How Biodegradable Plastic Is Made: A Comprehensive Guide

Plastic waste is a huge environmental problem, with over 8 million tons entering our oceans each year. Biodegradable plastics offer a potential solution, breaking down into harmless compounds. But how exactly are these eco-friendly plastics made?

If you’re short on time, here’s a quick answer to your question: Biodegradable plastics are made from plant-based materials like corn starch or cellulose, combined with additives that allow the material to break down faster. The ingredients are mixed together, heated and shaped into pellets or products through processes like extrusion or injection molding.

In this comprehensive 3000 word guide, we’ll explore the full manufacturing process for different types of biodegradable plastics, including key ingredients, production methods, standards and certifications. With detailed sections on polylactic acid (PLA), polyhydroxyalkanoates (PHA), starch blends, cellulose plastics and more, you’ll learn everything you need to know about how these innovative materials are created.

Overview of Biodegradable Plastics

Biodegradable plastics have gained significant attention in recent years, as the world continues to grapple with the environmental impacts of traditional plastics. In this comprehensive guide, we will explore the process of how biodegradable plastics are made and delve into their various types, benefits, and certifications.

Definition and Benefits

Biodegradable plastics, also known as compostable plastics, are a type of plastic that can be broken down by microorganisms into natural elements such as water, carbon dioxide, and biomass. Unlike traditional plastics that take hundreds of years to decompose, biodegradable plastics offer a more sustainable alternative.

The benefits of biodegradable plastics are numerous. Firstly, they help reduce the amount of plastic waste in landfills and oceans, thus mitigating the harmful effects on marine life and ecosystems. Additionally, biodegradable plastics can help reduce greenhouse gas emissions during the decomposition process, contributing to a healthier planet.

Moreover, biodegradable plastics can be produced from renewable resources such as corn starch, sugarcane, or vegetable oils, reducing reliance on fossil fuels. This makes them an attractive option for companies and individuals looking to decrease their carbon footprint and promote a circular economy.

Types of Biodegradable Plastics

There are several types of biodegradable plastics available in the market today. One common type is polylactic acid (PLA), which is derived from renewable resources such as corn or sugarcane. PLA is often used in packaging materials, disposable cutlery, and food containers.

Another type of biodegradable plastic is polyhydroxyalkanoates (PHA), which is produced by bacteria fermenting plant sugars. PHA is known for its versatility and can be used in various applications, including medical devices, agriculture films, and cosmetics packaging.

Other biodegradable plastics include polybutylene adipate terephthalate (PBAT), which is often used as a blend with PLA to improve its flexibility and toughness, and starch-based plastics, which are commonly used in single-use items like bags and food packaging.

Standards and Certifications

To ensure the quality and credibility of biodegradable plastics, various standards and certifications have been developed. One well-known certification is the “OK Compost” label, which is awarded by TÜV Austria. Products that bear this label have undergone rigorous testing to ensure their compostability in industrial composting facilities.

Another widely recognized certification is the ASTM D6400 standard, which defines the requirements for compostability in home composting environments. Products that meet this standard can be safely composted in backyard compost bins.

It is important to note that not all products labeled as “biodegradable” are truly compostable. Some plastics may only degrade under specific conditions, while others may leave behind harmful residues. Therefore, it is crucial to look for certifications and labels from reputable organizations to ensure the biodegradability and compostability of the products you choose.

By understanding the definition, benefits, types, and certifications of biodegradable plastics, we can make informed choices to reduce our environmental impact and contribute to a more sustainable future.

Key Ingredients


Starch is one of the key ingredients used in the production of biodegradable plastic. It is a natural polymer that is derived from various sources such as corn, potatoes, and wheat. Starch-based bioplastics are known for their excellent biodegradability and renewable properties. The starch is extracted from these sources and then processed to obtain a biodegradable plastic material.


Cellulose is another important ingredient used in the production of biodegradable plastic. It is the most abundant organic compound on Earth and is found in the cell walls of plants. Cellulose-based bioplastics are known for their strength, durability, and biodegradability. The cellulose is extracted from plant sources such as wood, cotton, and hemp, and then processed to create a biodegradable plastic material.

Polylactic Acid

Polylactic Acid (PLA) is a biodegradable thermoplastic that is derived from renewable resources such as corn, sugarcane, or other starch-rich crops. PLA is widely used in the production of biodegradable plastics due to its excellent biodegradability, low toxicity, and versatility. It can be molded into various shapes and forms, making it suitable for a wide range of applications.

Polyhydroxyalkanoates (PHA)

Polyhydroxyalkanoates (PHA) are a group of biodegradable polymers that are synthesized by microorganisms. They are produced by bacteria as a storage material for carbon and energy. PHA-based bioplastics have gained attention in recent years due to their excellent biodegradability, biocompatibility, and mechanical properties. These plastics can be used as a sustainable alternative to traditional plastics in various industries.

