As the expectation ramps up on designers to be conscious of their role in ensuring sustainable product development, an awareness of emerging ways to remove carbon from the design process is paramount. Reducing our dependency on fossil fuels is one of the key steps in decreasing our carbon footprint and adopting biopolymers may be the answer.
A biopolymer is a polymer derived from a renewable source. Crude oil is typically used to create virgin polymers, crude oil is refined, polymerised and processed to form pellets used to injection mould plastic parts. Instead of crude oil, biopolymers 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.
Renewable feedstocks are a carbon sink, as they absorb carbon throughout their life. As a result, many biopolymers have a negative carbon footprint and contribute to the reduction of carbon. Replacing virgin polymers with biopolymers contributes to a circular economy, removing the need for fossil feedstocks like crude oil.
This article explores the advantages of biopolymers, where and how they can be used along with their limitations.
The primary advantage of biopolymers is that they remove the dependency on crude oil and replace it with renewable sources that contributes to the reduction of carbon.
Before biopolymers the non-fossil alternative to virgin polymers was a mechanically recycled polymer. Mechanical recycling starts with the waste plastics that are collected from your door. Local councils send them for sorting, cleaning, shredding and reprocessing, where they become pellets used to injection mould recycled polymer parts. The primary limitation of mechanical recycling is the lack of complete cleanliness and traceability. For these reasons, mechanically recycled polymers can’t be used to manufacture medical or food/drink-safe products. Biopolymers remove this issue as they 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 lids, which had a negative carbon footprint, mechanical and thermal properties near identical to that of a virgin polypropylene and was fully recyclable at the end of its life.
IDC’s sister company, Naiad, became the first UK manufacture 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, contributed to a circular economy.
Cost is currently the main disadvantage of biopolymers, while virgin polypropolyne costs roughly £2/kg, bio-polypropolyne costs roughly £3/kg. The cost of biopolymers is largely driven by the expensive and low-yield processing of renewable feedstocks, but with time and economies of scale the price gap between bio and virgin polymers is expected to close significantly.
While there are thousands of virgin polymers available with properties to suit almost any applications, there are only a handful of biopolymers to choose from. Bio-polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET) and are amongst the most common. These polymers have a limited number of useful applications.
The use of biopolymers is supporting the push for a circular economy that isn’t dependant on crude oil. As the processing of renewable feedstock develops and economies of scale reduce raw material costs, the use of biopolymers is only going to increase.
About the author
Luke Williams is a Senior Design Engineer at IDC. Luke 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.