What is Polylactic Acid?
Polylactic acid, commonly referred to as PLA, is a thermoplastic aliphatic polyester derived from renewable plant sources such as corn starch, cassava roots, sugarcane, or sugar beets. The raw materials are gathered from these crop byproducts and undergo fermentation and polymerization processes to produce PLA in pellet or filament form.
How is PLA Made?
To manufacture PLA, the harvested plant matter like corn is refined to extract its starch content. This starch is then broken down into simple sugars like glucose through a process called hydrolysis. Through fermentation, the sugars are converted to lactic acid by microorganisms like bacteria. The lactic acid molecules are then linked together through a process called ring-opening polymerization into long chains, forming the poly-lactic acid polymer. Additional processes may be applied to produce Polylactic Acid in various grades optimized for different applications.
Biodegradability and Sustainability
One of the major advantages of PLA is that it is biodegradable. In commercial composting facilities, PLA will degrade within 3 to 6 months as the polymer chains break down when exposed to microorganisms. It can also degrade in natural environments like soil and marine water within a similar timeframe. Since PLA is produced from renewable plant resources rather than petroleum, its production has a lower carbon footprint than traditional plastics. Cultivating crops for PLA production also sequesters carbon from the atmosphere. Overall, PLA offers a more sustainable alternative to oil-based plastics.
Applications of Polylactic Acid
Thanks to its biodegradability and renewable sourcing, PLA has a variety applications across several industries:
- Packaging: PLA is used extensively in food packaging like disposable plates and cups, as well as bags and wrap. Its barrier properties make it suitable for perishable items while also being compostable.
- 3D Printing Filament: PLA is one of the most popular polymers used for 3D printing as it produces strong yet flexible prints. spool. It has high compatibility with desktop FDM printers.
- Textiles: PLA fiber offers a sustainable alternative to conventional textile fibers in clothing, upholstery and more. Garments made of PLA fabrics can biodegrade at the end of their use cycle.
- Medical Devices: As a biocompatible material, PLA is used in resorbable medical implants, sutures and other single-use equipment. It safely dissolves in the body after its role is served.
- Consumer Goods: Items like cups, cutlery, straws and more are now being produced from PLA to reduce waste. Major brands are switching to PLA to meet sustainability goals.
Properties and Processing of Polylactic Acid
PLA has properties suitable for the applications noted above due to its balance of strength, flexibility and processing viability. Some key properties of PLA include:
- Tensile Strength: With a tensile strength of 57-59 MPa, PLA is as strong as popular petroleum-based polymers like HDPE.
- Stiffness: PLA has a modulus of elasticity of 3.5 GPa, making it quite a rigid material suitable for molded items, 3D prints etc.
- Thermal Properties: PLA softens at temperatures upwards of 160°C and has a melting point around 145-180°C depending on composition.
- Optical Properties: Being partially crystalline, PLA has clarity properties useful for light packaging. It may become opaque upon processing depending on method.
- Processing: PLA can be easily extruded, molded, thermoformed and 3D printed using common polymer fabrication techniques.
- Biodegradability: In commercial composting, PLA breaks down within 6 months without toxic residues.
Drawbacks of Polylactic Acid
While PLA presents an eco-friendly alternative, it also has limitations such as:
- Higher Cost: Production costs of PLA are currently higher than petroleum-based plastics due to agricultural feedstock and multi-step synthesis.
- Sensitivity to Heat: PLA has a relatively low glass transition temperature and begins deforming above 60°C. It requires careful processing and use.
- Lower Impact Strength: PLA is more brittle than common plastics and more prone to breaking on impact at room temperature.
- Slow Degradation: While biodegradable, degradation of PLA may be slow under some environmental conditions in soil or oceans.
- Limited Resource Availability: Production is currently limited by availability of non-GMO corn and sugar sources for fermentation.
Overcoming Constraints and the Future of Polylactic Acid
Research is ongoing to enhance the properties and production viability of PLA. Methods include developing novel microbial strains for more efficient lactic acid synthesis, modifying PLA composition to enhance toughness and heat resistance, and exploring new feedstocks beyond corn. With advancements, PLA promises to become a higher performance and lower cost bioplastic alternative that can effectively compete with oil-based plastics in coming years while being more sustainable. Wider adoption depends on continued scale-up of infrastructure for supporting a bio-economy. Overall, PLA shows exciting potential as a renewable and earth-friendly plastic.
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About Author:
Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc. (https://www.linkedin.com/in/money-singh-590844163)