Weight-average molecular mass

The reactive nature of compound 22 is illustrated by the series of transformations shown in Scheme 7.12, in which its Zr—C bond reacts selectively with electrophilic reagents to produce a-haloboronates 36—38. Compound 22 also catalyzes the polymerization of styrene. The polymers thus obtained had weight-average molecular masses in the range 75000—100000 with polydispersities of 1.8—2.1. An X-ray analysis of 22 confirmed it to be a four-coordinate Zr complex with two cyclopentadienyl rings, chlorine, and the aliphatic C-l carbon atom as the ligands (Fig. 7.4). 

Consideration was given to multibranching processes finite aggregation distribution (a sol), infinite aggregate (a gel) existence criteria, and relations for the determination of mole- and weight-average molecular masses of the finite aggregates. 

Molecular weight measured by GPC. Weight-average molecular mass is Aiw = i A/2/ Number-... 

Molecular weight measured by GPC (polystyrene standard). Mw is weight-average molecular mass and Mn is number-average molecular mass. 

Weight-average molecular mass, 18 Weissenberg effect, 526 number, 57,556 Wet fastness, 881 Wide-line NMR, 368,373, 374 WLF... 

Figure 16 represents schematically a vatiation of molecular mass and content of sol fraction, calculated on the basis of the branching the ory, in the process of three-dimensional polycondensation of multifunctional compounds [89, W]. According to these calculations, the weight-average molecular mass of curing oligomer increases monotonically up to the gel point where it diverges. At this same point the gel appears. A real variation of the same characteristics, obtained on the basis of GPC analysis of curing of an epoxy resing with diamine and dibutylphthalate has a different nature (Fig. 17). Molecular mass of the resulting...

A weight-average molecular mass M also is used for polymer characterization. This parameter is given multiplying the weight fraction Wi/W by the molecular mass M and is defined by the formula ... 

Fig. 10. Dependence of weight average molecular mass of poly (methacrylonitrile) on conversion. Monomer concentration 1 = 1,2 2 = 2,1 mol/1 [Et3P] = 10 mmol/1...

My = viscosity molecular mass Af = weight average molecular mass) (b) example of a real mass distribution, more complex than the simple distribution in part (a)... 

Narrow molecular mass distribution (reduction of the weight-average molecular mass)... 

Fig. 5 Polypropylene degradation during dissolution at high temperature, (a) Shift of MMD and (b) weight-average molecular mass (M ) versus dissolution time in TCB with 300 ppm BHT, with and without nitrogen purge...

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