Circular Economy: The Importance of re-using Plastic Products and Materials
A world without plastics is today unimaginable. Plastics make an indispensable contribution to living standards and wellbeing, and are consequently globally ubiquitous. Plastics enable low cost mass production of complex articles, and their unique material properties provide engineering advances not otherwise possible. But recent years have seen a growing awareness of the adverse effects of plastic pollutants on ecosystems. The problem, however, is not the plastics themselves, but how to manage their use and re-use.
The single use of plastic items should, and is, being reduced, moving towards a Circular Economy model, where plastics never becoming waste is essential. Re-use of plastics contributes to de-carbonisation, and increasingly, companies are facing pressure from legislative and tax actions to move in this direction, and are perceiving economic and brand image benefits from so doing.
The traditional economy is based on take, make, and consumer throw away but in the Circular Economy, the life cycle of products or materials is extended indefinitely. This can be achieved by improved product durability, design for recycling, and improved understanding of how properties of recycled material may be degraded and restored, all underpinned by a strengthened infrastructure for waste collection, management and re-processing. Equally, avoidance of waste by business models based on return of used items, followed by re-manufacture or re-use of materials will play a part.
However, the practicalities of recycling plastics raise many issues, and in this article, we illustrate how ASTUTE2020+ has helped answer some typical questions faced by manufacturers in moving further on the road to a Circular Economy.
Can material recovered from returned end-of-use items be re-used in new products?
An example of a major enterprise placing their business at the forefront as an ethical and sustainable manufacturer of plastic components is Wrexham-based Brother Industries (U.K.) Ltd. (“BIUK”). BIUK manufacture office machinery and have a well-established returns system for end-of-life products, together with a zero-to-landfill policy. The company needed to address some key challenges in recycling plastics:
- Can high impact polystyrene (HIPS) recovered from returned end-of-life items be used in new products?
- How many times can HIPS be recycled before changes in properties become unacceptable?
- Can recycled HIPS originating from different original resin manufacturers be blended to provide suitable material?
Research by ASTUTE 2020+ and BIUK studied a range of HIPS material properties during repeated re-processing and after exposure to UV. The research confirmed that material properties are not adversely affected by eight or more cycles of reprocessing by injection moulding, nor by exposure to UV such as is experienced by products in use.
It was established that blending recycled HIPS originating from different manufacturers provided good quality material. As an outcome, BIUK are now manufacturing product from 100% recycled materials creating a directly beneficial environmental impact, reducing the use of raw materials, saving energy and reducing CO2 emissions.
Can all or some of our raw materials be replaced by recyclate bought in from a re-processor?
Vernacare are specialists in infection prevention solutions and manufacture a range of medical sharps containers for the healthcare and harm reduction sectors at their site in Blackwood, South Wales (formerly Frontier Medical).
As part of their ongoing commitment to reducing virgin material use and sustainable operations, they wanted to evaluate the use of recycled polypropylene in their production. Key performance criteria of the material in certain products require a combination of hardness and low-temperature impact resistance, properties which are often in conflict, but which can be achieved by careful selection of grades copolymerized with polyethylene.
Looking to substitute these partially or entirely by recycled material, Vernacare engaged in a collaboration with ASTUTE2020+ to identify and assess possible materials. A source of clean, post-industrial material was identified, providing a reliable and consistent stream of material in sufficient volume.
Tests showed, however, that the impact properties of this material on its own were inadequate. Established practice for enhancement involves compounding with impact modifiers by high intensity processing in twin screw extruders. In the present context, constraints applied that contra-indicated this route: firstly, from an economic viewpoint; secondly, because of the increased energy use and carbon footprint; and thirdly from the additional thermo-mechanical stresses applied to the material, leading, potentially, to degradation.
Following extensive trials, it was established that impact and hardness specifications could be met by blending a percentage of recycled polypropylene with a new resin and feeding this directly to the injection molding machine. Furthermore, a number of different products were identified, with less demanding performance criteria, where 100% recycled material could be used successfully. Following significant investment in new pneumatic conveying systems to handle the recycled polypropylene, recycled material is now being used in production.
Can we exploit a market for equipment to facilitate recycling in the present circumstances?
Expanded plastic foams, in particular expanded polystyrene, are widely used in packaging and in building applications. Thermoplastic foam poses particular problems for recycling due to its low density and bulky nature. The high costs of transportation generally make it uneconomical to collect and in many regions it is included in mixed waste for landfill or incineration. Landfill tax has doubled in the past ten years and is set to increase further.
Incineration is also environmentally negative and involves the loss of valuable material. The environmentally sound alternative is compaction, which creates a dense block of material, as little as 10% of the original volume, ready for recycling and reuse in the Circular Economy. To avoid transport costs, this needs to be done close to the waste source as part of a distributed network. Collaborating with the ASTUTE 2020+ team, Styrene Systems Ltd. engaged in an R&D project to develop small, low-cost densification units.
Traditionally, densification has used hydraulic compression; however, this is ineffective for some foams, such as polyethylene, because of their elasticity. The Styrene Systems unit instead combines mechanical compaction and melting of the foam. The developed units now being marketed make possible the profitable sale of compacted material for recycling, avoiding disposal costs and negative environmental impacts.
ASTUTE 2020+ can support manufacturing companies across a variety of sectors, such as aerospace, automotive, energy generation, oil and gas, medical devices, electronics, foods, etc., stimulating growth by applying advanced engineering technologies to manufacturing challenges driving cutting-edge research and innovation. ASTUTE 2020+ collaborations inspire manufacturing companies to improve and streamline their manufacturing processes, manufactured products and supply chain, generating sustainable, higher-value goods and services and bringing them to a global market.
The ASTUTE 2020+ operation has been part-funded by the European Regional Development Fund through the Welsh Government and the participating Higher Education Institutions.