Q: What conditions do I need to avoid to reduce the effects of moisture when curing a cyanate ester prepreg?

A: If you are using composite tooling make sure that the tooling is dried thoroughly and kept dry before the prepreg is laid upon to the tool. Use an active vacuum during the entire cure.

When storing the product be sure and keep all prepreg sealed in moisture proof bagging with a dry desiccant. Remove from the freezer and do not open the moisture proof bagging until the prepreg has reached room temperature and there is no risk of ambient moisture condensing on the product.

Q: When desiring to produce a co-cured sandwich structure with one of the cyanate ester prepregs, what system would be the most appropriate?

A: For co-curing to honeycomb the best system is the flow controlled version of RS-3, which is RS-3C.

Q: Can I co-cure a cyanate ester prepreg with an epoxy adhesive?

A: As long as the cure time and temperatures are compatible, we have not experienced adhesive skin co-cure problems with RS-3, RS-3C, RS-3M, RS-12B or RS-12 using many of the high quality commercial film adhesives. Please call a YLA representative for more information.

Q: How important are the temperature ramp rates used for curing and post curing composite structures?

A: Depending on the structure they can be very important. It is generally recommended that cure rates not exceed 7º F/ minute for nominal thickness laminates < 110". For thicker or large structures the cure rate may be much slower 2 - 3º F/ min is common. One important consideration is that when curing against metal tools, the prepreg resin gel temperature should be at or very near the final cure temperature of the part.

Post cure temperature rates should be slower than the cure rates. This is especially true when post curing to high temperatures. It is important the the structure is dry or is allowed to dry out from ambient moisture during the post cure. Temperature holds can be used in most cases. Depending on the material and the thickness of the part post cure temperatures typically range from 0.5 - 3º F / min. But if you have any questions, please call your YLA technical service contact for additional instructions.