From Plant to Product: The Eco-Friendly Production Journey of Polylactic Acid (PLA) and Uses

Plastic. It is in everything we use starting from the food they pack in to the clothes we wear and even the items we use at home. However, with the increasing awareness of the problem of plastic and its negative effects on the environment, many people are looking for eco-friendly options. Enter Polylactic Acid or PLA!

PLA is a type of bioplastic that is produced from renewable sources such as corn starch, sugarcane or beet pulp. In contrast to the conventional plastics which are made from crude oil, PLA is an environmentally friendly product that can gradually replace those materials that are produced from non-renewable resources.

Intrigued? In this blog, we will share more details about PLA including the process of manufacturing this material, its characteristics and possible uses. We will also talk about its advantages of this type of plastic to make your eco-friendly choice easier!

Introduction

Polylactic acid , or polylactide, is a biodegradable and bioactive polyester composed of lactic acid units. Currently, it stands out as one of the most promising biodegradable polymers (biopolymers). This thermoplastic aliphatic polymer boasts good mechanical properties, a semi-crystalline structure, and a biodegradable hydrophobic nature. Polylactic acid is fully compostable, breaking down into biodegradable components under specific conditions, making it a favored material in the packaging industry, particularly for food, beverages, and consumer goods. Unlike traditional plastics derived from petroleum, bioplastics like polylactic acid are produced from renewable organic biomass resources such as corn, sugarcane, and other plants.

Some of the amazing advantages of PLA are:

1. Biocompatibility: PLA is safe for human use, being non-toxic and suitable for prolonged skin contact without adverse effects. It degrades into harmless lactic acid, making it ideal for medical applications like stents and sutures that naturally break down in the body over time.
2. Low Energy Production: Producing PLA requires less energy compared to petroleum-based plastics due to its lower melting point of 165 °C. Additionally, PLA polymerization consumes 25 to 55% less energy than the production of traditional petroleum-based polymers.
3. Mechanical Properties: PLA exhibits good strength and stiffness at room temperature, though it is not suitable for applications involving sudden impacts.
4. Food Safety: PLA is non-toxic and has been recognized as safe by the FDA for use in food-related applications.
5. Compostability: PLA is entirely compostable; however, it requires specific temperature and pressure conditions available only at certain composting facilities to break down effectively.

Manufacturing Process

PLA, a polyester variant, is derived from fermented plant starches sourced from crops like corn, cassava, maize, sugarcane, or sugar beet pulp. Through fermentation, the sugars present in these renewable sources are transformed into lactic acid, which serves as the precursor for polylactic acid (PLA).

The manufacturing process of PLA from corn (depicted in Figure) comprises three primary stages: (1) Hydrolysis of starch; (2) Fermentation of glucose; and (3) Polymerization of lactic acid.

Step 1: ?Starch Hydrolysis

Shelled corn kernels undergo a series of processing steps starting with grain cleaning, followed by soaking in a dilute sulfur dioxide solution within steeping vessels, which is generated using a sulfur burner. The resulting slurry of solid material undergoes various unit operations to extract cornstarch, while the steep water is concentrated into evaporators, forming corn steep liquor (CSL) for subsequent processing stages. The extracted starch is combined with enzymes and sodium carbonate in the hydrolysis section to convert it into glucose, which is then directed to the fermentation stage.

Step 2: Glucose Fermentation

Fermentation occurs within a stirred, jacketed fermenter, where glucose, Corn Steep Liquor (CSL), and sodium carbonate are introduced. The resulting fermentation broth undergoes ultrafiltration to eliminate cell debris, followed by concentration in an evaporator. Subsequently, the broth proceeds to an extraction column to extract lactic acid (LA) into an organic phase, which is then directed to a distillation column to separate the extractant solvent from the LA. The LA-rich stream undergoes back-extraction with hot water in an extractor train, yielding a LA-lean organic phase recycled to the initial extraction stage and an aqueous phase abundant in LA. This aqueous phase is concentrated in an evaporator before proceeding to the polymerization phase.

Step 3: Lactic acid polymerization

• Following concentration, the lactic acid stream is channeled into a prepolymer reactor, where it engages in a reaction process to yield low-molecular-weight polylactic acid (PLA) alongside water, which is subsequently separated and discarded from the system. The produced low-molecular-weight PLA is then directed towards a depolymerizer unit, where it undergoes a breakdown process into lactide molecules. Lactide, being the cyclic lactone di-ester derived from lactic acid, is subjected to purification in both a drying column and a meso-lactide removal column, ensuring the removal of impurities and enhancing the quality of the final product.

