Polylactic Acid, commonly known as PLA, has become a familiar material in many everyday items, from 3D printer filaments to various packaging solutions. As its presence grows, a common question arises: Is PLA truly a polymer? This article explores what defines a polymer and clarifies how PLA aligns with this definition, shedding light on its characteristics and widespread applications.
What Defines a Polymer
A polymer is a substance made up of very large molecules, called macromolecules, which are formed by the repeated linking of smaller, simpler chemical units known as monomers. Think of a polymer like a long chain, where each link represents a monomer. These individual monomer units connect through a process called polymerization, forming extended chains or networks.
Polymers exist in both natural and synthetic forms. Examples of natural polymers include DNA, which carries genetic information, and proteins, which perform many functions in living organisms. Cellulose, found in plant cell walls, is another natural polymer. Synthetic polymers, created by humans, are equally diverse and include materials like polyethylene, used in plastic bags, and polyvinyl chloride (PVC), commonly found in pipes.
How PLA Fits the Definition
Polylactic Acid, or PLA, is indeed a polymer. Its name itself offers a clue, as “poly” indicates “many.” The building block, or monomer, for PLA is lactic acid. Lactic acid molecules link together repeatedly to form long chains, a defining characteristic of a polymer.
The production of PLA involves fermenting plant starches, such as corn or sugarcane, to yield lactic acid. These lactic acid units then undergo polymerization. This chemical process creates the extended molecular chains that classify PLA as a polyester. This structure aligns with the definition of a polymer, composed of many repeating lactic acid units.
Properties and Uses of PLA
The polymeric nature of PLA gives it several useful properties, including thermoplasticity, meaning it can be melted and reshaped. This characteristic makes it suitable for various manufacturing techniques like injection molding, extrusion, and 3D printing. PLA also exhibits rigidity and can be transparent.
Due to these properties, PLA finds use in numerous applications. It is a popular material for 3D printing filaments. In packaging, PLA is used for items like food containers, disposable cutlery, and films. Its biocompatibility and ability to break down into non-toxic lactic acid also make it suitable for medical applications, such as temporary implants and sutures. PLA’s structure allows it to biodegrade under specific industrial composting conditions, distinguishing it from many petroleum-based plastics.