Nanoclay‐Modified Rigid Polyurethane Foam

Abstract

Montmorillonite‐based organoclay was incorporated into rigid polyurethane foams. Clay was dispersed first in the isocyanate component ultrasonically. The dispersion was investigated using small angle X‐ray scattering and rheology. It was found that using toluene as common solvent enhanced dispersion significantly. The addition of 1 wt% clay resulted in reduced cell size from 0.40 to 0.28 mm and increased cell number density on 300‐index foams. Gas chromatography showed that diffusion of blowing agent out of the closed cells of the foam decreased by more than 82% with clay loading. The reduction in permeability is caused by the combined effect of smaller cell size and dispersed nanoclay acting as diffusion barrier. At 1% clay no mechanical strength improvements were observed. Higher levels of clay loading caused significant viscosity increase and a yield stress that made mixing the reactive components difficult.

Dedicated to Professor John L. Stanford on the occasion of his 60th birthday.

Keywords:

• montmorillonite‐based organo clay
• polyurethane foams
• thermal insulation

Acknowledgment

This research was made possible by funding from the Industrial Partnership for Research in Interfacial and Materials Engineering (IPRIME) at the University of Minnesota. The authors would like to thank Dr. Xia Cao and Dr. L. James Lee of Ohio State University for collaboration and helpful discussions; and Dr. Heinz Plaumann and Robert Riley of BASF Corp. for providing foam formulation, materials, and expert advice.

Notes

Dedicated to Professor John L. Stanford on the occasion of his 60th birthday.