Purge paddle

To a 50-mL three-necked flask (Fig. 3.18b) equipped with a stirrer (comprised of a stainless steel shaft and paddle), a head for the distillation of water, and a nitrogen inlet is added 20 g of purified 11-aminoundecanoic acid. The flask is then purged with nitrogen for 5 min. The flask is warmed in a silicon oil bath to 220° C and maintained at this temperature for 10 h. After raising the stirrer from the molten mass, the reaction is cooled under nitrogen and the resultant polymer removed by breaking the glass. The Tm of the polymer is 185—190° C and the rjmh in m-cresol (0.5% at 35°C) is 0.6—0.7. 

A 3-1., three-necked, round-bottomed flask is equipped with a glass paddle stirrer, a condenser containing a mixture of acetone and solid carbon dioxide, and a gas inlet tube. The outlet of the condenser is protected from the atmosphere by a T-tube through which a slow stream of nitrogen is passed. The flask is purged with nitrogen, and about 1.5 1. of anhydrous liquid ammonia is either poured or distilled into the flask. A small crushed crystal of ferric nitrate nonahydrate is added, followed by 23 g. (1 g. atom) of freshly cut sodium in small pieces (Note 1). 

Homopolymer DADMAC-Emulsion Polymerization. The equipment setup outlined in the solution polymerization was used to prepare the emulsion polymer. To the resin pot 321.5 g benzene, 138.5 g of 72.2% aqueous DADMAC monomer, and 40 g of 20% aqueous sodium octyl phenoxyethoxy-2-ethanol sulfate were added. The mixture was stirred at 170-180 rpm with a paddle stirrer and heated to 50° 1°C. The suspension was purged with nitrogen gas for 1 hr. Then, 7 ppm Fe+2 (added as Fe(NH4)2(S04)3 6H20) were added, followed by 2 X 10"3 mol f-butylperoxypivalate/mol monomer. The reaction mixture was stirred for 20 hr at 50° 1°C under a nitrogen blanket. The polymer conversion after 20 hr was 90 2%. The product was isolated by adding the benzene emulsion to acetone, filtering the product, and drying. 

Mechanical issues high speeds for the paddles calls for properly sized good-quality bearings and seals. Seals must be provided with air purge arrangements to insure that they stay dust free. 

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