Kinetics of SPS

Wu and Woo [26] compared the isothermal kinetics of sPS/aPS or sPS/PPE melt crystallized blends (T x = 320°C, tmax = 5 min, Tcj = 238-252°C) with those of neat sPS. Crystallization enthalpies, measured by DSC and fitted to the Avrami equation, provided the kinetic rate constant k and the exponent n. The n value found in pure sPS (2.8) points to a homogeneous nucleation and a three-dimensional pattern of the spherulite growth. In sPS/aPS (75 25 wt%) n is similar (2.7), but it decreases with increase in sPS content, whereas in sPS/PPE n is much lower (2.2) and independent of composition. As the shape of spherul-ites does not change with composition, the decrease in n suggests that the addition of aPS or PPE to sPS makes the nucleation mechanism of the latter more heterogeneous. 

Several authors have addressed crystallization measurements and kinetics of SPS [23-26,78-82]. The experiments were carried out in both isothermal and non-isothermal mode by means of differential calorimetry techniques (DSC) [24-26,78-82]. 

In the section on structure and fundamental properties of SPS, Chapter 9 summarizes the polymorphic behavior of this polymer, the structure of the different forms, and the crystallization and melting behavior. Chapter 10 describes co-crystals and nanoporous crystalline phases of SPS regarding preparation, structure, properties, and new interesting applications, for example, molecular sensors. The section concludes with Chapter 11 on selected topics of crystallization thermodynamics and kinetics of SPS. 

Protoplast fusion induced by polyethyleneglycol and Ca was carried out between two auxotrophic mutants of Aspergillus sp. CH-Y-1043. The hybrids obtained showed significant differences in endopectinase activity and morphology compared to the prototrophic strain. Strains grown on lemon peel showed production improvement with respect to the parental strain. Since H15 hybrid showed up to 90% higher endopectinase production than the wild type CH-Y-1043, kinetics of enzyme production in Fernbach flasks and Fermentor (14L) by H15 were determined. 

Four intraspecific hybrids were finally selected and they were grown to obtain the kinetics of endopectinases production and extracellular protein content. The course of endopectinase production by Aspergillus sp. CH-Y-1043 and hybrids during their growth on 1 % lemon peel is shown in Figure 1. 

Rapp P (2001) Multiphase kinetics of transformation of 1,2,4-trichlorobenzene at nano- and micromolar concentrations by Burkholderia sp. strain PS14. Appl Environ Microbiol 67 3496-3500. 

Tatara GM, Ml Dybas, CS Griddle (1993) Effect of medinm and trace metals on kinetics of carbon tetrachloride transformation by Pseudomonas sp. strain KC. Appl Environ Microbiol 59 2126-2131. 

Chang JS, Lin YC (2001) Decolorization kinetics of recombinant E. coli strain harboring azo dye decolorization determinants for Rhodococcus sp. Biotechnol Lett 23 631-636... 

In order to investigate the dependence of a fast reaction on the nature of the metal, Iwasita et al. [3] measured the kinetics of the [Ru(NH,3)6]2+/3+ couple on six different metals. Since this reaction is very fast, with rate constants of the order of 1 cm s-1, a turbulent pipe flow method (see Chapter 14) was used to achieve rapid mass transport. The results are summarized in Table 8.1 within the experimental accuracy both the rate constants and the transfer coefficients are independent of the nature of the metal. This remains true if the electrode surfaces axe modified by metal atoms deposited at underpotential [4]. It should be noted that the metals investigated have quite different chemical characteristics Pt, and Pd are transition metals Au, Ag, Cu are sd metals Hg and the adsorbates T1 and Pb are sp metals. The rate constant on mercury involved a greater error than the others... 

In this report the TTA process has been studied taking into account new experimental data indicating that the ADF emitted from metalloporphyrin upper electronic states is of dimeric nature. Moreover low values of P2 obtained in (6) can be explained by the lesser probability of dimer singlet staTes emitting in comparison with the monomer. But true probabilities of Sp state formation from TTA processes may be quite high. We have been able to establish simultaneous relations between diffusion parameters and annihilation characteristics obtained from spectral kinetic measurements. 

In addition, we investigated a nonlinear-like effect (NLE), activity, temperature dependence, and kinetics of hydroxy[2.2]paracyclophane ketimine ligands with the 1,2-addition reaction of diethylzinc to cyclohexylcarbaldehyde. A linear correlation between the enantiomeric excess of AHPC ketimine ligands bearing a phenylethyl side group and the product was observed with 0.5 mol% of catalyst loading. When the catalyst loading of (Sp,S)/(Rp,R)-4a was increased to 4 mol%, a precipitate of the inactive heterochiral species was formed and resulted in a positive nonlinear like effect (Fig.2.1.3.6), while a linear behavior is observed with 5b (Fig. 2.1.3.7). The enantiomeric ratio was found to have linear temperature dependence. [16]... 

Photochemical Generation of an Interfacial Shock Wave. Both the an-thocyanidine and the thioindigo monolayers showed a decrease in surface pressure at constant area during the photoisomerization reaction. A different behavior is observed with mixed monolayers of the surface active spiropyran SP and octadecanol (OD), molar ratio SP 0D = 1 5, on illumination with UV radiation. The isomerization of the spiropyran to the merocyanine MC causes an increase in surface pressure at constant area (5, 14). This is shown in Figure 4, where the sudden rise in surface pressure it upon repeated 0.5 s exposures (as indicated by the arrows) can be seen to occur in a wide surface pressure range (15). The kinetics of the relaxation process following the surface pressure increase depends on the surface pressure. 

Mertens R, von Sonntag C (1994) Determination of the kinetics of vinyl radical reactions by the characteristic visible absorption of vinyl peroxyl radicals. AngewChem Int Ed Engl 33 1262-1264 Mezyk SP, Madden KP (1999) Self-recombination rate constants for 2-propanol and ferf-butyl alcohol radicals in water. J Phys Chem A 103 235-242... 

However, even though this transformation is thermodynamically favored, the diamond allotrope still exists at high pressures and over long time periods. That is, if a particular phase transformation is predicted as spontaneous, the acmal rate of that process will depend on the kinetics of the transformation. Since the sp carbon bonds in diamond are extremely strong, the kinetics governing the migration of carbon atoms between diamond-graphite is extremely slow at normal temperatures and... 

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