Investigating the molecular structure of thermoplastic polyurethane elastomer upon acoustic and damping properties

Thermoplastic polyurethane elastomer (TPUs) were synthesized by poly (oxytetramethylene) glycol (PTMG), hexamethylenediisocyanate (HDI) and 1, 4- Butanediol (BD) at three different molar ratios (1:4.2:3, 1:2.1:1, 3:4.2:1).The effect of stoichiometric balance on the acoustic and damping properties was evaluated. Fourier Transformed Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-ray Diffractometry (WAXS), Scanning Electron Microscope (SEM), specific gravity, Dynamic Mechanical Thermal Analysis (DMTA) and specific gravity were used to investigate the structures. PUUEs chemical structures were characterized by FTIR. The data on the scattering of the wide-angle X-ray is ascribed to the TPU matrix hard parts phase segregation.The results of DSC and XRD backed up the amorphous and crystalline type of PUEs with 12 and 33 wt % of hard segment (HS), respectively. Changing in molecular structure cases changing in hard segment and specific gravity. This was enhanced in HS, leading to changing in storage modules and damping factor. Damping factor decrease 75% and velocity and acoustic absorption coefficient, in room temperature and 1Hz frequency, changes 200%.