I have degassed the resin, dried the fabric to remove moisture and use reduced vacuum pressure nothing worked. Just after infusion I have a perfect infused part without any bubbles. As the time passes, small microbubbles formation starts, these microbubbles expands over the time as part cure. However, reducing the vaccum pressure decrease the number of bubbles and size.
Is this is due to dissolved gasses in resin during resin mixing or the volatiles that are emitted during reaction.
How to deal with this problem?
Thank you
Hi Syed Zulfiqar Hussain Shah,
Have you tried to formulate the resin mixture (resin + catalyst)? If not, I suggest you to try this first and provide a certain time for mixture to remove the bubbles by itself, before applying this mixture to vacuum infusion. However, you have to consider the resin gel time and duration of your process. Based on my experience doing some projects in my lab, it might help to reduce micro-bubbles after infusion. Another thing that you may also be considered is post curing your product after infusion. Sometime it may also help to overcome this. I think you also have to control your environment as RH and temperature may influence the resin. And make sure you have enough resin left on your resin pot, so there is no micro-bubbles are sucked to the system.
Hopefully you can solve this problem.
Dear Onny and Israr,
Thank you for your suggestions, i have resolve the problem. I did the following things
1. Dried the fabric in an oven at 125 C for an hours to remove any moisture in the fabric.
2. Use low vacuum pressure to avoid resin boiling.
3. Prior to infusion allow the micro-bubbles to escape.
4. Reduced the length of flow mesh to 80% of the laminate length.
5. Reduce the vacuum pressure further after closing resin inlet and removing all micro bubbles from the laminate. In this step it was insured that there is enough clear resin in the outlet pipe. This will reduce the pressure on resin and restrict micro-bubbles to grow because dissolve gases/micro-bubbles in the resin expands more than 50 times under vacuum pressure and produce voids.
Thank you
Zulfiqar
This is a 2-fold problem and a very common manufacturing method for fixing it. First, vacuum degas to get rid of stirred in bubbles, then cure under pressure to prevent off-gassing and new bubble formation.
What is the cure time for your resin, there can be a chance the small bubbles can actually be the air entering into from environment this effect is more during high cure cycles. To test that, look if there are any loos of Vaccum throughout the process. To avoid this you can cure under pressure. Hope it helps you.
Many curing processes result in the creation of gaseous components as a result of the reaction (H2O, CO2, CH4, ...). Vacuum degassing only eliminates the bubbles stirred into or dissolved in the resin before curing. It does not eliminate gases that evolve from the resin curing reaction itself. These can be eliminated by curing under pressure so that they remain permanently dissolved in the cured resin. These gases will come out over time as they permeate to the outside air, but they will not result in bubbles.
- Badges
- Science topic
- Similar topics
- Geoscience
- Atmospheric Sciences
- Atmosphere
- Air