All about PLA & CPLA – compostable bioplastics made from plant starches

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In Environmental

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By lucy

At Vegware, we manufacture our catering disposables from a variety of plant-based materials. We use paper, board and pulp, but the big difference is that we don’t use conventional plastics.

Our cups still need to be leakproof, and our clients still want clear windows, so we use compostable bioplastics – compostable materials derived from plant sources.

What is PLA?

PLA is a compostable bioplastic derived from plant sugars. PLA stands for polylactic acid. It can be made from any sugar, such as corn starch, cassava, sugar cane, or sugar beet. NatureWorks is the world’s largest producer of PLA, and a key partner to Vegware. Industrial corn is the primary source crop at the moment, but NatureWorks are working actively to diversify feedstocks, investigating other fibrous non-food crops, or even creating lactic acid from carbon dioxide or methane.

NatureWorks refer to their PLA under the Ingeo brand, and offer full information online on how it is made, and end of life options.

How PLA is made

Corn plants are milled to extract the starch, in the form of glucose. The glucose is then fermented to produce lactic acid. Next up, a chemical process transforms the lactic acid into a polymer, which can be made into pellets, known in the industry as resin.

Just like a conventional plastic resin, the PLA pellets can be used in a variety of ways – extruded into a sheet or film, injection moulded, cast into sheets, or spun into fibres. PLA has a huge range of applications, but at Vegware we use it for:

• PLA-coated board for paper cups and soup containers
• Clear cold cups, salad containers, deli and portion pots, and lids for a variety of products
• Clear windows in sandwich wedges, salad boxes and bags

CPLA – crystallised PLA for higher heat use

PLA has a low melt point, so is best for cold use up to around 40ºC or 105ºF. Where more heat resistance is needed such as in cutlery, or lids for coffee or soup, we use a crystallised form. This involves adding chalk to the PLA to act as a catalyst, and then rapidly heating and cooling the PLA resin during production. The result is a product which is heat stable to 90ºC or 194ºF. Vegware’s CPLA products are still suitable for industrial composting, in either in-vessel or open windrow composting.

Corn for food, feed AND industrial uses

The industrial corn used to make NatureWorks Ingeo PLA is non-food-grade, so it is not competing with food for human consumption. The whole plant is harvested, and every part of it is used. The protein and starch have many different uses:

• the plant-based proteins are used to make animal feed;
• the starch has many industrial uses, including in airbags, corrugated cardboard, recycled paper, pharmaceuticals, condoms, oil refining and drilling…and making PLA.

Read more information on food and bioplastics from NatureWorks, the world’s largest producer of PLA.

Sustainable growing practices

The corn plants are grown using sustainable farming practices, without excessive pesticides and water use. In the same way that FSC can prove the sustainability of timber production, NatureWorks has independent ISCC PLUS certification – more info here. This in-depth scheme demonstrates the sustainable growing practices for the plants used by NatureWorks to make PLA:

1. No sourcing from land with high biodiversity, high carbon stock or from peatland (2008 as the reference year).
2. Agricultural practices (fertilizer & pesticide use, storage, disposal, tillage practices, equipment calibration, irrigation)
3. Environmental protection (protect natural vegetation & water courses, soil erosion, soil organic matter)
4. Social sustainability (child labour, workers protection, labour condition, land rights, training, water rights)
5. Greenhouse gas emissions on farm level.

Implementing this scheme has involved helping farmers to alter their growing practices for greater sustainability.

PLA – which waste stream?

Vegware’s compostable catering disposables can biodegrade in under 12 weeks in commercial composting, which provides the perfect balance of microbes, moisture and warmth. Our Environmental team offer our clients unparalleled zero waste support – see point 2 in our Composting FAQ.

Where there is no access to industrial composting, used Vegware should be put in general waste. Vegware’s takeaway packaging is made from plants using renewable, reclaimed, or recycled materials and these sustainability benefits still apply no matter what happens to them after use.

