The effects of composition and processing variables on the properties of thermoplastic polyaniline blends and composites

Pure polyaniline (PANI) has a high electrical conductivity and can be made soluble and thermoplastic, but it still lacks adequate mechanical propertie s for large-scale commercial use and therefore, it has been blended with ot her polymers such as poly(methyl methacrylate) (PMMA). In the work describe d in this paper, the scaled up synthesis of conductive polyaniline by an ox idative chemical method under controlled pH and temperature has been optimi sed. Re-doping of deprotonated insulating base with excess of the mono-func tional organic acids such as p-toluenesulfonic (TSA) or dodecylbenzenesulfo nic (DBSA) in aqueous media was successful. A wide range of techniques incl uding TGA, GPC, EA, FTIR, XRD and SEM were employed for the characterisatio n of PANI powders and blends. Compositions of PANI-HCI, TSA or DBSA and the rmoplastic matrix PMMA with or without a plasticiser were melt-processed by compression moulding for 3 min at 210 degreesC to produce plaques. The eff ectiveness of four different phenolic plasticisers was compared and hydroqu inone was found to produce the blends with the highest conductivities. A fe w preliminary injection-moulded plaques were made and their conductivities were compared with those of the compression-moulded samples. (C) 2001 Kluwe r Academic Publishers.