Nylon 6 or 66

[Drascomber]

A post in a thread about skin fittings reminded me that I have a question about nylon above deck and in other exposed places like trailer rollers.

I read that Nylon 6 absorbs up to 2% water whilst Nylon 66 doesn't have a water absorbtion issue.

The first question is - Is this correct?
The second question (bearing in mind that Nylon 6 is cheaper than 66) is - In freezing conditions will nylon 6 therefore be liable to spalling?

 

[Salty John]

Nylon 6 and 66 have very similar water absorption characteristics. Nylon 6 increases weight by 2.8% and Nylon 66 by 2.6% at the same temperature and relative humidity - 23C and 50%RH.
Neither product will be subject to spalling at low temperatures.

 

[Evadne]

We use Delrin at work if nylon is to be used underwater, but it still absorbs some water.

 

[whiteoaks7]

You need nylon 11 or 12 for low water absorption. The water that is absorbed causes swelling btw.

 

[Drascomber]

Looks like I can get away with Nylon 6 as I don't believe I need to worry about the water absorbtion unless when the water freezes it causes the nylon to break up.

Thanks John. That'll save me a fair few quid.

 

[Graham_Wright]

To find out if a plastic absorbs water, soak it for a while, then micowave it (with something else to avoid blowing up the microwave).

If it gets hot, it has absorbed water.

HDPE or acetal?