Poly initial growth rates

Dry poly(methyl methacrylate) layer thickness as a function of exposure time at a light intensity of 5mW/cm. Methyl methacrylate concentrations in toluene are ( ) 1.17, ( ) 2.34, and ( ) 4.68 M. Arrows indicate the apparent mushroom-to-brush transition for the concentrations studied, and the dotted lines show the behavior of an ideal, living photopolymerization. The slopes of these lines also represent the initial growth rates of the PMMA layer. (Reprinted with permission from Rahane, S. B., et al.. Kinetics Macromolecules, 38, 8202-8210, 2005, copyright (2005) American Chemical Society.)... 

Fig. 11.43 Plot of initial growth rate G for a 60/40 isotactic-atactic poly(styrene) blend as a function of molecular weight of the atactic component, at indicated crystallization temperatures. (From Okada et al. (94))...

The mesh plots show different slopes of productivity, depending on i and qp, and the poly(3HB) content. How an increase in i or qp enhances productivity is presented in Fig. 5, starting from two different pairs of actual jli and qp values. Each of the initial values was increased by 20% or 40%. If both specific velocities are increased, then the productivity increases in the same way. Starting from jli = 0.35 h 1 and qp = 0.15 g g 1 h 1 (A) optimization of the growth rate has a stronger effect over a broader range of final poly(3HB) contents than starting from jli = 0.2 h 1 and qp = 0.05 g g 1 h 1 (B). 

The dependence of the overall crystallization rate on the composition of these two blends differs from those of the growth rates.(77) The half-time for syndiotactic poly(styrene) crystallization is plotted against the crystallization temperature for both type blends in Fig. 11.33. The half-times for the pure syndiotactic polymer are represented again by the sohd circles. For this type of measurement the halftimes increase with the addition of either poly(vinyl methyl ether) or PPO. The addition of poly(vinyl methyl ether) causes a larger increase in the half-time and thus a greater reduction in the crystallization rate. The overall crystallization rate is a reflection of both initiation and growth of crystalUzation. Both of these processes... 

Polymers that show a rate maximum with respect to temperature in the pure state do so also when crystallizing from diluent mixtures.(42a,67,88) Two examples are shown in Figs. 13.32 and 13.33 for isotactic poly(styrene) crystallizing from ether benzophenone or dimethyl phthalate respectively.(42a,67) Characteristically, the addition of the diluent causes a shift of the crystallization range to lower temperatures. A similar effect was observed with bisphenol-A poly(carbonate).(88) In addition, the growth rate maximum increases with the initial addition of diluent. This phenomenon is observed up to about 20% diluent in the case of benzophenone (Fig. 13.32) and about 50% with dimethyl phthalate (Fig. 13.33). A similar pattern is also indicated for the poly(carbonate)-diluent mixture.(89) With further additions of diluent there is a continuous decrease in the growth maxima up to very dilute... 

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