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Characterizing of glass-rubber transition shift in filled HTPB-IPDI formulations by modified and normal Arrhenius equation

: Bohn, Manfred; Ferrapontoff, Mauricio; Mußbach, Günter

Pachman, J. ; University of Pardubice; University of Pardubice, Institute of Energetic Materials:
22nd Seminar on New Trends in Research of Energetic Materials, NTREM 2019. Proceedings. Pt.1 : Held at the University of Pardubice, Pardubice, Czech Republic, April 10-12, 2019
Pardubice: University of Pardubice, 2019
ISBN: 978-80-7560-210-7
ISBN: 978-80-7560-211-4
Seminar on New Trends in Research of Energetic Materials (NTREM) <22, 2019, Pardubice>
Conference Paper
Fraunhofer ICT ()
HTBP-IPDI formulations; glass-rubber transition shift; modified Arrhenius equation; equation; WLF equation; normal Arrhenius equation

The glass-rubber transition (GRT) in elastomer bonded energetic material as composite rocket propellants and high explosives is an important property for the use of these materials. The temperature range of application of such rubber materials is always above the GRT, in contrast to thermoplastic elastomers, which are used below the GRT. The GRT is strongly determined by intermolecular interactions. An important behaviour is the deformation rate dependence of the GRT. With increasing deformation rate, means measurement frequency in dynamic mechanical measurements, the GRT is shifted to higher temperatures, means the in-service temperature range changes. The interaction between the binder polymer chains surely changes with the type of solid filler, as RDX or AP (ammonium perchlorate). Based on recent work using HTPB-IPDI (hydroxyl-terminated polybutadiene-isophorone diisocyanate) polyurethane binder, the determined data on GRT shifts are re-characterized by the so-called modified Arrhenius equation (MAE), which has proven to be equivalent to the WLF (Williams-Landel-Ferry) equation. The MAE has some advantages against WLF: no data are lost by setting a reference point and the WLF invariant C1C2 is expressed with an activation energy, which is used to interpret interaction in the material. A comparison with the activation energies obtained with the normal Arrhenius equation (NAE) is made.