On the use of a SEBS polymer gel block as a new ballistic target to assess blunt ballistic impacts: Application to a wide range of LLKE projectiles

2021 ◽  
Vol 153 ◽  
pp. 103874
Author(s):  
A. Bracq ◽  
R. Delille ◽  
C. Maréchal ◽  
B. Bourel ◽  
F. Lauro ◽  
...  
Keyword(s):  
Polymer Gel ◽  
Ballistic Impacts ◽  
Wide Range

scholarly journals Gelation Impairs Phase Separation and Small Molecule Migration in Polymer Mixtures

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1576
Author(s):  
Biswaroop Mukherjee ◽  
Buddhapriya Chakrabarti
Keyword(s):  
Phase Separation ◽  
Rational Design ◽  
Surface Segregation ◽  
Multiscale Methods ◽  
Coarse Grained ◽  
Polymer Gel ◽  
Polymer Mixtures ◽  
Separation Processes ◽  
Surface Migration ◽  
Wide Range

Surface segregation of the low molecular weight component of a polymeric mixture is a ubiquitous phenomenon that leads to degradation of industrial formulations. We report a simultaneous phase separation and surface migration phenomena in oligomer–polymer ( O P ) and oligomer–gel ( O G ) systems following a temperature quench that induces demixing of components. We compute equilibrium and time varying migrant (oligomer) density profiles and wetting layer thickness in these systems using coarse grained molecular dynamics (CGMD) and mesoscale hydrodynamics (MH) simulations. Such multiscale methods quantitatively describe the phenomena over a wide range of length and time scales. We show that surface migration in gel–oligomer systems is significantly reduced on account of network elasticity. Furthermore, the phase separation processes are significantly slowed in gels leading to the modification of the well known Lifshitz–Slyozov–Wagner (LSW) law ℓ ( τ ) ∼ τ 1 / 3 . Our work allows for rational design of polymer/gel–oligomer mixtures with predictable surface segregation characteristics that can be compared against experiments.

scholarly journals Evaluation of Combat Helmet Behavior under Blunt Impact

2020 ◽  
Vol 10 (23) ◽  
pp. 8470
Author(s):  
Carlos Moure-Guardiola ◽  
Ignacio Rubio ◽  
Jacobo Antona-Makoshi ◽  
Álvaro Olmedo ◽  
José Antonio Loya ◽  
...  
Keyword(s):  
Brain Injuries ◽  
Linear Acceleration ◽  
Human Head ◽  
Critical Parameters ◽  
Head Model ◽  
Ballistic Impacts ◽  
Impact Surface ◽  
Blunt Impact ◽  
Wide Range ◽  
Design And Manufacture

New threats are a challenge for the design and manufacture of modern combat helmets. These helmets must satisfy a wide range of impact velocities from ballistic impacts to blunt impacts. In this paper, we analyze European Regulation ECE R22.05 using a standard surrogate head and a human head model to evaluate combat helmet performance. Two critical parameters on traumatic brain analysis are studied for different impact locations, i.e., peak linear acceleration value and head injury criterion (HIC). The results obtained are compared with different injury criteria to determine the severity level of damage induced. Furthermore, based on different impact scenarios, analyses of the influence of impact velocity and the geometry impact surface are performed. The results show that the risks associated with a blunt impact can lead to a mild traumatic brain injury at high impact velocities and some impact locations, despite satisfying the different criteria established by the ECE R22.05 standard. The results reveal that the use of a human head for the estimation of brain injuries differs slightly from the results obtained using a surrogate head. Therefore, the current combat helmet configuration must be improved for blunt impacts. Further standards should take this into account and, consequently, combat helmet manufacturers on their design process.

scholarly journals Pulsatile contractions and pattern formation in excitable active gels

2021 ◽  
Author(s):  
Michael F. Staddon ◽  
Edwin M. Munro ◽  
Shiladitya Banerjee
Keyword(s):  
Regulatory Networks ◽  
Mechanical Forces ◽  
Polymer Gel ◽  
Actin Cortex ◽  
Upstream Regulator ◽  
Cellular Environment ◽  
Chemical Signalling ◽  
Wide Range ◽  
Spatial Propagation ◽  
Quantitative Understanding

The actin cortex is an active adaptive material, embedded with complex regulatory networks that can sense, generate and transmit mechanical forces. The cortex can exhibit a wide range of dynamic behaviours, from generating pulsatory contractions and traveling waves to forming highly organised structures such as ordered fibers, contractile rings and networks that must adapt to the local cellular environment. Despite the progress in characterising the biochemical and mechanical components of the actin cortex, our quantitative understanding of the emergent dynamics of this mechanochemical system is limited. Here we develop a mathematical model for the RhoA signalling network, the upstream regulator for actomyosin assembly and contractility, coupled to an active polymer gel, to investigate how the interplay between chemical signalling and mechanical forces govern the propagation of contractile stresses and patterns in the cortex. We demonstrate that mechanical feedback in the excitable RhoA system, through dilution and concentration of chemicals, acts to destabilise homogeneous states and robustly generate pulsatile contractions. While moderate active stresses generate spatial propagation of contraction pulses, higher active stresses assemble localised contractile structures. Moreover, mechanochemical feedback induces memory in the active gel, enabling long-range propagation of transient local signals.

