Effect of solvent on the properties of thermoplastic polyurethane/clay nanocomposites prepared by solution mixing

Effect of different solvents on the clay dispersion and the final properties of the thermoplastic polyurethanes (TPUs)/clay nanocomposites prepared via solution mixing was studied. The polyether- and polyesterbased TPUs were used along with organically modified clays (C30B, C25A, and C15A) and the pristine montmorillonite (PM). Dimethylacetamide (DMAc) and tetrahydrofuran (THF) were used as solvents for solution mixing. Nanocomposites containing C30B prepared from DMAc solution showed the better clay dispersion than the ones from THF solution, while THF gave the better dispersion of clays for nanocomposites containing C15A. Morphologies of the nanocomposites were observed to be determined not only by the state of clay dispersion in different solvents but also by the interaction between the polymer and the specific clay. Affinity between solvents and clays becomes important when there is no specific interaction between the clay and the polymer of interest, or when the interaction between the two is rather weak. The compatibility between clays and polymers becomes dominating if there exists a specific interaction between the two. FTIR analysis was conducted. to study the interactions involved in the nanocomposites. Dynamic mechanical properties measurement was also carried out to see the effect of solvents. (C) 2008 Wiley Periodicals, Inc.