Everything You Need To Know About Polylactic Acid (PLA)

Polylactic Acid (PLA) is revolutionizing the plastic industry with its sustainable and versatile properties. Derived from renewable resources like corn starch and sugar cane, PLA offers a biodegradable alternative to traditional plastics.

This comprehensive guide delves into the production, properties, applications, and environmental impact of PLA, providing valuable insights for industries and consumers alike. Whether you’re involved in packaging, textiles, agriculture, or medical fields, understanding PLA’s benefits and limitations is crucial for making informed decisions about its use.

How Is PLA Produced?

Polylactic Acid (PLA) is a type of polyester that is derived from renewable resources like corn starch or sugar cane. The production process of PLA involves several steps, each contributing to its unique properties and making it a suitable material for various applications.

Conversion of Food Waste into Polylactic acid Fibre

Step 1: Extraction of Starch From the Plant Source

This is typically achieved through a process known as wet milling. The extracted starch is then converted into sugar, specifically dextrose, through a process called hydrolysis.

Step 2: Fermentation

The dextrose is then fermented by microorganisms to produce lactic acid. This process is similar to the fermentation process used in the production of yogurt and sourdough bread. The lactic acid is then purified and concentrated.

Step 3: Polymerization of the Lactic Acid to Form Polylactic Acid

This is achieved through a process known as condensation polymerization. During this process, water is removed, and the lactic acid molecules are linked together to form long chains or polymers. This process requires heat and a catalyst to initiate the reaction.

Step 4: Cooling and Cutting

The resulting PLA is then cooled and cut into small pellets. These pellets can be further processed and molded into various products, from packaging materials to medical devices.

What Are the Properties of PLA?

PLA has several key properties that make it a material of choice for various applications:

Biodegradability

Unlike many other plastics, PLA is biodegradable and compostable under specific conditions. It breaks down into its constituent parts when exposed to industrial composting processes, which involve high temperatures, humidity, and the presence of microorganisms.

Thermal Properties

PLA has a relatively low glass transition temperature, typically between 55-60°C. This means it becomes soft and pliable when heated above this temperature, making it easy to mold and extrude, but also means it may deform when exposed to high temperatures.

Mechanical Strength

According to the study “Mechanical and Thermal Properties of Polylactide (PLA) Composites Modified with Mg, Fe, and Polyethylene (PE) Additives,” the addition of different materials significantly affects the mechanical properties of PLA. Adding iron (Fe) powder improves tensile strength and yield strength, making the composite more robust and resistant to deformation. 

Processability

PLA can be processed using most standard thermoplastic processing methods, including injection molding, blow molding, thermoforming, and extrusion. This makes it a versatile material that can be used to produce a wide range of products.

“PLA has been the frontrunner in biopolymers since it presents a potential solution to the waste disposal problem, being biodegradable and derived from renewable resources.” ~ Polymers Research Team, MDPI (MDPI).

What Are the Uses of PLA?

Polylactic Acid (PLA) is a versatile material with a wide range of applications across various industries. Its unique properties make it suitable for a variety of uses.

Packaging Industry

PLA is extensively used in the packaging industry due to its clear and glossy finish, which is comparable to petroleum-based plastics. It is used in the production of bottles, cups, bags, and wraps. Its biodegradability makes it a preferred choice for producing compostable packaging materials.

Agriculture

In agriculture, PLA is used to produce mulch film that decomposes in the soil after a certain period, reducing waste and labor costs associated with film removal.

Electronics

PLA is also used in the electronics industry for the production of casings and components. Its insulating properties make it suitable for this purpose.

Automotive Industry

In the automotive industry, PLA is used to produce interior parts and components, contributing to the reduction of vehicle weight and fuel consumption.

Can PLA Be Used for 3D Printing?

Polylactic Acid, commonly known as PLA, is indeed a popular material for 3D printing. Its popularity stems from several key attributes that make it suitable for this application.

Why PLA is Ideal for 3D Printing

Low Melting Point

According to a study entitled “Poly(lactic acid) and polyhydroxyalkanoates (PHAs), green alternatives to petroleum-based plastics: a review,” PLA has a melting temperature (Tm) between 130-180°C. 

This makes it easier to work with in many 3D printers, which often operate within this temperature range. The low melting point also means that PLA can be used in 3D printers without the need for a heated print bed, which is a requirement for some other types of plastic.

