Effect of amine catalyst on polyurethane synthesis

Polyurethane elastomer was prepared from polycaprolactone (PCL), diphenylme thane diisocyanate (MDI), 1, 4-butanediol (1, 4-BD) and Trimethylolpropane (TMP) by prepolymer method. This amine catalyst was used:1, 4-diazabicyclo- (2, 2, 2) octane (DABCO). Effects of the catalyst on molecule structure and physical properties of polyurethane elastomer were also studied. When a ca talyst was used, the reaction rate was rapider than with the non-catalyzed system. In the observation of the polarizing microscope, some spherulites o f small hard segments were found dispersed in the soft segments. In the def ferential scanning calorimetry (DSC) measurements, the transition width whi ch originated from the glass transition temperature (T-g) of amorphous hard segments become larger, and it became clear that phase mixing of the hard segment advances. In the mechanical properties, by using amine catalyst, th e elastic modulus in the extension rose in comparison with non-catalyzed PU E, and the build-up of the stress was observed in the extension over 300%. A remarkable elongation drill effect was shown. Also, the stress relaxation slowed down, and so the stress continued throughout the long term and the elasticity rose.