Biodegradable Plastics – Advantages, Disadvantages

What is Biodegradable Plastics?

Plastics are very harmful to our planet. They produce them from petroleum-based sources which are fossil fuels and because of the very long molecular link structures, the degradation of the conventional polymers is very hard. If we do not recycle these materials, their waste of them will be very harmful to nature. They are one of the most important responsibilities for the pollution of nature. So, people are trying to develop a new types of materials that can degrade in nature. We call these materials biodegradable plastics or bioplastics. There are various advantages and applications of them and we will mention these in this article. 

What is Biodegradable Plastic?

Use of bioplastics.
Image Source: PxHere.

Biodegradable plastics are the type of polymers that can decompose in nature by themselves with microbes, living small organisms, carbon dioxide, and water. Conventional plastics are very hard to dissolve in nature but if we replace the conventional materials with them. It will be very good for the environment. 

Development of Biodegradable Plastics

Throughout history, there are different studies to develop plastics that they source from natural sources instead of petroleum. Because there are historical phases where the petroleum crisis is on the stage. They are making R&D on the production of natural polymers generally because of the different petroleum crises in history. 

Polyhydroxyalkanoate(PHA) is the first polymer that is discovered in a microorganism that lighted the development of biodegradable plastic. After this discovery, there are different studies on the extraction of polymers from microorganisms but these studies are not successful as expected. Because there is a need for serial manufacturing of plastics and it requires very high tonnages of polymer production. 

As a result of rising oil prices in the 1970s, Imperial Chemical Industries successfully produced and extracted the PHB with a yield of 70% by using microorganisms. But, their properties of them are not as expected from these materials. 

But the production costs of these natural materials are very high and they do not apply to the plastic market. The first low-cost production of natural polymers took place by Monsanto. The production of cheap natural biopolymers depends on producing them from plants. 

Applications of Biodegradable Plastics

Because of the biodegradable nature of the bioplastics, they are generally using them in items that are disposable by the user. The most important application of them is disposable packages and containers. Nature is polluted heavily by these conventional polymer packages and containers. The use of bioplastics will be a very big solution for it. 

Environmental Benefits

Environmental cycle of bioplastics.
Image Source: Parekhplast.

The first important benefit of the microbial degraded materials is the saving nature from the harmful pollution effect of the conventional materials. Biodegradable plastics can dissolve in water or soil without any side effects if we replace the conventional polymers with these materials. So, we prevent this pollution substantially.

A very big amount of solid waste produced from residential areas is plastic waste. We use these plastic wastes in landfills and this is very harmful to the environment. If they replace municipal polymers with biodegradable plastics, they will prevent this harmfulness.

Other Important Benefits of Them

Also, the consumption of petroleum is another important problem in the production of these materials. With bio-based materials, we can decrease the total petroleum use. Because fossil fuels are fossil products are very harmful to nature. On yearly basis, people use lots of petroleum products to produce conventional polymers.

In the decomposition phase, these materials are not releasing any harmful side products to the environment. Because of this situation, there are lots of additional regulations to use bio-polymers. This is also very important for human health.

And also, carbon dioxide levels are lower with the use of these materials. Because they make biomaterials from natural sources. So, the carbon footprint is much lower than usual.

Emission levels are also lower with the use of biodegradable plastics. Because, in the production of traditional plastics, the general machinery uses lots of fuel, and plastics produce lots of harmful emissions. So, these environmentally friendly materials will lower the total emissions.

Disadvantages

Plastic waste.
Heavy amount of plastic waste(Image Source: Flickr)

In general, we develop biodegradable plastics to decompose in industrial applications. They use a special industrial process to decompose these biodegradable plastics. But, if they throw them into nature, soil, or seas, the decomposition will only be at their level of them. These microplastics will stay in the soil and nature without any decomposition. Because of it, their disposal of them is not good for the environment.

Then another discussion about the production of biodegradable plastics is the use of very high amounts of water and ad fuel which will be a heavy effect on the food supply. Because of this overuse of sources, their environmental effects of them are controversial. 

Also, the general costs of manufacturing and composing them is more than the conventional plastics. So, this is one of the biggest obstacles to the serial production applications of these environmentally friendly materials.

Methane and Ocean Pollution Problems

Methane production can be a problematic issue. Because composing biodegradable polymers can produce very high amounts of methane which is very harmful to the air. And also, the production of these amounts of methanes can be very dangerous. There can be instant flares that cause very big fires.

It can be very surprising that these kinds of new plastics are not composing the cold oceans. So, these solutions are not the exact solutions for the plastic pollution in the ocean.

More Croplands

The production of these plastics requires much more area to produce the required crops. Because we use generally crops to produce these bio-plastics. This is also very big additional cost.

What are the Types of Biodegradable Plastics? 

The bioplastics can be classified into 2 groups according to their production source: bio-based bioplastics and petroleum-based bioplastics. We need to examine the bioplastics inside these two categories. 

Petroleum-based Biodegradable Plastics

Conventional polymers such as PET and PE are produced from petroleum-based sources such as crude oil, natural gas, or coal. But they are not biodegradable polymers. Some are produced from petroleum-based resources. 