Production Methods


The extrusion method is one of the most common ways to produce biodegradable plastic. In this process, plastic pellets are fed into a hopper and then melted in an extruder. The molten plastic is then forced through a die, which shapes it into a continuous profile. This profile is then cooled and cut into the desired length. Extrusion is widely used for producing plastic films, sheets, and profiles.

Injection Molding

Injection molding is another popular production method for biodegradable plastic. It involves melting plastic pellets in a heated barrel and then injecting the molten plastic into a mold cavity. Once the plastic cools and solidifies, the mold is opened, and the final product is ejected. Injection molding allows for the production of complex shapes with high precision and is commonly used for manufacturing plastic bottles, containers, and other household items.


Thermoforming is a process used to produce biodegradable plastic products with a specific shape. It involves heating a plastic sheet until it becomes pliable and then draping it over a mold. The mold is then cooled, and the plastic takes the shape of the mold. Thermoforming is commonly used for manufacturing trays, clamshell packaging, and disposable cutlery.

3D Printing

3D printing, also known as additive manufacturing, is a relatively new production method for biodegradable plastics. It involves creating a three-dimensional object layer by layer using a digital model. The biodegradable plastic filament is fed into a 3D printer, which heats and extrudes the material to create the desired shape. 3D printing allows for the production of highly customized and intricate objects, making it ideal for prototyping and small-scale production.

These production methods play a crucial role in the manufacturing of biodegradable plastic. Each method has its own advantages and applications, and the choice of method depends on factors such as the desired product, production volume, and cost considerations.

Polylactic Acid (PLA)

Polylactic Acid (PLA) is a type of biodegradable plastic that is derived from renewable resources such as corn, sugarcane, or tapioca. It is a popular alternative to traditional plastics because of its eco-friendly properties.

Raw Materials

The raw materials used in the production of PLA are plant-based sugars, such as glucose or starch. These sugars are derived from crops like corn or sugarcane, which are abundant and renewable resources. The sugars undergo a fermentation process, where microorganisms convert them into lactic acid. The lactic acid is then purified and transformed into a polymer through a process called polymerization.

Polymerization Process

The polymerization process involves heating the lactic acid to remove water and create lactide, which is a cyclic dimer. The lactide is then further heated and mixed with a catalyst to initiate a ring-opening polymerization reaction. This reaction causes the lactide molecules to link together and form long chains, resulting in the creation of polylactic acid. The process can be adjusted to produce PLA with varying properties, such as different molecular weights or degrees of crystallinity.

Advantages and Applications

PLA offers several advantages over traditional plastics. It is biodegradable and compostable, meaning it can break down naturally over time without causing harm to the environment. PLA also requires less energy to produce compared to conventional plastics, which helps reduce greenhouse gas emissions. Additionally, PLA has good mechanical properties, making it suitable for a wide range of applications.

PLA can be used to make various products, including packaging materials, disposable cutlery, food containers, and even 3D printing filaments. Its versatility and eco-friendly nature have made it a popular choice among environmentally-conscious consumers and businesses.

If you want to learn more about the production process and applications of PLA, you can visit NatureWorks LLC, a leading manufacturer of PLA. They provide detailed information on the various stages of PLA production and its sustainability benefits.

Polyhydroxyalkanoates (PHA)

Polyhydroxyalkanoates (PHA) are a type of biodegradable plastic that is derived from microbial fermentation. They are considered to be a sustainable alternative to traditional plastics due to their ability to break down naturally in the environment.

Microbial Fermentation

The production process of PHA begins with microbial fermentation. Microorganisms such as bacteria or algae are used to convert renewable carbon sources, such as sugars or plant oils, into PHA. These microorganisms consume the carbon sources and produce PHA as a byproduct. The fermentation process can be carried out in large-scale bioreactors under controlled conditions.

During the fermentation process, the microorganisms undergo a series of metabolic reactions to convert the carbon sources into PHA. This process requires specific enzymes and genetic engineering techniques to optimize the production of PHA. The duration of fermentation can vary depending on the type of microorganism used and the desired properties of the PHA.

Isolation and Purification

After the fermentation process, the PHA needs to be isolated and purified. This is typically done through a combination of physical and chemical processes. The first step is to separate the PHA from the microbial biomass. This can be achieved through methods such as centrifugation or filtration.

Once the PHA is separated, it undergoes further purification to remove any impurities or residual biomass. This can involve processes such as solvent extraction or precipitation. The purified PHA is then dried and processed into various forms, such as pellets or films, for further use.

