Conversion-time curve

Stoicescu and Dimonie103 studied the polymerization of 2-vinylfuran with iodine in methylene chloride between 20 and 50 °C. The time-conversion curves were not analysed for internal orders but external orders with respect to catalyst and monomer were both unity. Together with an overall activation energy of 2.5 kcal/mole for the polymerization process, these were the only data obtained. Observations about the low DP s of the products, their dark colour, their lack of bound iodine and the presence of furan rings in the oligomers, inferred by infrared spectra (not reported), completed the experimental evidence. The authors proposed a linear, vinylic structure for the polymer, and a true cationic mechanism for its formation and discussed the occurrence of an initial charge-transfer complex on the... 

The initial rate of polymerization was determined from the initial slopes of time-conversion curves (Fig. 1) using f-BuX/Me3 Al/MeCl systems at -40 °C. This... 

Fig. 7. Calculated time/conversion curves and experimental data points in the anionic polymerization of MMA (C0 = 0.1 mol/1) initiated by methyl-a-lithioisobutyate (C0 = 0.05 mol/1) at 25 °C in THF (Products higher than the tetramer are omitted) (A. H. E. Muller, L. Lochmann, J. Trekoval, Ref.S0))...

One of the calculation results for the bulk copolyroerization of methyl methacrylate and ethylene glycol dimethacrylate at 70 C is shown in Figure 4. Parameters used for these calculations are shown in Table 1. An empirical correlation of kinetic parameters which accounts for diffusion controlled reactions was estimated from the time-conversion curve which is shown in Figure 5. This kind of correlation is necessary even when one uses statistical methods after Flory and others in order to evaluate the primary chain length drift. 

Fig. 7. Time-conversion curves of thermally initiated emulsion polymerization of 1,4-DVB at 0.1 (I) 0.65 (II) and 0.85 (III) M SDS concentrations. Polymerization temperature = 90 °C water/monomer volume ratio = 12.5. [Reproduced from Ref.84 with permission,Hiithig Wepf Publ., Zug, Switzerland].

Along the discussion developed above, the shapes of time-conversion curves in Figures 2 and 3 are qualitatively interpreted. 

Figure 3. Time-conversion curves in the bulk polymerization of DAP using 0.1 mol/L of BPO at 80°C (O ) total polymer, ( ) gel polymer.

Figure 8.15. Time-conversion curves for the pol5nnerization of MM with Mn=46,500 and various multimonomer concentrations (o) [MM] = 6.30x10 mol/L (A) [MM]=25.20xl0 mol/L ( )...

Figure 11.2. Time-conversion curve for polymerization of multiacrylate in dioxane (o) at 75°C, and ( ) at 85°C. Reprinted from R. Jantas, J. Szumilewicz, G. Strobin, and S. Polowinski, J. Polym.

Fig. 33. Polymerization of 1,2-epoxypropane (PO) by the (Me4DBTAA)AlCl (12)-methylalu-minum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) system, [P0]o/[3e]o/[12]o=200/1.0/ 1.0, [12]o=71.4 mM, without solvent, rt. Time-conversion curve...

Although an appreciable amount of termination is found at elevated temperatures, rate constants can be calculated from the initial slope of the first-order time-conversion curve. The concentration of living ends is calculated from the linear plot of the number-average degree of polymerization vs. conversion.which still remains linear when termination occurs, since the total number of chains remains unaltered., provided nor intermolecular termination (grafting) nor transfer occurs. 

PMMA Ba in THF by adding monomer at certain time intervals and measuring the first-order time-conversion curve for monomer addition, the slope of which is proportional to c. The first-order de-... 

The time conversion curves of the polymerisation initiated by tributyl amine are shown in Fig 11. They resemble the curves presented in Fig. 10, indicating the basic similarity of the process initiated by tertiary amines, by salts of carboxylic adds and by LiCl in dimethyl... 

The time-conversion curves do not pass through the origin in spite of all precautions taken, there was always a small dark reaction. This dark reaction is obviously caused by traces of light penetrating into the ampule during the preparation and is not caused by a thermal reaction. The conversion of the dark reaction in experimental times is always so small that it does not have any implications for the size of the radiation-induced reaction. Irradiation of a solution of polyisobutene in carbon tetrachloride in the absence of chlorine showed that only negligible amounts of chlorine (about 2 weight %) were taken up from the solvent. 

