Does Polyester resin + catalyst react with uncured polyurethane foam?

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In summary, the speaker left a resin on for three weeks, with varying temperatures, but it did not cure and had a strong smell. They removed the hardened resin and found the underlying polyurethane foam to be strange and smelling of uncured resin. Upon digging deeper, they noticed a difference in the foam where the resin had been on top, suggesting partial absorption and curing. The speaker mixed the resin with cabosil and chopped fiberglass, making it difficult to determine the cause of the issue. They also questioned if there was a reaction between the two compounds and if the off-gassing could be more toxic than either compound alone. However, due to the variety of formulations in polyurethane foam and polyester resin, it is difficult to provide
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mess
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TL;DR Summary
I used some polyurethane spray foam in a cold environment, it did not fully cure and i put polyester resin ontop of it. It never cured.
I left it on for about 3 weeks, most of the time it was in below curing temperature, sometimes below freezing, but i gave it about 15 hours of 20c+ to try to cure it. It never did, and still smelt really bad. I decided to rip off the resin that had hardened. Underneath it, the polyurethane foam looked strange, and smelled very strong of uncured resin. I dug deep into the foam, about 15cm, and the foam seemed different wherever the resin had been on top, as if it absorbed part of the resin and only partially cured.

The resin i used, i mixed with cabosil and chopped fiberglass to give it a peanut butter consistency, so i am not sure how it could have gone that deep into the foam.

Was there a reaction between the two uncured compounds? If so, is the off gassing more toxic then either of the original two compounds could produce?
 
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You would need someone versed in resins, but even then the answer would be largely "it depends". There is no one polyurethane foam, there is no one polyester resin. There are many and they differ in formulations, so I wouldn't expect a single answer to "what happened when I mixed a random foam with a random resin?".
 
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1. What is the reaction between polyester resin and uncured polyurethane foam?

The reaction between polyester resin and uncured polyurethane foam is a chemical reaction that results in the curing of the foam. This reaction occurs when the catalyst in the polyester resin triggers the cross-linking of the polyurethane molecules, causing the foam to harden and become solid.

2. Can I use polyester resin and catalyst on uncured polyurethane foam?

It is not recommended to use polyester resin and catalyst on uncured polyurethane foam. The reaction between the two can cause the foam to expand and potentially create air pockets or bubbles, which can weaken the structural integrity of the foam.

3. Will the reaction between polyester resin and uncured polyurethane foam produce any toxic fumes?

Yes, the reaction between polyester resin and uncured polyurethane foam can produce toxic fumes, such as carbon monoxide and isocyanates. It is important to work in a well-ventilated area and wear proper protective gear when handling these materials.

4. How long does it take for the reaction between polyester resin and uncured polyurethane foam to complete?

The reaction between polyester resin and uncured polyurethane foam can vary in time depending on factors such as the amount of catalyst used, temperature, and humidity. Generally, it can take anywhere from 5-30 minutes for the foam to fully cure and harden.

5. Can the reaction between polyester resin and uncured polyurethane foam be reversed?

No, once the reaction between polyester resin and uncured polyurethane foam has occurred, it cannot be reversed. The foam will remain in its hardened state and cannot be returned to its original liquid form.

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