Molecular weight z+1-average

Table 1.5 also includes two additional types of molecular weight average besides those already discussed. The following remarks describe some features of these two, the z-average molecular weight, and the viscosity average ... 

Note that the weight and Z average molecular weights so obtained are only approximate and less than the true values. This is a consequence of the universal calibration method giving the instantaneous number average molecular weight across the chromatogram. 

Similarly, we calculate the weight average molecular weight (Mw), z average molecular weight (Mz), and z + 1 average molecular weight (Mz+ J from Eqs, 5.2,5.3, and 5.4, respectively. 

Table 1 Key parameters of the molecular weight distribution for three samples of PpPTA polymer from which yarns have been spun. Mz is the z-average molecular weight [52]...

Figure 3.1 Schematic of a molecular weight distribution and the number average, weight average, and z average molecular weights...

The third important average molecular weight is the third moment or the z average molecular weight, M. This average is calculated from the molecular weight distribution as follows ... 

The z average molecular weight has been found to correlate with the shear viscosity of polymer melts when the molecular weight distribution is very broad and where very large molecules appear to dominate the resistance to fluid flow. 

A polymeric composition for use in foam manufacture comprises a linear low density polyethylene and a resiliency modifier resin. The linear low density polyethylene is present in an amount of from about 1 to 90 weight percent of the polymeric composition and has a z-average molecular weight greater than about 700,000. The resiliency modifier resin is present in an amount of from 10 to about 99 weight percent of the polymeric composition and may be a low density polyethylene. 

However, melt elasticity is more closely related to the third moment known as the z-average molecular weight M. The values of are most often determined using either light-scattering photometry or ultracentrifugation. It is shown mathematically as ... 

Weight-average molecular weight, z-average molecular weight, z + 1-average molecular weight. 

Thus a plot of 1/Mw ipp(cell) vs. c0, could yield B from the limiting slope, and BLs could be estimated from Equation 90, provided one had an estimate of Mz, the z-average molecular weight. This method was restricted to lower speeds (to avoid solute redistribution problems) and to solutions that were not too nonideal. More recently, Deonier and Williams (37) showed that... 

The Z-average molecular weight follows from the formula... 

The commonly used molecular weight parameters are the number, weight, and z average molecular weight, which are defined, respectively, as 6... 

---