Composite materials that can cure at low pressure and low temperature

[weiyew]

I'm looking into some prepregs/fabric/resin systems in which they can be cured under vacuum pressure at temperature below 250°F and yet able to withstand its strength at elevated temperature of up to 350°F. Can anyone give me some information? This is for aerospace application.

Please advice. Thanks with best regards.

 

[Compositepro]

How do you define use temperature and the properties you need at this temperature? I assume that you want a 250F cure because of limitations in your tooling. To get 350F use, though, you will have to post-cure at 350F or above. Depending on what kind of properties you need, high-temp. epoxies may work or you may have to go with a bismaleimide resin. BMI cannot be cured at 250F yet, but we are working on it. We do VARTM with BMI at 350F.

 

[weiyew]

Hi,

Use temperature is operating tempeature. In this case, the component operating temp is 350°F. Curing temp are suppose to be set at 250°F because of limitations due to repair. What is your company? How can you help me in selecting an appropriate resin system and fabric?

Can you advice? Thanks!

 

[airborne12]

A resent developement is to use UV curing. Check out:

http://www.compositesworld.com/ct/issues/2005/April/795

Maybe it works for your problem. ONly thing is that you cannot use it for CFRP, since UV rays cannot penetrate them.

 

[Compositepro]

Fibraplex is working on a an SBIR to develop a BMI repair material for the Airforce. My point about use temperature, though, was that you generally must make some compromise in properties if you use a lower temperature cure, otherwise everybody would be using low temperature cures to start with. Cure reactions stop when the polymer gets so hard and stiff that the polymer molecules can't move enough to get together any more. Heat increases molecular motion and will allow the cure to proceed further and increase the Tg, or softening temperature of the polymer. This is very characteristic of high Tg polymers. Low Tg polymers may complete their cure at low temperatures and heating them to higher temperature will not make the Tg any higher.

 

[RPstress]

ACG (Advanced Composites Group) do MTM44-1 and MTM45 as prepreg or for RFI. MTM44-1 cures under vacuum at 135 C (275 F) and has a free-standing post-cure at 180 C (350 F) which gives a good Tg wet of about 145 C. MTM45 is newer, and cures at 80 C (175 F) with the same free-standing post cure. To get to 350 F service temp is tricky...