Why Polylactide (PLA) 3D-Printing Plastic Is So Brittle
canopic jug writes:
Hackaday has an overview of why poly(lactic acid) (PLA) is so brittle, yet used all the time in 3D printing.
Over the years poly(lactic acid) (PLA) - also known as polylactide - has become a popular thermoplastic for a variety of reasons. One of these reasons is that it's easily produced from a renewable resource, i.e. lactic acid, with the resulting polymer even being compostable if you assume that your compost pile hits a steady 65C or more, well above the polymer's glass transition temperature (Tg).
That said, PLA by itself is a pretty crummy material, being exceedingly brittle and inferior to common alternatives like PET(G) in many metrics. Over the decades much research has gone into figuring out this material, its amorphous and crystalline states, as well as how to use plasticizers, copolymers, mechanical manipulation and PLLA/PDLA blends to produce more useful variants of PLA.
Today's spools of thermoplastic filament that gets marketed as 'PLA' are the result of such engineering, though with plenty of remaining issues, as anyone who has struggled through a spool of brittle PLA filament can attest to. Although you can find plenty of tips online about how you should 'just' toss said spool into an filament dryer, oven or similar to bake it - with accusing fingers pointed at moisture intrusion, hydrolysis and kin - it helps to understand the fundamentals of how PLA works, and how it degrades.
Previously:
(2026) Investigating 3D-Printed Metals for Aeronautical Engineering
(2025) Bye-Bye Microplastics: New Plastic is Recyclable and Fully Ocean-Degradable
(2022) Innovative 3D-Printing Technology Creates Glass Microstructures With Rays of Light
(2021) Polymer Discovery Gives 3D-Printed Sand Super Strength
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