Engineering Company Seeks Industry-Academia Collaboration to Develop Advanced Heat Densification Technology to Recycle Waste Expanded Foam Material
Styrene Systems Ltd. is an SME based in Pembrokeshire. The company designs, manufactures and sells machines to compact expanded foam packaging and industrial process waste such as Expanded Polystyrene (EPS), Polypropylene (EPP) and Polyethylene (EPE). The product range includes screw and hydraulic compaction technology as well as heat densification.
Most expanded foam material is 100% recyclable, but due to its light weight (up to 98% air) it is generally considered uneconomical to collect for recycling and is largely mixed with other waste destined for landfill or incineration. This incurs high disposal costs and the loss of a non-renewable resource. 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 re use in the circular economy.
Working with the ASTUTE 2020 team, the research project focussed on performance improvement of the H100 heat densification product. This utilises a complex combination of auger and heat profile technology with a software configurable process to optimise throughput and quality of compacted material. The H100 will compact all expanded foam but is primarily aimed at EPP and EPR packaging which cannot be compacted with screw or hydraulic methods.
Challenges – Optimisation of the EPS Densifier
The EPS foam undergoes a number of processes within the device: shredding, mechanical compaction and heating. The resulting material (shown in the figure above) is dense and now is a viable recyclate with commercial value. The optimisation of the process parameters and their interaction was vital to ensure a consistent product and develop reliable densifying machinery capable of high production throughput.
Solution – Experimental based Statistical Analysis
Calling upon ASTUTE 2020’s expertise in the mechanical, fluidic and thermal behaviour of plastic foams a “design-of-experiments” approach was used to carry out measurement trials to identify the most influential parameters during the processing operation.
Working closely with the company and observing the densifier in operation, a number of recommendations was made in the light of current published research. Changes to the auger dimensions and adjustments to other geometries within the device were proposed. Modifications to the measurement sensors were also suggested to ensure that the control system was sufficiently responsive to accurately reflect the conditions within the machine.
Time was scheduled into the project plan to enable changes to be made and then additional validation testing was undertaken by the company to assess whether the predicted improvements had been achieved.
In addition, a computational simulation of the whole process was proposed, but at this stage there was insufficient data on the through process material and mechanical behaviour of the eps to establish such a model with any confidence.
The collaborative research project has examined the processes that the foam plastic material undergoes and examined the current technology in use to solve problems inherent from the original approach. The experimental based statistical analysis of the machine process elements and parameters has defined the importance, relevance and the impact that change has on individual stages of the total process.
One of the major benefits of this work was the transfer of knowledge to the company through interaction with the ASTUTE 2020 team. This knowledge can enhance future product developments and allow the company to upskill their staff.
This project has assisted Styrene Systems to draw closer to their objective of preparing a package of detailed plans and expertise that can be sold or licensed to third-party manufacturers for the large scale production of these devices.