Effect of glycerol cross-linking and PDI on the shape memory effect and mechanical properties of polyurethane

A series of shape memory polyurethane (PU) copolymers synthesized from 1,4-phenyldiisocyanate (PDI), poly(tetramethyleneglycol) (PTMG), 1,4-butanediol (BD) as a chain extender, and glycerol as a cross-linking agent were tested for the mechanical properties and the shape memory effect at the temperature 20 degrees C above melting temperature (T-m), and were compared with other PUs synthesized from 4,4'-methylene-bis-phenyldiisocyanate (MDI), PTMG and BD. Mechanical properties and shape memory effect were improved substantially by adopting both PDI and glycerol. Interestingly, enthalpy of melting and T-m were not affected by the glycerol content. Vibration and shock absorption ability was investigated by measuring both loss tan delta and storage modulus with dynamic mechanical analyzer (DMA).