EFFECT OF FILLERS ON THERMAL AND MECHANICAL-PROPERTIES OF POLYURETHANE ELASTOMER

The effects of five different types of fillers on the thermal and mech anical properties of hydroxyl-terminated polybutadiene-based polyureth ane elastomers were explored to develop a filled polyurethane elastome ric Liner for rocket motors with hydroxyl-terminated polybutadiene-bas ed composite propellants. Two types of carbon black, silica, aluminum oxide, and zirconium(III)oxide were used as filler. Based on the impro vement in the tensile properties and the erosion resistance achieved i n the first part of the study, an ISAF-type carbon black was selected to be used as the main filler in combination with an additional filler , The second part involves the investigation of polyurethane elastomer s containing a second filler in various amounts in addition to the ISA F-type carbon black used as the main filler. In addition to the therma l and mechanical properties, the processability of the uncured polyure thane mixtures were also explored by measuring the viscosity in this s econd part of the study. The studied fillers do not considerably chang e the thermal degradation temperatures and the thermal conductivity of the polyurethane elastomers with a filler content up to 16 wt %. The best improvement in the erosion resistance and tensile strength of the polyurethane elastomers with additional fillers is also achieved when filled with the ISAF-type carbon black, whereas the use of zirconium( III) oxide as additional filler provides almost no improvement in thes e properties. Viscosity of the uncured polyurethane mixtures increases with the increasing filler content and with the decreasing particle s ize of the filler. Aluminum oxide-filled elastomers seem to be the mos t suitable compositions having sufficiently high thermal and mechanica l properties, together with the processability of uncured mixtures. (C ) 1998 John Wiley & Sons, Inc.