Distribution of a brominated acrylate flame retardant in polypropylene

Thermal polymerization of pentabromobenzylacrylate (PBBMA) in a polypropyle ne (PP) composite that contains glass fibers and magnesium hydroxide has be en studied using scanning and transmission electron microscopy techniques c oupled with energy-dispersive spectrometry. The addition of PBBMA imparts f lame retardant (FR) properties to the PP composite but also affects adverse ly its mechanical properties, It is of practical importance to determine th e spatial distribution and the extent of polymerization of the FR in the PP composite in order to understand better its role in the system. The method s presented here allow the distinction between the monomeric and polymeric forms of the FR and to determine their spatial distributions. PP itself sho ws poor adhesion to the glass fibers, which may be improved by the addition of the reactive PBBMA. The latter is polymerized during reactive extrusion through an antimony-catalyzed reaction. Antioxidant hinders self-thermal p olymerization but the presence of antimony overcomes this interference. PP shows good adhesion to sized Mg(OH)(2) as expected from a property surface- treated filler. (C) 2001 Elsevier Science Ltd. All rights reserved.