Studies of Polymers for Shock Absorption Applications

The purpose of this study was to evaluate polymers with potential shock damping properties. Many soft polyurethane elastomers were prepared in the laboratory and evaluated by thermal and mechanical analysis; these include mostly poly(propylene oxide) and polythioether-based elastomers prepared with toluene diisocyanate. Tri- and tetrafunctional chain extenders were used in all cases, as well as some unusual secondary diamines. The objective was to soften the polymers, disorganize the hard phase, and broaden the soft segment glass transition temperature while still allowing a rather broad use temperature. Comparisons were made to commercially available shock absorbing polymers. The synthesis of the polyurethanes is discussed in detail and the results of characterization of all of the polymers are described. The polymers exhibit T sub g's ranging from -68 C to -19 C, final softening temperatures between 115 C and 246 C, Shore A hardness values ranging from 13 to 87, tensile strengths of 0.7 MPa to 20 MPa and elongations of 175% to 2900%. Several display low Bashore rebound values in the temperature range of interest. Dynamic mechanical data were extrapolated to high frequency through the assembly of master curves and revealed that the polymers evaluated probably would exhibit good high frequency shock absorbing properties at room temperature or somewhat above room temperature, but that they would not display satisfactory behavior at temperatures significantly below room temperature.