Everything You Need To Know About Polylactic Acid (PLA)

Where does PLA come from, and what does it do?

Unlike other thermoplastic polymers, polylactic acid (PLA) may be produced from renewable resources such as corn starch or sugar cane. On the other hand, most plastics come from the polymerization and distillation of finite petroleum resources. Biodegradable plastics (such as polylactic acid, or PLA) are often referred to as “bioplastics.”

Polylactic acids, like polypropylene, polyethene, and polystyrene, is biodegradable and has some of its properties. To make it, you need to adapt machinery already built for the plastics used in the petrochemical industry. As a result, it can be mass-produced at a low cost. Thermoplastic starch is the most widely recognized bioplastic, whereas PLA is the second most produced.

Polylactic acid can be used for a wide variety of purposes. Plastic films, bottles, and biodegradable medical equipment (such as screws, pins, rods, and plates) are some of the most popular applications. Read this article for additional information about the prototypes of biodegradable and nonbiodegradable medical devices. Because of its shrinking properties when heated, PLA can be used as a type of shrink wrap. Moreover, since polylactic acid melts so easily, it can be used in some intriguing 3D printing applications (including “lost PLA casting”; see below for more). However, many products made from PLA (such as plastic cups) cannot contain hot liquid due to their low glass transition temperature.

How does polylactic acid work, and why is it used so frequently?

Racemic PLLA (Poly-L-lactic acid), regular PLLA (Poly-L-lactic acid), PDLA (Poly-D-lactic acid), and PDLLA (Poly-D, L-lactic acid) are all kinds of polylactic acid. Traditional plastics are made from nonrenewable petroleum, but the bioplastics discussed here are created from lactic acid (C3H6O3), a renewable resource.

Making plastics from PLA is a hot topic because it offers the possibility of producing low-cost, petroleum-free plastics. PLA’s adaptability and the fact that it biodegrades in the presence of environmental conditions are two of the bioplastic’s greatest advantages. In the ocean, a PLA bottle, for instance, would break down in around six to twenty-four months. Considering that traditional polymers can take hundreds to thousands of years to decompose in the same conditions, this is quite remarkable. Therefore, PLA has great promise as a helpful material for short-term uses where biodegradability is particularly advantageous (for example, as a plastic water bottle or as a container for fruit and vegetables). Although PLA can deteriorate when left exposed to the weather for extended periods of time, it is remarkably durable when used as intended (for example, in a plastic electronic component).

Prototype Development with PLA on CNC and 3D Printers: Choosing the Right Plastic

The other major plastic utilized on FDM machines (also known as 3D printing) and readily available as 3D printable filament is ABS. The PLA filament used in 3D printing comes in a rainbow of hues. CNC machining is possible with polylactic acid; however, the material is rarely found in sheet stock or rod form. However, it is commonly sold as plastic pellets for injection moulding or as a thin film for thermoforming. Plastic injection mould pellets are commonly manufactured and/or mixed to modify material qualities.

Lost PLA casting is one of the coolest things you can do with a 3D printer and PLA. In this method, a plaster-like material is cast over a printed PLA mould of a hollow space. Since PLA has a lower melting point than the surrounding material, it is eventually burned away. When finished, the space created can be filled (often with molten metal).

Where does PLA come from?

The main routes to producing polylactic acid are condensation and polymerization. Ring-opening polymerization is by far the most frequent method of polymerization. Metal catalysts and lactide are used in this method to produce the bigger PLA molecules. Similar to evaporation, condensation differs mostly in the temperature at which it occurs and the nature of the byproducts (condensates) it produces.

What are some of the polylactic acid’s distinguishing features?

Now that we know its primary function, let’s take a closer look at polylactic acid’s most notable characteristics. As opposed to “thermoset” polyesters, which are resistant to heat, PLA is categorized as “thermoplastic” due to its heat resistance. At their melting point, thermoplastic polymers (PLA’s are between 150 and 160 degrees Celsius) become liquids. The ability of thermoplastics to be heated to their melting point, chilled, and then reheated without significant degradation is one of their most useful properties. Thermoplastics like polylactic acid liquefy instead of burning, making injection moulding and recycling a breeze. In contrast, once heated (during the injection moulding process in most cases), thermoset plastics cannot be reshaped. Thermoset materials undergo irreversible chemical changes at the first heating, causing them to set (much like a 2-part epoxy). Repeatedly subjecting a thermoset plastic to high heat would cause it to melt and then burn. Because of this quality, thermosets aren’t great candidates for reuse or recycling.

Will PLA kill you?

Not in its solid form. Polylactic acid (PLA) actually breaks down in natural environments. Biodegradable medical implants and packaging are common applications. In the same way that most plastics can be harmful if inhaled or absorbed via the skin or eyes as a vapour or liquid (during production), this one can be too. Take caution and follow all safety precautions when working with molten polymer.  

Ultrafine particle (UFP) emissions from commercially accessible 3D printers using ABS and PLA feedstock were recently the subject of a report by researchers at the Illinois Institute of Technology. The findings are detailed in this article.

In what ways does polylactic acid fall short?

The glass transition for PLA occurs at a moderate temperature (usually 111–145 °F). Because of this, it is not ideal for use in environments with high temperatures. A heated car in the summer may soften and distort even the most sturdy of parts.

While polylactic acid is slightly more brittle than ABS for 3D prototyping, it does have its benefits.

Video 01: What is PLA Plastic? | What are the Pros and Cons of this “Green” Plastic