Design and manufacturing pros who want to play their part in creating more sustainable products need to keep a close eye on biopolymers, writes Luke Williams of industrial design consultancy IDC
Since designers are now expected to be conscious of their role in sustainable product development, an awareness of emerging ways to remove carbon from the design process is paramount. Reducing our dependence on fossil fuels is one of the key steps in decreasing our carbon footprint — and adopting biopolymers may be the answer.
So what actually are biopolymers? Crude oil is typically used to create virgin plastic. Crude oil is refined, polymerised and processed to form pellets used to injectionmould plastic parts. Biopolymers are derived from renewable sources. Instead of crude oil, they are created from a renewable feedstock, in the form of crops, waste cooking oils or algae. These renewable feedstocks are processed at a biorefinery, polymerised and similarly processed to form pellets for injection moulding.
Replacing virgin polymers with biopolymers helps to build a circular economy, removing the need for fossil feedstocks like crude oil
Renewable feedstocks are a carbon sink, as they absorb carbon throughout their life. As a result, biopolymers exhibit a negative carbon footprint and contribute to the reduction of carbon. Replacing virgin polymers with biopolymers helps to build a circular economy, removing the need for fossil feedstocks like crude oil.
Saying no to virgin plastic
The primary advantage of biopolymers is that they remove the dependence on crude oil and replace it with renewable sources that contribute to the reduction of carbon. Before biopolymers, the nonfossil alternative to virgin polymers was a mechanically recycled polymer.
Mechanical recycling starts with the waste plastic that is collected from your door. Local councils send it for sorting, cleaning, shredding and reprocessing, where it becomes pellets for injection moulding.
The primary limitation of mechanical recycling is the lack of complete cleanliness and traceability. For these reasons, mechanically recycled polymers cannot be used to manufacture medical or food/ drink-safe products. Biopolymers, by contrast, have cleanliness and traceability attributes identical to virgin polymers.
IDC recently worked with Reuser to develop a reusable coffee cup lid. Bio- Polypropylene was used to manufacture the product, which has a negative carbon footprint, offers mechanical and thermal properties nearly identical to that of a virgin Polypropylene and is fully recyclable at the end of its life. IDC’s sister company Naiad became the first UK manufacturer to use Bornewables’ bio-Polypropylene within the food and drink industry, while the use of biopolymers contributed to Reuser’s mission of replacing the disposable, single-use food and beverage system with innovative reusable solutions. The fully recyclable bio-Polypropylene, with an established end-of-life infrastructure, formed a circular economy.
Much of the attention around sustainability is focused on one-off projects where face masks or plastic bags have been recycled to form an exotic piece of art or furniture. While this removes single-use products from landfill, the elaborate and laborious processing means this can never be adopted at a scale where the positive environmental impact would be meaningful.
Earlier in 2022, Philips launched the world’s first breakfast set made from bio-based plastics. The toaster, kettle and coffee machine were manufactured from biopolymers derived from recycled cooking oil. It is hoped that other manufacturers will follow suit and embrace the use of biopolymers at scale as a direct replacement for fossil-based plastics.
Injection moulding biopolymers is no different from virgin polymers. No special set-up or processing is required, and mass production can begin immediately using existing infrastructure.
Biopolymers // What’s stopping us?
The primary drawback of biopolymers is cost. While virgin Polypropolyne costs roughly £2/kg, bio-Polypropolyne costs roughly £3/kg. The cost of biopolymers is largely driven by the expensive and lowyield processing of renewable feedstocks, but with time and economies of scale, the price gap between bio and virgin polymers is expected to close significantly.
In addition, the price of virgin polymers is linked to the price of crude oil, which is only going to increase as stocks are depleted. While there are thousands of virgin polymers available with properties to suit almost any application, there are only a handful of biopolymers to choose from. Bio Polypropylene (PP), Polyethylene (PE) and Polyethylene terephthalate (PET) are among the most common. These polymers have a limited number of useful applications.
Chemical recycling is an emerging process that can produce a wider range of available bioplastics. Here, non-mechanically recyclable waste plastics are broken down into hydrocarbons that are polymerised and processed to form virgin-equivalent biopolymers. This will play a key role in reducing the quantity of conventionally unrecyclable plastic sent to landfill.
The use of biopolymers is supporting the push for a circular economy that isn’t dependent on crude oil. As the processing of renewable feedstocks develops and economies of scale reduce raw material costs, the use of biopolymers is set to have a significant positive impact on the plastics industry.
About the author:
Luke Williams is a Senior Design Engineer at IDC.
He plays a key role in design for manufacture, in particular design for injection moulding. As well as detailed design, this involves polymer selection across a range of parts for medical and industrial devices.
Recent work has involved the analysis and implementation of biopolymers to deliver sustainable solutions