Abstract
Original language  English 

Qualification  Doctor Degree 
Awarding Institution 

Supervisors/Advisors 

Award date  9 May 2014 
Place of Publication  Helsinki 
Publisher  
Print ISBNs  9789521098925 
Electronic ISBNs  9789521098932 
Publication status  Published  2014 
MoE publication type  G5 Doctoral dissertation (article) 
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Keywords
 Fieldflow fractionation
 continuous fractionation
 twodimensional separation
 thermal gradient
 polystyrene
 polymer
Cite this
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Development of continuous twodimensional thermal fieldflow fractionation for polymers : Dissertation. / Vastamäki, Pertti.
Helsinki : University of Helsinki, 2014. 96 p.Research output: Thesis › Dissertation
TY  THES
T1  Development of continuous twodimensional thermal fieldflow fractionation for polymers
T2  Dissertation
AU  Vastamäki, Pertti
N1  BS541 University of Helsinki, Department of Chemistry, Laboratory of Analytical Chemistry 61 p. + app. 35 p.
PY  2014
Y1  2014
N2  This research work is focused on the development of instrumentation, operation, and approximate theory of a new continuous twodimensional thermal fieldflow fractionation (2DThFFF) technique for separation and collection of macromolecules and particles. The separation occurs in a thin diskshaped channel, where a carrier liquid flows radially from the center towards the perimeter of the channel and a steady stream of the sample solution is introduced continuously at a second inlet close to the centre of the channel. Under influence of the thermal field, the sample components are separated in radial direction according to the analytical ThFFF principle. Simultaneously, the lower channel wall is rotating with respect to the stationary upper wall, when a sheardriven flow profile deflects the separated sample components into continuous trajectories that strike off at different angles over the 2D surface. Finally, the sample components are collected at the outer rim of the channel, and the sample concentrations in each fraction are determined using the analytical ThFFF. The samples were polystyrene polymer standards and the carrier solvents cyclohexane and cyclohexaneethylbenzene mixture in continuous 2DThFFF and tetrahydrofuran in analytical ThFFF. Positive effect of the thermal field on the sample deflection was observed, although broadening of the sample zone was observed. By decreasing the channel thickness and the radial and angular flow rate of the carrier, the zone broadening was significantly narrowed. The systematic variation of the experimental parameters allowed to determine the conditions required for the continuous fractionation of polystyrene polymers according to their molar masses. As an example, almost baseline separation was achieved with two polystyrene samples of different molar masses. Meanwhile, an approximate theoretical model was developed for prediction the trajectory of the sample component zone and its angular displacement under various operating conditions. The trends in the deflection angles without and with a thermal gradient were qualitatively in agreement with predictions of the model, but significant quantitative differences between the experimental results and theoretical predictions were also found. The reasons for discrepancies between the theory and the experiment could be the following: the sample is already relaxed at the sample inlet, effect of solvent partition using binary solvent as the carrier, dispersion of the sample, the instrumental limitations, and/or geometrical imperfections. However, the theoretical model will provide quidelines for future interpretation and optimization of separations in continuous 2DThFFF method
AB  This research work is focused on the development of instrumentation, operation, and approximate theory of a new continuous twodimensional thermal fieldflow fractionation (2DThFFF) technique for separation and collection of macromolecules and particles. The separation occurs in a thin diskshaped channel, where a carrier liquid flows radially from the center towards the perimeter of the channel and a steady stream of the sample solution is introduced continuously at a second inlet close to the centre of the channel. Under influence of the thermal field, the sample components are separated in radial direction according to the analytical ThFFF principle. Simultaneously, the lower channel wall is rotating with respect to the stationary upper wall, when a sheardriven flow profile deflects the separated sample components into continuous trajectories that strike off at different angles over the 2D surface. Finally, the sample components are collected at the outer rim of the channel, and the sample concentrations in each fraction are determined using the analytical ThFFF. The samples were polystyrene polymer standards and the carrier solvents cyclohexane and cyclohexaneethylbenzene mixture in continuous 2DThFFF and tetrahydrofuran in analytical ThFFF. Positive effect of the thermal field on the sample deflection was observed, although broadening of the sample zone was observed. By decreasing the channel thickness and the radial and angular flow rate of the carrier, the zone broadening was significantly narrowed. The systematic variation of the experimental parameters allowed to determine the conditions required for the continuous fractionation of polystyrene polymers according to their molar masses. As an example, almost baseline separation was achieved with two polystyrene samples of different molar masses. Meanwhile, an approximate theoretical model was developed for prediction the trajectory of the sample component zone and its angular displacement under various operating conditions. The trends in the deflection angles without and with a thermal gradient were qualitatively in agreement with predictions of the model, but significant quantitative differences between the experimental results and theoretical predictions were also found. The reasons for discrepancies between the theory and the experiment could be the following: the sample is already relaxed at the sample inlet, effect of solvent partition using binary solvent as the carrier, dispersion of the sample, the instrumental limitations, and/or geometrical imperfections. However, the theoretical model will provide quidelines for future interpretation and optimization of separations in continuous 2DThFFF method
KW  Fieldflow fractionation
KW  continuous fractionation
KW  twodimensional separation
KW  thermal gradient
KW  polystyrene
KW  polymer
M3  Dissertation
SN  9789521098925
PB  University of Helsinki
CY  Helsinki
ER 