Thermoplastic Polyurethane Elastomer Nanocomposites: Morphology, Thermophysical and Flammability Properties

Wai K. Ho, Joseph H. Koo*, and Ofodike A. Ezekoye
Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712-0292, USA
*To whom all the correspondence should be addressed (jkoo@mail.utexas.edu)
 
Novel materials based on nanotechnology creating nontraditional ablators are rapidly changing the technology base for thermal protection systems. Formulations with the addition of nanoclays and carbon nanofibers in a neat thermoplastic polyurethane elastomer (TPU) were melt-compounded using twin-screw extrusion. The TPU nanocomposites (TPUNs) are proposed to replace Kevlar®-filled ethylene-propylene-diene-monomer rubber, the current state-of-the-art solid rocket motor internal insulation. Scanning electron microscopy analysis was conducted to study the char characteristics of the TPUNs at elevated temperatures. Specimens were examined to analyze the morphological microstructure during the pyrolysis reaction and in fully-charred states. Thermophysical properties of density, specific heat capacity, thermal diffusivity, and thermal conductivity of the different TPUN compositions were determined. To identify dual usage of these novel materials, cone calorimetry was employed to study the flammability properties of these TPUNs.