With the introduction of cassava-based plastic in 2018 and the popular corn plastic (bioplastics both of them), which is the best and how do they stack up against one another?
Both readily available, cassava tends to be more durable than corn starch and has less negative impacts in terms of sustainability in rural areas as it’s easier to grow and harvest.
How Is Cassava And Corn-Based Compostable Plastic Made?
Compostable plastic is made in a similar way regardless of which main material is used. Compostable plastic is made typically from fermented food starch often from corn, sugarcane, sugar beet pulp or cassava and combined with lactic acid and cyclic di-ester lactide.
This means that a mixture is created to then be fermented and the starch extracted, which is the base material for compostable plastic. The materials fermented and used for the production o are chosen as they are carbohydrate sources that are then manufactured in a controlled environment and have the starch extracted. This is then mixed with enzymes or acid and heated to break down the starch into dextrose or corn sugar.
The following fermentation process produces L-Lactic acid which is the building block of the compostable plastic.
Essentially the basic process which can differ depending on country and manufacturing facility is:
- Gather materials – cassava starch, glycerin, vinegar, water
- Extraction and testing of starch
- Preparation of bio-film (mixture of the materials heated under mild heat until sticky)
- Molding of bioplastic
- Pellets created using twin screw extruder machine
- Pellets heated and converted into shapes
- Pellets converted to bags.
Under this process, a ‘blown film extrusion process’ is utilized with these small plastic pellets. To make bags, the process includes:
- Resin (pellets) melted under controlled temperature and pressure
- Air injected into the plastic which extrudes through a die in circular form to create a tube
- Tube is cut off while hot, stretched and inflated
- Inflated bioplastic is cooled and made into rolls to convert to bags
- Bioplastic tubing fed to a machine that rolls out the tube to the right length and heat sealed.
Is Cassava Based Plastic More Sustainable Than Corn?
Compostable plastic provides a better option than typical plastic which contributes to landfill and doesn’t break down or compost. Being a natural product also means no toxic chemicals are present.
Polylactic acid (PLA – a popular compostable plastic) is a polymer made from renewable resources – in this instance, corn starch. The difference being that other thermoplastics are petroleum-based, whereas raw materials used for the production of this particular PLA includes cornstarch and other natural products.
PLA containing corn starch is a renewable plastic substitute that looks and feels like regular plastic but is 100 per cent compostable! PLA plastic bags are renewable, 100 per cent compostable when disposed of in an industrial composting facility, will rapidly break down in a home composter, replace fossil-fuel based products and generate less greenhouse gas with no toxins released when being manufactured.
Cassava based compostable plastic is essentially the same as corn-based except known as more durable. It’s also slightly more sustainable to farm as it’s simpler and available in many countries.
It’s also important that both resources are widely available which often relies on farming in rural areas (think corn, soy, cassava and potato). The renewable aspects of these products do contribute to lowering manufacturing costs in terms of electricity and water usage.
What Is Compostable?
Compostable plastic is classed as a bioplastic and is made from 100 per cent natural ingredients. It’s a great alternative to traditional plastic, particular when it comes to single-use plastic carry bags. The environmental impact of traditional plastic is creating havoc for our environment and wildlife.
A next-generation plastic, compostable plastic is renewable and will completely break down into natural matter when disposed of correctly. The materials used to create compostable plastic will vary but they are typically made from renewable items such as potato, corn, soy protein, cellulose and tapioca starches.
These natural ingredients also mean that compostable plastics are non-toxic and will decompose in a worm farm or composter (home or industrial). This is great news for the environment, wildlife and landfill contributions (zero!)
It’s worth looking into your compostable plastic options as many companies are now offering compostable plastic alternatives at good prices. These can be found online and in many stores. Consider where you can make some small changes in your everyday life away from traditional plastic.
Read more about the benefits of composting in this blog.
Which Is Better: Cassava Or Corn Plastic?
