Lecce, Italy - A group of researchers at the Department of Innovation Engineering at the University of Salento, in Lecce, Italy, has developed viscoelastic polyurethane foam with poly(ethylene oxide) (PEO) polyols filled with a more compatible form of organically modified montmorillonite (omMMT).
The aim of the work was to develop viscoelastic flexible foam which has improved flame retardance as a result of the nano-structured MMT.
The team said traditionally polyether polyols, with their high polarity, have poor affinity with commercial omMMT, so their work focussed on developing a montmorillonite with better affinity. They used polyetheramines with different amounts of ethylene oxide/propylene oxide and said this gave a "strongly intercalated/exfoliated structure," after mixing the polyol with the omMMT.
The work, reported in a paper called 'Nanofilled polyols for viscoelastic polyurethane foams' (Polymer International, Vol 59, N0 4, pp 486-491, 2010, Society of Chemical Industry) shows that the viscosity of the polyol increased by three orders of magnitude, while the diffraction angles of the MMT, measured by x-ray analysis, decreased to values lower than 1.5°.
According to the research, the intercalated structure was preserved after curing, when the isocyanate was added to the polyol/omMMT.
The Lecce team said, "The resulting polyurethane had an irregular open cell structure, and was characterised by mechanical properties comparable to those of unfilled polyurethane."