Design for sustainability

Design for sustainability

Kirsty Wood, Development Technologist and Sustainability Lead at Hexpol TPE, shares how TPE materials fit into a circular economy.

One of the fundamental concepts of how Hexpol TPE developed the Dryflex Green and Circular ranges required much thinking into how materials suppliers can consider sustainability right from the start. 

There are thousands of different recipes or formulations for TPEs, and some have unusual properties such as the ability to swell in water or flame-retardancy, as well as TPEs that come from plants in the case of the bio-based materials, and those that contain recycled content. When designing for sustainability, we’re producing a thermoplastic elastomer using a ‘baking a cake’ analogy. The reason for this is that we're taking ingredients, usually many different ingredients for a compound, weighing them out at different proportions, mixing, and then entering a heating process stage, but rather than going into an oven, obviously they go through processing equipment such as a twin-screw extruder. At the end, we get plastic pellets and that's what we sell on.

Considerate questions

Sustainability is changing the way that we work, and how we develop a material is massively affected by it. We've always had to consider some aspects such as what does the material do and what kind of properties does it need to have? Does it require special regulatory considerations? How should it look and feel: the colour, the aesthetics, the haptics? Then we consider the environment that it's going to be used in, i.e. indoor or outdoor products. Does it need to be able to resist certain types of weather? Furthermore, we always have to consider how it's processed. But that material will exist in an entire lifecycle, so we also think about things like the energy that we use, how much are we using and where does it come from? We also think about things like how the materials will be shipped and how are they being shipped to us? What kind of waste do we produce within our operations? Where does that go after production? And then, finally, we think about the end of life of a product.

We can design something that is easily recyclable by suggesting materials that are compatible with one another so that they can be recycled together. Perhaps the product needs to be repairable or have parts that can be repurposed. The other aspects to this lifecycle include where our raw materials come from. In the case of Dryflex Green, we're using bio-content and we can look at using recycled content with the intention of reducing reliance on fossil fuels. The final step is validating all of these things. It's great to have the intentions of reducing the impact of a material and where it comes from, but we need to make sure that that's actually happening – and that's done in a number of different ways that need to be considered not only by us but at every step on that supply chain.

Alternative answers

Here at Hexpol TPE we like to use what we call the ‘resource saving materials’ because we’re looking at alternative ways of producing TPE without having to rely on virgin fossil fuels. These fall under the Dryflex Green and Dryflex Circular brands. Similar to standard TPEs in terms of hardness and appearance, the Dryflex Green range has up to 90 per cent bio-content from a variety of different feedstocks. ‘Soft plastics from plants’ really is the best description.  They’re bioplastics – specifically, bio-based plastics – which refers to where they come from rather than what happens to them at the end of life as with biodegradable plastics.

In the case of Dryflex Green, we fall firmly into the bio-based camp, although they are not biodegradable so they're not really for single-use applications and packaging but for long-life products such as automotive applications, building and construction, and household and consumer goods. We don't want them to be breaking down into biological nutrients, we want them to become technical nutrients in a circular economy. For the properties and customisation of our materials there are various different things that we can change. We do have what we refer to as a ‘standard Green series of materials’ that are bio-based, but we often deviate from that through customisation. They can have up to 90 per cent renewable content and come in a range of hardnesses from 15 to 60 shore A.

Moving on to the Circular grades, these are TPEs with recycled content – and we're obviously very aware that by calling them ‘circular’, we’re making reference to the circular economy. We're not assuming that everything can be solved through recycling alone, but recycled polymers have a really important role to play. High-value materials can become high-value nutrients for another technical cycle, and that's what we're aiming to achieve. We're looking at waste as a resource and trying to keep its value high throughout its multiple potential lifetimes.

Maintaining value

We've split the series into two distinct groups: PCR and PIR. We take recycled scrap material that has been sorted, washed and granulated by a recycler and then compound it into one of our TPEs, which we can then sell to a converter for automotive, sports and leisure, or household and consumer goods applications. Maintaining that value throughout its lifespan is a huge part of the whole sustainability discussion. It's not just about what we're making in terms of the materials, but about how we run and how we communicate on that. The sustainability discussion should therefore be open and honest and ensure we're on the same page. There are many different standards out there. Our customers all have their own requirements, so if a manufacturer has a Dryflex Green material for use in a product that they wish to be certified, Hexpol TPE would partner with them to make sure that they get all the information on the supply chain. And that goes for recycled content too. We can select a recyclate based on the certifications that it has, meaning that the producer of the final product can then go on to achieve various different certifications for their finished article.

To conclude, sustainability (for me, at least) is an irreversible part of our business, as for many others. We're only going to see growth in this area, as well as increasing interest and pressure from different angles. It's really exciting to be part of a team looking at these new and emerging materials and technologies, and it's exciting to think about what is yet to happen. There’s much more that needs to happen in this industry and further afield, and everyone’s got a role in business to think about sustainability. As we often say here, it's not one person's responsibility – it's everybody's.

 

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