Klaus Rathberger, Georg H. Luh, Germany, outlined the benefits of his company’s expanded graphite as a PIN flame retardant system component. Applications include EPS, foams in transport applications (automotive, aircraft), compounding for thermoplastics, rubber, silicones, roof bitumen, intumescent fire seals and gaskets. Quality of product is essential to achieve processing and fire performance objectives, for example: particle size (although expanded graphite seems to be effective with somewhat larger particle size than some other mineral PIN FRs), presence of impurities, balance between fast fire reaction at lower temperatures and compatibility with higher processing temperatures (today, the upper processing limit is around 230°C, but products enabling higher temperature processing are being researched). Thermal conductivity both contributes to reduce fire ignition and can improve heat dispersion in applications. Low dusting masterbatches are now available for cleaner processing. A limit to application remains the black colour.
Georg H. Luh
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