Homopolymer apparent viscosity

With most homopolymers and copolymers the apparent viscosity is less dependent on temperature and shear stress (up to 10 dyn/cm ) than that of the polyolefins, thus simplifying die design. On the other hand the melt has a low elasticity and strength and this requires that extruded sections be... 

Figure 6.2 Apparent viscosity of PVDF homopolymer vs temperature at 100 l/sec.i >...

Figure 7.28 Apparent viscosity of PVDF homopolymer vs shear rate at 232°C." ...

If reductions in gloss are desired, crosslinked PVC resins can be blended with homopolymer resins. In order to maximize gloss reduction, the apparent viscosity of the crosslinked resin should be higher than that of the homopolymer resin it is being blended with. 

If no primary standards are available two approaches can be taken, either polystyrene standards are used to provide an apparent molecular weight or alternatively for homopolymers and copolymers the universal calibration can be employed. This method developed by Benoit utilises the fact that the elution volume of different polymer types in the same solvent is proportional to their molecular weight and their intrinsic viscosity. The intrinsic viscosity can be obtained either by a viscometer detector or be calculated from the Mark-Houwink equation... 

The viscosity for high molecular weight SPS homopolymer as a function of apparent shear rate is shown in Rgure 14.3 for typical melt processing temperatures [3]. 

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