• The purified lactide molecules are then fed into a polymerization reactor, where they undergo a polymerization process to form PLA. This newly synthesized PLA is then subjected to a devolatilizer unit, where any unreacted lactide is removed from the PLA stream. Following this purification step, the PLA undergoes extrusion to attain the desired form and is subsequently packed into bags for storage. This comprehensive process ensures the production of high-quality PLA, suitable for a wide range of applications across industries, while also adhering to stringent quality standards and environmental considerations.

Key Applications of Polylactic Acid (PLA)

PLA: The eco-friendly plastic superstar! This stuff is easy to work and gets major points for being awesome in 3D printers thanks to its low melting temperature.? You'll find PLA in everything from medical implants that dissolve on their own to food containers and disposable cutlery. Talk about a material that's good for you and good for the environment!

• Food & Beverage Packaging

PLA is approved by the Food and Drug Administration (FDA) for use as a food contact material, ensuring its safety in direct contact with food. This versatile polymer is commonly used in a variety of packaging applications, including containers, drinking cups, sundae and salad cups, overwraps, and blister packages. Its biodegradable nature makes it an eco-friendly choice for these uses. Additionally, PLA is particularly effective for packaging short-shelf-life products such as fruits and vegetables, where its properties help maintain freshness while also offering a sustainable alternative to traditional plastics, aligning with growing consumer demand for environmentally responsible packaging solutions.

• Medical & Healthcare

The biocompatibility and biodegradability of PLA make it suitable for the healthcare and medical industry. It is used to produce tissue engineering scaffolds, delivery system materials, covering membranes, and various bioabsorbable medical implants. PLA's versatility extends to membrane applications like wound covers, implants and medical devices such as fixation rods, plates, pins, screws, and sutures, as well as dermatological treatments including facial lipoatrophy and scar rejuvenation.

• Textiles

PLA is also well-suited for textile fiber applications, such as shirts, carpets, bedding, mattresses, and sportswear, owing to its advantageous properties. It has low moisture absorption, which helps maintain the integrity and comfort of fabrics. Its low smoke generation capability enhances safety, particularly in household and industrial settings. Additionally, PLA exhibits good resistance to UV light, ensuring durability and longevity of textile products. Beyond textiles, PLA is versatile enough for use in mulch films, compostable garden waste bags, structural protective foams, and insulation materials, offering sustainable solutions across various industries. This broad applicability makes PLA a valuable material in promoting environmental sustainability.

• Electronics & Automotives

Biobased PLA and its composites are emerging in automotive, electrical, and electronics applications due to their enhanced tensile strength and impact characteristics. These properties make PLA composites ideal for interior automobile parts and safety helmets. The improved material properties allow PLA to be used in floor mats, pillar covers, door trim, front panels, and ceiling materials. Additionally, PLA bio composites are being considered for covering spare wheels and creating translucent roofs in hybrid concept vehicles.

Polylactic Acid (PLA) Market Dynamics

The packaging industry's growing demand for Polylactic Acid (PLA) serves as a significant driver of market expansion in developing nations. Governments worldwide are incentivizing the adoption of biodegradable products through subsidies, driven by concerns over pollution control and environmental safety. This shift towards bioplastics over petroleum-based alternatives reflects a broader trend among stakeholders. Moreover, technological advancements coupled with rising consumer demand in emerging markets, are spurring the establishment of new manufacturing facilities across sectors such as packaging, textiles, and electronics are likely to push the PLA market expansion in the forthcoming years. These factors collectively contribute to the escalating demand for PLA and its integration into various industries.

Polylactic Acid (PLA) Major Market Players

Major players in the Global Polylactic Acid (PLA) market are NatureWorks, BASF SE, Zhejiang Hisun Biomaterials Co, Futerro (GALACTIC) & BBCA, Jilin Cofco Biomaterials, Hengtian, Synbra Technology BV, and Others.

Conclusion:

In conclusion, PLA can be regarded as the key material in the transition towards the use of environmentally friendly materials as it is suitable in numerous industries. Its biodegradable characteristic which is obtained from renewable resources makes it a better solution to the problems that are associated with the use of conventional plastics. PLA’s good mechanical characteristics and general applicability have led to it being the most sought-after bioplastic material amongst manufacturers who are in search of biodegradable products that do not lack in quality. As the world becomes more conscious of pollution and climate change, PLA’s position as an advocate for the circular economy and waste reduction has been brought to the forefront. It is backed by government policies which help in its market growth especially in the developing countries where concern of environment is very crucial. Future work on PLA technology is expected to open up further practical applications of the material as researchers continue to refine the polymer. PLA and other forms of bioplastics are expected to gain more demand from the consumers as they seek to buy environmentally friendly products and as the regulatory authorities put pressure on industries to reduce their waste output. Lastly, the transformation of PLA exemplifies a major shift toward a world that is more sustainable, where the products we use are not only useful but also have a positive impact on the environment and creating a better world for everyone.