Exhibits Minimal Warping

Warping is a common problem in 3D printing where the material shrinks as it cools, causing the corners of the print to lift and distort. PLA’s minimal warping makes it easier to achieve high-quality prints with fine detail.

Available in a Wide Range of Colors and Finishes

This includes transparent and glow-in-the-dark options. This makes it a versatile choice for 3D printing projects that require a specific aesthetic.

Limitations of PLA as a 3D Material

However, it’s important to note that while PLA is a great material for 3D printing, it does have some limitations.

Durability and Heat Resistance

Polylactic acid (PLA) is not as durable or heat-resistant as some other plastics, such as ABS. This limitation means that PLA may not be the best choice for 3D printed objects that will be exposed to high temperatures or heavy wear and tear.

Biodegradability

While PLA is biodegradable under industrial composting conditions, it can take a long time to break down in a home composting setup or in the environment. This indicates that PLA 3D prints should still be disposed of responsibly.

PLA is a popular and versatile material for 3D printing, but like all materials, it has its strengths and weaknesses. Understanding these can help you choose the right material for your 3d printing project.

Can PLA Be Used in Medical Applications?

Polylactic Acid (PLA) has found a significant place in the medical field due to its unique properties.

It is a biocompatible and bioresorbable material, which means it can be safely used in the human body and will naturally break down over time. This makes it an excellent material for a variety of medical applications.

Surgical Applications

One of the primary uses of PLA in medicine is in the field of surgery, specifically for sutures, screws, pins, and rods. These are used to hold bones and tissues together while they heal.

The advantage of using PLA for these applications is that the material gradually dissolves in the body, eliminating the need for a second surgery to remove the devices.

Tissue Engineering

According to the study “Polylactic Acid: Synthesis and Biomedical Applications” by Singhvi, Zinjarde, and Gokhale, PLA is widely used in tissue engineering for creating scaffolds that support cell growth and tissue regeneration. Its properties can be adjusted to match the mechanical needs of different tissues. This adaptability makes PLA an ideal material for developing various biomedical devices and implants that can degrade safely within the body, facilitating natural tissue repair and regeneration.

Drug Delivery Systems

According to a study published in the National Center for Biotechnology Information (NCBI), PLA’s biodegradability and biocompatibility make it highly suitable for use in controlled drug delivery systems.

PLA microparticles can regulate drug release over different durations, from a few days to several weeks or even up to a year. The release rate is influenced by factors such as the molecular weight of PLA, the size of the microparticles, drug loading, solubility, and diffusion properties.

PLA, like any material, it is not without its challenges.

The rate of degradation can vary, and in some cases, the byproducts of PLA degradation can cause inflammation. Therefore, careful design and testing are necessary to ensure the safety and effectiveness of PLA-based medical devices.

What is the Impact of PLA on the Environment?

Polylactic Acid (PLA) has a significant impact on the environment, both positive and negative. 

As a bioplastic derived from renewable resources, it offers several environmental benefits over traditional petroleum-based plastics. However, it also presents certain challenges that need to be addressed.

Positive Environmental Impacts of PLA

Biodegradable and Recyclable

Firstly, according to the National Center for Biotechnology Information (NCBI), PLA is a bio-based aliphatic polyester that is both biodegradable and recyclable. It is a thermoplastic polymer synthesized from a monomer called lactic acid, which can be derived from renewable resources.

This means that the raw materials for its production can be regrown, reducing the depletion of finite resources.

Carbon Dioxide Absorption

Additionally, the process of growing these plants absorbs carbon dioxide from the atmosphere, which can help to offset the greenhouse gas emissions from PLA production.

Biodegradability

PLA breaks down into water and carbon dioxide under industrial composting conditions. This is a significant advantage over many traditional plastics, which can persist in the environment for hundreds of years.

However, it’s important to note that PLA requires specific conditions to biodegrade effectively – namely, a high-temperature industrial composting facility.

In a landfill or a backyard compost pile, PLA will not decompose significantly faster than conventional plastics.

Energy Efficiency

The production of PLA also uses less energy and results in fewer greenhouse gas emissions compared to many other plastics.

According to the National Center for Biotechnology Information (NCBI), the production of PLA utilizes fewer fossil resources and results in lower carbon dioxide emissions compared to petrochemical-based products.

