Polydisperse coefficient

By means of the latter relations, kinetic schemes can be completely solved, mean degrees of polymerization can be derived, as well as the polydispersity coefficients of polymers terminated by disproportionation (= Sf +1 V p) and of macroradicals or inactive macroradicals after transfer (= S + 1 /S l). For the number, weight, and z average, k = 0, 1, and 2, respectively. 

Szwarc and Zimm described the consequences of transfer in the sense of eqn. (41) by means of differential equations [29], and O Driscoll simulated the system corresponding to the above scheme by the Monte Carlo method [30], Both kinds of approach produced polydispersity coefficient (PJPn) vs. time plots which were practically identical at longer times. 

The width of the distribution function can be roughly characterized by the polydispersity coefficient, v, which is equal to the ratio of the weight and number averages... 

Both kinds of approach produced polydispersity coefficient vs. 

Polydispersity coefficient kd is one more significant value characterizing the quality of resulting disperse systems [146] ... 

Polydispersity coefficient ko (1.22) is one more important magnitude characterizing resulted emulsions. For monodisperse systems - kn = 1 and for polydisperse kn < 1, and the lesser the ko parameter value, the bigger the dispersal of particles by their sizes. The ratio Ls/dd practically doesn t influence on resulted emulsions polydispersity as in the case of dispersions formation with surface-volumetric diameter d32 (Fig. 3.33). Particles dispersal is increased when dd/dc ratio is raised and sufficiently homogeneous emulsions are formed in divergent-convergent canal of tubular apparatus with dd / d = 1,6. In particular for Ls / dd = 2-3 the value of ko at dd / dc = 1,6 is 0,72-0,75, where as at da / d = 2 and 3 kn is decreased down to 0,63 and 0,41 accordingly. 

Figure 5.21. Dependence of polydispersity coefficient Fw/ Tn of BaS04 particles on mixing rate. Tubular turbulent apparatus (1) variant 1 (3) variant 2 (2, 4) after preliminary formation in the absence of mixing and aging for 90 min (4).

Another important parameter characterising the quality of dispersed systems is the polydispersity coefficient [78] ... 

An increase of the reactor radius during polymer production creates a more perceptible effect on changes of the polymer MW characteristics, the P valne for method I does not demonstrate significant changes with an increase of the intensity of heat removal through a metallic wall. The polydispersity coefficient stays constant in this case. Catalyst input method II (model II) shows a substantial decrease of PJP , which approaches exponential behaviour and simultaneous growth of P . 

Another important quantity that characterizes the quality of the emulsion is the polydispersity coefficient k. Ratio Lyd almost no effects on the polydispersity of emulsions obtained. The increase in the spread of the dispersed phase in size is observed during increasing of the ratio d /d, and quite homogeneous emulsion is formed in the diffuser confused channels tubular device with d /d = 1.6. In particular, the value of k in d /d =1.6 for Lydp = 2-3 equals 0.72-0.75, whereas the k is reduced to 0.63 and 0.41when the ratio d /d is 2 and 3, respectively. 

For molecular weight distributions with a finite width Mw is always larger than Mn- The ratio of the two mean values may be used to specifiy the width of the distribution. One introduces the polydispersity coefficient U defined as... 

Table 2.2. Polydispersity Coefficients of Oligomer Systems According to Parameters of Molecular Weight Distribution and Functionality Type Distribution. [16-18]...

Type Numbe r Oligomer Formula Polydispersity Coefficient Possible Reasons of Functionality Type Distribution... 

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