Emulsion copolymerization of acrylonitrile and butyl acrylate, 10. Effect of 1,1‐diphenyl‐2‐picrylhydrazyl on the polymerization process

Abstract

AbstractThe emulsion copolymerization of acrylonitrile with butyl acrylate, initiated by ammonium persulfate in the presence of disodium dodecylphenoxybenzenedisulfonate and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), was kinetically investigated at 70°C by conventional GLC and gravimetric methods. The copolymerization under batch conditions was conducted to both low and high conversion. In the presence of a small amount of DPPH the molecular weight of the copolymer is little decreased when compared with that prepared without DPPH. In addition, the rate of copolymerization unexpectedly decreases with increasing emulsifier concentration. The radical scavenger was found to decrease the average particle size. In the interval 2 the rate of polymerization is approximately proportional to the 0,35th power of the emulsifier concentration and to the 0,5th power of the initiator concentration (without DPPH). The dependence of the rate of polymerization on the final particle number and of the final particle number on the emulsifier concentration also deviates from the simple micellar theory predictions. The results can be explained by a coagulative nucleation mechanism.