Negative Environmental Impacts of PLA

However, the production of PLA can also have negative environmental impacts. The cultivation of crops for PLA production can lead to deforestation, loss of biodiversity, and the use of pesticides and fertilizers that can pollute waterways.

Additionally, the conversion of these crops into PLA requires significant energy and can result in the emission of pollutants.

In terms of disposal, while PLA is technically recyclable, it cannot be processed in the same streams as most other plastics due to its different melting point and degradation process. This can cause issues in recycling facilities and lead to PLA being sent to landfill instead.

How Does PLA Compare to Other Plastics?

Polylactic Acid (PLA) is often compared to other plastics due to its unique properties and bio-based origins.

Here, we will delve into a detailed comparison of PLA with other commonly used plastics, focusing on their properties, applications, and environmental impacts.

Physical and Chemical Properties

PLA is a thermoplastic aliphatic polyester, which means it can be melted and reshaped without significant degradation. It has a relatively low melting point, which is lower than many other plastics such as Polyethylene Terephthalate (PET) and Polypropylene (PP).

This makes PLA easier to work within certain applications, such as 3D printing, but less suitable for high-temperature applications.

Mechanical Properties

According to the article “Poly(lactic acid) and polyhydroxyalkanoates (PHAs), green alternatives to petroleum-based plastics: a review,” PLA has good mechanical properties, comparable to some traditional plastics like PET (polyethylene terephthalate).

It offers high tensile strength and modulus but is relatively brittle, with low impact resistance and elongation at break. These properties can be modified through blending and copolymerization.

Use Cases

When it comes to applications, PLA is used in a wide range of products, from packaging to textiles to medical devices.

However, its use is not as widespread as other plastics due to its higher cost and certain limitations in properties.

For example, PET is more commonly used in beverage bottles due to its superior barrier properties, and PP is preferred for automotive parts due to its higher impact resistance and heat resistance.

Environmental Impact

The environmental impact of PLA is one of its key advantages over other plastics.

As a bio-based and biodegradable plastic, PLA has a lower carbon footprint and is less harmful to the environment when disposed of correctly.

However, it should be noted that PLA requires specific conditions to biodegrade, and it does not biodegrade as quickly as some other biodegradable plastics, such as Polyhydroxyalkanoates (PHA).

“Poly(lactic acid) (PLA) is considered the most promising biobased substitute for fossil-derived polymers due to its compostability, biocompatibility, renewability, and good thermomechanical properties.” ~ NCBI

Case Studies of Brands Embracing PLA

TotalEnergies Corbion

TotalEnergies Corbion is a global leader in the production and marketing of PLA. Their Luminy® PLA portfolio includes high heat and standard PLA grades, used in diverse markets such as fresh food packaging, consumer goods, fibers, food service ware, and 3D printing.

TotalEnergies Corbion PLA builds 75kTpa PLA plant in Thailand

In a notable case study, TotalEnergies Corbion demonstrated the efficient compostability of their PLA products in an industrial composting plant in the Netherlands, where PLA teabags degraded fully within 22 days. This initiative highlights the company’s commitment to promoting circular economy practices and reducing plastic waste.

NatureWorks

NatureWorks stands out in the PLA market with its renowned Ingeo™ brand, offering a wide variety of PLA biopolymers designed for numerous applications, including packaging, 3D printing, and textiles. Their commitment to sustainability is evident not only in their product innovation but also in their operational practices.

The Making of BioHome3D – The World’s First 100% Biobased 3D Printed Home

NatureWorks works closely with farmers to promote sustainable agricultural methods for their feedstock, significantly reducing their environmental impact.

What Are the Alternatives to PLA?

In the quest for sustainable alternatives to petroleum-based plastics, several materials have emerged as potential competitors to Polylactic Acid (PLA). These alternatives, like PLA, are often derived from renewable resources and offer varying degrees of biodegradability.

Here, we will explore three of the most prominent alternatives: Polyhydroxyalkanoates (PHAs), Starch-based plastics, and Polybutylene Succinate (PBS).

Polyhydroxyalkanoates (PHAs)

They are a family of biodegradable polymers produced by bacterial fermentation of sugar or lipids. They are fully biodegradable in both aerobic and anaerobic conditions, making them a more environmentally friendly option than PLA, which requires industrial composting facilities for efficient breakdown.

