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Low Temperature performance data for PEEK

Low Temperature performance data for PEEK

Low Temperature performance data for PEEK

(OP)
Can someone point me in the direction of some data/papers re performance of PEEK at (relatively) low temperatures (-50deg C)?

All the data I've found so far touts the high temp performance, but I cant find anything re lower temps.
We are looking at swapping out PCTFE seats for PEEK ones. Seat arrangement is a basic flat static seat (similar to a washer) with 316SS poppet operating around 6,000kPag.
We use PEEK seats on the same device for high pressure service, but we don't see the same temp swings as we do on this particular service.
The issue we are experiencing is that during temp changes as part of the process cycle, we are seeing deformation of the PCTFE seat when running @ approx +130deg C.
The PCTFE provides us with Class VI shutoff across our operating pressure ranges (0-30,000kPa), we've found the PEEK can be a bit hit or miss at pressures below around 3,000kPa, so my concern is that it will only get worse the colder it gets.

Victrex have suggested CT100 grade PEEK "should" be suitable. Their datasheet indicates that flexural modulus @ -196deg C is 5.4MPa vs 3.5MPa @ +23deg C.

I've also been referred to "brittleness temperature" in TABLE 5 of ISO-23936-1 for information on brittle temps (PEEK listed as -65deg C).

Any other sources I could try?

TIA!

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