food. The jury is still out on wether this is dangerous or not but add that to a brown toast cancer scare and cheesy beans don’t look so tasty!

Halogenated plastics like PVC will, when burnt, release dioxin one of the most powerful carcinogens known.

More animals are being found with plastic in their stomachs having mistaken for food and microplastics are being ingested by bottom feeders and plankton. Some reports claim that chemicals from plastic are being absorbed by animals with ill effects.You can read more on microplastic here and read reports on animals eating plastic.

Plastic particles attract persistent organic Pollutants (POPs). POPs are a small set of toxic chemicals that remain intact in the environment for long periods and accumulate in the fatty tissues of animals. Bottom feeders eat the plastic pellets and so the POPs enter the food chain.


Plastic Food 
What Are Chemicals?

Burning plastic in the home

Some feel my worrying about plastic in the home is taking it too far?  Disposables? Yes, they can see I ...
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Plastic Chemicals & Food

Plastic packed food is unappealing in many ways. For me the most immediate problem is the flavor, or lack of ...
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Endocrine disruption, fish & polyethylene

Early warning signs of endocrine disruption in adult fish from the ingestion of polyethylene with and without sorbed chemical pollutants from the marine ...
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Perfluorochemicals and plastic

Perfluorochemicals (PFCs) are a family of man-made chemicals. They have been around since the 1950s. They include perfluorooctane sulfonate (PFOS; ...
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are used as a plasticiser  used to make a material like PVC softer and more flexible. But they are also ...
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Endocrine System & Endocrine Disruptors

A few quotes on the endocrine system....... "Although we rarely think about them, the glands of the endocrine system and ...
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Is a persistent, bioaccumulative and toxic chemical - ie one that lasts a long time, accumulates in the food chain ...
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Persistant Organic Pollutants

I was under the impression that pops was some kind of horrid Yorkshire dish involving hot milk and bits of ...
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Chemicals & Additives In Plastic

The first stage in plastic production, the polymerisation of raw material. Then substances such as fillers and chemicals (sometimes called ...
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Polychlorinated Biphenyls

Polychlorinated biphenyls (PCBs) are a group of manmade chemicals. They are oily liquids or solids, clear to yellow in color, ...
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PTFE Non stick plastic

When I was young and innocent, I knew nothing of polytetrafluoroethylene (PTFE). Well, it's not the kind of thing a ...
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 A white brittle plastic until you add plasticisers the most common being phthalates then it becomes soft and flexible. PVC is ...
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What’s in a PET bottle?

I am lucky enough to live in a country that supplies clean drinkable tap water so obviously I don’t need ...
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Tin Cans, Plastic Liners & Health

So you think, no that you've given up plastic but at least you can buy stuff in tins. At least ...
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Bisphenol A or BPA is it is known to its chums is used in some thermal paper products such as till receipts. the ...
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Dioxins & Burning plastic

So, is it safe to burn plastic? Well most plastics don't  burn easily - it melts and bubbles.  It will burn eventually ...
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Naptha & Oil Derived Plastic

Crude oil is a mixture of different hydrocarbons each with a different boiling point. These substances are separated from each other  in a distillation tower.
This results in the separation of heavy crude oil into lighter groups called fractions. Each fraction is a mixture of hydrocarbon chains (chemical compounds made up of carbon and hydrogen), which differ in terms of the size and structure of their molecules.

How Stuff Works puts it like this
Hydrocarbons are molecules that contain hydrogen and carbon and come in various lengths and structures, from straight chains to branching chains to rings.
There are two things that make hydrocarbons exciting to chemists:
Hydrocarbons contain a lot of energy. Many of the things derived from crude oil like gasoline, diesel fuel, paraffin wax and so on take advantage of this energy.
Hydrocarbons can take on many different forms. The smallest hydrocarbon is methane (CH4), which is a gas that is a lighter than air. Longer chains with 5 or more carbons are liquids. Very long chains are solids like wax or tar. By chemically cross-linking hydrocarbon chains you can get everything from synthetic rubber to nylon to the plastic in tupperware. Hydrocarbon chains are very versatile!
Find out more about hydrocarbons here.


oil refinery

Petroleum Oil Refinery Process Diagram

From crude oil you can distill a whole load of products including;
lubricating oils
jet fuel
diesel fuel
heating oil
Naptha a feedstock for plastic

How much in a barrel?
Oil is sold between countries in quantities called barrels.
One barrel of oil is 42 US gallons 159 litres or 35 gallons or 280 pints
The weight of a barrel depends on where the oil comes from. However, there are about 8 barrels in a tonne
A barrel of crude oil can make about

