L.p.b.m. Janssen | University of Groningen (original) (raw)

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Papers by L.p.b.m. Janssen

Journal of Vinyl and Additive Technology

IOP Conference Series: Materials Science and Engineering

Attempts to reduce net CO2 emission and to increase the use of sustainable ma- terials pose great... more Attempts to reduce net CO2 emission and to increase the use of sustainable ma- terials pose great challenges at the interface of chemical engineering and agricultural en- gineering. One of the products involved is thermoplastic starch that can partly substitute synthetic plastics, amongst others in packaging. In a first step a semi product is produced by mixing starch and a

... The value of the exponent, b. was in all cases higher in the second part of the plot. This re... more ... The value of the exponent, b. was in all cases higher in the second part of the plot. This result is in good agreement with some of the results of Malkin (13). ... 41, No. 3 599 Page 6. M. Cwa AC Ho@na.nn, and L. P. B. M. Janssen h 6 t! u) u) m a, c u) K U L 1000 1 1 600 - 400 - 200 - ...

De aanleiding tot het samenstellen van dit boek vormde het feit dat verschillende gegevens welke ... more De aanleiding tot het samenstellen van dit boek vormde het feit dat verschillende gegevens welke de fysisch technoloog vaak nodig heeft om 'snel' iets door te rekenen in de literatuur verspreid worden aangetroffen. Door de meest gebruikte tabellen, correlaties en grafieken te bundelen (en eventueel te herleiden tot S.I.-eenheden) is dit naslagwerk ontstaan, dat nuttig kan zijn, zowel bij het bestuderen als bij de beoefening van de Fysische Transportverschijnselen. Het boek is niet alles-omvattend; vaak moesten wij een keuze maken. Bij onze literatuurstudie is bijvoorbeeld gebleken, dat alleen voor de stofoverdracht aan deeltjes, druppels en bellen al meer dan 100 correlaties bestaan. In dergelijke gevallen hebben wij gekozen voor de meest algemene of de meest gebruikte correlaties. Dit betekent dat dit boek geen substituut is voor-een literatuurstudie. Dit tabellenboek bestaat uit vier onderdelen: Het eerste deel geeft de algemene informatie die, zoals de ervaring ons heef...

The aim was to understand and describe quantitatively Marangoni convection in order to determine ... more The aim was to understand and describe quantitatively Marangoni convection in order to determine its influence on mass transfer processes. The flow and concentration gradients in a well defined model system (acetone in water) in containers with different geometries under microgravity and terrestrial circumstances were studied. Developments in research on Marangoni convection to establish the influence of the actual shape of the interface in the onset of Marangoni convection, induced by the evaporation of acetone from a water/acetone mixture are discussed. As an extension of this research the acetone concentration was investigated in the liquid by means of interferometry. New experiments were performed during parabolic flights in order to record well defined flow patterns in the containers. A cooperation was also started with investigators of protein crystallization under microgravity in order to determine what the influence of fluid flow (Marangoni convection) could be on protein cr...

Starch - Stärke, 1995

A quantitative 1H-NMR method for the determination of the Molar Substitution (MS) of acetylated a... more A quantitative 1H-NMR method for the determination of the Molar Substitution (MS) of acetylated and hydroxypropylated starches was developed and tested for MS ranging from 0.09 to 0.5. Results were checked using the Johnson method and a titration method for hydroxpropylated and acetylated starch, respectively. Hydroxypropylated starch was produced using both a static mixer reactor (SMX type) and a co-rotating twin screw extruder. Acetylated starch was produced using a counter-rotating twin screw extruder. Quantitative analysis results of the 1H-NMR method were in good agreement with traditional analysis methods for all samples tested. Main advantage of the 1H-NMR method is the considerable time saving as compared to the traditional analysis methods.Quantitative Analyse von chemisch modifizierten Stärken durch 1H-NMR-Spektroskopie.Eine Bestimmungsmethode des Substitutionsgrades von acetylierter und hydroxypropylierter Stärke mittels 1H-NMR auf molare Substitution (DS) von 0,09-0,05 wurde entwickelt. Die hydroxypropylierte Stärke wurde in einem Static-Mixer (SMX) und einem selbstreinigenden Doppelschnecken-Kneter hergestellt. Die acetylierten Stärken wurden in einem gegenläufigen engschließenden Doppelschnecken-Kneter gewonnen. Die hydroxyopropylierten Stärkeprodukte wurden mit der Johnson-Methode und durch 1H-NMR analysiert. Die acetylierten Stärkeprodukte wurden durch Titration und 1H-NMR untersucht. Beide Methoden erbrachten ähnliche Ergebnisse mit guter Korrelation.

Rheologica Acta, 1980

An explanation for wall slip in polymer solutions is given from a thermodynamic point of view. Du... more An explanation for wall slip in polymer solutions is given from a thermodynamic point of view. Due to flow induced diffusion, a slip film at the wall consisting of pure solvent can form if a dimensionless number exceeds its critical value. The general conclusions agree qualitatively with experimental findings of others.