Handbook of Size Exclusion Chromatography and Related ...

Figure 6 Analysis of two commercial polyethylene samples, three columns PLgel
10 mm MIXED-B, 300 7.5 mm, eluant trichlorobenzene, flow rate 1 mL/min,
temperature 1608C, detector refractive index (RI).
these “capillaries” may have effective diameters 0.4 times the particle diameter.
Therefore it can be predicted that higher shear rates associated with small particle
size packings would prove to be more likely to incur polymer shear degradation in
SEC (22). This phenomenon is most relevant to the analysis of high molecular
weight polymers that exhibit high intrinsic viscosity in solution since shear stress
t ¼ hg, where h is the viscosity of the polymer solution and g is the shear rate. In
order to minimize the effects of shear degradation in SEC it is therefore necessary
to use larger particle size packings to reduce g and lower sample concentrations to
Figure 7 Effect of column length on separation using PLgel 10 mm MIXED-B columns,
eluant tetrahydrofuran (THF), flow rate 1 mL/min, detector RI, (a) one 300 7.5 mm, (b)
three 300 7.5 mm, PL EasiCal polystyrene standards; (1) M p ¼ 3,040,000; (2)
Mp ¼ 330,000; (3) Mp ¼ 66,000; (4) Mp ¼ 9200; (5) Mp ¼ 580; (6) toluene.
© 2004 by Marcel Dekker, Inc.