Arrhenius plot polymerization

Figure 51. Arrhenius plot of ln 1/(3 [ Q t)ldt2]) from data corresponding to Fig. 54. The conformational energy consumed per mole of polymeric segments in the absence of any external electric field (AH) can be obtained from the slope. (Reprinted from T. F. Otero and H.-J. Grande, Reversible 2D to 3D electrode transition in polypyrrole films. Colloid Surf. A. 134, 85, 1998, Figs. 4-9. Copyright 1998. Reproduced with kind permission of Elsevier Science-NL, Sara Burgerhartstraat 25, 1055 Amsterdam, The Netherlands.)...

Fig. 2. Arrhenius plots of the rate constants of the anionic polymerization of methyl methacrylate in THF as the solvent and with Na+ orCs+ as the counterion. (R. Kraft, A. H. E. Muller, V. Warzelhan, H. Hocker, G. V. Schulz, Ref.35>)...

Figure 6, Arrhenius plot of A for polymerization of MM A initiated by AIBN using data of Figures 1-4...

Figure 2. Arrhenius plot for net polymerization rate constant.

Fig. 2.8 Arrhenius plot of permeation coefficients (a) bare glass plate (b) glass plate with unpolymerized monolayer (c) glass plate with polymerized monolayer. Reprinted with permission from [46], K. Ariga and Y. Okahata, /. Am. Chem. Soc., 1989, J J J,...

Another important feature is that all the terms are composite, and therefore it is not to be expected that the Arrhenius plots for the intercepts and slopes of the Mayo plots will be rectilinear. In fact, historically, the nonlinearity of such Arrhenius plots obtained for the polymerization of isobutene by titanium tetrachloride and water gave the first clue to the existence of simultaneous propagation by free ions and ion-pairs in that system [23]. 

Fig. 10 Arrhenius plots for the polymerization of various 2-oxazolines in acetonitrile. (Reprinted with permission from [68]. Copyright (2005) American Chemical Society)...

A review is given on the kinetics of the anionic polymerization of methyl methacrylate and tert.-butyl methacrylate in tetrahydrofuran and 1,2-dimethoxy-ethane, including major results of the author s laboratory. The Arrhenius plots for the propagation reaction+are linear and independent of the counterion (i.e. Na, Cs). The results are discussed assuming the active centre to be a contact ion pair with an enolate-like anion the counterion thus exhibiting little influence on the reactivity of the carbanion. 

Figure 1. Arrhenius plot of the propagation rate constants in the anionic polymerization of methyl methacrylate in THF using Na and Cs+ as the counterions (25)...

A differentiation of the Arrhenius-plot from Fig. 18 by means of spline polynomials gives the second term of the activation enthalpy (31), whereas its first term can be calculated in the way shown in Section 3.1. The results are given in Fig. 20 for three typical degrees of polymerization. The full lines show the temperature-dependence of the activation enthalpy (31), whereas the dashed lines show the corresponding reversible contributions (10a), as predicted by Casper s approximation ( q = 0, v = 1, a = 1) of Eq. (19) of the PDC-calibration curves. The dependence of AH on the degree of polymerization P at two typical column temperatures is shown in Fig. 21 where also the P-dependence of the corresponding activation entropies (33) is plotted for comparison (dashed lines). 

The stereochemistry of diene polymerization is somewhat dependent upon temperature note however the results of Morton and Rupert209 (Table 19). In general, linear Arrhenius plots are obtained. Some pertinent data are summarized in Table 21 for convenience results are presented for both solvating and non-solvating media. The structures obtained in solvating media are very different from those obtained in hydrocarbon solvents (cf Tables 17 and 22). The sensitivities to tempera-... 

Dilution with toluene slowed the copolymerization rate, and kinetic measurements were carried out in toluene at 0°-30°C. As reported previously (II), the over-all activation energy of the spontaneous copolymerization of CPT and S02 was calculated to be 16.5 kcal/mole from the Arrhenius plot of the initial rate vs. polymerization temperature. Dependence of the intial rate of copolymerization upon monomer concentration was checked at various monomer concentrations and found to be quite high (II) this could not be explained without participation of the monomer in the initiation step. 

Figure 1. Arrhenius plots of dependence of number of particles formed per cm3 water on temperature in the thermal polymerization of styrene emulsified with (I) potassium octadecanoate and (II) sodium dodecyl benzene sulfonate...

Figure 4. Arrhenius plot of the propagation constant, k , of sodium polystyryl polymerization in THF (lower curve) and in dimethoxyethane (upper curve). Note the negative activation energy (the lower curve) and the maximum in the upper curve...

Conversion vs. time at 30°, 40°, 50°, and 60° C. is shown in Figure 4. An Arrhenius plot of the polymerization rate vs. temperature in Figure 5 indicates an activation energy of about 15 kcal. 

FIGURE 14.12 Arrhenius plot for rotational correlation time data from TREPR spectra of polymeric radical 2a. Squares are the experimental data, solid line is the linear fit, with... 

Previous studies of the decomposition of cellulose reported Ea for absorbent cotton as 54.3 kcal/mol at a high-temperature range of 270-310 °C (23). For temperatures below pyrolysis, Ea = 20 kcal/mol reflects the low-temperature degradation effects of loss of H and OH from adjacent carbon atoms in cellulose (dehydration) and the concomitant creation of C=C bonds (24). In another work Ea = 21 kcal/mol was estimated from Arrhenius plots of the degree of polymerization versus time for cellulose heated in air at 150-190 °C (25). 

These apparent contradictions can be rationalized in terms of a model which incorporates plasma-induced polymerization along with depolymerization. PBS has long been known to exhibit a marked temperature-dependent etch rate in a variety of plasmas. This is clearly seen in the previously published Arrhenius plots (3,7) for two different plasma conditions (Figure 1). This dependence is characteristic of an etch rate that is dominated by an activated material loss as would occur with polymer depolymerization. The latter also greatly accelerates the rate of material loss from the film. Bowmer et al. (10-13) have shown in fact that poly(butene-l sulfone) is thermally unstable and degrades by a depolymerization pathway. A similar mechanism had been proposed by Bowden and Thompson (1) to explain dry-development (also called vapor-development) under electron-beam irradiation. 

Johnston and Pepper conclude that phosphines initiate near ideal living polymerizations. However, when the authors turned to amine initiators they found that, although macrozwitterions were formed, the polymerization kinetics were very different. At comparable reagent concentrations room temperature rates were at least one thousand times slower, but paradoxically increased as temperature was reduced. Arrhenius plots indicated that by -100°C amine and phosphine polymerization rates would be equal. Polymer molecular weights were much higher than would have been expected had initiation been complete, and were uninfluenced by polymerization conditions. It is believed that molecular weights are determined by traces of weak acid transfer agents present in the monomer. 

Toby et al. also determined activation enei es for gaseous formaldehyde polymerization from the Arrhenius plots (Fig. 19). The slopes in... 

---