Initial monomer concentration

Seed No. Initial Monomer Concentration (moles/kgm) Initial BuLi Concentration (moles/kgm) M n D n M w M n Used In Runs Nos. 

M , = equilibrium monomer concentration Mo = initial monomer concentration (mol/L)... 

Simultaneous integration of these equations by numerical methods can provide the concentrations of A,B1,B2 and B3 as a function of time and the concentrations of o-methylol, p-methylol and methylene ether (note earlier definition) groups can be calculated as follows, where CONC is the initial monomer concentration. 

The data given below are typical of the polymerization of vinyl phenylbutyrate in dioxane solution in a batch reactor using benzoyl peroxide as an initiator. The reaction was carried out isothermally at 60 °C using an initial monomer concentration of 73 kg/m3. From the following data determine the order of the reaction and the reaction rate constant. Note that there is an induction period at the start of the reaction so that you may find it useful to use a lower limit other than zero in your integration over time. The reaction order may be assumed to be an integer. 

Determine the order of the reaction and the reaction rate constant if the initial monomer concentration is M0. 

Some of the vinyl monomers polymerized by transition metal benzyl compounds are listed in Table IX. In this table R represents the rate of polymerization in moles per liter per second M sec-1), [M]0 the initial monomer concentration in moles per liter (M) and [C]0 the initial concentration of catalyst in the same units. The ratio i2/[M]0[C]0 gives a measure of the reactivity of the system which is approximately independent of the concentration of catalyst and monomer. It will be observed that the substitution in the benzyl group is able to affect the polymerization rate significantly, but the groups that increase the polymerization rate toward ethylene have the opposite effect where styrene is concerned. It would also appear that titanium complexes are more active than zirconium. The results with styrene and p-bromostyrene suggests that substituents in the monomer, which increase the electronegative character of the double bond, reduces the polymerization rate. The order of reactivity of various olefinically unsaturated compounds is approximately as follows ... 

The initial rates of polymerization of styrene (R) at 30°C in toluene for different initial concentrations of Zr(benzyl ([C]o), while maintaining the initial monomer concentration ([M]0) constant, is shown in Fig. 12. The relationship between the initial rate of polymerization of styrene and monomer concentration was complex, and a plot of [M]0/i against... 

Fig. 16. Changes in the number average molecular weight of polystyrenes prepared in toluene at 30°C using Zr(benzyl) as initiator at different initial monomer concentrations...

Polymerization of Styrene by Zr(benzyl)t ([C]o = O.OS M) in Toluene at SO°C. Dependence of Molecular Weights and Polydispersity on Initial Monomer Concentrations... 

Although the initial monomer concentration was very high (25-200 g/1), soluble polymers were obtained even after complete conversion of DIPB. The measurements of the content of pendant isopropenyl groups indicated that poly(4-iso-propenyl-a-methyl) styrene was formed. 

Thus, within the approximations on which scheme (1) is based, the yield Y/( 1 + Y) of ring product is solely determined by the value of the initial monomer concentration relative to the kintra/kdim ratio, which Stoll et al. termed the cyclisation constant C. C has units of mol 1 1 and represents the monomer concentration at which intra- and intermolecular processes occur at the same rate. That Stoll et al. disregarded the fact that two monomer units are used up in the intermolecular condensation, as well as that the monomer disappears by reaction with functional groups at the ends of polymer chains was pointed out by Morawetz and Goodman (1970), who proposed an alternative approximate solution to the problem, as based on... 

The variation of DP with initial monomer concentration in n-pentane solution at -78° was studied in a series of experiments [54] in which the catalyst concentration was so adjusted that the conversion was always below 10 per cent. Flowever, these results and similar ones obtained with the same system presented in a later paper [56] are so scattered that no detailed correlation can be deduced. The only possible firm conclusion is that with increasing monomer concentration the DP declines from a peak of about 1.6 x 104 at [i-C4H8] 1 mole/l to about 2.5 x 103 for the polymerisation of the undiluted monomer. 

The subsequent fall-off means that the DP decreases as the monomer concentration at which the polymer is being formed decreases. This is the normal behaviour, but it appears to be in direct contradiction to the results obtained at very low conversion with different initial monomer concentrations. These, however, can also be explained by impurities present initially being progressively consumed. 

In the first tube we found a (so far unidentified) phenyl ether its concentration increased with the initial monomer concentration and corresponded to about 10"2 M in the monomer, and it was independent of, and much smaller than the acid concentration. In the second tube we also found phenyl ether, whose concentration was also much smaller than that of the perchloric acid. 

Although the self-assembly of polymeric structures can involve nucleation and elongation steps (See Actin Assembly Kinetics Microtubule Assembly Kinetics), one can simplify the assembly process through what is known as seeded assembly. At an initial monomer concentration [M], seeded assembly is induced by the addition of pre-assembled polymeric structures consequently the polymer number concentration must remain constant. The rate of monomer incorporation into indefinite length polymers can be written as follows ... 

In batch reactions, where the yield is high and no additional monomer is added, at the end of the reaction the average content of each monomer imit in the total copolymer formed will necessarily be directly related to the initial ratio of the two monomers. Thus, the copolymer content will vary depending on when the particular chains are formed but the final overall product will have an average of units in it reflective of the initial monomer concentrations. 

In a homogeneous isothermal liquid polymerization, 20% of the monomer disappears in 34 minutes for initial monomer concentration of 0.04 and also for 0.8 mol/liter. What rate equation represents the disappearance of the monomer ... 

---