We examine the simplest relevant molecular model for large-amplitude shear (LAOS) flow of a polymeric liquid: suspension rigid dumbbells in Newtonian solvent. find explicit analytical expressions rate amplitude and frequency dependences first third harmonics alternating stress response. include detailed comparison these predictions with corresponding results continuum model: corotational Maxwell model. that responses both models are qualitatively similar. The dumbbell relies entirely on...

The microstructure of plastic bonded explosives (PBXs) is known to influence behavior during mechanical deformation, but characterizing the can be challenging. For example, explosive crystals and binder in formulations such as PBX 9501 do not have sufficient X-ray contrast obtain three-dimensional data by situ, absorption imaging. To address this difficulty, we formulated a series PBXs using octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) low-density systems. binders were...

Additive manufacturing (AM) is an attractive approach for the design and fabrication of structures capable achieving controlled mechanical response underlying deformation mechanisms. While there are numerous examples illustrating how quasi-static responses polymer foams have been tailored by additive manufacturing, limited understanding these materials under shockwave compression. Dynamic compression experiments coupled with time-resolved X-ray imaging were performed to obtain insights into...

When measuring rheological properties in oscillatory shear flow, one worries about experimental error due to the temperature rise sample that is caused by viscous heating. For polymeric liquids, for example, this causes measured values of components complex viscosity be systematically low. such linear viscoelastic property measurements, we use an analytical solution Ding et al. [J. Non-Newtonian Fluid Mech. 86, 359 (1999)10.1016/S0377-0257(99)00004-X] estimate rise. However, large-amplitude...

In our previous work, we explored the dynamics of a dilute suspension rigid dumbbells as model for polymeric liquids in large-amplitude oscillatory shear flow, flow experiment that has gained significant following recent years. We chose since these are simplest molecular to give higher harmonics components stress response. derived expression dumbbell orientation distribution, and then used this function calculate response, normal difference responses flow. paper, deepen understanding polymer...

We examine the simplest relevant molecular model for large-amplitude oscillatory shear flow of a polymeric liquid: The dilute suspension rigid dumbbells in Newtonian solvent. find explicit analytical expressions orientation distribution, and specifically test conditions frequency rate amplitude that generate higher harmonics stress normal difference responses. solve diffusion equation analytically to explore induced by flow. see distribution is neither even nor odd. zeroth, first, second,...

Although direct ink writing (DIW) allows the rapid fabrication of unique 3D printed objects, resins-or "inks"-available for this technique are in short supply and often offer little functionality, leading to development new, custom inks. However, when creating new inks, ability lead a successful print, or "printability," must be considered. Thus, work examined effect filler composition/concentration, printing parameters, lattice structure on printability polysiloxane inks incorporating high...

We present our discovery of switchable high explosives (HEs) as a new class energetic material that cannot detonate unless filled with fluid. The performance fluid-filled additive-manufactured HE lattices is herein evaluated by analysis detonation velocity and Gurney energy. energy the unfilled lattice was 98% lower than equivalent water-filled changing fluid mechanical properties allowed tuning 8.5% 13.4%, respectively. These results provide, for first time since development HEs, method to...

Cast-cure formulations of plastic-bonded explosives (PBX) present some advantages in manufacturing and application compared to traditional pressed slurry formulated materials. For example, these can be cast specific shapes then cured place, avoiding the need for machining precision parts. However, microstructure materials greatly affected by process. Here, we evaluate effect minor changes formulation process on several cyclotetramethylene-tetranitramine (HMX) PBXs. The binders were based...

Abstract When molten plastic is extruded from a die, it sometimes collects on the open face of die. Known as die drool, this phenomenon costs plastics manufacturers by requiring cleaning. This has been attributed to many causes, but none these led an equation for drool rate. In work, we provide exact analytical solution rate, and base postulate cohesive slip layer near walls. We thus attribute failure within fluid at internal surface where slips itself. adimensionalize rate with production...

We report a [3+2] cycloaddition using 3,6-bis-propargyloxy-1,2,4,5-tetrazine and azides to synthesize energetic polymers containing 1,2,4,5-tetrazine within the scaffold.

Recent research has demonstrated that additive manufacturing (AM) can be used to produce directionally sensitive high explosives (HEs), but detonation wave propagation in AM HEs with variable internal structure not been studied. In this work, samples were printed using a 73 wt. % octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine-based HE ink. Flash x-ray radiography imaging was observe density changes two planes of each sample during detonation, and high-speed calculate the velocity at...

An energetic nitrate ester acrylate monomer (4) was synthesized in a total yield of 68% and polymerized to form the polymer (NEAP). Compound 4 is liquid at room temperature with melting point -8.6 °C NEAP solid glass-transition -8.8 °C. Intermediates leading were characterized by high-resolution mass spectrometry, elemental analysis, Fourier transform infrared spectroscopy, proton carbon nuclear magnetic resonance spectroscopies (1H 13C{1H} NMR). Both have electrostatic discharge, friction,...

The off-normal detonation behavior of two plastic-bonded explosive (PBX) formulations was studied using explosively-driven aluminum fragments created by types detonators. A generic aluminum-cupped detonator contained 100 mg PETN which sufficient to fragment the into hundreds sub-mm particles moving at hypersonic velocity; for comparison, a Teledyne RISI® RP-80 also tested generated more substantial flyer plate aluminum. Low-density polystyrene foam used as witness material with subsequent...

In this work, we study the slip behaviors common to plastics die extrusion metals or platings using a new instrument called dual-plate slipometer. By dual-plate, mean that whereas stationary plate incorporates local shear stress transducer, moving does not. The and transducer are made of one stainless steel, but is from, plated with, different materials under study. This allows velocity be measured without having build from each metal plating We explore effect composition surface morphology...

When molten plastic is extruded from a die, it sometimes collects on the open face of die. Known as die drool, this phenomenon costs plastics manufacturers by requiring cleaning. This has been attributed to many causes, but none these led an equation for drool rate. In work we provide exact analytical solution rate, and base postulate cohesive slip layer near walls. We thus attribute failure within fluid at internal surface where slips itself. adimensionalize rate with production call build...

When plastic pipe is extruded, it emerges from an annular die as hot molten plastic. This highly viscous liquid must then be solidified. normally accomplished by either plunging under cold water, or spraying water onto its outer surface. Called ”quenching”, this unit operation solidifies the maintaining wall temperature at cold-water temperature. We first provide exact analytical solution for quenching of with phase change, subject to cold, wet isothermal wall. give dimensionless...

Submicron particles are formed during the detonation and deflagration of carbon-rich energetic materials known as high explosives (HE) that can be lofted transported long distances in atmosphere. Particles include refractory species like soot, a.k.a. black carbon (BC), have impacts to climate human health at local, regional, global scales. Here, we contrast soot aerosol physical, optical chemical properties more efficiently terms emission factors ratios with traditional combustion sources...

Traditional slow detonation velocity (Dv) explosives components, such as Baratol (76% Ba(NO3)2 and 24% TNT), rely on dilution of a traditional explosive with dense relatively inert material, while some utilize Ca(NO3)2, ZnO or BaCO3. However, our applications require solely CHNO-based formulations that exhibit Dv near theoretical maximum density. Given target 6.5 mm/µs, ammonium picrate was chosen convenient to be diluted high binder level (14-20%). Thermal equilibrium calculations were...