structural properties of imides 3

[Rattinox]

I understand that the imides are the only plastics rated as "excellent" for UV-resistance/stability. My interest in the imides is also structural: machined supports for antenna elements. The loads will actually be rather low; wind-loading on the elements only. Cost is irrelevant. Color and color stability is irrelevant.

Does anyone have any structural experience with the imides?

 

[ornerynorsk]

Thermoplastic polyurethanes are also UV resistant and can be formulated with some incredible mechanical properties. Plastics are not my area of expertise, but was involved with a project using this material about 10 yrs ago.

 

[patprimmer]

Your understanding is quite wrong.

Acrylic (Poly Methyl Methacrylate) and PTFE are virtually perfect re resistance to UV light.

PET is also excellent and Nylons are reasonable and can easily be stabilised.

The inclusion of UV opaque pigments (UV blocking power depends on particle size and chemical composition) and other stabilisers also helps. Organic stabilisers which are soluble in the polymer tend to be sacrifical but protect to the surface where opaque to UV pigments or fillers tend to be permanent but do not protect to the surface.



Regards
Pat
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[Rattinox]

I've priced some of the imides- and clutched my head howling.

I'll pass on the imides.

Just to clarify, Pat; acrylic will keep it's mechanical/structural properties after, say, 10 years daily UV sunlight exposure?

And PTFE? And PET?

Thanks!

 

[patprimmer]

Acrylic is extensively used for back painted outdoor signs. Although it is extremely good to UV it is reasonably brittle due to its very low elongation.

It is also extensively used in car tail light lenses, back painted badges, car weather shields, bonnet, number plate and head light protectors, and aircraft windows and windshields.

Its first major use was WW11 aircraft gun turrets and cockpit canopies. Common trade names in sheet form are are Perspex, Oroglass, Plexiglass, Lucite and Shinkolite. It is also available in injection moulding compounds.

PTFE is also commonly known as Teflon. It is not injection mouldable and is quite soft and relativly weak.

PET or nylon will easily last 10 years if it is correctly filled and stabilized. Both have been extensively used as boat fittings and as sails in fibre form. PET is also used as automotive seat belts and Nylon for automotive roof racks. Glass fibre helps stop surface cracks from propagating. Finely dispersed carbon black blocks UV light. In nylon, copper based antioxidants protect the surface. I am not sure of the organic stabilisers used in PER, but they are available and effective.

Regards
Pat
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[patprimmer]

I am not sure of the organic stabilisers used in PER , but they are available and effective.

This sentence should read

I am not sure of the organic stabilisers used in PET , but they are available and effective.

Regards
Pat
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