Investigation of Soft Component Mobility in Thermoplastic Elastomers using Homo- and Heteronuclear Dipolar Filtered 1H Double Quantum NMR Experiments
✍ Scribed by Marko Bertmer; Lothar Gasper; Dan E. Demco; Bernhard Blümich; Victor M. Litvinov
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 237 KB
- Volume
- 205
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
Summary: Information about segmental mobility in thermoplastic elastomers was obtained using static ^1^H double quantum (DQ) NMR experiments in combination with homo‐ and heteronuclear dipolar filters, e.g. ^13^C editing of ^1^H DQ buildup curves. Block copolymers of poly(butylene terephthalate) (PBT) as hard blocks and poly(tetramethylene oxide) (PTMO) as soft blocks (PBT‐block‐PTMO) were investigated by varying composition and block length. By simulation of the DQ buildup curves, residual dipolar couplings and with this the average order parameter were deduced for the mobile PTMO blocks which are sensitive to the segmental mobility responsible for the viscoelastic properties of thermoplastic elastomers. A strong correlation exists between residual dipolar coupling and composition. Furthermore, the average order parameter correlates linearly with the amount of PTMO in a PTMO‐rich phase as determined in previous studies. Additionally, ^1^H transverse magnetization relaxation measurements revealed a direct correlation between the effective T~2~ relaxation time of the soft domain and the composition of the thermoplastic elastomers.
Correlation of the average order parameter vs. the fraction of PTMO in the PTMO‐rich phase.
imageCorrelation of the average order parameter vs. the fraction of PTMO in the PTMO‐rich phase.