Sedimentation Boundary Analysis of Interacting Systems: Use of the Apparent Sedimentation Coefficient Distribution Function

1994 ◽  
pp. 119-137 ◽  
Author(s):  
Walter F. Stafford
Keyword(s):  
Distribution Function ◽  
Sedimentation Coefficient ◽  
Boundary Analysis ◽  
Coefficient Distribution ◽  
Interacting Systems

An analysis of the sedimentation coefficient distribution of a sample of calf thymus DNA

1965 ◽  
Vol 12 (3) ◽  
pp. 517-524 ◽  
Author(s):  
Verne N. Schumaker ◽  
E. Glen Richards ◽  
S.T. Freer
Keyword(s):  
Sedimentation Coefficient ◽  
Calf Thymus Dna ◽  
Coefficient Distribution ◽  
Calf Thymus

Sedimentation Analysis of Styrene Butadiene Copolymer Rubber

1966 ◽  
Vol 39 (3) ◽  
pp. 622-630
Author(s):  
Terutake Homma ◽  
Hiroshi Fujita
Keyword(s):  
Molecular Weight ◽  
Distribution Function ◽  
Mass Distribution ◽  
Sedimentation Coefficient ◽  
Distribution Functions ◽  
Sedimentation Analysis ◽  
Molecular Weights ◽  
Integral Distribution ◽  
Styrene Butadiene ◽  
Theta Solvent

Abstract Methods are presented by which the limiting viscosity number [η]Θ and the limiting sedimentation coefficient s0 of a monodisperse linear polymer in its theta solvent as functions of the molecular weight M may be deduced from data taken with a series of polydisperse samples of the polymer. The necessary data are the limiting viscosity numbers and the distribution functions of s0 of the chosen samples in the theta solvent, plus their number-average molecular weights. The methods are applied to unfractionated and fractionated samples of a styrene-butadiene co-polymer rubber (SBR) having 24 weight per cent bound styrene in a theta solvent, 2-pentanone, at 21.0° C. The following relations are deduced for monodisperse unbranched SBR in this theta solvent: [η]Θ=1.73×10−3M21 and s0=0.83×10−15M21, where [η]Θ is expressed in deciliters/gram and s0 in seconds. Besides these, the viscosity—molecular weight relations for this cold rubber in toluene and in cyclohexane, both at 30° C, are established. The new relation for the toluene system does not accord with the French-Ewart relation for “hot” rubber in the same solvent. The integral distribution of molecular weight in an unfractionated SBR is calculated from its distribution function of s0 in 2-pentanone at 21.0° C by using the derived s0 versus M relationship, and is found to coincide well with the mass distribution obtained from fractionation data if the new viscosity—molecular weight relation is used for the molecular weight of each fraction.

scholarly journals Direct Measurement of Sedimentation Coefficient Distributions in Multimodal Nanoparticle Mixtures

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1027
Author(s):  
Claudia Simone Plüisch ◽  
Rouven Stuckert ◽  
Alexander Wittemann
Keyword(s):  
Sedimentation Coefficient ◽  
Practical Implementation ◽  
Particle Sizing ◽  
Physical Separation ◽  
Coefficient Distribution ◽  
Multimodal Distributions ◽  
Hazard And Risk ◽  
Hazard And Risk Assessment ◽  
Actual Shape

Differential centrifugal sedimentation (DCS) is based on physical separation of nanoparticles in a centrifugal field prior to their analysis. It is suitable for resolving particle populations, which only slightly differ in size or density. Agglomeration presents a common problem in many natural and engineered processes. Reliable data on the agglomeration state are also crucial for hazard and risk assessment of nanomaterials and for grouping and read-across of nanoforms. Agglomeration results in polydisperse mixtures of nanoparticle clusters with multimodal distributions in size, density, and shape. These key parameters affect the sedimentation coefficient, which is the actual physical quantity measured in DCS, although the method is better known for particle sizing. The conversion into a particle size distribution is, however, based on the assumption of spherical shapes. The latter disregards the influence of the actual shape on the sedimentation rate. Sizes obtained in this way refer to equivalent diameters of spheres that sediment at the same velocity. This problem can be circumvented by focusing on the sedimentation coefficient distribution of complex nanoparticle mixtures. Knowledge of the latter is essential to implement and optimize preparative centrifugal routines, enabling precise and efficient sorting of complex nanoparticle mixtures. The determination of sedimentation coefficient distributions by DCS is demonstrated based on supracolloidal assemblies, which are often referred to as “colloidal molecules”. The DCS results are compared with sedimentation coefficients obtained from hydrodynamic bead-shell modeling. Furthermore, the practical implementation of the analytical findings into preparative centrifugal separations is explored.

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