• Used Vegware should NOT be placed in standard recycling bins which collect paper, plastics and metals, as those materials go to a different type of sorting facility. Another reason is that food waste harms the quality of mechanical recycling – the same applies to any used foodservice disposables.
• General waste goes to either incineration or landfill. If Vegware is incinerated, energy is produced. Incineration studies from NatureWorks, a key materials supplier of ours, show that their PLA bioplastic produces more heat than newspaper, wood or food waste; also that it produces no volatile gases and leaves little residue. Some in the waste sector prefer plant-based materials over conventional plastics as they give off fewer toxic gases.
• In landfill, studies have shown that compostable packaging is inert and does not give off methane.
• Please do not litter – compostable packaging is not expected to break down when discarded in the environment, and is not a solution to marine pollution.
• Home composting conditions vary with the skill of the householder, so we don’t make any claims there, but there have been successful trials using hot compost bins.

PLA – not a threat to plastics recycling

Compared to conventional plastics, bioplastics currently represent a tiny fraction of packaging, so it is not currently economical to sort PLA from other waste streams. If there is a major increase in bioplastics volumes, then waste sorting facilities can be calibrated to recognise and sort bioplastics using near-infrared identification. As well as composting, PLA is suitable for mechanical recycling into new PLA, as practised by Looplife Polymers in Belgium.

Studies have shown that low levels of bioplastics do not harm plastics recycling. German and Italian researchers have found there was no reduction to quality, up to these levels:

• Up to 3% PLA in post-consumer PP plastic recyclate (1)
• Up to 10% PLA in PS plastic re-granulates (1)
• Up to 1-2% PLA in recycled PET plastic short-spinning plant (2)
• Up to 10% MaterBi in the recycling of PE plastic shopping bags (2)

This information comes from (1) the report PLA in the Waste Stream, a report initiated by the German Ministry of Food and Agriculture. And (2) from CONAI, the National Packaging Consortium of Italy: Working Group Biodegradable Packaging Recovery Project report, 2012.

We don’t encourage anyone to put PLA into plastics recycling, but these studies offer comfort to plastics reprocessors, who are understandably keen to maintain quality.

Corn plastic is made from polylactic acid (PLA), which is a plastic substitute, made from fermented plant starch. It is becoming a popular alternative to traditional plastic, which is derived from petroleum based chemicals. The different uses of polylactic acid could be a way of how to reduce a carbon footprint that is left by fossil fuel plastics.

Corn starch plastic is an alternative product to petroleum based plastic. It has the same characteristics, but corn plastic is made from corn starch polymers, a biodegradable and renewable resource. It looks like oil-based plastic, but can corn plastic reduce our dependence on oil?

A demand for green products has led to a growing industry for manufacturing corn starch plastic. Many countries around the world have banned the use of traditional, petroleum based plastic bags, so polylactic acid (PLA) is poised to play a big role as a viable and biodegradable replacement. But is it really the case?

What is Corn Starch Plastic and Corn Starch Polymers?

According to Wikipedia, corn starch or maize starch is the starch that is derived from the corn grain. Starch is a natural, organic polymer of glucose and the corn starch polymer is obtained from the endosperm of the kernel and is commonly used in food preparation. Polymers are long chain molecules that have a basic repeating unit.

Corn starch polymers are used to produce bio plastics and it can also be used in the manufacturing of airbags. Corn starch polymers are polymers that are made from alkenes that are mixed with corn starch. This makes them easily biodegradable and can therefore be used as an eco friendly alternative to petrochemical based plastics.

Bioplastics are also known as organic plastics, as it is derived from renewable biomass sources such as corn. Bioplastics can be made from agricultural byproducts or agri waste and is a great way of how to reduce a carbon footprint. Renewable biomass sources, like vegetable oils and fats, corn starch, straw, recycled food waster, wood chips and sawdust, are used to produce bio plastic materials.

Synthetic polymer materials on the other hand, are produced from petroleum, which can be expensive, depending on the price of oil and of course, it is not sustainable.

Corn is the cheapest available source of commercially available sugar, and also the most abundantly available. Corn starch plastic has become very popular as a replacement for traditional plastics as it is more environmentally friendly.

