I am looking for additives/filler to decrease thermal conductivity of cross linked closed cell polyethylene foams? please advise me what kind of fillers I can use for my research purpose.
The material that provides the thermal insulating property to insulating foams is indeed its expansion gas. Therefore, one possibility to decrease thermal conductivity is to use a heavy, low thermal conductivity gas for expansion.
Another way, very efficient in polystyrene foams, is to coat the cells walls with an infrered reflective coationg, such as graphite. This reduces the heat transfer by radiation in the cells and hence decreases the global, apparent thermal conductivity.
Hi Roulet, Thanks for the information. I am using azodocarbmide expansion gas. and i am getting higher k value overtime. can you suggest me which kind of expansion gas will be good for low thermal conductivity especially in cross linked polyethylene foams. if graphite helps in this application which micron of graphite will be good for this?
Hi Pramod
I am not a specialist of polymer foam expansion and cannot propose you a specific gas. The attached file provides you the thermal conductivity of some of them.
The graphite layer should be thick enough to reflect the thermal radiation. Unfortunately, I don't know the necessary thickness. You may ask BASF, the provider of the graphitized EPS called NEOPOR (http://www.neopor.basf.us/contact )
Claude-Al.
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