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	t tsombnik posted 7 Years Ago HOT Topic Details
t Group: Forum Members Posts: 6, Visits: 147	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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tsombnik	t tsombnik posted 7 Years Ago HOT Post Details
t Group: Forum Members Posts: 6, Visits: 147	+x Warren (Staff) - 1/8/2018 5:12:44 PM 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 maybe some reaction with the sizing and because the resin is thicker, it shows up more there. What kind of tooling are you using? What sort of curing environment.? The surface of the part seems to have quite a poor quality generally. 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 sizing. So you are saying, because the resin is thicker at these spots, the reaction is stronger and therefore somehow the white colour appears? Our Hardener is a 300 Minute hardener. I guess there shouldnt be a reaction heat problem or something like that. Although, it could be possible. As tooling we use SikaBlock M600. This was actually a bad decision, since the material is way too soft. It was a decision, made by low costs... next time we use SikaBlock M1000 or something like that. This is also the reason for the surface quality. We milled the tool, cleaned everything, grind the surface to make it smooth, cleaned everything again, and then applied epoxy resin for sealing. The surface of the tool seems to be okay if you look at it only with your eyes. What do you mean by curing environment? The part stays inside of the tool for 2 days, until the resin is cured. Then we take the part out of the mould. I dont know if the humidity is high or low inside of the room. We have temperatures around 20-23°C. All the best, Nik
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