Polyvinyl alcohol (PVOH) is familiar to us as the small laundry pouches that dissolve in the washing machine. The ability to dissolve means the polymer can be separated easily from other plastics.
Birmingham-based Aquapak Polymers has invented a way for this material to be repelletised for closed-loop recycling. The company claims this will revolutionise plastics recycling, and it is gearing up for production on a commercial scale.
It has also developed patented processes for producing PVOH films with different properties such as strength, thickness and the ability to dissolve at different temperatures. Crucially, the PVOH pellets are compatible with polyethylene (PE) blown film production facilities, making rapid upscaling viable.
With the Ellen MacArthur Foundation calling for a “superpolymer” and “moonshoot” innovations, Aquapak has something in the way of an answer. A manufacturing facility is currently under construction and production is due to begin in early 2017, while a number of potentially game-changing applications are now being investigated.
The company has spent the past six years working with PVOH. It is a common polymer that has been in use for a long time in products such as eye drops, play putty and fishing bait. What makes PVOH special is its ability to dissolve. While this has been known for some time, it was Aquapak that started to explore the properties and potential wide-ranging applications of this unusual plastic.
Plastics are generally unreactive, which makes them suitable for storing food and chemicals safely but difficult to dispose of. Micro-organisms cannot break them down so they last for many years in the environment or landfill. Crucially, most plastics do not dissolve.
Aquapak managing director Mike Everard explains: “Most plastics repel water and attract oils, which is why grease clings to your plastic washing bowl. Conversely, PVOH dissolves in water, so it is easy to recover for recycling.”
The patented process enables MRF operators to recover the PVOH from water and convert it back into pellets, which can be sold directly to manufacturers in a closed-loop system. To minimise the initial investment required for manufacturers to enter into blown PVOH film production and allow produc-tion lines to be repurposed efficiently, Aquapak has designed the pellet and process to fit standard PE manufacturing equipment.
Usually it is difficult to separate plastics, particularly flexible plastics attached to solid trays, which is what makes PVOH very interesting from a waste management perspective. By dissolving the PVOH from water and then turning it back into solid pellets, the polymer can be recovered in a 100% pure form – with no contamination from other plastics, oils or food.
The polymer is made up exclusively of carbon, hydrogen and oxygen atoms and, being non-toxic, does not pollute the environment (see Q&A box). Once dissolved in water or during anaerobic digestion (AD), it can be consumed by micro-organisms, which convert it to carbon dioxide, water and a benign biomass.
Speaking from a council perspective, Lee Marshall, chief executive of the Local Authority Recycling Advisory Committee, says: “Studies show that nearly all of the top recycling local authorities use food waste bags. Councils trialling Aquapak bags will want to know that AD plants can cope with the material and that the price is competitive.”
The company is confident now that PVOH is preferable to both bio-based and other plastics for packaging food and food waste. Being from a petrochemical source, polymer production can be scaled up rapidly, allowing it to compete strongly on price and performance.
The material is also considered to be safe in the marine environment, with tests showing no negative effects – and even promoting algal growth, an important precursor in the development of artificial reefs, for example. Its intoxicity also makes it suitable for the controlled release of drugs and eye drop solution.
Aquapak began operating in 2010 with activities largely outsourced to adi Electrical, part of the Systems adi Group. In 2012, the company became independent and brought in an experienced team to develop its business: Everard develops early-stage companies to commercial success; Paul Northover, production director, is a senior player in the global plastics industry; and business development director John Williams is a former technical adviser to the Government, and is well-known in European industry for a number of high profile bio-plastic innovations.
The team is supported by polymers expert, emeritus professor Anthony Johnson at Gluco Technologies.
The firm has secured confidential collaborations with global plastic film manufacturers and packaging experts, and has been undertaking detailed trials with UK partners to refine the technology, manufacturing process and establish effective routes for recovering, reuse and recycling.
Williams says: “We have produced a competitive packaging polymer that also has excellent end-of-life qualities. Biogen and Biffa have both been impressed. It is also generating a lot of interest from manufacturers and packaging companies in all sorts of sectors.”
Potential markets for PVOH include food wholesale and retail, hospital hygiene, agriculture, paints and coatings, detergents, electronics and the oil and gas industry. But initial trials have focused on how well it performs as a food packaging and food waste bag material. To this end, Aquapak has achieved approval from the US Food and Drug Administration.
The company has also become an approved member of the Social Stock Exchange (SSE), the first regulated exchange dedicated to businesses and investors seeking to achieve a positive and social environmental impact through their activities.
Williams says: “Aquapak is set to transform the flexible packaging landscape by offering brand owners and retailers a fully recyclable and biodegradable monolayer polymer that can replace many single and multi-material alternatives. With no need for additives or mixed materials, it is a sustainable packaging solution, and a great story to tell consumers.”
- The SSE report on the testing that the products have been through is available to download at socialstockexchange.com.
- The company is inviting interested parties to make contact with a view to running further trials in 2017. Councils and businesses interested in trialling the material are requested to email email@example.com
Aquapak material Q&A
How does Aquapak material differ from oxo-degradable plastics?
Oxo-degradable properties arise from chemical additives causing a polymer (such as polyethylene, which is not normally degradable) to break down into smaller pieces in the presence of heat or light. Microbes are then capable of degrading the small pieces of plastic.
In 2010 Defra concluded that oxo-degradable plastics take too long to break down to be considered ‘biodegradable’ (two to five years in the open UK environment and not at all in landfill), and the small flakes of oxo-degraded plastic and the additives could both pollute the environment.
Aquapak’s PVOH does not need additives and is readily biodegradable in water, which is present in landfills and anaerobic digestion (AD) facilities.
How is it different to bio-based plastics?
Bio-based plastics are usually unidentifiable from petro-chemical plastics, cannot be recycled and contaminate other plastic streams. They also cause problems in AD facilities because the cornstarch (or similar) material they are made from turns into a spongy foam when processed, which binds the machinery and has to be cleaned out.
Aquapak’s polymer is currently made from a petro-chemical source, although the company is planning long-term programmes with key suppliers to substitute the source of carbon to more sustainable bio-sources.
What compounds does it dissolve into?
It degrades to a benign carbon biomass, carbon dioxide and water.
It promotes algae growth – isn’t this a bad thing?
Such algal growth demonstrates that it is non-toxic – this is a standard aquatic safety test.
It should not be confused with eutrophication, caused by nitrogen-rich fertiliser washing into streams, resulting in an algal bloom, with the appearance of pea soup. Micro-organisms consume the algae and use up the oxygen in the water, resulting in the death of fish.
Aquapak material would not be entering natural water bodies in such concentrations as to cause this type of problem.
Zoë Lenkiewicz is waste and resource management consultant and campaigner