Definition of Polyer Polyols in a scientific sense
Polymer polyols are defined as very fine and stable dispersions of solid polymers(vinylic polymers and copolymers, polyurea, polyurethanes [PU] ) in liquid poly-ethers. Currently, polymer polyols represent one of the most important group of pol-yolic intermediates for elastic PU .The experience of flexible foam manufacture using polyols containing inor-ganic fillers (BaSO4, CaCO3) leads to the observation that fillers act as nucleatingagents during the foaming process and aid cell opening at the end of the rise pro-cess, and the hardness or load-bearing properties of the resulting filled flexible PUfoams are markedly improved. Generally, the inorganic fillers substantially increasethe flexible foam density.As with the inorganic fillers, the organic polymers can be successfully used asfillers. The preferred method is the synthesis of polymeric filler in situ, by radicalpolymerisation, polycondensation or polyaddition processes, developed in liquidpolyether media .These kind of polyether polyols containing polymeric fillers are called polymerpolyols and are produced on a large industrial scale, because they are one of themost important group of polyols used for high performance flexible PU foams andPU elastomers.
Polymer polyols are divided by the nature of the polymer finely dispersed inthe polyether matrix into following categories:
a) Graft polyether polyols (the dispersed polymer is a carbocatenary vinylic poly-mer or copolymer obtained by radical polymerisation);
b) Polyharnststoff dispersion (PHD) polyols (dispersions of polyurea);
c) Polyisocyanate polyaddition (PIPA) polyols (PU dispersions); and
d) Other polymer polyols (epoxy dispersions, aminopl