The Use of FT-IR and Dynamic SAXS to Provide an Improved Understanding of the Matrix Formation and Viscosity Build of Flexible Polyurethane Foams

Effect of Chain Extenders on the Morphology Development in Flexible Polyurethane Foam

“…Because they can be correlated to morphological features, inter-urea and inter-urethane hydrogen bonding are frequently used to study the degree of phase separation. In the infrared analysis of hydrogen bonding, three spectral regions have been studied: (1) the N−H stretching region between 3500 and 3200 cm -1 , (2) the carbonyl region between 1800 and 1600 cm -1 , and (3) the amide II region below 1600 cm -1 . ,− Because of the variations in extinction coefficient with hydrogen bonding in the N−H stretching region and the generally complex nature of the peaks in the amide II region, only the carbonyl region has been chosen to monitor the evolution of urethane, urea, and hydrogen bonding. The formation of hydrogen bonds results in a shift of the absorption band of the CO stretching vibration mode from a higher frequency value to a lower one.…”

“…The small-angle X-ray scattering (SAXS) technique has been used to investigate the phase separation kinetics during the foaming process. , In Ryan and Elwell's 13 dynamic IR and SAXS studies of a methylene diphenyl diisocyanate (MDI) slabstock foam system, a close agreement between the onset of microphase separation detected by FTIR spectroscopy and SAXS was observed. Similar results have also been reported by McClusky 3 for a toluene diisocyanate (TDI) slabstock foam system.…”

“…FTIR spectroscopy has been employed to investigate both the reaction kinetics and the development of polymer structure during foam formation. − Hydrogen-bonding studies can often provide information concerning the phase separation of polyurea chains. In slabstock foam, the formation of urethane and soluble urea occurs simultaneously in the initial stages of the foaming reaction.…”

Monitoring the Effect of Relative Humidity During Curing on Dielectric Properties of Composites at Microwave Frequencies

“…A number of methods have been used to study the effect of water uptake in polyurethanes. Attenuated total reflectance Fourier-transform infra-red (FTIR) spectroscopy is commonly used [2,4,5] although in reference [5] this technique is augmented with small-angle X-ray scattering measurements. In reference [6], a fluorescence technique is employed to monitor water uptake in polyurethane adhesives.…”

Modulation of cavities and interconnecting pores in manufacturing water blown flexible poly (urethane urea) foams

“…Also, during this step, free and monodentate urea can be found without increase of the foam modulus. 18,19 Step 2 contains the maximum cavity growth and formation of the pores, and these two events simultaneously take place. Therefore, It is possible to be torn of the surface of the cavities due to the pressure build-up from CO 2 gas molecules, and also microphase separations can be induced during the cavity opening by formation of bidentate (hydrogen-bonded) urea.…”