1
Fritz Hostettler: Energy-attenuating polyurethanes. Polymer Dynamics, February 2, 1988: US04722946 (67 worldwide citation)

A non-liquid, energy-absorbing polyurethane is derived from the process which comprises reacting a mixture of linear and branched polyols, a polyisocyanate and, optionally, a blowing agent, under polyurethane-forming conditions at an isocyanate index of from about 65 to about 85.


2
Wen Yu Tiao, Chin Sheng Tiao: Methods for the manufacture of energy-attenuating polyurethanes. Polymer Dynamics Technology, Richard O Church, December 25, 1990: US04980386 (20 worldwide citation)

A method for the manufacture of shock attenuating, low rebound polyurethanes in which polyols are reacted with polyisocyanates having a functionality of at least 2.3 at an isocyanate index of from about 65 to about 90.