However, PHAs have a higher production cost and lower thermal stability compared to PLA, which can limit their applications.

Starch-Based Plastics

These are another alternative, made by blending starch with other biodegradable polymers. These plastics are fully biodegradable and compostable, and they can be produced at a lower cost than PLA.

However, they have inferior mechanical and barrier properties compared to PLA, making them less suitable for applications such as packaging.

Polybutylene Succinate (PBS)

This is a type of biodegradable polyester that can be produced from succinic acid and 1,4-butanediol, both of which can be derived from renewable resources.

PBS has excellent mechanical properties and a high melting point, making it suitable for a wide range of applications. However, its biodegradation rate is slower than that of PLA, and its production cost is currently higher.

While PLA has its advantages, there are several alternatives available that offer different balances of cost, performance, and environmental impact. The choice between these materials depends on the specific requirements of each application.

How Can PLA Be Recycled?

Polylactic Acid (PLA) is a unique plastic in the sense that it is derived from renewable resources and is compostable under industrial conditions.

However, its recycling process is different from conventional plastics due to its unique properties and origin.

The recycling of PLA primarily involves two methods: mechanical recycling and chemical recycling.

Mechanical Recycling

Mechanical recycling of PLA involves the physical process of grinding, melting, and reprocessing the plastic without altering its chemical structure. This method is commonly used for other types of plastics, but it presents challenges for PLA due to its sensitivity to heat and moisture.

The steps involved in the mechanical recycling of PLA are:

Step 1: Collection and Sorting

PLA products are collected and sorted based on their color, type, and contamination level.

Step 2: Cleaning

The sorted PLA is cleaned to remove any dirt, food residues, or other contaminants.

Step 3: Shredding

The clean PLA is then shredded into small flakes.

Step 4: Extrusion

The flakes are melted and extruded into pellets, which can be used to manufacture new PLA products.

Chemical Recycling

Chemical recycling, on the other hand, involves breaking down the PLA into its constituent monomers, which can then be purified and used to produce new PLA.

This method is more complex and energy-intensive than mechanical recycling, but it allows for the recycling of contaminated or degraded PLA that cannot be mechanically recycled.

The steps involved in chemical recycling of PLA are:

Step 1: Hydrolysis

The PLA is broken down into its constituent monomers, lactic acid and lactide, through a process called hydrolysis.

Step 2: Purification

The resulting monomers are purified to remove any contaminants.

Step 3: Polymerization

The purified monomers are then polymerized to produce new PLA.

Despite these methods, the recycling of PLA is not yet widespread due to the lack of infrastructure and the cost associated with the process.

Moreover, PLA can contaminate the recycling stream of other plastics if not properly sorted, which poses another challenge for its recycling. Therefore, while PLA is technically recyclable, practical recycling of PLA on a large scale is still a work in progress.

Is PLA Safe for Food Packaging?

PLA is generally recognized as safe for food contact applications by the U.S. Food and Drug Administration (FDA). This means that it has been evaluated for potential harmful effects when in contact with food and has been found to be safe under the conditions of its intended use.

One of the primary concerns with any material used for food packaging is the potential for chemical migration from the packaging material into the food.

Below are various reasons which makes PLA safe for food packaging.

Low Migration Rate

Studies have shown that PLA has a low migration rate, which means that very few, if any, substances are transferred from the PLA packaging to the food. This is particularly true under normal storage conditions. However, under certain conditions, such as high temperatures, the rate of migration may increase.

Stability and Degradation

Another factor to consider is the potential for PLA to degrade or break down over time. PLA is known to degrade under industrial composting conditions, but under normal storage conditions, it is quite stable. This means that it is unlikely to break down and release potentially harmful substances into the food during the typical shelf life of a food product.

Allergenicity and Microbial Resistance

In terms of allergenicity, PLA does not contain any known allergens. It is also resistant to microbial growth, which can help to maintain the safety and quality of the food.

Advantages Over Other Plastics

In comparison to other plastics used in food packaging, PLA offers several advantages. It does not contain potentially harmful substances such as phthalates or bisphenol A (BPA), which have been associated with health risks.

How Does PLA Affect Human Health?

One of the main concerns with PLA and human health is the potential for chemical migration from PLA-based materials into food or drink. This is particularly relevant for PLA used in food packaging or beverage containers.