  • Polybutylene succinate(PBS): PBS is a petroleum-based thermoplastic polymer that has similar properties to propylene. They use mainly in packaging films and agricultural biodegradable mulching plastic.
  • Poly(vinyl alcohol)(PVA, PVOH): This is a very important material that is soluble in water. Because this harmless solution is water, they use PVA and PVOH in packaging and coating applications.
  • Polyglycolic acid(PGA): It is a type of petroleum-based biodegradable thermoplastic polymer that they commonly use in medical applications such as sutures.
  • Polycaprolactone(PCL): PCL is used in implantation applications because of its ester linkages. 

Bio-based Biodegradable Plastics

As we stated above, if they produce biodegradable plastics with natural sources such as bacteria, and animals other than petroleum-based sources, they are classified as bio-based materials or bioplastics. There are various types of bio-based polymers. 

  • Polyhydroxyalkanoate(PHA): This is the first type of synthesized bio-plastic from microorganisms. 
  • Cellulose Acetate: These are the cellulose-based polymers that they generally use in packaging. But the implementation of these bioplastics is very hard because of the high prices. 
  • Polylactic acid(PLA): PLA is the most used and consumed bio-plastic among others. We use the fermentation of corn starch or sugarcane to produce PLA. But the decomposition of the PLA is made by artificial industrial conditions. Because of this reason, we do not call them biodegradable by the US and European standards. 
  • Starch-Plasticizer Blends: Starch-based polymers are biodegradable but they are very brittle thermoplastics. To add more plastic behavior, they add plasticizers to the starch. But the biodegradability of these blends depends on the used plasticizers. If the use of plasticizers is not biodegradable, they are not considering these blends as biodegradable. 

Classifications of Degradable Plastics and Technologies

As you understand above, there are different types of biodegradable materials that decomposed in different ways. According to their decomposing capabilities, we are not considering some of them biodegradable materials by various standards. So, there is a strict classification of bioplastics. 

Compostable Bioplastics

The compostable materials group refers to the polymers that we compost for industrial applications. These groups of bioplastics do not decompose in the natural environment, they require a special industrial process to decompose the plastics. These conditions are provided by providing special high temperatures and pressures. Because of this reason, we do not consider these materials biodegradable plastics by American and European standards. 

Bioplastics

Bioplastics is a degradable polymer class that refers to the plastics that they produce from natural sources such as bacteria or plants and they can dissolve in nature such as water, soil, etc. Not all bioplastics are biodegradable polymers. If bioplastic does not degrade in nature, we do not call this bioplastic biodegradable polymers. For example, plant-based PET is a bioplastic but it does not degrade in nature. Because of is, plant-based PET is not called one of these materials. 

Oxy-Degradable Plastics

To degrade these polymers, they create a special oxidation process and environment. It takes a long time to oxide and degrades the oxy-degradable polymers in normal environmental conditions. Because of this reason, we do not call these plastics biodegradable plastics by American and European standards. 

Additional Information About Them

The most important feature of bioplastics is that natural bacteria can degrade these materials in nature. So, the total solid waste will reduce with the advancement of these material technologies. We need to give special care to them also.

Also, we can mix these brand-new materials with the other conventional polymers. So, we can obtain materials that are a combination of environmentally friendly materials and other conventional materials.

Commercial Use of Biodegradable Plastics

With the advancing technology and time, the use of biodegradable plastics gets more common in different industries. In China alone, the yearly use of these plastics increased by 13% each year. This means they will replace the conventional ones in the preceding years.

Also, Coca-Cola makes some of its bottles from bioıdegradable materials and bioplastics.

Conclusion

The field of biodegradable plastics is very controversial as you see above. The technical terms of these materials can be confused by first readers. This is generally because biodegradable materials and polymers are recently developing technology and there are very big R&D investments in this area. If sustainable biodegradable plastics are produced and replaced the conventional polymers, all the terms will be more straightforward. 

These are the most general information about the latest situation of biodegradable plastics in the world. 

Do not forget to leave your comments and questions below about bioplastics!

Your precious feedbacks are very important to us!

FAQs

Why conventional plastics are not completely replaced by biodegradable plastics?

The production costs, production difficulties, and ongoing developments are the main obstacles to the replacement of conventional plastics with these materials. 

Is the biodegradable plastics field a good field to study and work in?

Yes, it is. There are very big R&D investments in the development of biodegradable plastics. You can take a part in these studies by developing and improving yourself in this area. 

How can I participate in the development of biodegradable plastics?

In general, R&D developments and studies on these materials are carried out at the academic level. Academicians and big companies are working together to develop bioplastic technologies. You can take a part in this area by studying related areas such as chemistry, chemical engineering, materials engineering, bioengineering, etc. You can take your master’s degree in these areas to take a part in these studies. 

Why biodegradable plastics are better for the environment?

The biggest problem with conventional materials, they can not dissolve in nature. Because of this, they cause very big pollution problems in the ocean and nature. So, bio-plastics are very good for the environment in that they can dissolve in nature easily.

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