Studies of domain morphology in segmented polyurethanes by pulsed NMR

Idiyatullin, Djaudat; Khozina, E. V.; Смирнов, В. С.

doi:10.1016/0926-2040(96)01229-5

Cited by 17 publications

(6 citation statements)

References 9 publications

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“…The ratio with the value closer to unity corresponds to the 3D morphology. The morphology of the TPU samples under investigation with high HS content is different from that found by Idiyatullin et al 11 in TPU samples obtained by copolymerization of poly(diethylene glycol) adiapte as soft blocks with 2,4-tolylene diamine and 2,4-toluene diisocyanate as hard blocks. In the latter case a 2D morphology was detected by spindiffusion experiments with a variable Goldman-Shen filter.…”

Section: Dominant Morphology and Effective Domain Sizescontrasting

confidence: 67%

“…We note that this is not the case for some segmented polyurethane samples, especially with low SS concentration. In this case the domains of the soft segments are surrounded by hard segments . The most simple structural units for the cases of 1D, 2D, and 3D spin diffusion for a SS/HS/SS morphology are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…In this case the domains of the soft segments are surrounded by hard segments. 11 The most simple structural units for the cases of 1D, 2D, and 3D spin diffusion for a SS/HS/SS morphology are shown in Figure 9. The initial localization of the magnetization produced by the DQ dipolar filter is shown by gray and belongs to the HS phase.…”

Section: Dominant Morphology and Effective Domain Sizesmentioning

confidence: 99%

“…Thus, an estimation of the size and morphology of the domains is of considerable interest. The spin-diffusion experiment to select the mobile phase with dipolar filter and varying preparation interval was proposed by Idiyatullin et al 11 for the study of domain morphology and sizes of polyurethane samples. This study was a continuation of the results presented by Demco et al 10 which shows that the spin-diffusion experiment can provide information about the morphology independent of scattering methods.…”

Section: Introductionmentioning

confidence: 99%

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Morphology of Thermoplastic Polyurethanes by¹H Spin-Diffusion NMR

et al. 2006

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The morphology and domain sizes are reported for a series of thermoplastic polyurethane (TPU) samples with different content in hard segments and the same molecular weight of the soft segments. NMR spin-diffusion experiments were employed with a 1H double-quantum dipolar filter to establish the dominant dimensionality of the spin-diffusion process, which is shown to take place in two and three dimensions for investigated samples. The correlation between mesoscopic and microscopic properties of the TPU samples is discussed. To this purpose the effective volume of the hard domains is correlated with the TPU content of the hard segments and the segmental orientation of the hard segments obtained from the 1H residual dipolar couplings. A semiquantitative model is developed to explain the functional dependence of the residual second van Vleck moment on the effective volume of the hard segments.

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Section: Dominant Morphology and Effective Domain Sizescontrasting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: Dominant Morphology and Effective Domain Sizesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Morphology of Thermoplastic Polyurethanes by¹H Spin-Diffusion NMR

et al. 2006

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“…The NMR spin-diffusion or magnetization transfer experiment taking place on a mesoscopic scale is mediated by the dipolar couplings and provides information on different aspects of structural heterogeneities in a broad range of spatial dimensions from 0.1 nm to about 200 nm. ,− Despite the impressive efforts to analyze quantitatively the spin-diffusion process, several fundamental problems remain to be solved. − It is mainly the one-dimensional or lamellar model, with a two- or three-phase morphology, that has been considered earlier in analytical 5,11-14 and numerical solutions − of the spin-diffusion equations. In many cases the analytical solutions which provide more physical insight into the spin-diffusion process were used in the short-time regime to obtain information about the domain sizes.…”

Section: Introductionmentioning

confidence: 99%

General Analytical Description of Spin-Diffusion for a Three-Domain Morphology. Application to Melt-Spun Nylon 6 Fibers

et al. 2003

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The NMR spin-diffusion process taking place in a morphology represented by three different domains with arbitrary sizes and diffusivities is investigated. General analytical solutions valid for the full range of spin-diffusion times were obtained for a one-dimensional lamellar morphology. The accuracy of these solutions has been tested by predicting the domain sizes for a poly(styrene-b-methyphenylsiloxane) diblock copolymer and semicrystalline poly(ethylene oxide) and comparing them with previously reported data. The effects of large changes in the size of the interface domain and the spin-diffusion coefficients of this domain on the spin-diffusion decay and build-up curves can be analyzed by numerical simulations. General analytical solutions of the spin-diffusion equations were used for investigating the complex morphology of high-speed melt-spun nylon 6 fibers. The NMR mobile amorphous, NMR less-mobile amorphous, and crystalline phases of nylon 6 fibers hydrated with D2O were detected and quantified using 1H spectra and spin−lattice relaxation rates. Proton spin-diffusion experiments were performed on nylon 6 fibers using a dipolar filter based on magic- and polarization-echoes for the mobile amorphous phase. The results of this experiment can be interpreted by considering that the 1H magnetization front which emanates from the mobile amorphous phase explores crystalline/less-mobile amorphous aggregates. The domain sizes of the mobile amorphous phase, the interface, and aggregates can be estimated using analytical solutions of the spin-diffusion equations and correlated with the spinning speed and the draw ratio of the nylon 6 fibers.

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