Another aspect to consider is the potential for allergic reactions. Some people may have an allergic reaction to PLA, although this is rare. Symptoms can include skin irritation, respiratory problems, and in severe cases, anaphylaxis.

However, these reactions are typically associated with direct skin contact or inhalation of PLA particles, rather than ingestion.

In the medical field, PLA is often favored for its biocompatibility – the ability to perform with an appropriate host response in a specific application.

However, as with any medical device, the safety of PLA-based devices depends on the specific application, the duration of exposure, and individual patient factors.

In terms of environmental exposure, the potential health effects of long-term exposure to high concentrations of lactic acid in the environment are not well understood and warrant further research.

What Is the Cost of PLA Compared to Other Plastics?

Polylactic Acid (PLA) is often compared to petroleum-based plastics in terms of cost. The cost of PLA can be influenced by several factors, including the cost of raw materials, the production process, and market demand.

Raw Material Costs

The cost of PLA raw materials can fluctuate based on agricultural conditions and market demand.

In contrast, petroleum-based plastics are derived from non-renewable fossil fuels, the prices of which can be volatile due to geopolitical factors and extraction costs.

Production Costs

The production process for PLA involves fermenting plant sugars to produce lactic acid, which is then polymerized to create PLA. This process can be more complex and costly than the production of traditional plastics, which involves the polymerization of petroleum derivatives. 

However, advancements in technology and increases in production scale are helping to reduce the production costs of PLA.

Market Demand

The demand for PLA is growing due to increasing awareness of environmental issues and the need for sustainable alternatives to traditional plastics. This growing demand can drive up the price of PLA.

However, as production capacity increases and more competitors enter the market, the price of PLA is expected to decrease.

What is the Future of PLA in the Plastic Industry?

The future of Polylactic Acid (PLA) in the plastic industry is promising, with several trends and potential developments shaping its trajectory.

Increasing Demand for Sustainable Materials

The increasing demand for sustainable and eco-friendly materials is driving the growth of PLA in the market.

As consumers become more environmentally conscious, the demand for biodegradable and bio-based plastics like PLA is expected to rise. This trend is further bolstered by regulatory pressures, with governments around the world implementing policies to reduce the use of non-biodegradable plastics.

Technological Advancements

Advancements in technology and research are expected to enhance the properties and applications of PLA.

For instance, scientists are exploring ways to improve the heat resistance of PLA, which is one of its main limitations. If successful, this could expand the use of PLA into areas currently dominated by traditional plastics, such as automotive and electronics.

Cost-Effective Production Methods

The development of more efficient and cost-effective production methods could make PLA more competitive. Currently, the production cost of PLA is higher than that of petroleum-based plastics, which is a significant barrier to its widespread adoption.

However, research is underway to optimize the production process and reduce costs, which could make PLA a more viable option for many industries.

Recycling Infrastructure Expansion

The expansion of PLA recycling infrastructure is a crucial factor for the future of PLA. While PLA is biodegradable under industrial composting conditions, it does not readily decompose in a landfill or in the ocean.

Therefore, the development of effective recycling systems for PLA is essential to fully realize its environmental benefits.

Future Developments

Genetically Modified Organisms (GMOs)

One potential area of interest is the use of genetically modified organisms (GMOs) to produce lactic acid, the raw material for PLA. This could potentially lower costs and increase the efficiency of PLA production.

PLA Blends and Composites

Another research focus is developing PLA blends and composites to enhance properties and expand applications. These advancements could make PLA more versatile in various industries.

Challenges and Opportunities

The future of PLA in the plastic industry is promising, with numerous opportunities for growth and innovation. However, challenges remain, particularly regarding cost, performance, and recycling. With continued research and development, PLA has the potential to play a significant role in transitioning towards a more sustainable plastic industry.

Adopt PLA for a Sustainable Future

By embracing Polylactic Acid (PLA), we can drive sustainability and innovation across various industries. PLA helps reduce our reliance on fossil fuels and minimizes environmental impact. Understanding its production process, properties, and applications enables us to make better choices in utilizing this eco-friendly plastic.

While PLA has its challenges, such as cost and recycling complexities, its potential to transform the plastic industry is undeniable. As technology advances and demand for sustainable materials grows, PLA stands out as a promising solution for a greener future.