I am working on polyester polyol based rigid polyurethane foam. I am trying to develop a polyol using castor oil after transamidation with diethanolamine.
When I react this polyol with pMDI and pour into a closed mold it rises and get the shape but the skin peals off from the surface. I want to prepare rigid foam having uniform, hard and shiny surface.
Dear Zeeshan Ahmad, the problem most likely is due to bed mixinig of OH/NCO and/or inhomogeneity in heating/heat release (exotherm). Please check the following documents. My Regards
https://doi.org/10.1155/2021/6638109
https://doi.org/10.1021/ed8000599
Abdelkader BOUAZIZ Dear Sir my reaction of pMDI and Polyol is highly exothermic may be due to this i am facing the problem of skin peeling of foam surface.. Can you guide me in this regard that what should I do.. Which compound i should add in it??
Abdelkader BOUAZIZ is there any chemical which can tighten the surface and reduce peeling..
I think the solution lies in optimizing the operating/processing conditions. When the components are highly reactive, prepolymers are the best choice. Mold release agents may also solve the pealing off. Best of Luck
What foaming agent do you use and is there optimum pressure to form an integral skin? Which type of catalyst do you use and is there a balance of gas forming reaction(s) and gelling? Which auxiliary agent do you use to facilitate demoulding? Please, consider these questions, in case you answer I'll comment on these.
I agree with Abdelkader that you need to use a functional release agent ( probably a silicone copolymer to avoid colapse on surface) and also cool the mold with circulating water or by air blow.
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