Question It is observed that composites materials properties vary with temperature. Ultem filled 50% with carbon fiber at 70 degree celsius there is reduction is tensile strength but there is not reduction in tensile modulus in fiber direction. Why do they behave like this?
Answer Hi Caesar,
I'm not familiar with ULTEM sorry but understand it is a thermoplastic PEI-type material.
Difference is believed due to different CTE's and load-bearing ability between fibre and matrix.
It is necessary to match the resin properties (or matrix properties) to the fibre properties for best results. The carbon may well be too stiff for this application and would suggest experimenting with different chop lengths, tow sizes, and or material itself (S2 glass or BMC filler).
I hope this helps, feel free to expand on your question.