Formation and characterization of polyurethane-vermiculite clay nanocomposite foams

Nanocomposites of rigid polyurethane foam with unmodified vermiculite clay are synthesized. The clay is dispersed either in polyol or isocyanate before blending. The viscosity of the polyol is found to increase slightly on the addition of clay up to 5 pphp (parts per hundred parts of polyol by weight). The gel time and rise time are significantly reduced by the addition of clay, indicating that the clay acts as a heterogeneous catalyst for the foaming and polymerization reactions. X-ray diffraction and transmission electron microscopy of the polyurethane composite foams indicate that the clay is partially exfoliated in the polymer matrix. The clay is found to induce gas bubble nucleation resulting in smaller cells with a narrower size distribution in the cured foam. The closed cell content of the clay nanocomposite foams increases slightly with clay concentration. The mechanical properties are found to be the best at 2.3 wt% of clay when the clay is dispersed in the isocyanate; the compressive strength and modulus normalized to a density of 40 kg/m 3 are 40% and 34% higher than the foam without clay, respectively. The thermal conductivity is found to be 10% lower than the foam without clay.

[1]  D. Khakhar,et al.  Rigid polyurethane–clay nanocomposite foams: Preparation and properties , 2007 .

[2]  D. Khakhar,et al.  Polyurethane Foam-Clay Nanocomposites: Nanoclays as Cell Openers , 2006 .

[3]  Christopher W. Macosko,et al.  Nanoclay‐Modified Rigid Polyurethane Foam , 2005 .

[4]  Jing Xu,et al.  Preparation of poly(propylene carbonate)/organo-vermiculite nanocomposites via direct melt intercalation , 2005 .

[5]  L. J. Lee,et al.  Polyurethane/clay nanocomposites foams: processing, structure and properties , 2005 .

[6]  S. Tjong,et al.  Synthesis of poly(arylene disulfide)-vermiculite nanocomposites via in situ ring-opening reaction of cyclic oligomers , 2003 .

[7]  L. Mathias,et al.  Effects of melt-processing conditions on the quality of poly(ethylene terephthalate) montmorillonite clay nanocomposites† , 2002 .

[8]  S. Tjong,et al.  Novel Preparation and Properties of Polypropylene−Vermiculite Nanocomposites , 2002 .

[9]  L. Goettler,et al.  Predicting the binding energy for nylon 6,6/clay nanocomposites by molecular modeling ☆ , 2002 .

[10]  L. J. Lee,et al.  Poly(methyl methacrylate) and polystyrene/clay nanocomposites prepared by in-situ polymerization , 2001 .

[11]  K. Seefeldt,et al.  Rheology of Polypropylene/Clay Hybrid Materials , 2001 .

[12]  Richard H. Harris,et al.  Flammability Properties of Polymer - Layered-Silicate Nanocomposites. Polypropylene and Polystyrene Nanocomposites , 2000 .

[13]  Thomas J. Pinnavaia,et al.  Nanolayer Reinforcement of Elastomeric Polyurethane , 1998 .

[14]  E. Giannelis,et al.  Synthesis and properties of new poly(dimethylsiloxane) nanocomposites , 1995 .

[15]  T. Kurauchi,et al.  Synthesis and properties of polyimide–clay hybrid , 1993 .

[16]  Toshio Kurauchi,et al.  Synthesis of nylon 6-clay hybrid , 1993 .

[17]  T. Kurauchi,et al.  Swelling behavior of montmorillonite cation exchanged for ω-amino acids by ∊-caprolactam , 1993 .

[18]  Toshio Kurauchi,et al.  Synthesis of nylon 6-clay hybrid by montmorillonite intercalated with ε-caprolactam , 1993 .

[19]  D. Khakhar,et al.  Castor Oil - Glycerol Blends as Polyols for Rigid Polyurethane Foams , 1993, Cellular Polymers.

[20]  W. J. Ward,et al.  Gas barrier improvement using vermiculite and mica in polymer films , 1991 .

[21]  E. Morillo,et al.  Expansibility of some vermiculites , 1989 .

[22]  Roberto J. J. Williams,et al.  Curing kinetics of a rigid polyurethane foam formulation , 1982 .

[23]  C. Macosko,et al.  Viscosity changes during isothermal and adiabatic urethane network polymerization , 1980 .

[24]  G. Jameson,et al.  Some ion exchange properties of exfoliated vermiculite , 1976 .