Correlation Among the Structure of Hard Segment Micro-Phase, Mechanical Properties and Heat Resistance for PUU Elastomers
A series of polyurethane urea (PUU) elastomers were prepared,based on polytetramethyleneether glycol(PTMG) used as soft segment,tolylene diisocyanate(TDI),diphenyl methane diisocyanate(MDI) and mixture of TDI/MDI for their mole ratio of 1:1 as hard segment.The mechanical properties and heat resistance of PUU were investigated through correlation among the structure of hard segment micro-phase.The results show that the NH group stretching vibration band of TDI-based appears at 3270 cm-1,and that of MDI-based appeares at the higher wave number (3285 cm-1).Additionally,Tg(-57.6 ℃) of TDI-based (-57.6 ℃) is lower than that of the MDIbased (-49.5 ℃),and the initial degradation temperature instead.Mixture-based is located between them.Compared with MDI-based,the TDI-based shows the higher micro-phase separation degree,but exhibits worse mechanical properties.And with the temperature increasing,the absorption intensity of hydrogen bonded NH stretching vibration band is gradually weakened,and the band site shifts from the lower wave number to the higher wave numbers,and the mechanical properties of the PUU decrease gradually.When the temperature is 70 ℃,the slightly jump of wave numbers is observed,and the mechanical properties drop quickly.
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