As a designer, plastics and sustainability can be difficult to navigate. There are so many parameters to consider – from the origin and environmental footprint of raw materials to the durability and quality of specific materials and maximising the chances of recovery and recycling at the end of life of plastics products.
Starting with the origin of the raw materials that go into plastics production, the vast majority of plastics today are petrochemical-based virgin materials, but increasingly plastic suppliers are exploring alternative raw materials such as bio-based feedstocks or recycled materials. Typically, suppliers offer plastics that are made with a combination of petrochemical- and bio-based raw materials, or virgin and recycled material. Always ask suppliers to confirm the ratio of specific raw materials and relevant certificates such as ISCC Plus or SCS Recycled Content.
The development of renewable, bio-based chemistry for plastics production is already well underway, with many plastic suppliers offering materials that are derived from a wide variety of plants – from agricultural food crops to by-products from forestry and plants that are more associated with the textiles industry. A small but growing number of plastic suppliers have also launched products that are based on carbon capture and utilization, CCU. Both topics are explored in the "Industry Climate Neutrality: Wish – Reality – Future" K Talk roundtable discussion, available to watch here.
The specific type of plastic material will have a massive impact on the durability, functionality and user experience of plastic products. Generally speaking, commodity plastics such as polypropylene, polyethylene and PET will have a lower environmental impact than high-performance engineering polymers like ABS, polycarbonate and polyamide. Understanding the expected life-span and likely usage scenarios of a product is crucial for selecting the right material – the larger environmental footprint of an engineering polymer will be balanced if it is put to good use in a product with a long-life span.
The use of additives to enhance certain properties and aesthetics of plastics are another element to consider in this context. Several suppliers and compounders offer non-halogenated fire retardants, antimicrobial additives that do not contain heavy metals, and non-toxic mineral-based colourants, to name just a few examples. Additives also have an impact on the recyclability of plastics, so it is always worth confirming the impact of specific additives with a recycler that is specialising in the type of plastic you are considering using.
Designing for circularity with plastics is a big topic in itself that you can read more about in the Functional Plastics feature, but selecting the right type of recycled plastic is also a complex task that deserves a closer look. The vast majority of recycled plastics offered by suppliers will be available in black or shades of dark grey colour only. This is a result of the specific way that most plastics are recycled today, so-called mechanical recycling. This process takes plastic waste, separates it by type, grinds it down and remelt it into flakes or pellets that can be moulded into new plastic products. Most recyclers do not separate plastic waste by colour, meaning the resulting material will be an unattractive greyish-brownish mix of all the colours of the plastic waste. Most recyclers get around this problem by adding black or dark grey pigments to the recycled material to give it colour consistency.
While black and dark greys are fine for many applications, there are several recyclers that specialise in colour separation for bright and light colour recycled plastics, as well as recyclers that are able to provide transparent recycled plastics. These materials require careful sorting and cleaning for good results, which means that they typically have a larger environmental footprint compared with black and dark grey recycled plastics that are less complex to recycle. In this context, selecting the right recycled plastic for the right application is crucial. This and other aspects of circular plastics are discussed in the "Climate protection and plastics - do they go together?" K Talk, available to watch here. Also be sure to take a look at the theme days programme at the Plastics Shape the Future space at K 2022, which covers many of the topics outlined above.