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White spots inside of my Carbon Fiber Epoxy Laminate
White spots inside of my Carbon Fiber Epoxy Laminate
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White spots inside of my Carbon Fiber Epoxy Laminate
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tsombnik
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tsombnik
posted 7 Years Ago
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Hello friends,
i am currently working on a project where we are manufacturing CFRP Parts with vacuum assisted RTM process. We are using infusion resin with infusion hardener (HP Textiles (HP-HE3000RI-30) / HP Textiles (HP-HTE300RI-9)) and Semiperm Monofilm R&G Release Agent. We are experiencing weird white spots inside of the part after curing of the resin and arent able to fix them. The wierd thing is, that we have these white spots very concentrated at a few positions of the part. The rest of the resin inside the resin pot is clear! What could be the problem? This is how the process looks like:
1) Inserting preform into the tool
2) Closing of the tool
3) Vacuuming of the tool
4) Injecting of the resin with 0,7 bar injection pressure
5) Wait 2 days until resin is cured
6) Open the tool
I have added a picture inside of my post. I hope you can help.
Thank you very much for your potential help,
All the best, Nik
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White spots inside of my Carbon Fiber Epoxy Laminate
tsombnik
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7 Years Ago
From the picture it is hard to tell exactly but it looks a bit like some form of bridging in those areas meaning thicker resin. The reason it appears white could be simply a moisture reaction or mayb...
Warren (Staff)
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7 Years Ago
Hi Warren, thank you very much for your fast reply! Indeed you are right, the resin is thicker in the white areas, since the fibers can't really adapt to the honeycombs. I like the idea about the...
tsombnik
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7 Years Ago
Im not sure its your case... but I have had similar problems when I used too much (wax based) release agent and did not polish it into the mold.
fibernoob
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7 Years Ago
Hello fibernoob, we also used wax based release agent in the area of the sealing cord, so that we can use it again if resin reaches the sealing areas of the tool. So yeah, im pretty sure this can be....
tsombnik
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7 Years Ago
After getting some information, i discovered that wax based release agent has to be applied and thoroughly polished and left for some time for the solvents to evaporate and leave just a thin film of....
fibernoob
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7 Years Ago
I've had similar effects caused by moisture. the storage of the resin might be too cold, so that water condense on the resin, once it's in the mixing pot. Do you degas your resin before the process?....
oekmont
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7 Years Ago
Hi oekmont, yes, we use an Exicator for degasing. Something like this: ( https://goo.gl/images/W822mS) So i guess the degasing foam cant be the reason? For future experiments we will degas way...
tsombnik
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7 Years Ago
during infusion, the outgassing happens where the pressure is the lowest, which is at the flow front. At bridging areas, this gas can accumulate, and stay there during the solidification. This gas...
oekmont
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7 Years Ago
We are not directly doing an infusion. We close the tool, pump out all the air and therefore create a vacuum. Then we have a resin storage which is set under a pressure of 0,7 bar. After the vacuum i...
tsombnik
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7 Years Ago
still, there is a vacuum inside the mold, and the resin front is under vacuum. What kind of pump are you using? Are you using the same pump for the evacuation as for the degassing? What negative...
oekmont
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7 Years Ago
Ah okay, yes you are correct. We are using the same pump for evac and degassing. We reach a value up to 30 mbar remaining pressure
tsombnik
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7 Years Ago
what type of pump are you using? what do the specifications say how much pressure it can reach? 30mbar happens to be the boiling point of water at room temperature. If you got a moisture problem, the...
oekmont
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7 Years Ago
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