Molecular weight distribution curve

Fig. 3. Molecular weight distribution curves as determined by gel-permeation chromatography. A represents i9f2v (9-phthahc resins B, highest molecular...

Fig. 4. Molecular weight distribution curves for representative polystyrenes.

Fig. 24a and b. Differential molecular weight distribution curves of polyisoprene prepared, a) with oligoisoprenyl-Li b) with oligoisoprenyl-Li in the presence of NNN N tetramethyl ethylenediamine [TMDA]/[OLi] = 0.01) (A. Davidjan, N. N. Lolaev, V. Sgonnik, B. Belenkii, V. Nesterov, B. Erus-salimsky, Ref. 1531... 

At present, however, the determination of the Molecular weight distribution curve is rather difficult. Hence, in polymer chemistry, the so-called Molecular weight of a polymer is merely a statistical average. 

The breadth of the Molecular weight distribution curve can be obtained as follows. The degree of polymerisation in given by... 

The manner in which the Macromoleculars of a product are distributed over the different Molecular weights can be seen from the Molecular weight distribution curve, which has its maximum at the Molecular weight most fraudulently present. However, in some cases two or more maximise may occur in distribution curves. Such a situation has been observed with natural products and also when we mix two polymers with different Molecular weights. 

Fig Typical cumulative molecular-weight distribution curve for a sample of polypropylene gradient-elution data (O) and data from gel permeation chromatography. 

Fig Gel permeation chromatography data for polystyrene to a molecular-weight distribution curve calculated from polymerisation kinetics. 

Calculate the number-average and weight-average molecular weights of this polymer sample. Draw a molecular weight distribution curve analogous to Fig. 1-4. 

In order to convert a chromatogram into a molecular weight distribution curve, a calibration curve relating molecular weight to retention volume is required. Narrow MWD standards (polydlspersity, M /li, is usually less than 1.1) of the polymer of interest are used to generate retention volume curves. A one to one correspondence of peak retention volume with peak... 

Figure 1.5 is a typical molecular weight distribution curve for a hgnosulfonate obtained by means of gel permeation chromatography (a sophisticated analytical method where molecules are sieved according to their molecular size). 

Data from the GPC of the unknown polymer samples are used to calculate the Mn, Mw, and Mw/Mn, and molecular weight distribution curves. The amount of polymer at any particular Ve or corresponding molecular weight, through correlation using the calibration curve, is proportional to the height of the curve, Ht, at that particular Ve ... 

Calculated from integral molecular weight distribution curves. 

Fig. 8. GPC elution (molecular weight distribution) curves of polypropylenes obtained at different polymerization times at —78 °C with the soluble V(acac)3/A1(C2H5)2C1 catalyst (from Ref. 47))...

For compounds bearing acrylate or methacrylate groups, the copolymer compositions were almost the same as the monomer feed compositions, and the molecular weights were nearly identical to that of poly(methyl methacrylate) (PMMA) synthesized as a control under the same reaction conditions. In addition, the dye-bearing repeat units were present uniformly in all molecular weights, as seen by comparing GPC molecular weight distribution curves determined by differential refractometry and by visible absorbance detection at the X of the... 

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