Influence of modified rheology on the efficiency of intumescent flame retardant systems

Optimal concentration of boroxo siloxane elastomer synergist was determined by LOI and cone calorimetric measurements on ammonium polyphosphate and pe ntaerythritol containing intumescent flame retardant for polypropylene. The increased viscosity of the melt and plasticity of intumescent char due to boroxo siloxane elastomer could be proved by a thermal scanning rheometric investigation. It is presumed, the increased melt viscosity is created by t he product of boroxo siloxane-pentaerythritol, formed during the compound p reparation, while the improved char plasticity is the result of product for med at high temperature from boroxo siloxane and ammonium polyphosphate. (C ) 2001 Elsevier Science Ltd. All rights reserved.