Preparation of Magnetic Alginate-Based Biogel Composite Cross-Linked by Calcium Ions and its Super Efficient Adsorption for Direct Dyes

2021 ◽  
Vol 1035 ◽  
pp. 1022-1029
Author(s):  
Bei Gang Li ◽  
Wen Jie Lin
Keyword(s):  
Removal Efficiency ◽  
Raw Materials ◽  
Crosslinking Agent ◽  
Dye Adsorption ◽  
Polymer Gel ◽  
Direct Dyes ◽  
High Concentration ◽  
Solution Ph ◽  
Gel Beads ◽  
Wide Range

Magnetic sodium alginate (SA)-based biosorbent Fe₃O₄@SA-Ca gel beads were synthesized by droplet polymerization using Ca2+ ions as crosslinking agent, and characterized by Scanning Electron Microscopy (SEM). Fe₃O₄@SA-Ca polymer was used for the removal of Direct Orange 26 (DO-26) dye from water. The ratio of raw materials and some important conditions affecting the adsorbent performance were carefully examined. The adsorption kinetics, isotherms and thermodynamics were investigated. When the concentrations of SA, CaCl2 and Fe3O4 solutions were 1.9, 10 and 10 g/L, respectively, the black Fe₃O₄@SA-Ca gel beads with about 3 mm diameter were successfully prepared by curing 6h at room temperature. The polymer gel exhibits ultra-high adsorption capacity of 1252 mg/g and removal efficiency of 96.2 % for DO-26 under the conditions of 0.05 g polymer dosage, 2600 mg/L of dye initial concentration, solution pH 2.0 and 90 min of the adsorption time at 298 K. The dye removal efficiency can be all over 92 % in a wide pH range of 2.0 to 10.0. The adsorption process completely accorded with the pseudo-second-order rate model at different temperatures (298 ~ 328 K). The dye adsorption behavior was well in line with Freundlich model. The thermodynamic study indicated that the adsorption reaction was of spontaneous and exothermic nature. SEM analysis showed that the Fe₃O₄@SA-Ca gel beads appeared uneven surface with irregular folds and grooves. A high-cost-effective magnetic biosorbent, Fe₃O₄@SA-Ca can super effectively remove direct dyes from high-concentration wastewater in a wide range of acidity, and can be easily separated and recovered from water after adsorption without secondary pollution, and would have a good application prospect.

On the modeling of a visco-hyperelastic polymer gel under blunt ballistic impacts

2018 ◽  
Vol 118 ◽  
pp. 78-90 ◽  
Author(s):  
A. Bracq ◽  
G. Haugou ◽  
B. Bourel ◽  
C. Maréchal ◽  
F. Lauro ◽  
...  
Keyword(s):  
Polymer Gel ◽  
Ballistic Impacts

Design and Characteristic Analysis of Amalgamated Transparent Materials for Armor Structures Using Defeating Ballistic Experimentation

2018 ◽  
Author(s):  
Emad Attalla ◽  
Badih Jawad ◽  
Steve Grate ◽  
Vernon Fernandez ◽  
Sabah Abro ◽  
...  
Keyword(s):  
Low Cost ◽  
Research Work ◽  
Computer Software ◽  
Yield Response ◽  
Material Strength ◽  
Matrix Glass ◽  
Characteristic Analysis ◽  
Ballistic Impacts ◽  
Wide Range ◽  
Selection Of

In armored platforms industry, the dominant material solution for ballistic transparency protection applications is relatively low-cost polycarbonate matrix glass. This research work aims to investigate the effects of geometrical designs of the amalgamated layers, engineering characteristics of the materials, and the interaction of both on the ballistic resistance of the transparent armor. The resulted models are used to analyze the strength feasibility of the material in the cost base. Ballistic measurements over a wide range of impact velocities including those well above the ballistic limits are deployed to the model. Under simple loading conditions, the polycarbonate matrix glass or ceramic can be regarded as elastic-brittle materials, however, when considering ballistic impacts the post-yield response of the ceramic becomes significant. A post-yield response model of ceramic materials is used for simulating the characteristics. The model incorporates the effect of damage on residual material strength and the resulting bulking during the compressive failure of the ceramic. A combination of relevant factors including the ability to dissipate ballistic energy and manufacturing processes was considered for the proper evaluation and selection of the armor. The model has been implemented into computer software to predict unsuccessful solutions and optimize the amalgamation with capabilities of defeating a wider range of ballistic impacts. The results will show more physical insight of the behavior and performance of the complex armor systems and provide guidelines/principles for the design and selection of the constituent materials.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Observation of Atom Rows in Thorium Pyromellitate Using a Field Emission STEM

1977 ◽  
Vol 35 ◽  
pp. 80-81
Author(s):  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Field Emission ◽  
Amorphous Carbon ◽  
Carbon Film ◽  
Dark Field Image ◽  
Dark Field ◽  
Amorphous Carbon Film ◽  
Atomic Size ◽  
Wide Range ◽  
A Chain

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3 CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.

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