Two-phase engineered polymer polyurethane synergy with clay nanocomposite reinforcement

6 Two-phase engineered polymer (polyurethane) synergy with clay nanocomposite reinforcement 

Polyurethanes are noted for their unique mechanical toughness. The combination of hard and soft segments in the polymer chain can lead to segregation of the hard segments into separate domains dispersed in the soft segment continuous phase. The size of the dispersed polymer 

Instead of the diols above, Maji et al. [56] evaluated a hydroxyl functional polyester-polyurethane prepolymer prepared by the ester formation of diethylene glycol with adipic acid and subsequent urethane formation with the 2,4-toluene diisocyanate (TDI) reaction with the excess hydroxyls on the polyester (Urepan 600 prepared by M/s Rhein 

Chemie Rhenau GmbH). The excess hydroxyl content of the prepolymer was determined at 25.8 mg KOH/g of polymer based on Karl Fischer titration. The prepolymer was dissolved in THF (10 g of polymer per 90 g of THF) by soaking the polymer in the solvent overnight and then by high-speed dispersion for 1 h. This was accomplished at room temperature. 

SEM indicated well-defined regions of segregated layers of montmorillonite and polymer. The bilayer thickness decreased respectively with montmorillonite content by 53, 31, 24, 17, and 11 nm. The modulus of the constructions increased from 0.025 0.005 GPa for the pure polymer to 3.6 GPa for the construction with 41 wt.% montmorillonite. The tensile strength increased from 13.2 0.9 MPa for the pure polymer and plateaued at approximately 39.4 3.0 to 41.2 3.8 MPa in the range of 13 to 21 wt.% montmorillonite content in the construction. The percent elongation to failure steadily decreased from 4.10 0.10 for the pure polymer to 0.008 0.003 for the construction with 41 wt. % montmorillonite. Apparently, the restriction of the polymer in the 

---