Feed composition, viscosity function

A general exponential equation (see Appendix for detailed discussions) of the form tj = rj0 exp (aXbt), at constant temperature, has been developed to predict the viscosity (97, CP) as a function of feed composition (X, mol fraction of DCP) and time (t, hr) rj0, a, and b are empirical constants rj0 is the viscosity at t = 0, a is in units of reciprocal time, and b is dimensionless. The assumptions made here are ... 

C with two feed compositions are shown in Tables I and II. Surface tension has been measured as a function of time, and the viscosity of the solutions are shown along with surface tension. The data clearly show that as the viscosity increases with time, surface tension increases, and the higher the rate of increase of viscosity, the higher the rate of increase of surface tension. It has been shown for silicone polymers that as the viscosity increases from an increase in molecular weight, the surface tension increases (27). A step growth copolymerization mechanism, as mentioned earlier for the sulfur-DCP solutions, will have an increase of molecular weight with time, and the surface tension behavior appears to support this mechanism. 

In many applications, improved performance is observed in the case of the polyelectrolytes with uniform charge distribution. If the comonomers have different reactivity ratios, these copolymers are synthesized using semibatch techniques. In this case, monitoring the monomer concentrations and composition would allow for monomer feed connol. This would be particularly useful for systems where monomer reactivity changes as a function of conversion [65]. Also, this capability would help automate and standardize processes with critical in-process additions. One such process is the manufacture of dispersion polymers where in-process viscosities are sensitive to the concentrations of monomer, polymer, and various salts. Through strategic additions of various components, in-process viscosities can be significantly reduced. 

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