oxidative attack of GF nylon components
oxidative attack of GF nylon components
(OP)
Is it possible that the removal of a lubricating oil containing antioxidant additives may give rise to the nylon components within the system suffering oxidative attack. What i'm trying to say is........do the antioxidant additives in lubricant oil also act as an antioxidant film that protects components from oxidative attack..? Also, would the free radicals contributing to oxidation be neutralised by the additive , thus reducing potential for oxidative attack of the nylon components.





RE: oxidative attack of GF nylon components
Some oils have huge concentrations of antioxidants. You can dissolve much more antioxidant in an oil than you can in a polymer. So, that may also contribute. The oil could be a reservoir for antioxidant.
Chris DeArmitt
www.phantomplastics.com
Consulting to the plastics industry
RE: oxidative attack of GF nylon components
RE: oxidative attack of GF nylon components
Water at 65 deg C will be worse than dry as the nylon is hydrolysed and the sizing agent on the fibres is attacked, but 5000 hours still seems a low temperature to get severe degradation.
Regards
Pat
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RE: oxidative attack of GF nylon components
I think your selection of nylon (which is high polarity) was good when in contact with oil (which is low polarity).
Now that you intend contact with water (high polarity), nylon (high polarity) is not a good choice because it will be swollen by the water and get soft. In contrast polypropylene (low polarity) is ideal because it resists water. It's used for washing machines and dishwasher internals for just that reason. Contact the PP supplier and get a grade with appropriate antioxidants in it to resist the temperature. PP in washing machine parts can survive oven ageing at 150C for 8000 hours.
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: oxidative attack of GF nylon components
RE: oxidative attack of GF nylon components
RE: oxidative attack of GF nylon components
Is not green the colour of copper salts? This would indicate water take-up.
Is it PA6 or PA6.6? The latter is somewhat better for hydrolysis. Much depends on the processing conditions also. Is the surface crystalline - correct tool temp?
There should be alternatives available without tool mods as most semi-crystalline materials have a similar shrinkage. (e.g. Acetal, PP as mentioned, PA12, mPPO, etc.)
I have assumed it's not coloured white with TiO2...
H
www.tynevalleyplastics.co.uk
RE: oxidative attack of GF nylon components
H
www.tynevalleyplastics.co.uk
RE: oxidative attack of GF nylon components
RE: oxidative attack of GF nylon components
Nylon is stabilized with copper salts so that could in theory cause green. If you have copper in solution in your system that could be the cause of failure. Any transition metals (iron, copper, chromium, vanadium etc) accelerate the polymer degradation hugely even at ppm levels.
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: oxidative attack of GF nylon components
Nylons are particularly susceptible to attack from zinc chloride from water treatment and galvinised plumbing fittings or even poor quality brass.
Regards
Pat
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RE: oxidative attack of GF nylon components
RE: oxidative attack of GF nylon components
RE: oxidative attack of GF nylon components
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules