Nanofilled polyols for viscoelastic polyurethane foams

The use of polyether polyols is common in the polyurethane (PU) industry, particularly for soft PU applications. In particular, viscoelastic foams, characterized by slow recovery after compression, are obtained using poly(ethylene oxide) (PEO) polyols. Nanofilled polyols can be used for the production of viscoelastic foams with improved fire-resistance properties. The high polarity of polyetherpolyols is responsible for a poor affinitywiththeorganicmodifiersusedincommercialorganicallymodified montmorillonite (omMMT). The aim of the work reported here was the development of a procedure for enhanced polyether polyol intercalation using modified MMT. The exfoliation of the lamellar nanofiller is obtained during the mixing stage of the polyol and the MMT. The MMT is modified using polyetheramines with different amounts of ethylene oxide/propylene oxide. Aftermixingwith the modifiedMMT, the polyol shows an increase in viscosity by three orders of magnitude, and the diffraction angles of the MMT measured by X-ray analysis decrease to values lower than 1.5◦. The intercalated structure is preserved after the curing stage, when isocyanate is added to the polyol/omMMT. The resulting PU has an irregular open-cell structure, and is characterized by a higher flame resistance compared to unfilled PU. Organically modified MMT was prepared, having an improved affinity with polyether polyols. The modified MMT has an improved compatibility with the PEO-based polyether polyols commonly used for soft PU foam production. The properties of the nanofiller can be tailored by varying the type and amount of organicmodifier. A strongly intercalated/exfoliated structure is obtained aftermixing the polyol with the omMMT.