For more compostable resin Manufacturerinformation, please contact us. We will provide professional answers.

The FDA has approved uses of Polylactic acid (PLA) as a polymer that is Generally Regarded as Safe (GRAS).

How is Corn Starch Plastic Made?

Through modern biotechnology, a colorless transparent liquid called lactic acid, is obtained from starchy corn kernels. A special polymerization process is used to generate a polymer material, called polylactic acid. The components in corn are starch, protein and fiber, and these need to be separated.

These are the steps that are involved in the process:

• Corn is harvested and the crop is soaked and ground in order to separate the endosperm from the fiber and gluten. This is a typical step in harvesting the grain crop. The corn kernels are immersed in a solution of hot water and sulfur dioxide, where the components break down to starch, protein and fiber.
• It is centrifuged to remove the corn oil and almost pure starch is what is left behind.
• Enzymes are added to the starchy endosperm, which converts the endosperm into dextrose, a simple sugar.
• Bacterial cultures are added, which causes the sugar to ferment and turn into lactic acid. Brewers use this same fermentation process to produce beer.
• Lactic acid consists of lactide molecules, which bond into long chains of polymers.
• Bioplastic producers have pellets of polylactic acid plastic at the end of the process. These can be melted to take almost any form, or it can be spun into fibers.

Uses of Polylactic Acid (PLA)

Polylactic acid plastic can be made into a film or a fiber, making it ideal for use in packaging materials. Various manufacturing processes, like thermoforming and injection molding can be used.

The properties of polylactic acid means that corn starch plastics have these qualities:

• Food safe and resistant to food fats and oils.
• Good for print applications.
• Low flammability.
• High aroma barrier.
• Resistant to ultra violet rays from the sun.
• Compostable.
• Recycled by regrinding.

So basically polylactic acid (PLA) comes from fermented plant starch, which mostly comes from corn starch polymers, and is commonly referred to as corn starch plastic.

What is Corn Starch Plastic Used for?

The polylactic particles that are extracted from corn are called corn plastic. The uses of polylactic acid is varied and starch based plastics can be used in a variety of applications, It is increasingly being used in a number of markets from packaging, automotive, catering products, consumer electronics, agriculture and horticulture, toys and textiles.

A multitude of products are currently being made from corn plastic and more are continuously being developed.

• It can be used to make biodegradable packaging materials, food bags and food packaging materials.
• Take out and disposable plates, bowls, cups, cutlery etc.
• Also used in medical implants and surgical devices such as sutures, ligatures and meshes.
• Biodegradable mulch films used in horticulture and farming as it can simply be ploughed back into the soil.
• Binliners and Doggy waste poop bags
• Textiles and accessories.

To use corn plastic plates, cups and cutlery at large gatherings and festivals where everything is thrown away, will be better for the environment, but only if it is disposed of, and composted, in the correct way.

So if you have an event, like Thanksgiving, a birthday party, Christmas, wedding etc. where you require disposable plates and cutlery, then corn starch plastic could be your solution.

Lego is looking at bio plastic as an alternative source for making their plastic building bricks and toys, but corn starch plastic is unfortunately too soft to be used for bricks.

Pros and Cons of Corn Starch Plastic

Advantages of corn starch polymers:

• Corn plastic packaging or items made from corn plastic, will decompose within two months of being in a high humidity composting environment, at a temperature of above 60° Celsius or 140° Fahrenheit. So it returns to the earth, where it originally came form.
• It comes from a renewable source, corn, which can be planted again.
• Bioplastics will not emit toxic gasses when it is incinerated as it contains no toxins.
• A reduction of 68% of greenhouse gas emissions, compared with production of conventional fossil fuel plastic, so much less greenhouse gases are emitted.
• Corn starch plastic needs 65% less energy to be produced than conventional petroleum based plastics.
• PLA plastic is cost competitive with conventional plastic.
• Using corn starch polymers to make plastic have no danger of explosion during the production process as is the case with petroleum, so it is much safer to work with.
• Organic food waste can be composted with it.
• The bio plastic is free of BPA’s and phthalate, so no worries about endocrine disruption.
• Corn starch packaging has less static electricity than synthetically made packaging materials.

