Separator trimodal

Zorbax PSM Bimodal and Trimodal columns are packed with mixed pore-size packing to achieve linear size separations over a broad molecular weight range (Table 3.3). Zorbax PSM Bimodal columns are packed with PSM 60 and PSM 1000 particles, and Trimodal columns contain PSM 60, PSM 300, and PSM 3000 particles (Fig. 3.4). Carefully selecting and mixing different pore-size particles in columns provide much better linearity than coupling columns that are each packed with single pore-size particles. 

A trimodal distribution is a frequency distribution of a certain phenotype with three peaks separated by two antinodes. 

G enesky, G. Cohen, C., Toughness and Fracture Energy of PDMS Bimodal and Trimodal Networks with Widely Separated Precursor Molar Masses. Polymer 2010,51, 4152-4159. 

Poly(N,N-dimethylacrylamide) (PDMA) star polymers with 2, 3, and 4 arms and with dodecyl chains as hydrophobic end-caps were obtained in high yield with narrow polydis-persities by means of the RAFT technique. At sufficiently high concentration they form interconnected hydrophobic domains, i.e., a transient network. SANS experiments show that these hydrophobic domains contain about 20 dodecyl chains and they interact repulsively due to the PDMA chains that separate them. While the static structure is only very little affected by the number of arms this applies not at all to the dynamic properties as observed by DLS and rheology. Here one observes in DLS a complex, trimodal relaxation process, where the slower modes become more pronounced with increasing munber of arms. The fast mode corresponds to the diffusion of the hydrophobic domains while the second mode shows no q-dependence and corresponds in its values to the time deduced from the cross-over of G and G" in the oscillatory rheological experiments. Finally the slowest motion shows a rather pronounced q-dependence and is pre-stunably linked to a more complex relaxation mechanism of... 

The polysilanes synthesized usually show a trimodal mass distribution containing a low molecular weight cyclic and a medium and a high molecular weight fraction of linear polymer. The oligomeric fraction can easily be separated from the other two by solvent extraction, whereas the fractionation of the medium and high molecular weight products requires more effort. 

Some methods of producing polymers can lead to distinct subpopulations, widely separated in mass. When there is a distribution with only a single maximum, the population is termed unimodal. When two or more identifiable maxima exist within a polymer population, it is termed multimodal that is, bimodal for two subpopulations, trimodal for three, and so on. 

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