Current trends in organic peroxides for poly(vinyl chloride)

A wide range of organic peroxides is commercially available today, covering the whole range of polymerisalion temperatures used in the production of poly(vinyl chloride). The main criteria for the selection of the most suitable type for an individual process are reactivity and polymerisation performance, but storage and handling properties are also important. Current developments are targeting at new initiators with increased activity, as well as the creation of forms of supply that have improved handling and safety properties. Among the manifold supply forms of organic peroxides, water based formulations are gaining increasing importance. Suspensions of solid percarbonates combine the advantage of only moderate cooling with the ease of handling of a liquid initiator and the enhanced safety properties of a diluted peroxide. Non-freezing emulsions of liquid percarbonates and peresters were developed in order to minimise the solvent content. The supply in intermediate bulk containers is an option for both formulation types. High activity initiators arc required for the reduction of polymerisation and cycle times in order to achieve higher productivity, and for the expansion of the product range by high molecular mass poly(vinyl chloride) grades. A survey of current status is presented, focusing on l,3-di(2-neodecanoylperoxy isopropyl)benzene and on a new and promising peroxalate initiator. PRC/1557