  • 7.27 gallons (27.5 liters): Other products (feedstocks for petrochemical plants, asphalt, bitumen, tar, etc.)
  • 1.72 gallons (6.5 liters): Liquefied Petroleum Gases (LPG)
  • 3.82 gallons (14.5 liters): Jet Fuel
  • 1.76 gallons (6.6 liters): Heavy Fuel Oil (Residual)
  • 1.75 gallons (6.6 liters): Other Distillates (Heating Oil)
  • 9.21 gallons (35 liters): Diesel
  • 19.15 gallons (72.5 liters): Gasoline
  • Approximate figures because every barrel of crude is different.
  • A flight from San Francisco to Tokyo may take about 9,000 US gallons of jet fuel which requires about 2,250 barrels of crude oil to extract. From Econtrader


    Definitions of naptha vary but
    the fraction that boils between 27 °C and 93 °C (5 – 7 C atoms) is often called light naphtha.
    the fraction that boils between 93 °C and 177 °C (6 – 10 C atoms) is heavy naphtha.
    Crude oils from different sources contain different percentages of naphtha.
    Naptha cannot be refined into gasoline or motor oil.
    Naptha is the plastic feedstock of choice for many but in the US, most plastic is made from natural gas.

    Google says you can get anything from 27 to 54L of naptha from 1 barrel of crude.

    Naptha to Plastic

    Cracking & Polymerisation
    Hydrocarbon chains can be further refined by cracking and polymerising.
    Very basically cracking breaks the existing chains and polymerisation is remixing them into something new. You can read more about it here.

    Ethane and Propane are derived from Naptha
    Using high-temperature furnaces
    Ethane is cracked into ethylene
    Propane is cracked into propylene,
    Using a catalyst, a reactor and some heat these are now remade into plastic polymers
    Ethylene becomes polyethylene also called polythene, the world’s most widely used plastic,
    Propylene joins together to create polymers called polypropylene.
    Most of the plastics we use are derived from polyethylene and polypropylene
    Polypropylene and polyethylene were discovered in  1951 by two chemists working for Phillips Petroleum Company.

    There are enough petrochemicals in one barrel of oil to make one of the following

    • 39 polyester shirts
    • 750 pocket combs
    • 540 toothbrushes
    • 65 plastic dustpans
    • 23 hula hoops
    • 65 plastic drinking cups
    • 195 one-cup measuring cups
    • 11 plastic telephone housings
    • 135 four-inch rubber balls


    Processing can include the addition of plasticizers, dyes and flame-retardant chemicals – see  additives….


    The polymers are now melted, cooled then cut into small pellets called nurdles.
    These pellets are now shipped to manufacturers who make plastic products by using processes such as extrusion, injection molding, blow molding, etc.

    Qualities & Biodegradability

    These plastics are chemically inert and will not react chemically with other substances which makes them very useful. It also means that they do not break down chemically so do not biodegrade. This has a huge environmental impact as plastic trash lasts forever. See plastic lifespan.

    These plastics can be recycled
    Useful links



Monomors and Polymers

We are going to start right at the beginning – before plastic there were polymers – before polymers it was monomers..

A monomer is a molecule that can join with other molecules to form a chain of molecules.

A chain of monomers (or molecules) is called a polymer.

So, a polymer is a chain of repeating monomers or molecules.

A polymer is a large molecule that is made out of many smaller molecules that are joined together by covalent bonds. It may also be called a macromolecule.

Polymers may consist of just one type of monomer or many different monomers. But the pattern must repeat

So a polymer is many  monomers or small molecules, joined together in a repeating pattern. The pattern has to repeat a number of times, (a minimum of 500 was one number I read)

Chains of polymers then bond or stick together to form stuff like cellulose, the woody stuff in plants.

Natural polymers are created as part of ongoing biological processes – cotton is part of a plant, wool is grown by sheep and leather is the skin of what ever unfortunate animal.

Synthetic Polymers

Synthetic polymers are, as the name suggests, manmade. The key point here is that though the base material may be a natural product such as oil, the polymers derived from it are not. They are not the result of a natural process but have been created artificially.

Monomors have been isolated and then rearranged in new groupings to form new polymers in a precess known as polymerisation. Read more about it here.



Cardboard Boxes With Plastic Liners

The plastic free cocoa quest has suffered something of a setback.

Last week Mother came bustling in flushed with pride.“I don’t know what all the fuss is about”, she carrolled handing me a box of cocoa from Sainsburys.

Yes, a cardboard box, of cocoa.As if!

How many times have I told her “Squeeze and listen!”.

Most food products in cardboard boxes are further wrapped in plastic bags. To find out if this is so, you have gently squeeze the box and listen for the tell tale crackling of the plastic bag inside.

And yes, you look a right idiot in Supermarkets doing this

Sure enough the cocoa was further packed in a plastic bag – and not even one we can recycle.

