Apparent average molecular weight

By osmotic pressure. M is apparent weight average mol.wt. yielded directly from LS experiment M is true weight average molecular weight obtained from the three values of M. ... 

In Equation 70 MWapp is the apparent weight-average molecular weight at any radial position r, where rm r r6. Now Equation 70 can be written... 

Sector-Shaped Centerpieces. Method 1. Do the Archibald experiment and calculate MWappft at rm and r6 using standard procedures (32, 34). Here MWapp/t is the value of the apparent weight-average molecular weight at rm or r6. Extrapolate these values of Mw pp)t to zero time to get MWapp° details for this extrapolation have been given by Fujita et al. (32). 

Analysis by the Archibald Method or by Sedimentation Equilibrium Experiments at Different Speeds. Instead of using Mweq here, one uses Mwa, the apparent weight-average molecular weight. For the Archibald experiment one obtains Mwa,t at rm or r6 by the application of Equations 13-16. The extrapolation of Mwa>t to zero time gives Mwo. For sedimentation equilibrium experiments at different speeds, one can evaluate Mwa by two different methods here one uses either Equations 17 or 18. For a mixed association such as A + B AB, the basic sedimentation equilibrium equation can be written as... 

Apparent Weight-Averaged Molecular Weight, kDa (Dextran Scale)... 

Analogous calculations give for the apparent weight-average molecular weight in the theta state... 

Figure 6-7. Concentration dependence of the inverse apparent weight-average molecular weight of a poly(y-benzyl-L-glutamate) in dimethylformamide at 70°C and in hexane-chloroform (v/v = 47.7/52.3) at 25°C (H.-G. Elias and J. Gerber).

Figure 9-5. The dependence on solvent of the apparent weight-average molecular weight (at c -> 0) of one industrially (T) and one azeotropically (A) produced copolymer of styrene and acrylonitrile with refractive index increments of the polystyrene (Ys), the polyacrylonitrile (Yan), and the copolymer (Ycp) (according to H. Benoit). The (M )app used here is extrapolated to c 0, and so is not the (M )app of Section 6.5 or the M pp of Section 9.5.4.

Table II Apparent weight-average molecular weight (g/mole) of PS-b-PEO block copolymers in chloroform, toluene and after complexation of LiCl to the PEO block in toluene...

The absorbance of the sample at 410 nm was measured across the cell and the data was analysed to give the dependence of apparent weight average molecular weight upon total d-bs concentration (Calabro et al., 1976). These data, in turn, were analysed to give the dependence of weight fraction of monomer upon the total d-bs concentration, assuming a monomer-octomer system (Calabro et al., 1976). 

It is apparent that numerous other special systems or effects could be considered to either broaden the range or improve the applicability of the derivation presented. Our interest, however, is in illustrating concepts rather than exhaustively exploring all possible cases, so we shall not pursue the matter of gelation further. Instead, we conclude this section with a brief examination of the molecular weight averages in the system generated from AA, BB, and Af. For simplicity, we restrict our attention to the case of r . = u... 

Typical of thermoplastics (see Chapter 8) the melts are pseudoplastic and also in common with most thermoplastics the zero shear rate apparent viscosity of linear polyethylene is related to the weight average molecular weight by the relationship... 

This new edition not only includes information on the newer materials but attempts to explain in modifications to Chapter 2 the basis of metallocene polymerisation. Since it is also becoming apparent that successful development with these polymers involves consideration of molecular weight distributions an appendix to Chapter 2 has been added trying to explain in simple terms such concepts as number and molecular weight averages, molecular weight distribution and in particular concepts such as bi- cmd trimodal distributions which are becoming of interest. 

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