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MaterialMatters Series N°1: PLA Plastic

Material Matters is a new series of articles that will come regularly on MakingSociety featuring… materials.  From prototyping to final product, manufacturing machines to packaging boxes, knowing materials and what you can do with them is a high priority! And it’s a fun one too.

corn-plastic

Cup made of PLA. Picture credit: Dan Klimke

I decided to start this series with PLA, the favorite 3D printing material. PLA is used in many many applications, not only in 3D printing. In this article, you will learn about what it is, which uses it’s best suited for and where to buy it.

PLA, or “the future of plastic in a post-petroleum world” as called by Smithsonian Magazine

What is PLA used for?

PLA is a resin known as a polylactic acid. It’s a thermoplastic derived from renewable resources. Depending on where it’s from, PLA can come from different plants: corn stach in the US, tapioca roots, chips or starch in Asia and sugarcane in the rest of the world. Products made of PLA are almost everywhere around you.

Food Packaging and Containers

As of today, food packaging and containers are the primary use of PLA plastic. It is food safe and recyclable. This salad bowl is made of clear PLA and is fully compostable:

3D printing

PLA is massively used by users of personal 3D printers using deposition modelling technique. PLA melts at a temperature of about 180°C and cools down faster than ABS, which means that no heated bed is needed. Because of its property (it heats up and cools down fast), PLA can be a bit more difficult to use at first than ABS. But it smells much better.

Casing for electronics

Even if it’s still really rare to find electronics casings made of PLA, a few products have been launched on the market, mostly for communication purpose (“look how green we are!”). Examples below were experiments from big brands such as Samsung, Fujitsu or Sony. They used PLA as a marketing tool, surfing on the “green tech” trend.

Clothing Fiber

Other kind of products made with PLA can involve: pillow stuffing, wrap for flowers, gift cards and … bone engineering

How is PLA made ?

There are 4 main ways for producing PLA:

  1. metal-catalyze
  2. direct condensation
  3. racemic mixture of L- and D-lactides (produces PDLLA, that stands for Poly-L-lactide)
  4. direct biosynthesis

The main manufacturers of PLA are:

  • NatureWorks in the United States (biggest lactic-acid plant in Blair, Nebraska)
  • PURAC biomaterials in the Netherlands
  • Sulzer
  • Synbra

PLA comes in many shapes:

Pellets

PLA Pellets

PLA resin pellets on Inventables. Credit: Inventables

Fiber

Corn-Fiber

PLA fiber

Filament

PLA-filament

PLA filament

Main characteristics of PLA

Appearance

PLA comes transparent but can be coloured. It can be translucent or opaque depending on the degree wanted. Objects made in PLA have usually a glossy look.

Resistance and Solidity

PLA is more sensitive to environment than other types of plastic such as ABS. If put in the water for too long, your PLA product can slightly loose its colours. Because it melts at a low temperature (180°C), it is usually not recommended to use PLA products in a very hot environment. You may have experienced it when your stirrer gets deformed in your hot coffee. PLA is stronger than ABS and also a bit less flexible, which makes it less suitable for designs that clip and assembly. For more details about material properties of PLA, this link might be of great interest.

Post-finishing

PLA can be machined and sanded. 3D printing users are sometimes using acetone for giving a nice smooth finishing look to their parts.

PLA Myths and Truth

Is PLA easily biodegradable ?

The love for PLA comes from the fact that it’s biodegradable. If you look at it quickly, you may think it’s the perfect plastic of the future, made from nature and returning to nature. It’s actually a bit more complicated as PLA cannot be recycled in a home compost trash. It needs an industrial composting facility heated to 60 °C and the addition of digestive microbes to really disappeared.

PLA-tea-bags

Tea bags made of PLA

There is actually only a very limited number of facilities around the world designed for degrading PLA, which means that it takes energy to bring the trashed products there. PLA products also tend to be confused for other types of plastics by the end users, and often end up in the general trash. Composting times can greatly vary, taking from 1 to 6 months in a commercial composting facility.

Is PLA always food-safe?

Many users of home 3D printers think that it’s 3D printed objects in PLA for food-related purpose: cups, eating ustensiles, juicers…. Don’t do it! 3D printed PLA is usually NOT safe. Filament of PLA goes through pieces of your 3D printer that contain lead, and PLA filament rolls sold for 3D printing are usually mixed with other materials. If you want to 3D print food-safe products in PLA, you will have to use pure PLA and a 3D printer made of stainless steel. With the rapid growth of 3D printing, PLA is gaining in popularity. Hobbyists love it for its green and low-cost qualities, professionals love it for its strengh and appearance.

Where to buy PLA ?

So you are thinking about using PLA for prototyping your next product or using it as the final material for your parts? I guess you need know where to find it, and how much it’s going to cost you. Here are a few answers:

PLA Filament Suppliers

PLA Pellets Suppliers

PLA Plastic Film Suppliers

PLA Fiber Suppliers

Bonus Resources:

Reference book about biodegradable plastics: Green Plastics: An Introduction to the New Science of Biodegradable Plastics by E.S. Stevens.

HowStuffWorks article about corn plastic.

Smithsonian Magazine article about corn plastic.

Share your experience with PLA in the comments.

Cheers,

signature2 Home picture credit: Kevin Dooley

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  • Yoonseo Kang

    Great article, keep it up!

    • http://www.makingsociety.com/ MakingSociety

      Thanks so much! Gives me energy!

  • Paco

    This is gold! Thanks for all the resources

    • http://www.makingsociety.com/ MakingSociety

      Thanks a lot for the kind words. Glad to help you!

  • digitaluddite

    PLA is also available in sheet form:
    http://www.mcmaster.com/#1104t714/=r1cjfa
    Although I would love to find out who actually manufactures PLA in sheet form – it laser cuts well.

  • LongJohn

    This is laid out perfectly! Thanks a lot for this, I appreciate it and hope to see more from this series.

  • Tomek Brzezinski

    This is a good article! Those tea bags are usually made of nylon, though, not PLA. You said it yourself, PLA starts melting at 60C, and tea is made around 90C. Nylon has a much higher melting temperature, and can be made food-grade. :)

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