TY - JOUR A1 - Omara, Shereen Shabaan A1 - Turky, G. A1 - Ghoneim, A. A1 - Thünemann, Andreas A1 - Abdel Rehim, M. H. A1 - Schönhals, Andreas T1 - Hyperbranched poly(amidoamine)/kaolinite nanocomposites: Structure and charge carrier dynamics JF - Polymer N2 - An ex-situ approach was applied to prepare nanocomposites from hyperbranched poly(amidoamine) and modified kaolinite (Ka-DCA). The structure of the polymer and the corresponding nanocomposites was investigated by FTIR, DSC, SAXS and TEM. SAXS might suggest a partly exfoliated structure of the nanocomposites, which was supported by TEM. The molecular dynamics was studied by means of broadband dielectric spectroscopy (BDS). The dielectric spectra are dominated by a conductivity contribution at higher temperatures for all samples investigated. The obtained results further indicated that DC conductivity is increased by 4 orders of magnitude with increasing concentration of Ka-DCA nanofiller. Further, a significant separation between the conductivity relaxation time and that of segmental dynamics was observed. The decoupling phenomenon and the conductivity mechanism were discussed in detail. This study provides insights about the influence of the nanofiller on the structure and the conductivity contribution of nanocomposites of hyperbranched polymers including the decoupling phenomenon and fragility. KW - Hyperbranched polymers KW - Nanocomposites KW - Conductivity PY - 2017 DO - https://doi.org/10.1016/j.polymer.2017.06.017 SN - 0032-3861 VL - 121 SP - 64 EP - 74 PB - Elsevier Ltd. AN - OPUS4-40648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Täuber, Karoline A1 - Marsico, F. A1 - Wurm, F. R. A1 - Schartel, Bernhard T1 - Hyperbranched poly(phosphoester)s as flame retardants for technical and high performance polymers JF - Polymer chemistry N2 - A structurally novel hyperbranched halogen-free poly(phosphoester) (hbPPE) is proposed as a flame retardant in poly(ester)s and epoxy resins. hb polymeric flame retardants combine several advantages that make them an extraordinary approach for future flame retardants. hbPPE was synthesized by olefin metathesis polymerization according to a straightforward two-step protocol. The impact of hbPPE on pyrolysis, flammability (reaction-to-small-flame), and fire behavior under forced flaming conditions (cone calorimeter) was investigated for a model substance representing poly(ester)s, i.e. ethyl 4-hydroxybenzoate, and an epoxy resin of bisphenol A diglycidyl ether cured with isophorone diamine. The flame retardancy performance and mechanisms are discussed and compared to a commercial bisphenol A bis(diphenyl phosphate) (BDP). Both hbPPE and BDP combined gas-phase and condensed-phase activity; hbPPE is the more efficient flame retardant, and is proposed to be efficient in a greater variety of polymeric matrices. The hydrolysis of hbPPE is suggested to produce phosphorous acids, which, when available at the right temperatures, enhance the charring of the polymer in the condensed phase. The better fire protection behavior of the hbPPE is due not only to its higher phosphorus content, but also to the higher efficiency of the phosphorus it contains. KW - Hyperbranched polymers KW - Flame retardancy KW - Flammability KW - Poly(phosphoester)s PY - 2014 DO - https://doi.org/10.1039/c4py00830h SN - 1759-9954 SN - 1759-9962 VL - 5 IS - 24 SP - 7042 EP - 7053 AN - OPUS4-32014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -