Structure effect on the peel strength of polyurethane

A series of hydroxyl-terminated polybutadiene (HTPB) and 4,4'-dicyclohexylmethane (H12MDI)-based polyurethanes (PUs) with different molecular weights and hard segment contents were synthesized by solution polymerization. The peel strengths between these PUs and 3M-600 tape were measured. Surprisingly, PUs with the most hydrophobic composition showed the largest peel strength. The hydrogen bonding index (HBI) measured by Fourier transform infrared (FTIR) spectroscopy was employed to assess the extent of interchain hydrogen bonding, which affects the phase segregation, surface composition, and the peel strength of the prepared PUs. The surface composition was also determined by ESCA, which was used to identify the hard segment distribution on the surface. The results of FTIR and ESCA explain well the segregation and surface composition, and hence the peel strength as well.