Effect of monomer concentration

We have studied the effect of monomer concentration in the dispersion polymerization of styrene carried out in alcohol-water mixtures as the dispersion media. We used AIBN and poly(acrylic acid) as the initiator and the stabilizer, respectively, and we tried isopropanol, 1-butanol, and 2-butanol as the alcohols [89]. The largest average particle size values were obtained with the highest monomer-dispersion medium volumetric ratios in 1-butanol-water medium having the alcohol-water volumetric ratio of 90 10. The SEM micrographs of these particles are given in Fig. 15. As seen here, a certain size distribution by the formation of small particles, possibly with a secondary nucleation, was observed in the poly-... 

Figure 1 Effect of monomer concentration on the total conversion percent and grafting efficiency. LR 30 I, acid concentration l%, initiator concentration 0. l%, grafting time 1 h, and reaction temperature 27°C — = total conversion (%) O—O = grafting efficiency (%).

Cotton linters and viscose grade wood pulp were grafted with acrylamide using the xanthate method. The effects of monomer concentration, reaction time, hydrogen peroxide concentration, reaction temperature, and liquor ratio on the grafting process were studied. Optimum conditions for the grafting reaction were established [26]. 

In experiments in which the effect of monomer concentration was studied the polarity of the medium was maintained by replacing aliquots of the monomers by /i-hexane cosolvent, so that the total volume of n-hexane and monomer remained constant. This technique was also used in model studies. 

Table 7. The effect of monomer concentration on the polymerization of aMeSt using the HSi(CH3)2CH2CH2

The effect of monomer concentration was studied using n-pentane solvent and maintaining the total volume of isobutylene plus n-pentane constant. Methyl halide concentration was kept constant so as to maintain constant medium polarity. Attempts were made to keep conversions below 20%. At -30 °C, due to almost explosive polymerizations, conversions could only be maintained below 40%. 

While the effect of monomer concentration [M] on Mv of PIB has been studied by a number of workers using a ariety of initiator systems11-13, such studies have not yet been carried out using M . The objective of this phase of research was to determine the effect of [M] on M and thus to calculate relative rate constants of isobutylene polymerization from GPC data. 

The effect of monomer concentration [M] on the molecular weight may be expressed... 

Figure 4 The effect of monomer concentration on DP [56]. Temperature -78°. Solvent CH3C1. Catalyst A1C13 in CH3C1...

In a series of experiments at -180° the effect of monomer concentration on DP was investigated [61]. The catalyst concentration was much smaller than that used in the previous series, so that the reactions stopped at about 10 per cent conversion. 

The effect of monomer concentration on the dependence of the DP on temperature. Further studies [12,52, 62] of the temperature dependence of the DP showed that the Arrhenius plot was approximately linear over the temperature range -5° to -78° for all concentrations of isobutene from about half-molar to undiluted monomer, and that the slope of the line increased with decreasing concentration in such a way that all the lines crossed at approximately the same temperature, -50°. This means that at -50°, the inversion temperature , the DP is independent of monomer concentration at lower temperatures it decreases, at higher temperatures it increases with increasing monomer concentration. This behaviour was found for polymerisation in methyl, ethyl and vinyl chloride as solvents. 

Polymerization of Styrene with 2,2 -Azobisisobutyronitrile in Solution (Effect of Monomer Concentration)... 

Fig. 8. Polymerization of vinyl monomers by vibromilling polyamide. Effect of monomer concentration on yielding 1) styrene 2) acrylonitrile (13)...

Fig. 30a-d. Polymerization of methyl methacrylate by high speed stirring of polyethylene oxide solution, a) effect of monomer concentration on polymerization rate (PEO 4 g/100 ml, stirring speed 30000 rpm. b) effect of monomer (MMA) concentration on intrinsic viscosity of reaction mixture (PEO 4 g/100 ml, stirring speed 30000 rpm, solvent benzene, c) effect of PEO concentration on polymerization rate, d) effect of PEO concentration on intrinsic viscosity of reaction mixture (Stirring speed 30000 rpm)... 

Effect of Monomer Concentration, Coinitiator Concentration, and Conversion on the Composition of Poly(4-methyl-l-pentene). 77... 

Effect of Monomer Concentration on the Number-Average Molecular... 

The second objective of our work was to investigate the relation between synthesis conditions and the composition of poly(4-methyl-l -pentene). Having developed a satisfactory method for determining the composition of the polymer, a study was undertaken of the effect of monomer concentration, coinitiator concentration, conversion, temperature, coinitiator type, and solvent polarity on the composition of the polymer. 

Table 4. The effect of monomer concentration, EtAlCl2 concentration, and conversion on the composition of poly(4-methyI-l-pentene)...

Table 4 shows the effect of monomer concentration, coinitiator concentration, and conversion on the composition of poly(4-methyl-1-pentene) using EtAlCl2 coinitiator at — 50° C. The 1,2-, 1,3-, and 1,4-repeat unit concentrations in the polymer have been determined from polymer spectra by use of a computer curve simulator-plotting program and are rounded to the nearest percent. No limits of error are indicated since none could be determined analytically. A reasonable error is thought to be +15% of the measured value. 

The effect of monomer concentration on the rate of polymerization of 4-methyl-1-pentene was investigated using ethylaluminum dichloride coinitiator in ethyl chloride solvent at — 30°, — 50°, — 70°, and — 80° C. Results are compiled in Table 5 and shown in Fig. 18. 

The investigations of the effect of monomer concentration on polymer composition and polymerization rate provide detailed insight into the polymerization mechanism. 

The effect of monomer concentration on number average molecular weight indicates that while transfer to monomer occurs within an ion-counterion-monomer complex with an activation energy equal to that of propagation, termination occurs in an uncomplexed ion-counterion pair and decreases relative to propagation with decreasing temperature. 

Figure 13. Effect of monomer concentration fed into a piston flow prereactor on steady-state particle number produced (reaction conditions SF = 6.25 g/L H20 lF = 1.25 g/L H20 residence time 0t = 20 min)...

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