Properties and Uses

Polyhydroxyalkanoates have a range of properties that make them suitable for various applications. They have similar mechanical properties to traditional plastics, such as high tensile strength and flexibility. However, unlike traditional plastics, PHA is biodegradable and does not contribute to plastic pollution.

PHA can be used in a wide range of applications, including packaging materials, agricultural films, disposable cutlery, and even medical implants. Their biodegradability makes them particularly useful in single-use products that would otherwise contribute to landfill waste. Additionally, PHA can be blended with other materials to enhance their properties or create new materials with specific characteristics.

It is important to note that the production of PHA still faces certain challenges, such as cost-effectiveness and scalability. However, ongoing research and development efforts are being made to overcome these obstacles and expand the use of biodegradable plastics in the future.

Starch Blends

Starch blends are a key component in the production of biodegradable plastics. These blends are made by combining starch with other materials to enhance their properties and make them suitable for various applications. Let’s take a closer look at the different aspects of starch blends in the production of biodegradable plastics.

Sources of Starch

Starch can be obtained from a variety of sources, including corn, potatoes, and tapioca. Each source has its own unique characteristics, such as the amount of amylose and amylopectin present, which can influence the properties of the final product. Corn starch, for example, is widely used in the production of biodegradable plastics due to its abundance and affordability.

Plasticizers and Additives

To improve the flexibility and processability of starch blends, plasticizers and additives are often incorporated into the mixture. Plasticizers help to reduce the brittleness of the biodegradable plastic, making it more flexible and less prone to cracking. Additives, on the other hand, can enhance the strength, durability, and moisture resistance of the material.

Blending and Processing

The process of creating starch blends involves blending the starch with plasticizers and additives, followed by processing to form the desired shape and structure. This can be done through various techniques such as extrusion, injection molding, or blow molding, depending on the specific requirements of the end product. The temperature, pressure, and processing time are carefully controlled to ensure the optimal properties of the biodegradable plastic.


One of the key advantages of biodegradable plastics made from starch blends is their ability to compost. These plastics can break down into natural components, such as carbon dioxide and water, under specific composting conditions. This makes them an environmentally friendly alternative to traditional plastics, which can take hundreds of years to decompose.

It’s important to note that the compostability of biodegradable plastics depends on various factors, including the composition of the blend, the thickness of the material, and the composting conditions. Therefore, it is essential to follow proper disposal guidelines and ensure that the biodegradable plastics are disposed of in appropriate composting facilities.

For more information on the production and compostability of biodegradable plastics made from starch blends, you can visit the website of the Bioplastics Magazine. They provide a wealth of resources and up-to-date information on the latest advancements in biodegradable plastics.

Cellulose Plastics

Cellulose plastics are a type of biodegradable plastic that are made from cellulose, a natural polymer found in plants. This type of plastic is becoming increasingly popular due to its eco-friendly properties and its ability to break down naturally over time. In this section, we will explore the process of making cellulose plastics.

Cellulose Sources

Cellulose can be sourced from a variety of plant materials including wood pulp, cotton, and hemp. These materials are rich in cellulose fibers, which can be extracted and used as the raw material for making cellulose plastics. The use of renewable plant sources makes cellulose plastics a sustainable alternative to traditional plastics derived from fossil fuels.

Dissolving Cellulose

The first step in making cellulose plastics is to dissolve the cellulose fibers in a solvent. This process breaks down the cellulose into its individual molecules, creating a thick liquid called cellulose solution. The solvent used in this step can vary, but common solvents include sodium hydroxide and carbon disulfide. This cellulose solution is the key ingredient for creating cellulose plastics.

Regenerating Cellulose

Once the cellulose fibers are dissolved, they can be regenerated into a solid form to create cellulose plastics. This is done by either extruding the cellulose solution through a spinneret to form fibers, or by pouring the solution into molds to create sheets or other shapes. The regenerated cellulose is then dried and hardened to create a finished product that can be used in various applications.

Molded Cellulose Products

Cellulose plastics can be molded into a wide range of products, including packaging materials, disposable cutlery, and even 3D printing filaments. The versatility of cellulose plastics makes them a great alternative to traditional plastics in many industries. Additionally, these products can be composted or broken down naturally, reducing their impact on the environment.


Biodegradable plastics help tackle plastic pollution by breaking down into harmless byproducts like carbon dioxide and water. As we’ve explored, they are derived from renewable materials like plants and can be produced through methods like extrusion and injection molding.

While traditional plastics take centuries to degrade, biodegradable alternatives offer similar functionality but decompose within months to years in the right conditions. With growing environmental awareness among consumers, innovations in bioplastics will continue to develop and help create a more sustainable future.

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