Disadvantages of corn starch polymers:

The biggest disadvantage of bio plastics and corn plastic, is associated with the rate of bio degradation and recycling. Because PLA is plant based, it needs to be disposed of in a composting facility. 

• Corn plastic will only break down and decompose in the hot and humid environment of a commercial composting facility. So it can not be composted at home.
• Very few industrial composting facilities currently exist where corn starch plastic can be composted correctly.
• Composting is not the perfect disposal method as greenhouse gas, methane, is produced when they decompose.
• The recycling stream can be contaminated when consumers put corn starch plastic into recycling rather than composting.
• Inadequate infrastructure to compost PLA, might mean that it still goes into landfill. If commercial composting is not available, PLA plastic could end up in landfill where it will take as long as traditional plastic to break down, or it could get mixed up in plastic recycling.
• Corn starch polymers make regular compost more acidic.
• Material Recovery Facilities are responsible for sorting and disposal of PLA.
• Polylactic acid and corn plastic is typically made from genetically modified corn, so even more concerns about the whole GMO debacle.
• There are moral issues with corn being used as there are people going hungry in the world.

Questions and Answers About Corn Starch Plastic 

Why must you not recycle corn plastic with conventional plastic? The two plastics might appear to look the same, but their chemical composition is different. Bio plastic can contaminate traditional plastic recycling and it could mean that the salvaged plastic cannot be used.

A landfill is packed so tight, that there is no light or oxygen available to help with the breaking down of the corn starch polymers.

To avoid complication with recycling and composting of corn plastic, many commercial composters will only accept bio plastics from food service operations, and unfortunately not from normal households.

Related post: What is Compostable Plastics?

Is corn starch plastic biodegradable? Yes, it is biodegradable, carbon neutral and edible.

How long does corn starch plastic take to biodegrade? In a controlled composting environment, PLA will decompose into water and carbon dioxide in less than 90 days.

Criticism against corn plastic is that it depends on the industrial farming of large fields of crops and these fields could be used to grow food crops. Much of the corn that is used for bio plastics, is a variety called Number 2 Yellow Dent, which is mainly used for animal fodder. Corn is also used to make ethanol fuel, placing more strain on the farmland.

Is there a Future for Corn Starch Plastic?

I certainly think there is a future for corn plastic. Although the bio plastics market is growing by around 20% each year, it only accounts for less than 1% of the 200 million tons of plastic that is produced each year.

The raw materials that are used to get corn starch polymers are cheap and easy to produce and is a great way how to reduce a carbon footprint. The uses of polylactic acid is varied and diverse and has a lower environmental footprint than fossil fuel plastic.

With a shift towards sustainability and greener options, a company can choose packaging materials that are good for the environment. The advent of corn starch based materials is allowing companies and consumers to use more sustainable plastic alternatives to petroleum based plastics.

Final Thoughts – Can Corn Plastic Replace Traditional Plastic?

Although the uses of polylactic acid (PLA) have a possibility as an alternative to conventional plastic, the issue of disposal needs to be addressed and properly sorted out before it can be completely viable. PLA is a way of how to reduce a carbon footprint, but consumers are better placed switching to reusable products.

So if you really want to make a difference, switch to reusable containers, from water bottles to produce bags and shopping bags, safe lunch boxes and glass containers. Related post: My Plastic Free Life.

Although corn starch plastic sounds promising as an alternative to conventional plastic, the correct disposal and composting of it, means it is not the optimal solution to the plastic waste problem. A far better alternative is to eliminate plastic and take reusable produce and shopping bags with you when you go out.

Switch to reusable food storage containers at home. You are on track to a better and safer environment when you say goodbye to single use plastic.

Related post: What is Wheat Straw Plastic?

I hope you have enjoyed following the journey of a corn kernel to a drinking cup, and if you have any questions or comments about corn starch polymers and what is corn starch plastic, then please leave them below and I will get back to you.

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