Sustainable Plastics - we trial some of the latest new materials

NEWS – November 2022

Sustainable Materials

A look at the current offerings

The sustainable plastics industry is now worth $20 billion and a steady stream of new materials is coming to market.

At White Horse Plastics we have noticed an increase in enquiries from customers wishing to use them and we look forward to the time when this is common practice.

The Challenges Facing the Uptake of Bioplastics

However, no perfect alternatives to traditional polymers have yet emerged in terms of performance, provenance, end-of-life and cost, and in the short term, uptake will depend on these problems being solved. For example, the technology to produce Polyhydroxybutyrate (PHB), from the bacterium Bacillus Megaterium (a bio-derived, biodegradable polymer with a low SG (1.14-1.25)), has been around since 1926, when it was discovered by the French researcher, Maurice Lemoigne. Its viability was explored by ICI in the 1980s under the trade name, ‘Biopol’ and it was used by Wella to produce shampoo bottles. However, despite its clear advantage at end-of-life, it was dropped due to its limited applications and production cost.

The Confusion Around Bioplastics’ Terminology and Feedstocks

Bioplastics’ terminology is also problematic, particularly around terms used to describe end-of-life, such as degradable, home compostable and industrial compostable. Some of these new materials labelled ‘compostable’ will only compost using industrial processes which are not available in all parts of the UK, so they end up in landfill. Others do not degrade but leave microplastics or toxic residue. There have also been concerns raised around the use of first generation feedstocks such as corn and palm oil, which can compete for land that is currently used for food production. Second generation feedstocks are considered better, because they use waste generated by food production, but even this option is open to misinterpretation because as manufacturers, we need to know what they are mixed with, so we can offer our clients transparent options. Bio-derived materials mixed with traditional plastics may seem friendlier, but they are potentially locking the natural material in to an object that will still take decades or longer to decompose.

There are Currently no Bioplastic Options for Medical Applications

None of the new, sustainable offerings can be sterilised, but there is a demand for this. We have just found out that our own, pre-industrial medical consumable recyclate is an option, however, we can only generate a finite quantity and its credentials are limited.

The Good News

But the good news is that this market is young and full of potential. Upstream there are many designers working on the bioplastics of the future. And in the market today we have found at least seven that can be injection moulded, that offer a range of advantages over traditional plastics.

Sustainable Material Trial

We chose seven materials to trial using an injection mould tool we designed to make a medical dosing cup.

Biogaer – Standard Green
Forewood
BioFase
BiomeHT90 Injection
PVOH
Limex
WHP Medical Grade Recyclate

All the materials were easy to process using traditional methods and those that included a natural filler, such as Limex, Forewood and BioFase, produced a cup with an attractive appearance and a warm hand feel. These aesthetic qualities could accelerate their uptake, however, they were also a little heavier than traditional plastics, meaning they will be more expensive to use (by volume) and more costly to transport as a final product. But these issues can be tackled at the Design for Manufacture (DFM) stage when a designer can optimise a component’s wall thickness and other elements so less material is used.

Material 1: Biogaer BioGaer (wardpolymers.com)

Ward Polymers Ltd

Tipton – West Midlands, UK

From the Biogaer website:

‘Biogaer material is a product range of patented bio-materials made from plant-based ingredients and manufactured in the UK. Designed to encourage micro-organisms to feed and thrive that will bio-degrade the products produced, this happens either in the outdoor environment at moist ambient temperatures, industrial composting facilities or most preferable the home composting environment, however Biogaer material remains stable when dry and in-doors, just like cardboard and paper products.’

Accreditations:

EN13432

ASTM D6400

ISO 17088

Features

Home compostable in months – 100% anaerobic soil composting in 12 weeks for thin wall.

Contributes to the composting of other items in the compost by encouraging micro-organisms to feed.

High rigidity – Flexural Modulus 1950.

Food contact compliant.

Manufactured in the UK.

Can be processed using traditional injection moulding equipment.

Suitable for hot runners.

Material 2: Forewood wood-based applications (forewood.de)

A Rezemo GMBH Brand – Germany

An injection mould material made of wood fibres and PLA – 100% bio based.

Material developed by Julian Reitze and Stefan Zender for their sustainable coffee capsule. In collaboration with the University of Stuttgart and the affiliated Fraunhofer IPA.

From their website:

‘Returning raw materials to nature – that is the goal of organic recycling. This loop can be closed by 100% bio-based products that can be composted at the end of the product life cycle. Even if the products end up in nature by mistake or are used for energy recovery, they will not harm our planet. No microplastics is created when using degradable biopolymers, as they decompose completely according to their name. Even when burned, the carbon footprint does not increase as the CO2 was previously bound during plant growth.’

