Metering, emulsifier

Control of Particle Size Distribution Through Emulsifier Metering Based on Rate of Conversion... 

The reactor system used for these experiments is a 190 liter, jacketed/ stainless steel vessel equipped with initiator and emulsifier metering system. The reactor is monitored and controlled by a minicomputer. The computer monitors the reactor temperature and pressure/ the jacket water inlet and outlet temperatures and flow rate, and the initiator and emulsifier flow rates. The computer calculates the amount of heat transferred through the jacket from the process measurements and transmits signals to control the reactor temperature and metering pumps. 

Figure 14. Rate of conversion and emulsifier metering vs. time (Run No. 11127-88 start date 03-JUN-80 start time 05 55 42)...

For the next run to narrow the small particle distribution, it was envisioned that emulsifier metering should be carried out rapidly over a short period of time. The metering would then be stopped for a given time so that micelle formation would cease. The emulsifier would be restarted to give enough emulsifier to stabilize the growing particles, yet not exceed the emulsifier level needed to cover all the growing particle surface area (not produce new micelles). With the aid of a computer controlled 190 liter reactor, this was accomplished in Run 11127-90. 

This work has shown that by monitoring conversion curves by a computer, emulsifier metering can be varied to produce a desired particle size distribution of smalls in a seeded PVC emulsion polymerization. 

Figure 16. Percent conversion and emulsifier metering vs. run time (Run No.

Gordon, D. L. and Weidner, K. R. (1981) Control of particle size distribution through emulsifier metering based on rate of conversion, Emulsion Polymers and Emulsion Polymerization (eds D. R. Bassett and A. E. Hamielec), ACS, Washington, pp. 515-32. 

The work reported here used a tubular reactor of approx. 2.5 cm id and 150 meters in length. The reactor, lined with a fluorinated polymer, was coiled in a helical shape. The recipe employed standard concentrations of initiator and emulsifier. 

Methyl parathion may also be introduced into the air as a result of its volatilization from plant surfaces, and somewhat from soil, especially in the period just after application. Under simulated field conditions (20° C air velocity 1 meter/second relative air humidity 40-60%), an emulsifiable concentrate formulation of methyl parathion was applied to bare soil and bean plants. After 24 hours, the amounts of methyl parathion that had volatilized from bare soil and bean plants were 5 and 64% of the applied amount, respectively (Rudel 1997). 

Latex Preparation Analysis. Deionized water was used for the aqueous phase in the polymerization and commercial grade vinyl chloride monomer (99.9% pure) was used without further purification. The emulsifier was a salt of a sulfated fatty alcohol, and the emulsifier solution for metering was prepared to have 0.15 mol/L in water. The initiator system was a water soluble redox system. 

The required amount is metered into an emulsion tank. If emulsifiers are used, they are melted and mixed with a small amount of fat before being transferred to the... 

Nasal spray products contain therapeutically active ingredients (drug substances) dissolved or suspended in solutions or mixtures of excipients (e.g., preservatives, viscosity modifiers, emulsifiers, buffering agents) in non-pressurised dispensers that use metering spray pumps. (FDA 1999)... 

To a 4-liter, stirred reactor at 8°C are added 2 liters of deaerated water, 8 ml of Triton X-100, 300 gm (5.6 mole) 1,3-butadiene, 67.0 gm (1.0 mole) of cyclopentadiene, and 80 gm (1.25 mole) of sulfiir dioxide. The reaction is polymerized at 80°C after adding 2 ml of 20% aqueous ammonium persulfate solution. Ehiring the polymerization additional initiator and reactants are cautiously metered into the reactor 0.18 gm/min (initiator), 1.0 gm/min (cyclopentadiene), and 1.7 gm/min (sulfur dioxide). The temperature of the polymerization is approximately 8°-12°C for the 50 min polymerization period. The reaction is stopped by discharging the reactor into 8 liters of methanol. The product is filtered, washed with water several times to remove emulsifier, and then washed with methanol to give 207 gm of a white polymer having 36 mole% cyclopentadiene derived units in the polymer and having an inherent viscosity of 0.75 dl/gm in 1 1 p-chlorophenol m-cresol at 25°C. 

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