Carbon/Fiberglass Prepreg Excessive Oven Cure Time

[stephannelle]

I am looking for the effects of what happens when carbon and/or fiberglass prepreg layups are left at cure temp for too long. The specifics in this case are an oven vacuum bag cure layup of 2 plies of Toray FGF7781-071 Fiberglass Prepreg and 10 plies of Toray F6273C-07M Carbon Fiber Prepreg. Left at cure temp of 270°F for 180 minutes instead of the normal 120 minutes. Ramp up and down temps and time were normal. I've spoken to a few different folks, including Toray themselves, and gotten differing opinions (surprise surprise). Though, the general consensus has been that this short of an overage time will not cause problems with the part. Does anyone have experience of the effects of 'overcooking' prepreg layups? Resin breakdown, embrittlement, etc?

 

[SWComposites]

Most modern epoxy prepreg resin systems can go thru multiple cure cycles or extended cure times without any significant effect. Might get a small increase in Tg. Adhesives on the other hand tend to br more sensitive to time at cure tep - can get more brittle.

 

[Compositepro]

Such a short time would certainly have no measureable effect. I am not familiar with that particular product, but it would be a pretty poor one if it could not tolerate hundreds of hours at such a low temperature.