Dispersity index

Figure 6. Cumulative dispersion index vs. conversion with batch-mass styrene...

In summary, the attributes of the elastomer that contribute to the enhanced impact strength of a plastic in plastic mbber blend include the type of mbber, plastic to mbber ratio, particle size, particle size distribution, cross-Unk density, and degree of grafting, if any. Molecular weight and molecular weight distribution of the plastic also exert some influence. For example, for high-impact PS, the optimal molecular weight of PS is between 170,000 and 220,000. The dispersity index is... 

Pollock et al.(12) have also exploited the fact that poly dispersity index is a function of C2 only in a study utilizing a Monte-Carlo simulation technique to compare error propagation in the method of Balke and Hamielec to a revised method (GPCV2) proposed by Yau et al. (13) which incorporated correction for axial dispersion. 

A round-bottom flask was charged with 15 ml of a toluene and water, 2 1, respectively, phenyltrimethoxysilane (0.02 mol), p-chloromethylphenyltrimethoxysilane (0.02 mol), and methanesulfonic acid (5 mol%) and then stirred at ambient temperature for 12 hours. The organic layer was isolated, concentrated, and then added dropwise to a large quantity of -hexane. The precipitated solid was filtered, dried, and the product isolated in 93 % yield having an Mn of 1300 Da with a poly dispersity index (PDI) of 1.25. 

Abbreviations ODA = ortho dispersant index, BAPP = butyl acetate poly propylene, PDMA = poly dimethyl acrylate, and PDA = phenylene diamine. 

Abbreviations-. PEO = poly ethylene oxide, PHB = poly hydrobutyrate, and PDI = poly dispersity index. 

The severity of agitation and separation determines whether the separated medium is considered to have proteins in solution (protein solubility values) or in dispersion (protein dispersion values). The terms Nitrogen Solubility Index (NSI) and Protein Dispersibility Index (PDI) are to be used only when the official... 

Thus, from a log-log plot of any of the above equations, and W and n obtained from the universal calibration curve and the GPC trace, the dispersity index D can be easily determined. 

Method C makes use of a so called dispersion analyzer, which is a particular form of stylus type surface roughness meter. The principle is that the worse the dispersion the rougher the surface. A dispersion index is obtained from the number of peaks/cm and average height of peaks measured, plus material constants obtained by method B. The object appears to be to use the analyzer as a convenient routine control method after the compound has been evaluated by the more tedious method B. 

Protein dispersibility index Dry product is dispersed in water by blending, then centrifuged at 880 x g for I0 min Protein dispersibility index (%) = (% water-dispersible prolein/% total protein) x 100 Advantages Tested in a collaborative study and found to be reproducible between laboratories. Disadvantages Limited to soy products protein is determined by Kjeldahl analysis, which can be a lengthy procedure. AOCS Method B a 10-65 (AOCS, 1999) AACC Method 46-24 (AACC, 2000)... 

The polydispersity of dendritic molecules, expressed in the form of their poly-dispersity index (PDI), is directly related to their structural perfection. The PDI is a measure of molecular weight distribution. 

The variance measures the absolute breadth of the distribution, but properties that depend on the width of the distribution would depend on the width relative to the average. For this reason the dispersion index is defined as the ratio of the weight to the number average molecular weight, which is related to the variance as follows ... 

Figure 14 shows a plot of the Dispersion Index DI = Mw/M wersus the conversion X of the monomer for segregated flow (S) and well micromixed flow (M). The dramatic influence of segregation can be noticed at high conversion, especially with transfer to polymer. Moreover, an interesting effect is observed with diluted and slow initiators, namely an inversion of the relative position of S and M curves when the transfer constant ktp is increased. 

Figure 15. Effect of segregation on polymerization of styrene in cyclohexane solution. Standard CSTR with h baffles and a 6-blade turbine, V = 670 cm, T = 75 °C. Dispersion Index DI vs. space time. Influence of agitation speed. Curves S (segregated flow) and M (well-micromixed flow) calculated from batch experiments. Initiator PERKAD0X l6, A = 0.033 mol L - -, kd = 5 x 10 5 s-1, f = 0.85 Mq = 6.65 mol L l, SQ = 2.22 mol IT1.

Average particle area fraction AF, standard deviation (6AF), and normalized dispersion index (NDI). 

The normalized dispersion index NDI was calculated from the data of the particle area fraction in each TEM micrograph (at least twenty photographs were taken from different sites in a sample). 

The proposed normalized dispersion index (NDI) has been shown to be a sensitive measure of the "goodness" of particle dispersion in space. An NDI value of. 142 was shown to be a critical level of dispersion that demarcates two totally different types of crazing behavior in HIPS. 

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