The mechanical properties of the PUU largely depend on the specific diisocyanates, long-chain polyols, and short-chain diamines in play, because how these components interact determines how well the soft and hard segments of the elastomers both crystallize and undergo microphase separation.
As a result, variations in this molecular arrangement of chemical compounds have been shown to greatly affect the elastomer’s morphology and the macroscopic, mechanical properties that it exhibits.
In comparison, the polycarbonate lacked the broad range of relaxation times, a characteristic that reflects how efficiently the molecules in the polymer chains respond to an external impulse, that PUUs are known to have.
[7] As a result, the researchers concluded that even the most rubber-like variant of the PUU, specifically the 2,000 g/mol (32,000 oz/lbmol) PTMO sample, demonstrated greater robustness and dynamic stiffening than the glassy polycarbonate.
[5] ARL researchers have stated that the PUU’s primary benefit comes not from its extra strength but its fabric-like flexibility, which demonstrates its potential as a replacement material for the rigid ceramic and metal plates generally found in military battle armor.