Hexane dispersion polymerization

The suspension polymerization of 65% acrylamide aqueous solution dispersed in n-hexane (aqueous phase -hexane = 1 5) in the presence of a stabilizer (sorbitan monostearate, 1.4% with respect to -hexane) and an initiator (2,2 -azo-bis-A/, A/ -dimethyleneisobutylamide chloride) carried out at 65°C for 3 h, with subsequent holding at 110°C, yields a powdered product with the granule size of 0.5 mm, while the addition of Na2S04... 

The action of water in the titanium tetrachloride catalyzed polymerization is paradoxical, since water at —60 to —80° was present only in the solid phase its solubility in hexane at these temperatures is in the order of 10-10 moles per liter (Plesch et al., 83). It was found to be essential that the water be present as an extremely fine dispersion such as might result from the rapid bubbling of moist air through the liquid at the low temperature. Addition of liquid water which formed lumps of ice in the reaction mixture did not initiate polymerization. It may be concluded that a fine dispersion is necessary in order that reaction with titanium tetrachloride can occur and a chain reaction is initiated ... 

It was felt that the carbanion, CH2=CHS02CH2K , was too weak to initiate polymerization. The same dimer was obtained in a heterogeneous reaction with lithium metal dispersion in both hexane and tetrahydrofuran. 

Finally, the HDPE slurry from the second reactor is sent to the postreactor (3) to reduce dissolved monomer, and no monomer recycling is needed. In the decanter (4), the polymer is separated from the dispersing medium. The polymer containing the remaining hexane is dried in a fluidized bed dryer (5) and then pelletized in the extrusion section. The separated and collected dispersing medium of the fluid separation step (6) with the dissolved co-catalyst and comonomer is recycled to the polymerization reactors. A small part of the dispersing medium is distilled to maintain the composition of the diluent. 

The catalyst is only fed to the first reactor. Polymerization occurs in a dispersing medium like n-hexane using a Ziegler catalyst with very high activity. No deactivation and catalyst removal is necessary because a very low level of catalyst residue remains in the polymer. For unimodal-grade production, the catalyst, dispersing medium, monomer and hydrogen are fed to the first reactor (1) where the first polymerization takes place. The slurry is then sent to the post reac-... 

BF. The anodic oxidation of BF4 yields BF 3 which, as has been postulated by Funt and coworkers105,106-> and by Tidswell and Doughty107 some years ago (see also Ref. 7 pp. 595 and 602) can initiate, in the presence of traces of protic substances, cationic polymerization processes. More recently Mengoli and Vidotto have employed Bu4NBF4 in the electroinitiated polymerization of TRO dispersed in n-hexane and n-heptane81 (see page 21), getting evidence of the formation of acid species of boron, presumably BF 3. 

Uses Anti-resoil agent for carpet shampoo and carpet mfg. surfactant in emulsion polymerization pigment dispersant in overprint varnishes, inks Features High heat resist. high gloss exc. compat. re ubilityfink transfer Properties Off-wh. flakes or poviKf. sol. > 50 100 ml in acetone, MEK, THF, ethyl acetate sol. < 1 g/100 ml in n-hexane, toluene, 190 proof ethanol vise. 50 cP (20% sol n., 30 C) m.p. 160-170 C acid no. 255-285 99% act. 

The microencapsulation method utilized is as follows. An oil phase containing a catalyst (1,4-diazobicyclo [2,2,2] octane), MCR, diol and crosslinker trimethylol-propane (TMP) is dispersed in paraffin oil containing a steric polymeric stabiHzer (poly(butadiene-b-ethylene oxide)) in a reaction kettle maintained at 35 °C. The emulsion is stirred at 1200 rpm and TDI is added dropwise to the reaction mixture. After stirring the system at a specific stirring rate and temperature, PU microcapsules are formed which are then isolated by filtering the mixture, washing with hexane, and drying under vacuum. 

Another method described is that of dispersing an aqueous monomer solution in hydrophobic solvents, such as toluene, hexane, or mixed hydrocarbons. The water may be removed during polymerization as an azeotrope with hydrocarbon, if desired [518,519]. 

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