Two types of graphene nanoribbons: (a) potassium-split nanoribbons (GNRs), and (b) oxidative unzipped chemically converted (CCGNRs) were investigated for their magnetic properties using the combination static magnetization electron spin resonance measurements. The two ribbons possess remarkably different properties. While low temperature ferromagnet-like feature is observed in both ribbons, such room persists only ribbons. GNRs show negative exchange bias, but CCGNRs exhibit a 'positive...

We study the solubility and dispersibility of as-produced purified HiPco single-walled carbon nanotubes (SWNTs). Variation in specific operating conditions process are found to lead significant differences respective SWNT solubilities oleum surfactant suspensions. The diameter distributions SWNTs dispersed solutions batch-dependent, as evidenced by luminescence Raman spectroscopies, but identical for metallic semiconducting within a batch. thus find that small disperse at higher...

Here we report the results of a multifrequency (~9, 20, 34, 239.2, and 336 GHz) variable-temperature continuous wave (cw) X-band (~9 pulse electron spin resonance (ESR) measurement performed at cryogenic temperatures on potassium split graphene nanoribbons (GNRs). Important experimental findings include following: (a) The cw ESR data infer presence only carbon-related paramagnetic nonbonding states, any measured temperature, with g value independent microwave frequency temperature. (b) A...

Abstract We aim to understand how microwaves interact with high explosives by studying the complex permittivity from 1–18 GHz of HMX, RDX, TNT, TATB, PETN, Octol, Comp B, 95 % RDX/5 Viton A (PBX‐RDX), PBX 9404, PBXN‐5, PBXN‐7, PBXW‐14, 9501, and 9502. The combination a resonant cavity perturbation technique for determining room‐temperature dielectric constant at discrete frequencies wide band open circuit method (1–18 GHz) provides an accurate, broadband measurement that describes properties...

This paper builds upon our previous work where we defined distinct physically-based parameters of the Scaled Uniform Reactive Flow (SURF) model Shaw and Menikoff for heterogeneous high explosives (HE) reactive flow calculations. We call this Physically-Informed version PiSURF, or πSURF. Here, re-derived in a manner that resulted dependency on fraction overall specific surface area (associated with void space consolidated sample) is 'activated' by shock wave. perspective appealing consistent...

Microstructural characterization of composite high explosives (HEs) has become increasingly important over the last several decades in association with development fidelity mesoscale modeling and an improved understanding ignition detonation processes. HE microstructure influences not only typical material properties (e.g., thermal, mechanical) but also reactive behavior shock sensitivity, wave shape). A detailed nondestructive 3D examination generally been limited to custom-engineered...

Inert surrogates or mocks for high explosives are commonly used in place of the real material complex experiments situations where safety is a concern. Here, several materials were tested as potential HMX terms density, thermal stability, and processability. Selection criteria developed literature search was conducted primarily using Cambridge Structural Database. Out over 200 potentially acceptable materials, six chosen crystallization suite analytical characterization. Of these six,...

When the void content and/or structure of a high explosive (HE) is altered by some means (i.e., bulk heating or mechanical damage), shock initiation behavior material changes. The ability to precisely predict change in sensitivity after an HE has undergone microstructural changes crucial capability multi-scale reactive flow models. Here, we utilize thermally expandable microspheres (TEMs) as dopant polymer bonded (PBX) matrix alter properties controlled fashion. Using mesoscale modeling...

Triaminotrinitrobenzene (TATB) is a highly anisotropic molecular crystal used in several plastic-bonded explosive (PBX) formulations. A complete understanding of the orientation distribution TATB particles throughout PBX charge required to understand spatially variable, macroscale properties charge. Although texture these materials can be measured after they have been subjected mechanical or thermal loads, measuring evolution situ important order identify mechanisms deformation and...

Thermal ignition via self-heating (cook-off) of cyclotetramethylene-tetranitramine (HMX)-containing plastic-bonded explosives (PBXs) is driven by the β → δ phase transition in HMX, which affected if not dominated microstructure. Here, HMX-binder interface and were studied for several variations PBX 9404 (HMX with plasticized nitrocellulose [NC] binder). Neutron reflectometry was used to examine under conditions—pristine, after aging, thermal treatment. The initial interfacial structure...

Temperature gradients will appear in any microwave-heated heterogeneous system where there is contrast the complex permittivity of constituent materials. The magnitude depends on several factors that include permittivity, thermal conductivity, length scale, and diffusivity. In general, it challenging to measure absolute temperature accurately a strong microwave field; presence large can further complicate interpretation measurements. These issues are especially important during heating...

Detecting explosives without setting them off is, obviously, a prime goal in security applications. Avoiding detonation requires deep understanding of the complex, spatiotemporal interplay chemistry and heat transport heterogeneous solids. The authors combine three-dimensional structural data, dielectric simulations to study hot-spot formation thermal gradients energetic mesostructures under electromagnetic radiation. They find that enhanced light absorption at hot spots, below initiation...

2,4,6-Trinitrotoluene (TNT) is a common insensitive energetic material for variety of applications. Previous studies on TNT have revealed complex nature the in terms physical and chemical properties. We demonstrate use recrystallization spray drying to produce unique particle morphology with high purity investigate important changes observed that fully isolated less stable orthorhombic crystalline phase, following Ostwald's rule stages, due fast precipitation time elevated temperature...

Abstract Graphene nanoribbons (GNR), can be prepared in bulk quantities for large-area applications by reducing the product from lengthwise oxidative unzipping of multiwalled carbon nanotubes (MWNT). Recently, biomaterials application GNR has been explored, example, pore to used DNA sequencing. Therefore, understanding polymer behavior solution is essential predicting interaction with biomaterials. Here, we report experimental studies solution-based mechanical properties and their parent...

Recently, there has been increased interest in developing new inert surrogate materials, or "mocks," for plastic-bonded explosives (PBX). Idoxuridine (IDOX) similar density and mechanical behavior to the explosive HMX, formulated IDOX showed promise emulating HMX-based PBX 9501 preliminary experiments. Several improvements manufacture of have made are characterized here by Brazilian Disk testing. Compression tests were performed on these disk specimens under quasi-static loading conditions...

In this investigation, we study the mechanical performance of new idoxuridine (IDOX) based-mock and compare that to PBX 9501 using Brazilian disk compression configuration combined with digital image correlation (DIC) technique. We similarities differences in their deformation, damage, failure when subject loadings. series experiments, loading speed was kept same (quasi-static) for all specimens, while test temperature varied at −15°C, 23°C, 50°C, respectively. The general behavior two...