Bioplastics vs. regular petroleum-based plastics: How do they compare?
By Tim Uchikura
Plastics play an important role in our lives. Look around you — there’s a good chance that you have many types of plastics near you right now. Can you spot them? You may see an appliance, electrical cord, clothing, shoes, pet food or water dish, pens, cups, or a garbage bin. You are probably reading this on a device that is made using some plastic. You’ll likely notice many types of plastics with many different properties, with some plastic products meant to be used for a long time, and others for just an instant.
The advantage of plastics, and the reason for their wide use, is that they are quick and easy to shape into products or packaging using pre-made molds. They are durable, low cost, and waterproof, making plastic a perfect material for manufacturing. But you are probably aware that many scientists, innovators, and students like yourself are now looking to solve the big plastic problem. Why?
The Big Plastic Problem
Traditional plastics have three significant impacts on the environment: they use fossil fuels, have a large carbon footprint, and stay in the environment for hundreds of years. One major problem with plastic that needs to be addressed right away is that it is too durable! Most petroleum-based plastics are not biodegradable; instead, they degrade so slowly that they stay in the environment, landfills, beaches, and oceans for decades up to hundreds of years.
Most products, even plastic products, will have some sort of plastic packaging which is only used once, unfortunately resulting in a lot of wasted plastic. You may have encountered alternatives such as cardboard or wood packaging which can be better for the environment, but more time-consuming and costly to make. Instead of transitioning to different materials, altering the plastic itself to be more biodegradable has become a real possibility thanks to recent technological and scientific developments.
How are regular plastics made?
Regular plastics are made from repeating units of carbon molecules that form long chains called polymers. The single molecules that make up the polymers are obtained by refining petroleum oil. Along with other additives, the polymers are heated and liquified then injected into molds where they solidify. The plastic has different properties than the individual compounds that it was composed from. At the molecular level, unique chemical bounds not found in nature are formed, which lend themselves to increased durability, thermostability (the ability to resist permanent change at high temperatures), and water resistance.
Polymers, whether artificial (such as the plastic shown) or natural, are made of repeating chains of smaller chemical units. Here, carbon atoms are shown as black, oxygen as red and hydrogen as white. MOLEKUUL/ISTOCKPHOTO
How do regular plastics decompose?
In natural decomposition, microbes such as bacteria and fungi break the chemical bonds holding substances together. The chemical bonds in organic compounds have specific shapes that entices microbes to bind and then begin decomposition. In petroleum-based plastics, the polymers are longer molecules than what would occur in nature, making it harder for microbes to recognize them and bind, leading to the inability of plastic to be broken down. While several factors impact the timeline to degrade plastics, like the polymer it is made from and the environment it is discarded in, on average, single-use plastic bottles will take about 450 years to degrade, while a plastic bag can take anywhere from 10 to 1,000 years to degrade in a landfill!
What are bioplastics?
To solve this problem, scientists are working to create new types of plastics made with biological materials that can degrade quickly, do not rely on fossil fuels, and have a smaller carbon footprint.
These new types of plastics made with biological-based ingredients are called bioplastics. Early research indicates that they could be a significant improvement over petroleum-based plastics. To clarify, bioplastics are plastics made at least in part with renewable biological matter (like vegetable fats and oils, corn starch, woodchips, sawdust, and food waste), or they are plastics that can degrade in a reasonable time.
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How do bioplastics decompose?
Surprisingly, the structural similarity between bioplastic and petroleum-based plastics are very similar. They both contain polymers but are distinguished based on the source. A common polymer used in bioplastics is polylactic acid (PLA) which is synthesized by fermenting plant starch from agricultural waste. Lactic acid molecules are bound together in this natural process, forming long chains that become polymers. These polymers, unlike petroleum-based ones, possess molecular bonds that can be broken apart by water, heat, and the sun — making them a more eco-friendly choice than regular plastic. This difference in degradability comes from the bonds that makeup the structure of the polymers.
What is the future of bioplastics?
With this in mind, bioplastics are being developed and tested as sustainable replacements for single-use plastics for packaging, utensils, food containers, 3D printing, fashion, and even medical implants. But since bioplastics have different properties than their petroleum-based counterparts it can require an innovative mindset to use them industrially. Not all bioplastics possess the same durability, thermostability and waterproof properties of conventional plastic. In addition, refining polymers from agricultural waste at an industrial level needs further research and development to be as efficient as petroleum refinement.
The world is in need of young scientists to come up with new ideas on how to improve bioplastics! Want to learn more about bioplastics, and learn to make your own? Try our bioplastics kit!