‘By using plant-based resources that bind carbon dioxide in their growth, our materials save about half of the carbon dioxide emission in direct comparison to conventional fossil plastic.

Material 3: BioFase Biofase.cz

Avocado Bioplastic

The Mexican company, BioFase, has developed a process that turns avocado pits into bioplastic. The avocado pits are donated by a manufacturer of ready-to-eat guacamole. This is a second generation feed stock.

BioFase produce two materials – the first is suitable for thermoforming and is used to produce disposable cutlery and plates, the second is an injection mould grade. This is the material we used for our trial.

Material 4: BiomeHT90 Injection Biome Bioplastics

Biome Bioplastics Ltd

Southampton UK

From their website:

‘Biome Bioplastics is one of the UK’s leading developers of intelligent, natural plastics. Our mission is to produce bioplastics that can challenge the dominance of oil-based polymers, and ultimately replace them completely.’

Features:

HT90 is made from plant starches – a non-food derived, GM-free source.

Rigid materials with softening point up in excess of 100 degrees centigrade, which is 40 degrees centigrade higher than other standard bio-materials.

Compostable, with a bio-based carbon content greater than 50%.

Suitable for food service products, hot beverages, cosmetics, electrical and other heat sensitive applications.

EU and FDA food contact approved.

Material 5: PVOH

Various suppliers

Description

From the British Plastics Federation:

‘Polyvinyl Alcohol (PVOH, PVA, PVAI) is a synthetic polymer which is both colourless, odourless and water soluble. It was initially discovered in the early 1920s and since has been used in numerous applications from the lamination of safety glass to the packaging of laundry detergents.’

‘PVOH film has many distinctive and useful properties. It exhibits excellent tensile strength and elongation. It has one of the best oxygen barriers known to science, making it ideal for preventing food spoilage. It also provides a superior barrier to oil, grease and solvents, which can damage adhere to or bleed through other substrates.

However, most impressive are its biodegradable credentials. PVOH in solution simply breaks down into carbon dioxide and water when consumed by any of the 55 acclimated organisms found in municipal wastewater treatment or activated sludge. In most water-soluble applications, such as laundry unit-dose, PVOH film is readily or inherently biodegradable as measured by OECD 301B criteria’.

Material 6: Limex Limex – LXD (lxduk.com)

Limex is the creation of Limex-Japan and is distributed in the UK by LXD, who offer plastic and paper alternatives.

From the LXD website:

‘Limex is used as a material to reduce plastic.’

‘Limex is an advanced material produced from calcium carbonate (CaCO3), which is derived from limestone, and a small amount of polymeric resin added as a binder. These materials are heated and kneaded in a twin screw extruder, creating a molten, homogenous composite containing over 50% calcium carbonate by body weight. Next, the composite is heated and pressurized treated under Limex’s proprietary manufacturing process, resulting in material properties ideal for post-processing.’

Ingredients: over 50% Calcium Carbonate by weight.

Features:

Because it contains over 50% CaCO3 less virgin polymer is used.

It can be processed using traditional methods and machinery.

It is aesthetically pleasing – its hand-feel and appearance would make it desirable for cosmetics packaging or similar.

Because of the CaCO3 content, it is not liable for Plastic Packaging Tax.

Material 7: WHP Pre-Industrial, Medical Grade Consumable Recyclate

This material is produced at White Horse Plastics by grinding the sprue waste generated by our medical consumable production.

100% Polypropylene

Features:

It can be sterilised, so it is suitable for medical applications.

It is cheap compared to other sustainable materials.

It is light – the SG of this material is 0.9 meaning it will be relatively cost efficient to transport components.

It is amorphous, meaning it can be melted down and recycled again – thus it could be used in a circular economy.

Invented in 1951, PP has a proven track record for performance.

It gives purpose to our waste from production.

Its carbon footprint is lower than virgin material because significantly less power is used to produce it and it is not transported off-site before it is used to make new components.

If not used for sterilised medical components, it could be mixed with one of the new masterbatches for PP and PE that contain additives and/or prebiotics that help it degrade in the natural environment without leaving toxic residue.

Limitations:

This is a traditional plastic – therefore if it is discarded in landfill or the natural environment and it is not mixed with a masterbatch catalyst, it will not biodegrade for decades and will leave a toxic residue.

Because it is a by-product of our medical consumable production, we have a limited supply.

Further Resources

See a list we have compiled of sustainable plastics terminology as defined by ISO – the International Standardization Organization.