In view of the almost ideal behaviour of this copolymerization, the polymerization process could be continued to complete conversion without any inhomogenity in the composition of the products. The time conversion curve for the copolymerization is shown in Fig. 3.4. 

UV light induced grafting onto wood cellulose is reported for several vinyl monomers. The reaction is initiated by free radical initiators such as phenylace-tophenone and benzophenone derivatives. Percent grafting-time conversion curves are determined as a function of the initiators, monomers, pulps and additives. Additional typical results obtained in IR spectroscopy, GPC and thermal analysis are reported. A discussion about the use of a photochemical procedure in obtaining cellulose graft copolymers is presented. 

Figure 2. Time conversion curve for the reaction of inulin monosuccinate with CDI in DMSO at 25°C. [anhydrofructofuranoside units]0 = 31 mM, [CDI]Q = 240 mM.

Figure 1. Time-conversion curve for DOL polymerization with EtsOBFh at 30°C.

Figure 1 shows time-conversion curves of MMA polymerization in phenolic resol by using various initiators. 

Figure 2 shows time-conversion curves of MMA polymerization in phenolic resol compared with that in toluene. In phenolic resol, MMA polymerization proceeded more rapidly. However, there was a short induction period. These results suggest that by selecting the appropriate initiator, vinyl compound/phenolic IPNs can be expected. 

Figure 2. Time-conversion curve of MMA polymerization. (Reproduced from ref. 11. Copyright 1986 American Chemical Society.)...

Added salt can increase the rates of aliphatic amine polymerization more than ten fold. Salt effects are generally more marked under conditions which promote slow polymerization. Even lithium bromide increases the polymerization rate and at low temperatures in the presence of this salt, initiation is complete and polymer molecular weights are determined by monomer/initiator ratios. The time-conversion curves for the butyl monomer at low temperatures in the presence of lithium bromide are not first order throughout, but like the ethyl ester show an initial acceleration. 

In their second paper these authors investigated in detail the rde of the dielectric constant of the medium. Their ingenious experiments proved that the parent dependence of the conversiwi upon the initial monomer concentration was solely due to changes in the solution polarity and that for a given acid concentration the time-conversion curves relative to a series of pdymerisations with different mcmomer con-centraticais could be reduced to a sin e line simply by adjusting the dielectric constant... 

Fig. 1. The similarity of behaviour in the polymerisation of styrene by two strong acids. A Time-conversion curves for the polymerisation of styrene by perchloric acid in CH2Q2 at 0 °C with low [M]q/...

The system ethylaluminium dichloride-isobutene- -heptane in the temperature range —55 to 21 °C was shovwi to initiate in the absense of any cocatalyst No mention was given in this paper about the pol3unerisation 5 ields, but from a figure giving the time-conversion curve for a typical mn it can be concluded that reactions did not reach 100% conversion, at least within the first few minutes. 

Fig. 4. Time-conductivity and time-conversion curves for a polymerisation of isobutene initiated by EtAlQ2 with subsequent addition of EtsAl. [MJq = 0.1 M (EtAia2l = l.Ox lO- M (EtsAlJ = 1.1 X 10 M solvent CHaQ T = -45 C (Taken from Ref. 409))...

On the basis of a presumed stationary state, k was equated to kjkp/kt. No mention was made of S-shaped time-conversion curves despite the fact that this is a general feature in systems involving styrene and trityl salts ... 

Kohjiya and Yamadiita investigated the polymerisation of cyclopentadiene by acetyl perchlorate in toluene-methylene chloride mixtures. They found a kinetic behaviour entirely simUar to that of the system cyclopentadiene-perchloric acid, which they had studied previously. In fact, in the same solvent mixture and at the same temperature the time-conversion curves were practically identical. For a criticism of the method... 

In 1970, Funt and Blain published a thorough study of the electroinitiated polymerisation of styrene in the presence of tetrabutylammonium perchlorate. The kinetics of these reactions were followed in methylene chloride with a cell provided with a sintered-glass membrane and a sampling device at the anode compartment. S-shaped time-conversion curves were obtained indicating the accumulation of chain carriers during the electrolysis. The results were treated assuming that the concentration of active species was directly proportional to the time-integrated current flow, and that no termination oc-... 

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