Plastics
There are thousands of variations of different plastics available, all touting slightly varying properties and so we are only going to cover the most widely used in the industry here.
But first let’s start with an overview of bio-based vs fossil fuel derived. This useful chart breaks down the groups of plastics available on the market. As you can see, bio-based and biodegradable are not synonymous. And within the biodegradable material group, there are some that will break down in natural conditions (such as a home compost) and others that require industrial conditions.
Fossil fuel derived plastics
The following plastics are the more widely used non-biodegradable plastics derived from fossil fuels.
Polypropylene (PP)
Widely used in consumer goods, polypropylene is a flexible plastic that is softer than ABS but stiffer than PE. PCR PP (post consumer recycled polypropylene) is also available. High levels of PCR content will affect the material properties, so you may not be able to use 100% recycled material and PCR PP is typically not food safe.
PP can be injection moulded, blow moulded and thermoformed.
You’ll know if from our Wild deodorant case and HUNU cup lid.
Melting Point: 130 to 171 °C
Density: between 0.895 and 0.92 g/cm²
Recycling symbol: 5
Polyethylene (PE)
Polyethylene comes in different densities: high (HD), medium (MD) and low (LD). In general, however, it is a softer, more flexible plastic than PP and has excellent chemical and solvent resistance.
It can be blow moulded, thermoformed, injection moulded, extruded and roto-moulded and typically has a high shrinkage rate.
You’ll know it from the base of the Boxx boxing bag and Joseph Joseph chopping boards (HDPE) and the traditional plastic shopping bag (LDPE).
Melting point: 120-140°C
Density: 0.93 to 0.97 g/cm3
Recycling symbol: 2
Polyethylene Terephthalate (PET)
PET is the most widely recycled plastic, it’s typically clear, provides an excellent gas and moisture barrier and is food grade even with very high PCR content (often referred to as rPET). It is relatively soft and can be easily scratched, so texture choice is important for consumer goods.
It can be blow moulded, injection moulded and thermoformed.
You’ll know it from packaging, predominantly plastic bottles, however a crystalline version of rPET is used to make the Wagamama takeout packaging.
Melting:240°C–265°C
Density: 1.3-1.4 g/cm3
Recycling number: 1
Polyethylene terephthalate glycol (PETG)
A variant of PET modified with glycol, the added heat resistance and toughness makes it an ideal material for 3D printing and as an alternative material to glass.
It can be blow-moulded, thermoformed and injection moulded.
You’ll know it from it being one of the most common 3D printing materials.
Melting point:240°C–265°C
Density: 1.23g/cm3
Recyclable through independent recycling streams, number: 7
PCTG
(A glycol modified polyethylene terephthalate co-polymer)
Not related to polycarbonate (PC) but another variation on PET, PCTG is a BPA free clear polymer that has excellent optical properties and high stiffness and impact resistance.
It can be blow-moulded, thermoformed and injection moulded.
You’ll know it from reusable water bottles and orthodontic aligners
Melting point: 240°C–265°C
Density: 1.23g/cm3
Can be recycled, but not curb-side, number: 7
Acrylonitrile butadiene styrene (ABS)
A widely used plastic for consumer tech products for its high rigidity and excellent surface finish and colour possibilities. It is often combined with PC for more industrial or high impact products.
It can be injection moulded and extruded.
You’ll know it from the Apex bike body and the Quell controllers.
Melting point: 200°C
Density: 1.0 - 1.05 g/cm3
Can be recycled, but not curb-side, recycling number: 7
Polycarbonate (PC)
A lighter-weight alternative to glass (it has historically contained BPA, although BPA-free PC is now available) PC is often used for it’s optical properties, however it can also be coloured. PC is a tough, abrasion and UV resistant material.
It can be injection moulded, extruded, thermoformed and blow moulded.
You’ll know it from hard suitcase shells and helmet visors.
Melting point: 240°C–265°C
Density: 1.2 – 1.22 g/cm3
Recycling number: 7 - can be recycled, but not curb-side
As you can imagine, there is less demand for a biodegradable plastic derived from fossil fuels. Therefore we have only listed one:
PVOH (PVA)
A water soluble plastic used in laundry and dishwasher pods there is some controversy surrounding how the material breaks down and if it leaves micro-plastics behind. However there is no conclusive evidence to support this. PVOH has excellent liquid and oxygen barrier properties and is FDA compliant for use in food and drink (and human consumption!).
Bio-properties: fossil fuel based, biodegradeable and compostable
You’ll know it from the dissolvable layer around dishwasher tabs
Bioplastics plastics
Bioplastics are derived from biological substances rather than from petroleum, some may be biodegradable, but that’s not always the case. Let’s dig in, in more detail…
The following plastics are bioplastics that are derived partly or fully from renewable plant based materials that are not biodegradable. You will recognise that many of these are just plastics listed above with ‘bio’ at the front. That’s because the polymer chains are fundamentally the same, it’s just the source of the raw material is the same. Instead of listing out the same properties again, we have given some examples on the market that you might be able to integrate into your own projects.
Bio-PET
Typically based on 30% renewable raw material from sugarcane and 70% oil-based, bio-PET is considered a ‘drop-in’ material and can be substituted for, and recycled alongside, fossil based PET.
You’ll know it from Coca-cola’s Plant Bottle
Bio-PE
Ranging from 94-100% bio-based content, bio-PE is a good drop in option for your product and packaging projects. Similar to bio-PET, sugar cane is processed to produce ethylene, which can then be used to manufacture polyethylene.
You’ll know it from Lego parts including the leaves and tree blc
Bio-PP
Bio-PP is typically made from bionaphtha (a biofuel) derived from renewable resources, such as organic waste and residue oil such as used cooking oil.
You’ll know it from not much, yet. To date it’s not been a widely adopted material, but there are companies looking into it for applications including baby bottles.
The following plastics are bioplastics that are derived from renewable plant based materials and are biodegradable.
PLA
Otherwise known as Polylactic Acid, PLA is made from the sugars of corn starch, cassava or sugarcane. It is widely used packaging and 3D printing and its properties sit somewhere between polystyrene and PET. It is generally accepted that the carbon footprint of PLA is less than traditional fossil fuel based plastics and as the raw material is both renewable and widely available, it has fast become the most popular biodegradable plastic.
However, there has been questions about the land-use, pesticides and water required to grow the raw material and whether we should be using this land to grow food or forests. As it can only be composted in industrial facilities and cannot be recycled curbside, there are those that consider it to be more greenwash than truly sustainable. However, as with any material, decisions should always be made based on the application and context of use, and with consideration for the full life-cycle.
You’ll know it from coffee cup lids, plastic cutlery, biodegradable shopping bags and 3D print filament
PHA
A home-compostable bioplastic made from microbes that feed on plant based material (either sugars from corn/sugarcane or, in some cases, food or agricultural waste) and convert it to a polymer through a fermentation process that is harvested and turned into a plastic-like material. Due to this complex process, PHA is up to 8 x more expensive than PE.
Because it is not derived from fossil fuels, and is safe for home-composting, describing it as a plastic feels unfair, however it is still classed as such by the EU.
You’ll know it from medical applications including biodegradable surgical staples, screws, plates, pins and suture materials, however it is finding its way into traditional packaging applications.
Bio-PBS
A relatively new material, PBS has properties similar to PP yet it decomposes in water if used in thin film form. Mechanically it has similar properties to PP.
Bio-properties: plan fuel based, biodegradable
You’ll know it from films and liners in packaging e.g. in biodegradable coffee cups