Characteristic ratio molecular weight

The emulsifying effect of a copolymer can be characterized by determining the type of emulsion (DMF in hexane or hexane in DMF), its stability, its viscosity, and the particle size of the dispersed phase. These characteristics of oil-in-oil emulsions obtained with PS-PI block copolymers were studied as functions of solvent volume ratio, molecular weight, composition, and structure of the copolymer (5). Although Bancroft s rule was established for conventional oil-water emulsions, it appears to apply also to oil-in-oil emulsions—the continuous phase of the emulsion is preferentially formed by the solvent having the best solubility for the emulsifier (6, 7). Thus, block or graft copolymers can be prepared giving hexane/DMF, DMF/hexane, or both types of emulsions. 

As shown in Refs. 22 and 33, the performance of the feedforward control allows perfect compensation of disturbances that can arise, for example, from a step-change in the purge ratio, so that the reactor polymer characteristics (composition, molecular weight) are unaffected. Without the presence of the feedforward controllers the reactor dynamics and hence its control can be affected directly by the presence of three lags in series (reactor, separator, hold tank) and thus become unnecessarily more complex. 

The dilute solution properties of copolymers are similar to those of the homopolymer. The intrinsic viscosity—molecular weight relationship for a VDC—AN copolymer (9 wt % AN) is [77] = 1.06 x 10 (83). The characteristic ratio is 8.8 for this copolymer. 

Thus, if the ratio AT//3 is constant, then the behavior shown in Fig. 12 could be described by the net solution. For many polymers, the characteristic ratio is around 7-10, the ratio Mo/j is the molecular weight per backbone bond (ca. 30-50) and will not vary extensively, b = 1.54 A and the density is about 1 g/cm such that the parameter is nearly constant. Since K is not very sensitive to the polymer properties, Eq. 6.5 is considered to describe the observed fracture behavior shown in Fig. 12. However, the data are not expected to fall on the straight line due to differences in K and j6 for each polymer. As a specific test case, consider... 

Observable Characteristics - Physical State (as normally shipped) Liquid Color Colorless to slight yellow Odor Extremely sharp - lachrymator piercing and disagreeable extremely Physical and Chemical Properties - Physical State at 15 °C and 1 atm. Liquid Molecular Weight 56.1 Boiling Point at 1 atm. 127, 53, 326 Freezing Point -125, -87, 186 Critical Temperature 489, 254, 527 Critical Pressure 737, 50.0, 5.08 Specific Gravity 0.843 at 20 °C (liquid) Vcq>or (Gas) Density 1.94 Ratio of Specific Heats of Vapor (Gas) 1.1487 Latent Heat of Vaporization 216, 120, 5.02 Heat of Combustion -12500, -6950, -290 Heat of Decomposition Not pertinent. 

Observable Characteristics -Slfatc (as normally shipped) Solid Color White Odor None. Physical and Chemical Properties - Physical State at IS T7 and I atm. Solid Molecular Weight 142.11 Boiling Point at I atm. Not pertinent (decomposes at 70°C) Freezing Point Not pertinent (decomposes at 70°C) Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.50 at 18.5°C (solid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats afVqtor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat of Combustion Data not available Heat of Decomposition Not pertinent. 

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