PA versus PP in warm conditions (hot weather) 1

[seppederoeck]

Hi all,

I am in discussion with our factory to change POM material of a part which needs to be quite strong. The POM material is very tough but breaks on impact (when dropped from a certain height). Factory now suggests to change to PP while I would prefer PA for its extra strength. The PP part can be bent slightly which is not the purpose.
Factory reasoning is that the PA part will loose strength in hot conditions compared to PP.

Is it correct to assume that PA in hot conditions will become more weak than PP ?
Will the strength loss be so big that the PA part will be weaker than it's PP counterpart ?

We are not talking about 100°C or extreme conditions, just hot weather conditions.

tx,
Seppe

 

[Pud]

Any reason you can not just use an impact modified POM?

I would also put money on the POM being moulded with a too low a tool temperature to achieve max properties. (e.g 80 - 120ºC min)

www.tynevalleyplastics.co.uk

Beauty is in the eye of the beer holder.

 

[patprimmer]

Pud is right.

Also nylons start off a lot stronger than PPs and retain their properties BETTER at high temperature than do PPs. Also, there are many types of PA and PP so comments become vague unless specific types at least are specified.

What does happen to nylons is that in hot HUMID conditions, they slowly absorb moisture from the atmosphere and soften and swell, however they rarely if ever lose enough properties to get down to PP levels.

Properly moulded acetal of correct grade should not be brittle enough to break if dropped alone, from a reasonable height.

Regards
Pat
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[seppederoeck]

Thanks both. I will suggest our supplier to test impact modified POM and PA with your comments above.
Regarding modified POM, we do have to watch out for chemical additives as we have to comply with toy standards.