Molecular weight distribution. See

Monomer conversion was 100% Multimodal molecular weight distribution, see Figure 1... 

The zero-shear viscosity r 0 has been measured for isotropic solutions of various liquid-crystalline polymers over wide ranges of polymer concentration and molecular weight [70,128,132-139]. This quantity is convenient for studying the stiff-chain dynamics in concentrated solution, because its measurement is relatively easy and it is less sensitive to the molecular weight distribution (see below). Here we deal with four stiff-chain polymers well characterized molecu-larly schizophyllan (a triple-helical polysaccharide), xanthan (double-helical ionic polysaccharide), PBLG, and poly (p-phenylene terephthalamide) (PPTA Kevlar). The wormlike chain parameters of these polymers are listed in Tables... 

Those reactions in which N,N,N, N -tetramethylethylenediamine was added gave no formation of insoluble material. In addition, the rate of formation of the soluble polysulfides was increased as shown not only by the amount of these polysulfides formed but also by their molecular weight distributions (see below). With a 25% loading after 1 hr, reaction is incomplete, with unreacted olefin still present. But, if the diamine is used, all the olefin reacts after 1 hr, and the resultant material contains 31.5% soluble polysulfides. 

Reactors used in ethylene polymerizations range from simple autoclaves and steel piping to continuous stirred tank reactors (CSTR) and vertical fluidized beds. Since the 1990s, a trend has emerged wherein combinations of processes are used with transition metal catalysts. These combinations allow manufacturers to produce polyethylene with bimodal or broadened molecular weight distributions (see section 7.6). 

Phenylurethane (carbamate) derivatives of insoluble polysaccharides, produced by reaction with PhNCO in neutral organic solvents, are used in determination of molecular weight distributions (see Section 4.5.1) carbamates are acid stable and base labile and have better alternatives as protecting groups in synthesis. 

Three basic characteristics of PEs determine their processing and end-use properties their density, melt index, and molecular weight distribution (see Chapter 2). Their range in density, from 0.890 to above 0.96 g/cm, is a result of their crystalline structure. This difference accounts for their property variations seen in Chapter 2. As one example, reducing PE s crystallinity increases its impact resistance, cold flow, tackiness, tear... 

In this case, it is useful to use the whole molecular weight distribution (see [60]) or a higher number of pseudocomponents for the modeling. As an example. Fig. 18 shows the molecular weight distributions of polystyrene in the two coexisting phases observed with cyclohexane/carbOTi dioxide solvent mixture [63]. An initially bimodal mixture of two polystyrene samples (40 kg/mol and 160 kg/mol) was mixed with cyclohexane and carbon dioxide at 170°C and different pressures to generate two hquid phases. 

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