1997
DOI: 10.1021/ma961851n
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NMR Investigations of Self-Diffusion and Shear Thinning for Semidilute Polymer Solutions near the Demixing Transition

Abstract: Pulsed gradient spin echo and rheo-NMR methods are used to investigate semidilute solution properties of high molecular mass polystyrene in cyclohexane, in the vicinity of a demixing transition. The dependence of polymer self-diffusion on temperature and molar mass is measured using PGSE NMR. The molar mass variation is consistent with M -2 scaling while the temperature variation in approach to demixing can be modeled as a glass transition process using the WLF equation. The measured values of the demixing tra… Show more

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Cited by 19 publications
(24 citation statements)
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“…For uncorrelated, Brownian motion of many molecules, the amplitude of the echo signal decreases due to molecular self-diffusion. By measuring the NMR signal with increasing gradient strength, flow velocities as well as self-diffusion and dispersion coefficients can be determined (Callaghan, 1991;Callaghan & Xia, 1991;Manz & Callaghan, 1997;Manz et al, 1998Manz et al, , 1999aManz et al, , b, 2003Seymour et al, 1999;Manz, 2004).…”
Section: The Mri Methodsmentioning
confidence: 99%
“…For uncorrelated, Brownian motion of many molecules, the amplitude of the echo signal decreases due to molecular self-diffusion. By measuring the NMR signal with increasing gradient strength, flow velocities as well as self-diffusion and dispersion coefficients can be determined (Callaghan, 1991;Callaghan & Xia, 1991;Manz & Callaghan, 1997;Manz et al, 1998Manz et al, , 1999aManz et al, , b, 2003Seymour et al, 1999;Manz, 2004).…”
Section: The Mri Methodsmentioning
confidence: 99%
“…The phase shift arises from correlated molecular displacements (e.g., flow) over the well-defined interval D. For uncorrelated, Brownian motion the amplitude of the echo signal decreases due to molecular self-diffusion. By measuring the NMR signal with increasing gradient strength g, flow velocities as well as self-diffusion coefficients can be determined (Callaghan, 1991;Callaghan and Xia, 1991;Manz and Callaghan, 1997).…”
Section: Magnetic Resonance Imagingmentioning
confidence: 99%
“…As demonstrated here, substantial information about the putative role of xylem lipids in withstanding drying and facilitating subsequent rehydration could be obtained by light and electron microscopy and in particular by the numerous complementary variants offered by NMR spectroscopy and imaging (Kuchenbrod et al ., 1995, 1996, 1998; Volke & Pampel, 1995; Bentrup, 1996; Manz & Callaghan, 1997; Manz et al ., 1997, 1999; Meininger et al ., 1997; Volke et al ., 1997; Pampel et al ., 1998; Rokitta et al ., 1999; Seymour et al ., 1999; Wagner et al ., 2000; Wistuba et al ., 2000; Peuke et al ., 2001; Zimmermann et al ., 2001). In contrast to the microscopy techniques, the noninvasive NMR methods allowed measurements on lipid composition, mobility and distribution on the same branch both in the presence and absence of water.…”
Section: Introductionmentioning
confidence: 99%