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The dynamic (shock) responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little- to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE) composite to 18.6GPa in the through-thickness direction, in which the shock propagates normal to the fibers. The data are best represented by a linear Rankine-Hugoniot fit: Us = 2.87 + 1.17 × up(ρ0 = 1.536 g/cm³). The shock wave structures were found to be highly heterogeneous, both due to the anisotropic nature of the fiber-epoxy microstructure, and the high degree of void volume. Plate impact experiments were also performed on a carbon fiber-filled phenolic (CP) composite to much higher shock input pressures, exceeding the reactants-to- products transition common to polymers. The CP was found to be stiffer than the filament-wound CE in the unreacted Hugoniot regime, and transformed to products near the shock-driven reaction threshold on the principal Hugoniot previously shown for the phenolic binder itself. [19] On-going research is focused on interrogating the direction-dependent dyanamic response and dynamic failure strength (spall) for the CE composite in the TT and 0° (fiber) directions. [ABSTRACT FROM AUTHOR]

Brillouin scattering is a powerful tool for probing the acoustic properties of materials. Coupled with high pressure environments, such as those accessible using diamond anvil cells, the method can reveal rich materials physics under extreme conditions, in addition to providing fundamental data for the development of equations of state. For the first time, the acoustic properties of two classes of polymers-rubbery elastomers and semi-crystalline fluoropolymers- have been measured from ambient pressure to ∼12 GPa. From the measured acoustic properties for the elastomers, elastic constants, and moduli were determined as a function of pressure. P-V isotherms were also constructed, and fit to a range of empirical/semi-empirical isothermal equation-of-state (EOS) forms. From this analysis, the isothermal bulk modulus and its pressure derivative are reported. [ABSTRACT FROM AUTHOR]

Fluoropolymers are widely used in a variety of applications due to their favorable properties that include chemical inertness, low coefficient of friction, and ability to withstand high-temperature operating conditions. Additionally, their high densities also make them desirable materials for use as high explosive binders in plastic bonded explosives. Here, we present the first investigation of the dynamic (shock) and static compression behavior of the fluorinated binder poly(chlorotrifluoroethylene-co-vinylidene fluoride) (Kel-F 800). Kel-F 800 samples prepared by both compression molding and melt-processing methods were studied. We observed little difference in the dynamic behavior of the two materials, despite a difference in crystallinity of 10–15%. A linear Rankine-Hugoniot fit to the Hugoniot loci in the Us-up plane gives Us = 1.838 + 1.824 up. Langrangian sound velocities at pressure were also measured at 3.0 (cL = 4.7 mm/μs) and 4.9 (cL = 5.8 mm/μs) GPa. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Nitroplasticized Estane (hereafter NP-Estane) is the plastic binder used to hold HMX grains together in the plastic bonded explosive PBX 9501. It is a mixture of 49 wt. % Estane®5703 (BF Goodrich), 49 wt. % Nitroplasticizer (a 50/50 eutectic mixture of bis(2,2-dinitropropyl)formal and bis(2,2 dinitropropyl)acetal), and 2 wt. % Irganox® 1010 stabilizer. NP-Estane samples 0.1 – 2 mm thick were prepared by compression molding at 110°C. Hydrostatic compression to 2 kbar was measured at 34, 43, and 53°C. CP was measured at ambient conditions. NP-Estane was also isentropically compressed to ≈ 35 kbar in experiment Z1251 on the Sandia Z-Machine. Profiles of ramp waves transmitted through NP-Estane were measured and compared with a free surface reference profile using Hayes’s “Backward” analysis and repeated forward analysis with the CTH hydrocode. The following thermodynamic quantities have been obtained; volume coefficient of thermal expansion α = 7.2(10-4)/C, CP = 1.76 J/g C, CV = 1.41 J/g C, isentropic and isothermal bulk moduli, BS = 36.4 kbar, BT = 29.3 kbar, Grüneisen constant Γ = 1.45. The Z1251 experiment is well fit using a Mie-Grüneisen equation of state with the quadratic US - uP relation, US = 1.69 + 2.7uP - (0.7/1.69)uP2 km/s. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]