When looking at which is the most superior compostable plastic out of cassava or corn, they are very similar in many ways:
- Sustainable when farming is controlled
- 100 per cent compostable when disposed of correctly
- Non toxic to humans, wildlife, marine life, air and soil
- Reduced electricity and water usage in manufacturing
- Reduced greenhouse emissions during manufacturing
However, when it comes to durability, cassava is known as the stronger of the two and potentially the more sustainable:
- More durable – less chance of rips
- More durable – can be used more times
- More durable – can carry heavier items
- More durable – can be carried longer distances
- Less pollutants produced – corn requires fertilizers and chemical processing oftentimes
- Less land use than corn plants.
What Are Other Bioplastics?
With interest rising in consumers looking to find an alternative to plastic, ‘bioplastics’ are becoming more and more popular. Of course, there are not enough items made to replace all plastics but there are some great alternatives to lower your personal landfill contributions.
Bioplastics are classed as a range of plastic alternatives made from renewable sources such as organic materials. These plastics are more sustainable and environmentally friendly than traditional plastics. They are currently more expensive to manufacture as they aren’t as widely used as traditional plastic yet.
Bioplastics are considered safer for the environment from their manufacturing process which uses less resources and produces lower emissions, through to their ability to be disposed of and return to natural matter.
These plastics are made from renewable materials such as corn starch, tapioca starch and others. This means that when they are disposed of correctly, they reduce waste. They are able to be either quickly broken down (when it comes to landfill disposal) or composted back into the earth.
We can class compostable, PLA (polylactic acid) and biodegradable as the top three bioplastics on the market.
Other plastic alternatives in terms of bags include paper, fabric, recycled plastic and other woven options. These can be reused many times, washed (when it comes to fabric) and also able to be stored for long periods and carried longer distances with heavier weights.
Read more about other uses for plastic bags and their alternatives in this blog.
The Benefits Of Plastic Alternatives
The biggest benefit of using a plastic alternative for your plastic bags is reducing your environmental footprint. A typical plastic bag can take centuries to thousands of years to break down in landfill and so biodegradable or compostable plastic reduces this time vastly.
There are also less traditional plastic chemicals in biodegradable plastics which means less environmental issues in the future such as pollution, toxicity and methane production in landfill. The manufacturing process is also more environmentally friendly than traditional plastic manufacturing.
Some benefits of biodegradable plastic:
- It will break down more rapidly in a landfill environment – in months or a year rather than thousands of years.
- Some ingredients are bio-based and will break down into their natural state.
- They can be disposed of easily in landfill with the rest of your household garbage.
- You can dispose of it easily in a public garbage bin or your home bin.
- Safe for humans, wildlife, animals and the environment (mostly).
- Less greenhouse emissions released during manufacturing.
- Less electricity and water used during manufacturing.
It should be noted that biodegradable plastic can leave behind some toxic residue when breaking down, due to the plastic components still present in the plastic.
Read more about the difference between compostable and biodegradable plastics here.
Benefits of compostable plastic use:
Obviously the biggest benefit of compostable plastic is its ability to completely break down into natural components, rapidly speeding up the decomposition process to as little as 90 days in some cases.
Other benefits include:
- Reduces contributions to landfill.
- Does not leach or leave behind toxic chemicals.
- Less greenhouse gas emissions during manufacturing.
- Lower water and energy consumption during manufacturing.
- Safe for humans, animals, wildlife and the environment.
- Provide great fertilizer when composted correctly.
Read more about composting in this article.
Conclusion
Bioplastics provide an excellent alternative to traditional plastic due to their benefits for the environment. Since the introduction of cassava as a bioplastic material, we are seeing a more durable and potentially more sustainable option on the market.
When it comes to the more popular cornstarch-based bioplastic, cassava is seen as more durable and more sustainable and is widely available much like corn. Compostable plastic returns to 100 per cent natural matter when disposed of in a worm farm or composter.