Look here for other sneaky plastic.

Find out more about the cocoa quest here



Biodegrading and degradation – Plastic Lifespan,

So most plastics are made from oil and most plastics do not biodegrade. See how and why here…

But what does that actually mean?


Biodegradation refers to the breaking down of organic substances by natural means. Natural means, means the breaking down is done by naturally occurring entities – things that are made in the body such as enzymes ( clever things that enable chemical break downs) or micro organisms that inhabit the teeny tiny world ( bacteria, fungi and exceptionally small plants and animals ). Any plant-based, animal-based, or natural mineral-based product has the capability to biodegrade

The key point is, is that the process of biodegradation is an integral part of the natural cycle. This process could be called rotting or decomposing or other nasty sounding things and yes it can be smelly but it is the very basis of life. Because as natural materials break down they release all kinds of nutrients that are used to feed other living organisms. Orange rind becomes compost which releases nutrients the orange tree can utilize. The tree feeds and so has the energy to make fruit which we eat discarding the peel which then biodegrades into compost – feeding many other creatures along the way including worms. It’s a kind of magic

In short…..

Biodegrading is the breaking down of organic substances,  (plants, dead animals, rocks, minerals etc.), by natural means. It  happens all the time in nature. We live, we die, we rot and so we feed the next generation. Even if you are a rock. All plant-based, animal-based, or natural mineral-based substances will over time biodegrade.

Here’s how long it takes for some commonly used products to biodegrade, when they are scattered about as litter:

Paper ~ 2-5 months 
Cotton rags ~ 1-5 month
Natural fiber rope ~ 3-14 months
Orange peel ~6 months
Wool socks ~1 to 5 years
Leather shoes ~25 to 40 years
Tin cans ~ 50 to 100 years

Plastic – years? centuries? maybe never!

Why Plastic Doesn’t Biodegrade

Because they are man made, the majority of plastics do not biodegrade. “Nature doesn’t make things like that, so organisms have never seen that before ” says Kenneth Peters, an organic geochemist at Stanford University, quoted in this fantastic article I recommend you read

Which means the enzymes and the micro organisms responsible for breaking down organic substances  do not recognize plastic. Therefore plastic products are pretty much indestructible – they do not rot or biodegrade.


Plastic Eating Microbes

Of course it is not quite as simple as that. Some bacteria it seems can digest plastic. Don’t get too excited. They are rare and don’t eat a great deal but you can read the latest reports here

Biodegradable Musings

That said the term biodegradable can be difficult to define. It is often about the time something takes to biodegrade – the rate at which something breaks down. Arguably  everything, even man-made products, will eventually biodegrade. However if it takes centuries to do so, it is generally considered to be non-biodegradable.

It also depends where a product is dumped.

Why Landfill Doesn’t Work

“Many products that are inherently biodegradable in soil, such as tree trimmings, food wastes, and paper, will not biodegrade when we place them in landfills because the artificial landfill environment lacks the light, water and bacterial activity required for the decay process to begin.”

This is why newspapers landfilled back in 1952 can still be easily read!  The Garbage Project is an anthropological study ofwaste conducted by a group at the University of Arizona. From Greengood

Too Much Trash

The sustainable rate of biodegradation is only what an ecosystem can deal with. Too much and the microorganisms get overwhelmed and collapse sobbing, unable to cope.


Of course plastic breaks, tears  and degrades – but only into smaller pieces of plastic. Read more about that here


Useful stuff to know

Degradable, biodegradable or compostable

So most plastics are made from oil and most plastics do not biodegrade. See how and why here… And yet you will find plastics described as degradable ...
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Compostable Plastics

Plastic was the name given to early synthetic products such as cellophane,  that were derived from cellulose. These plastics  were biodegradable. Then they learnt how to make ...
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Biodegrading and degradation – Plastic Lifespan,

So most plastics are made from oil and most plastics do not biodegrade. See how and why here... But what does that actually mean? Biodegrading Biodegradation ...
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Plastic eating microbes

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Degradation Initiators & Degradable Plastic

Traditional plastics do not biodegrade. Of course plastic breaks, tears and cracks. It weathers and sunlight makes it brittle, It falls apart – it degrades – but ...
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Plastics – a big list of the different types of plastic

Plastics can be made in a variety of ways from a variety of materials; shale gas, oil, plants even chicken feathers can all be used to make plastic.
However oil derived plastics are the most common.
Plastics are created from single units combined in a variety of ways. This process is called polymerisation. Different combinations result in different products and there are hundreds of them.
Plastics can be used to make everything from varnish to stockings, bottles to car parts by way of varnish, crisp packets and computers.
Most plastics do not biodegrade and last for centuries possibly for ever.
But then there are other plastics that are truly compostable with a lifespan of months and dissolve in the dishwasher.

