Abstract
The reduction in the mean diameter of polystyrene and styrene-divinylbenzene copolymer granules, brought about by suspension polymerization, has been investigated. For this purpose, emulsifiers containing hydrophilic polyethylene glycol fragments were added to a stabilizer [starch, poly(vinyl alcohol) or polymethacrylic acid with 10 mol% methylmethacrylate units]. The emulsifiers investigated such as ‘Stearox’ (20s-oxyethylated stearic acid), ‘Phenoxol’ (15s-oxyethylated phenol) and ‘APhO’ (10s-oxyethylated alkylphenol) were found to reduce the mean diameters of granules by a factor of 10 or more. The same tendency was observed when benzoyl peroxide was replaced by the surface-active oligomeric peroxide of sebacinic acid whose surface activity is due to the polymeric chain ends.