Image: Paolo_galasso – Depositphotos.The rise of biodegradable or bioplastic plastics is accelerating, but what do we know about biodegradable plastics? What are the different types of biodegradable plastic?
In summary, we can find these types of biodegradable plastics:
- Bioplastics: produced partially or totally with biobased polymers. They can come from plants or be combined with synthetic polymers. Not all are biodegradable.
- Bioplastics – derived from synthetic polymers.
- oxodegradable plastics – conventional plastics with additives to decompose faster.
- Photo-biodegradable – react to ultraviolet light and require initial oxo-degradation.
- Hydro-biodegradable plastics – made from plant sources (such as starch) and degradation is initiated by hydrolysis.
The subject of bioplastics is complex, so we need to analyze the different types of biodegradable plastics and whether they are better than normal plastics.
Contents
Conventional plastics vs biodegradable plastics.
Many people often think that terms like “bioplastic”, “oxodegradable plastics”, “biodegradable” and “compostable” mean the same thing.
But there is a big difference between these terms, and they are not synonymous. And what is more important: not all bioplastics are biodegradable. We see them one by one.
classic plastic.
Traditional plastic is made from chemicals that can be harmful to the environment when the plastic melts.
The middle bag is used for about 20 minutes and then discarded. A plastic bag takes more than 1,000 years to break down into microplastics.
Normal plastics contain carbon. When plastic is discarded and begins to decompose or when it melts, this carbon is released into the atmosphere.
Methane and other forms of pollutants could also be released from traditional plastic when it is burned or dumped in a landfill.
Standard plastic bags are usually made from petroleum, while biodegradable bags are made from plant or organic material, which can decompose much faster.
Worldwide, we use around 2 million plastic bags every minute. Normal plastics, in particular, take hundreds or even thousands of years to break down.
There are 7 different types of non-biodegradable plastic:
- Polyethylene terephthalate (PETE or PET).
- High density polyethylene (HDPE).
- Polyvinyl chloride (PVC).
- Low density polyethylene (LDPE).
- Polypropylene (PP).
- Polystyrene or polystyrene foam (PS).
- Various plastics (mixed materials).
Bioplastics.
Plastic is considered bioplastic if it is partially or totally produced with biobased polymers.
In addition, it will be considered biodegradable if it can be degraded into water, carbon dioxide and biomass in a given time (according to the different standards).
Keep in mind that bioplastic is not synonymous with biodegradable. Not all bioplastics are biodegradable.
Moldable bioplastic material formed from chemical compounds derived from microbes such as bacteria or genetically modified plants.
Some bio-based plastics are made from renewable resources instead of fossil fuels, but not all.
Some examples of renewable carbon resources are corn, potatoes, rice, soybeans, sugar cane, wheat, and vegetable oil.
“Biodegradable” means when something is capable of being broken down by bacteria or other living organisms.
Biodegradable plastic is plastic that degrades under the action of natural microorganisms such as bacteria, fungi and algae.
This type of bioplastic is divided into 3 groups according to their origin:
- Bio-based (plant-based) biodegradable plastic
- Chemically biodegradable synthetic plastic
- NON-biodegradable bio-based plastic.
Most biodegradable plastics are a combination of organic materials, such as starch and cellulose, and chemical additives that break down into carbon dioxide, methane, biomass, water and mineral salts.
Biodegradable plastics should not release carbon, as there is normally no carbon in the manufacturing process.
Oxodegradable plastics.
Commonly perceived as biodegradable.
However, they are nothing more than conventional plastics with additives that accelerate decomposition through exposure to sunlight and oxygen.
The additives only promote the fragmentation of the materials, which means that the plastic does not degrade completely, but simply breaks down into small fragments which remain in the environment.
Thereafter, they persist as huge amounts of microplastics rather than biological material.
The objective of oxo-degradable plastics is to accelerate the natural processes of fragmentation, into smaller and smaller plastic particles.
However, there is no guarantee that oxo-degradable plastics will receive the necessary light and heat treatment to start the fragmentation process.
There are currently two types on the market: hydro-biodegradable plastic of vegetable origin and oxo-biodegradable plastic of petroleum origin.
Overall, “oxodegradability” may sound appealing, but the term is misleading as these plastics cannot be verified due to the lack of a standard specification.
Photobiodegradable plastics.
This plastic reacts to ultraviolet light and requires initial oxodegradation. This means that this type of bioplastic will not degrade in a different environment.
Other forms of biodegradable plastics are made from sugar, banana peel, avocado, and used frying oil.
These plastics are currently under study.
Hydro-biodegradable plastics.
Hydro-biodegradable plastics degrade faster than oxo-degradable plastics and can usually be composted in an industrial composter.
Hydrobiodegradable plastics are made from plant sources (such as starch) and degradation is initiated by hydrolysis.
This type of plastic is temperature resistant and is the only bioplastic that can decompose, both in soil and in water.
compostable plastic
The main difference between compostable and biodegradable plastic is that compostable products need different and specific environments to break down.
Composting generally takes place in aerobic environments (requires oxygen), while biodegradation can take place in anaerobic environments (does not require oxygen).
Composting consists of accelerating the decomposition of materials through the action of micro-organisms, under aerobic conditions.
Compostable plastic degrades into carbon dioxide, water, inorganic compounds and biomass. Leaves no toxic chemicals behind.
As compostable plastic is biodegradable in a composting environment, to be labeled as compostable it must meet specific standards.
Compostable resins are typically made from potato starch, soy protein, cellulose, as well as petroleum and petroleum by-products.
Keep in mind that compostable plastics do not break down on their own, in landfill, as litter, or in marine environments. They should be composted in commercial composting facilities.
Are biodegradable plastics really biodegradable?
Almost anything can biodegrade, given enough time. Furthermore, biodegradation will only be successful if it occurs under the right conditions.
Biodegradable plastics are made up of molecules that can break down naturally, but there is often no specific time frame for this degradation. In poor conditions, it can take many years.
For example, if biodegradable plastics end up in a landfill or in the ocean, they will most likely persist on our planet for hundreds of years.
Biodegradable plastics generally need to take three to six months to fully decompose.
But the time it takes for a biodegradable item to break down depends on a number of factors, including temperature and the amount of humidity.
How is plastic biodegradable?
Most biodegradable plastics are made from traditional petrochemicals, but are designed to break down faster.
They include additives that cause them to degrade rapidly in the presence of light, oxygen, moisture and heat.
Biodegradable plastics break down faster also thanks to natural microorganisms such as bacteria, fungi and algae.
Are biodegradable plastics still compostable?
First, remember that “biodegradable” and “compostable” are different terms and do not mean the same thing. Some biodegradable plastics are neither biodegradable nor compostable.
Are all compostable plastics suitable for home composting?
No. Some compostable products require industrial composting facilities because they operate at higher temperatures than home composters.
Can biodegradable plastics break down in a landfill?
No. Most landfills limit or even stop biodegradation due to lack of oxygen and moisture.
biodegradable vs. compostable: which is the best?
There may be a situation where it is essential and unavoidable to use certain compostable or biodegradable plastics.
If you’re wondering how to decide which is better, composting might be better because it’s also a faster process.
However, remember that it requires special conditions.
Alternatives to home composting may be the best option, especially if you have a home composter.
Can compostable plastics be put in home compost?
NOT ALL compostable plastics can biodegrade in home compost.
They need special circumstances, such as heat, which is the main biodegradability factor of compostable plastic.
It is usually necessary to take it to an industrial composting facility, where it can, under the right heat conditions, begin its biodegradation.
Look for labels, like “compostable at home,” if you want to be sure you’re getting something that can biodegrade in your compost pile.