Confused? Find out more here  What is plastic -an introduction.
Don’t know your P.E.T.s from your polymers?  Check out this collection of definitions essential for understanding plastic!

A List Of Plastics

Click on the name to find out more

Biaxially Oriented Polypropylene -BOPP when polypropylene  is biaxially oriented, it becomes Biaxially Oriented Polypropylene -BOPP the crisp crystal clear stuff used for greeting cards, the plastic wrapping round boxes of tea etc.  It is easy to coat, print and laminate to give the required appearance and properties for use as a packaging material.
Bioplastics are made from plants rather than oil.
Bio- degradable /Degradable Plastic has  additives to make it bio-degrade. NOT to be confused with compostable plastic!

Cellophane is one of the first plastics. Proper cellophane is plant derived and biodegradable. However the term is often applied to a petroleum derived product.

Compostable Plastic  has been certified compostable and can naturally biodegrade such as PLA plastic.

Degradable plastic with added chemicals to make them break down more quickly.

Ethane derived plastics – ethane comes from plants, oil coal and gas

Ethane derived plastics ethane comes from plants, oil coal and gas

Film plastics can be bonded together to create different kinds of product.All of which can be hard to RECYCLE

Halogenated Plastics include

  • Chlorine based plastics:
  • Chlorinated polyethylene (CPE)
  • Chlorinated polyvinyl chloride (CPVC)
  • Chlorosulfonated polyethylene (CSPE)
  • Polychloroprene (CR or chloroprene rubber, marketed under the brand name of Neoprene)
  • PVC
  • Fluorine based plastics:
  • Fluorinated ethylene propylene (FEP)
  • These are known as the poison plastics are carcinogens are produced when they are made and ageing when they are disposed of.

    Film – different plastics can be bonded together to create all manners of film. Read more HERE

    HDPE- High-density polyethylene plastic code 2  Used to carrier bags, toys, bottle s and a whole load of other stuff.  

    LDPE- Low density polyethylene plastic code 4  used to make everything from soft clear bags to parts that need to be weldable and machinable

    Nylon is often associated with the fabric of the same name but can be used to make all manner of things from fibre to  moulded objects.

    Polyethylene (polythene) derived from ethane.

        • High-density polyethylene (HDPE)
        • LDPE- Low density polyethylene plastic code 4
        • Cross-linked polyethylene (PEX or XLPE)
        • Medium-density polyethylene (MDPE)
        • Linear low-density polyethylene (LLDPE)
        • Low-density polyethylene (LDPE) 
        • Very-low-density polyethylene (VLDPE)

    PLA a plastic derived from poly lactic acid that is certified a compostable plastic. Fact Sheet or all posts

    Polyethylene terephthalat PET or PETE plastic code 1 most often used for making fibers and bottles

    Polyurethanes  can be used to make almost anything from cushions to varnish. Used to make  flexible foam in upholstered furniture and rigid foam such as shoe soles. It also comes in a fluid form in  varnishes, adhesives and  sealants.

    Polypropylene PP plastic code 5  is used to make ropes, thermal underwear, carpets, plastic parts and reusable containers of various types. Used in the automobile and construction industries, some car battery casings, oil funnels, and plastic drinking straws, laboratory equipment, loudspeakers, automotive components, and polymer banknotes.

    Polystyrene – PS  plastic code 6 disposable (ha!) products to food packaging like fast food clamshells, meat trays, protective packaging  and loose fill peanuts. Difficult to recycle.

    Polytetrafluoroethylene  (PTFE) is a synthetic non stick coating for cookware to armoured bullets. It is an efficient lubricant and can kill budgies. Check it out.

    Polyvinyl chloride PVC  plastic code 3  PVC is known as the “poison plastic” because of the lethal chemicals produced during its manufacture and possibly again when disposed of.

     Silicon and silicone rubber– Plastic? Rubber? Just plain weird? Used for everything  from ice-cube trays to adult toys to cake tins it certainly gets around. So what is silicone??

    The main polymers in use are

        • polyethylene,
        • polypropylene,
        • polyvinyl chloride,
        • polyethylene terephthalate,
        • polystyrene,
        • polycarbonate,
        • polyeurothene
        • poly(methyl methacrylate) (Plexiglas).

    According to Wikkipedia they account for ” nearly 98% of all polymers”. Wikkipeida

    Most of the plastic products we use are derived from these polymers with alternative plastics accounting for the rest.

    Most of the base components for these polymers are derived from oil.

    Why Do Some Plastics Have Numbers?

    Plastic codes are the number you find on some plastics to identify the polymers used. There are many more plastics than numbers and new plastics are being made all the time. Find out more here

     Brand Names