PLA lifespan? Will it biodegrade on me?

pwave

PLA lifespan? Will it biodegrade on me?
August 01, 2017 02:32AM

Registered: 8 years ago
Posts: 9

Hi, have any of you seen a case of PLA prints starting to degrade over time?
I was wondering what the lifespan on a PLA part keep indoors out of direct sunlight would be?
Googleed it but couldn't find any definitive answers...

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Srek

Re: PLA lifespan? Will it biodegrade on me?
August 01, 2017 04:36AM

Registered: 11 years ago
Posts: 2,470

Decomposition should not be a problem, PLA only biodegrades in industial bio recycling systems, calling it biodegradeable is a bit misleading. It is however prone to heat and UV light. I would not expose it to sunlight for a long time (months/years) and i wouldn't use it in an environment that could go beyond 35C, especially not under mechanical pressure.

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DjDemonD

Re: PLA lifespan? Will it biodegrade on me?
August 01, 2017 04:58AM

Registered: 7 years ago
Posts: 3,525

I've got a PLA, sink plug strainer currently on about 6-7 months in my sink. It was black, its discoloured to a greyish colour but is quite intact.

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

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VDX

Re: PLA lifespan? Will it biodegrade on me?
August 01, 2017 06:15AM

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Registered: 15 years ago
Posts: 13,708

... the physical properties of PLA depends highly on the additives - there are not only colours and pigments, but a bunch of other ingredients to change melting properties, viscosity and more ...

I'll bet, that you won't be able to get a complete list of the additives and changed properties ... but many of them influences the "biodegradability" too eye rolling smiley

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Dust

Re: PLA lifespan? Will it biodegrade on me?
August 01, 2017 07:44AM

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Registered: 12 years ago
Posts: 6,729

I have some purple PLA parts that's about 6.5 years old.

The part has been inside all its life... still fine, but the pigment has faded in normal daylight, to a blue.

The biodegradability of PLA is over marketed, the low melting point is a real consideration.

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newbob

Re: PLA lifespan? Will it biodegrade on me?
August 01, 2017 08:53AM

Registered: 5 years ago
Posts: 270

From wikipedia:

Quote
wikipedia
The melting temperature of PLLA can be increased by 40–50 °C and its heat deflection temperature can be increased from approximately 60 °C to up to 190 °C by physically blending the polymer with PDLA (poly-D-lactide). PDLA and PLLA form a highly regular stereocomplex with increased crystallinity. The temperature stability is maximised when a 1:1 blend is used, but even at lower concentrations of 3–10% of PDLA, there is still a substantial improvement. In the latter case, PDLA acts as a nucleating agent, thereby increasing the crystallization rate. Biodegradation of PDLA is slower than for PLA due to the higher crystallinity of PDLA.

I think all 3d printer PLA contains PDLA which, as per above, slows down biodegradation. Adding PDLA probably necessitates greater amount of plasticizers which is why you should not use PLA for parts in contact with food.

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frankvdh

Re: PLA lifespan? Will it biodegrade on me?
August 01, 2017 07:32PM

Registered: 8 years ago
Posts: 978

I have some PLA garden gnomes I printed. The oldest has been out in the weather (-5C to 35C) and sun (and NZ's UV is reputed to be more intense than anywhere else) for about 2 years. The PLA is Chinese, from a couple of sources (cheapest available at the time winking smiley

), in several different colours.

There's no noticeable deterioration of the plastic, although the colour has faded somewhat.

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