Jürgen Engelhardt
Bayer
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Featured researches published by Jürgen Engelhardt.
Polymer | 1996
Werner-Michael Kulicke; Arne Henning Kull; Wiebke Kull; Heiko Thielking; Jürgen Engelhardt; Jörn-Bernd Pannek
A set of car☐ymethylcellulose (CMC) samples was varied in degree of substitution (DS) from 0.71 to 2.95, with the partial degree of substitution being raised uniformly at positions C2, C3 and C6, so that a homologous series of CMC was made available. A further set of samples varied in molar mass from 200 000 to 2 000 000 g mol−1 at a constant DS of ∼ 1. The chemical structural parameters were determined by n.m.r. spectroscopy, showing that quantification of the degree of substitution at position C6 may be distorted by impurities of glycolic acid. The mean molar masses, for establishing the [η]-M relationship, were determined by multiangle laser light scattering preceded by size exclusion chromatography. The influence of concentration on zero-shear viscosity was given by η0 ∝ c4.3, whereas the influence of the molar mass was determined by η0 ∝ M3.9. An increasing DS within a homologous series influences the viscosity in different solvents (H2O 0.01 M NaCl, 0.1 M NaCl) at low polyelectrolytic concentrations. Surprisingly, the viscosity for all the CMC samples can be predicted by the single equation: η0[Pas]=8.91×10−4+1.30×10−5cMW0.9+5.33×10−8c2MW1.8+4.60×10−15c4.34MW3.91 at T = 298 K in 0.01 M NaCl. Increasing the DS up to a value of ∼ 1 improves the solubility characteristics (increases the viscosity), whereas above DS ≈ 1 this effect is overlapped by degradation of the molar mass. It was also possible to quantitatively determine the viscoelasticity as a function of frequency and molecular parameters.
Archive | 2008
Jürgen Engelhardt; Steffen Fischer; Kay Hettrich; Volker Dr. Kriegisch; Christa Maria Krüger; Klaus Nachtkamp; Manfred Pinnow
Archive | 2007
Klaus Nachtkamp; Christa Dr. Krüger; Jürgen Engelhardt; Volker Dr. Kriegisch; Steffen Fischer; Manfred Pinnow; Kay Hettrich
Archive | 2004
Roland Bayer; Frank Höhl; Hartwig Schlesiger; Arne Henning Kull; Jörn Dr. Pannek; Jürgen Engelhardt; Burkhard Kressdorf
Archive | 2008
Jürgen Engelhardt; Steffen Fischer; Kay Hettrich; Christa Maria Krüger; Klaus Nachtkamp; Manfred Pinnow
Archive | 2007
Jürgen Engelhardt; Birgit Kosan; Christa Maria Krüger; Frank Meister; Klaus Nachtkamp; Jens Schaller
Archive | 1996
Joachim Simon; Hanns Peter Dr. Müller; Dirk Dijkstra; Jürgen Engelhardt; Volkhard Müller; Gunter Weber
Archive | 1996
Jochen Kalbe; Reinhard Dr Koch; Hanns Peter Dr. Müller; Jürgen Engelhardt; Wolfgang Koch; Volkhard Müller
Archive | 1994
Jochen Kalbe; Hanns Peter Dr. Müller; Rainhard Koch; Jürgen Engelhardt; Wolfgang Koch; Klaus Szablikowski; Gunter Weber
Archive | 1995
Jochen Kalbe; Hanns-Peter Dr. Müller; Rainhard Koch; Jürgen Engelhardt; Wolfgang Koch; Klaus Szablikowski; Gunter Weber