E. B. Orler

Electron spin resonance study of oxidation in X-irradiated poly(ester urethane) containing nitroplasticizer

Abstract The effect of oxidation on X-irradiated Estane®5703 containing nitroplasticizer (NP) has been examined by electron spin resonance (ESR) spectroscopy, and the results are compared to similar data previously obtained on pristine Estane®5703. Although both specimens exhibit similar spectra immediately following X-irradiation, their decay upon exposure to air is quite different. The free radical concentration of the pristine specimen continuously decreases with time whereas the NP sample exhibits an initial decrease followed by a significant increase due to the growth of a newly-formed radical. Terminal species of the pristine and NP-Estane®5703 samples are identified as peroxy and nitroxide radicals, respectively. Hyperfine coupling constants and g-values are extracted for the nitroxide radical and a tentative model is proposed to explain the reaction pathway leading to its production.

Brillouin-scattering Determination of the Acoustic Properties of Polymers at High Pressure

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.

Quasi‐Static and Shock Compressive Response of Fluorinated Polymers: Kel‐F 800

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.

Isentropic Compression of Nitroplastized Estane to ≈ 35 KBAR on the Sandia Z‐Machine

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 is...