Hello All,
This is a rather long multi part question, so if any feedback is appreciated.
We are currently curing wood blocks that have been pressure impregnated with a resin mix that is 80% methyl methacrylate, with the remainder styrene,polyester and another methacrylate. Also contains small amounts of inhibitors and catalyst. We are currently curing unpressurized at temps between 180F and 250F.
We want to switch to a pressure oven utilizing inert gas. We want to push the boiling temp (214F at 1atm) of the MMA above the catalyzation temp to minimize resin loss from evaporation during the cure. I am a mechanical engineer with only a seat of the pants understanding of chemistry, so I have a limited understanding of the process. Obviously, the goal is to cure the wood without blowing up the facilities.
I should mention the pressure oven will be equipped with adjustable pressure relief valves, heaters, and a external forced air oven cooler.
The purpose of the inert gas (nitrogen) is to get below the LEL. But removal of the oxygen will stop the inhibitors and accelerate polymerization. Also,I assume that MMA has a latent heat of vaporization like water, so reduced evaporation will accelerate exothermic heating during cure.
My areas of concern:
1. What are the byproducts of polymerization? These will be trapped in the oven, unless the relief valves open.
2. By evacuating the air and filling with nitrogen I can get the oxygen down to about 2% , maybe ½% or better if I purge twice. I know increased pressure will reduce the LEL in terms of % Hydrocarbon as well as % oxygen necessary to support combustion, but how much?. Would 150 psi and a max temp of 300F be below the LEL?
3. Is there anything in this mix that under sufficient heat and pressure can support combustion without oxygen?
4. Any guess how much removal of the oxygen and application of pressure will increase the polymerization rate? Thanks
This is a rather long multi part question, so if any feedback is appreciated.
We are currently curing wood blocks that have been pressure impregnated with a resin mix that is 80% methyl methacrylate, with the remainder styrene,polyester and another methacrylate. Also contains small amounts of inhibitors and catalyst. We are currently curing unpressurized at temps between 180F and 250F.
We want to switch to a pressure oven utilizing inert gas. We want to push the boiling temp (214F at 1atm) of the MMA above the catalyzation temp to minimize resin loss from evaporation during the cure. I am a mechanical engineer with only a seat of the pants understanding of chemistry, so I have a limited understanding of the process. Obviously, the goal is to cure the wood without blowing up the facilities.
I should mention the pressure oven will be equipped with adjustable pressure relief valves, heaters, and a external forced air oven cooler.
The purpose of the inert gas (nitrogen) is to get below the LEL. But removal of the oxygen will stop the inhibitors and accelerate polymerization. Also,I assume that MMA has a latent heat of vaporization like water, so reduced evaporation will accelerate exothermic heating during cure.
My areas of concern:
1. What are the byproducts of polymerization? These will be trapped in the oven, unless the relief valves open.
2. By evacuating the air and filling with nitrogen I can get the oxygen down to about 2% , maybe ½% or better if I purge twice. I know increased pressure will reduce the LEL in terms of % Hydrocarbon as well as % oxygen necessary to support combustion, but how much?. Would 150 psi and a max temp of 300F be below the LEL?
3. Is there anything in this mix that under sufficient heat and pressure can support combustion without oxygen?
4. Any guess how much removal of the oxygen and application of pressure will increase the polymerization rate? Thanks
