Rheological investigation of microphase separation transition of polyurethane elastomer

Abstract

A technique of linear viscoelasticity measurements coupling with temperature scanning was found effective in the detection of microphase separation transition (MST) and in the determination of MST temperature. The validity and accuracy of the technique were confirmed and reinforced by atomic force microscopy and differential scanning calorimetry (DSC). The technique was applied to a study of the MST of a series of 13 polyurethane (PU) elastomers based on mixed toluene diisocyanate (TDI), 1,4 butadiol, and poly(tetramethylene oxide) (PTMO) of two different molecular weights; the MST temperatures of the PU elastomer samples were measured. Although each of the 13 polymer samples had distinct hard segment content and used PTMO of different chain lengths, or mixed PTMO, the MST temperatures of the 13 samples formed a linear master curve when the MST temperature was plotted against the fraction of hard segment. The master curve indicated that the MST temperature is independent of the length and type of PTMO. It was also found that 2,4 TDI prevailing over its isomer 2,6 TDI played a dominant role in the MST of this series of PU elastomers.

Linear viscoelasticity and thermorheological simplicity of n-hexadecane fluids under oscillatory shear via non-equilibrium molecular dynamics simulations

“…As a whole, we observed that the values of G 0 and G 0 0 both increased with increasing o, but decreased upon increasing the temperature. Such a result was in qualitative agreement with the findings from related experiments by Yang et al, 78 who adopted atomic force microscopy (AMF) and differential scanning calorimetry (DSC) to investigate the linear viscoelasticity measurements and detected the microphase separation transition for polyurethane (PU) elastomer. Surprisingly, at higher frequencies (o > 6.28 Â 10 11 rad s À1 ), all of the G 0 0 (o) curves closely matched each other, demonstrating the temperature independence of G 0 0 .…”

Tuning physical properties of polyurethane hard segments through extender chain length variation and doping of pentaerythritol and their effect on in vitro protein adsorption

“…Also, the shear rate versus shear stress curves give an idea about the flow behavior of the material under processing conditions. From these data, information about the macromolecular packing, crystallinity as well as a pattern of H‐bondings can be obtained 52–54 . The measurements of the solid samples were carried out at RT by varying the shear rate in the range of 0–100 s −1 .…”

“…From these data, information about the macromolecular packing, crystallinity as well as a pattern of H-bondings can be obtained. [52][53][54] The measurements of the solid samples were carried out at RT by varying the T A B L E 3 DSC analysis data of as-synthesized hard segments of PUs with different lengths of chain extenders.…”

Effect of fillers on the microphase separation in polyurethane composites: A review

“…In our another study, 119 the microphase separation, cross‐linking density (CLD), and mechanical properties of PU‐Fe 3 O 4 composites prepared through in situ polymerization were studied. We found that a small amount of nano‐Fe 3 O 4 can greatly improve the CLD.…”

“…Schematic representation for microphase separation of (A) pristine polyurethane (PU); (B, C) PU nanocomposites filled with low and high Fe 3 O 4 contents (reproduced with permission from Reference 119). HD, hard microdomains.…”