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SUMMARYAn experimental and numerical investigation of the effect of bisphenol A bis(diphenyl phosphate) (BDP) and polytetrafluoroethylene (PTFE) on the fire behaviour of bisphenol A polycarbonate/acrylonitrile butadiene styrene (PC/ABS) in the vertical UL 94 scenario is presented. Four PC/ABS blends were discussed, which satisfy different UL 94 classifications due to the competing effects of gasification, charring, flame inhibition and melt flow/dripping. For numerical investigation, the particle finite element method (PFEM) is used. Its capability to model the complex fire behaviour of polymers in the UL 94 is analysed. The materials' properties are characterised, in particular the additives impact on the dripping behaviour during thermal exposure. BDP is an efficient plasticiser; adding PTFE prevents dripping by causing a flow limit. PFEM simulations reproduce the dripping and burning behaviour, in particular the competition between gasification and dripping. The thermal impact of both the burner and the flame is approximated taking into account flame inhibition, charring and effective heat of combustion. PFEM is a promising numerical tool for the investigation of the fire behaviour of polymers, particularly when large deformations are involved. Not only the principal phenomena but also the different UL 94 classifications and the extinction times are well predicted.

Abstract. To study the electrical behavior of nanoscale carbon fibers (NCF)/epoxy nanocomposites under mechanical load, NCF/epoxy materials were produced using different mechanical dispersion methods like pearl mill and three roll mill. Various preliminary mechanical tests with simultaneous resistance measurements have been conducted. The influence of the filler content, the dispersion quality and the filler geometry on the electrical properties of NCF/epoxy composites was investigated as a function of the mechanical loading. The strain sensitivity strongly depended on the filler content and the filler geometry. In cyclic loading tests at low strains the resistance showed a reversible and linear behaviour. At higher strains irreversible resistance changes were observed. In addition, the specific surface resistance corresponded even during unloading with the highest strain level applied so far. This indicates the potential of NCFs/epoxy nanocomposites to monitor the loading history of a sample.