Random Copolyethers PO-EO Heteropolyether Polyols

It can be seen that moulded flexible PU foams using EO capped polyether polyols (block copolymers PO-EO with terminal poly[EO] block) represent only 22% of total worldwide consumption and that the majority of foams are flexible slabstock PU foams which use random copolyethers of PO-EO. It can therefore be concluded that the most important polyols for flexible PU foams production are in fact the random copolyethers PO-EO. 

Practically, the synthesis of random copolyethers of PO-EO is very similar to the synthesis of polyether PO homopolymers, with the difference that the starter (mainly glycerol) is reacted with an homogeneous mixture of PO-EO, containing around 10-15% EO, instead of PO alone. 

For continuous flexible PU slabstock production, the heteropolyether triols PO-EO are considered universal polyols used in conventional soft and supersoft flexible PU foams, covering a large range of densities (12-40 kg/m3) and load bearing properties. 

In the random copolymerisation of PO with EO, the following four important reactions take place (EO is monomer 1 and PO is monomer 2)  

All the copolymerisation reactions are characterised by the copolymerisation constant rl and r2 defined as  

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