Influence of Microstructure on Micro-/Nano-Mechanical Measurements of Select Model Transparent Poly(urethane urea) Elastomers.

摘要

Morphology of 4,40 -dicyclohexylmethane diisocyanateepoly (tetramethyleneoxide) (PTMO)ediethyl toluenediamine based poly(urethane urea) (PUU) elastomers is investigated by atomic force microscopy (AFM) and comparedwith elastic modulus data measured from AFM-enabled indentation, dynamicnanoindentation (nanoDMA), and dynamic mechanical analysis (DMA). These measurements highlight the effect of altering the molecular weight (Mw) of PTMO, which is used as a soft segment (SS), on the microstructure. Inparticular, at SS Mw 2000 g/mol, a strong microphase-separated morphology is observed, whereas a phase-mixed dominated microstructure is noted in PUU with SS Mw of 1000 and 650 g/mol. These observations arealso consistent with DMA tan d results. Furthermore, instrumented impactindentation is also utilized for elucidation of dynamic damping characteristics in these PUUs.