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Eco-friendly polymer material advances plastic-free packaging

Aquapak has developed a dissolvable, biodegradable polymer that can undergo thermal processing for various food applications.

The material is a patented hydropol polymer.

“Hydropol is a highly functional, environmentally friendly polymer which has been developed by Aquapak’s scientists and allows product design to support the circular economy by enabling recycling and delivering multiple end-of-life options,” John Williams, chief technical officer at UK manufacturer Aquapak, told Ingredients Network.

The polymer is designed to provide an alternative to traditional plastics, yet offering their versatility and functionality, without harming the environment.

From PVOH to hydropol

The company based its plastic alternative on polyvinyl alcohol (PVOH), which is hydropol’s primary polymer component. It is a water-soluble synthetic polymer that is colourless and odourless.

Aquapak developed the formulation over a 10-year research and development (R&D) process, combining PVOH with other chemicals to stabilise it and retain sought-after environmental properties. Aquapak used a range of PVOH-based formulations in its intellectual property (IP) to ensure its suitability in various applications. As part of its concept stage, the company screened over 180 stabilisers to identify which ones could combine with PVOH.

“PVOH is inert and suitable for ingestion, and due to its water solubility property, it is used in applications such as for tablet casings or coatings; as an example, for vitamins and supplements,” Williams said.

Tests suggest hydropol is non-toxic and marine-safe

The manufacturer wanted to ensure the final formulation could maintain key features, including water solubility, barrier properties, tensile strength, and environmentally-friendly characteristics such as biodegradability while avoiding the production of harmful microplastics.

“Hydropol is non-toxic and does not form harmful microplastics,” said Williams. “If it does escape into the environment, it biodegrades completely, leaving nothing behind, ie no harmful microplastics,” said Williams.

Aquapak has tested its plastic-alternative polymer for biodegradability and to ensure it is marine-safe. After a two-year marine toxicity study on zebrafish larvae, the polymer producer found that hydropol is hydrophilic, so it has no natural tendency to attract toxins or form toxic microplastics, and is itself non-toxic to marine fauna.

“Hydropol will not form harmful microplastics or persist in the environment, unlike conventional plastics, whose long-lasting micro-particles cause major problems to the marine food chain,” Williams added.

Researchers have called for collective action to restore the balance in marine ecosystems, after microplastics have been found to affect the metabolic activities and survival of marine species.

Not suitable for water-rich products

Aquapak recognises that PVOH has its limitations, but that it provides an effective starting point for developing new materials. One limitation of hydropol is its high water vapour transmission rate. It also cannot be used in food production that puts it in direct contact with products with high aqueous content.

“However, this can be overcome by using it in combination with other materials to bring down the rate of transmission and extend the shelf-life protection provided by the packaging,” said Williams.

For example, it can be combined with an ultra-thin metal layer to reduce water transmission in a recyclable crisp packet, while still allowing it to be recycled in standard paper recycling.

“It is also compatible with existing material/packaging production infrastructure, making it scalable and commercially viable,” said Williams.

Ideal for thermal processing

Unlike PVOH, hydropol can undergo thermal processing, which refers to the ability to heat and melt materials. A common preservation method in the food industry, manufacturers use it to eliminate the risk of harmful microorganisms and extend shelf life, ensuring food is safe for consumption.

The current packaging and materials industry relies on thermal processing, so new polymers must also meet this requirement. PVOH, however, cannot be thermally processed as it decomposes when it starts to melt. While some modified PVOH versions have been developed, they are only suitable for niche or low-grade applications.

“It is not suitable for mainstream thermal processing production in which converters and producers have invested millions over the past decades through machines and equipment,” said Williams.

Due to its chemical composition, hydropol is compatible with thermal processing and can be used in standard plastic and material production on existing equipment. “[This makes] it scalable and a viable alternative to conventional plastics because it retains its functionality and is environmentally friendly,” said Williams.​

Suitable for crisp, chocolate, and confectionery packaging

Crisp packets, chocolate wrappers and confectionery packaging are among the food categories that use hydropol as a plastic-alternative material.

Sachets, in both food and non-food applications, are widely regarded as consumer-friendly and convenient, enabling controlled portion sizes, reducing transportation weight and preserving contents. However, they are also a major source of plastic pollution and are not typically recycled.

Aquapak has been working to solve this problem by combining hydropol with biomaterials to create unique structures suitable for sachet production that have a safe end-of-life fate. The company is working with several converters to develop paper-based materials that use hydropol in place of conventional plastics. Their aim is to enable fully recyclable packaging to enter numerous food applications, including dried pet food, snacks, cooked meat, and convenience foods.

Designed to develop sustainable food packaging solutions and overcome recyclability barriers, Aquapak has already partnered with several brands to use Evopak hydropol-coated paper, replacing conventional plastic packaging.

Aquapak teamed up with sustainable paper-based flexible packaging manufacturer EvoPak, and primer and coating company Mica to develop new eco-friendly packaging for The British Crisp Co. The savoury snack developer subsequently launched its fully kerbside recyclable paper crisp packet.

Snack brand Awfully Posh Nuts has re-launched its range of peanut products in 100% recyclable paper wrappers, replacing polypropylene plastic packaging. ​Confectionery brand Walkers Chocolate has updated its Turkish Delight and Mint Cream bars to kerbside-recyclable paper packaging for large retailers Asda and Premier Stores. The switch from plastic to paper means wrappers can be recycled at home rather than returned to stores.