scholarly journals Modeling and Simulation of Ballistic Penetration of Ceramic-Polymer-Metal Layered Systems

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
J. D. Clayton
Keyword(s):  
Current Model ◽  
Thin Layers ◽  
Tungsten Alloy ◽  
Polymer Interfaces ◽  
Evaluation Of Performance ◽  
Absolute Residual ◽  
Polymer Metal ◽  
Experimental Values ◽  
Proper Resolution ◽  
Composite Protection

Numerical simulations and analysis of ballistic impact and penetration by tungsten alloy rods into composite targets consisting of layers of aluminum nitride ceramic tile(s), polymer laminae, and aluminum backing are conducted over a range of impact velocities on the order of 1.0 to 1.2 km/s. Computational results for ballistic efficiency are compared with experimental data from the literature. Simulations and experiments both demonstrate a trend of decreasing ballistic efficiency with increasing impact velocity. Predicted absolute residual penetration depths often exceed corresponding experimental values. The closest agreement between model and experiment is obtained when polymer interfaces are not explicitly represented in the numerical calculations, suggesting that the current model representation of such interfaces may be overly compliant. The present results emphasize the importance of proper resolution of geometry and constitutive properties of thin layers and interfaces between structural constituents for accurate numerical evaluation of performance of modern composite protection systems.

Diffusion Measurements Using FT-IR ATR Spectroscopy: Lubricant Diffusion in Polypropylene

2002 ◽  
Vol 56 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Xiaohua Yi ◽  
Karen Nerbonne ◽  
John Pellegrino
Keyword(s):  
Current Model ◽  
Mineral Oil ◽  
Attenuated Total Reflection ◽  
Lubricant Layer ◽  
Polymer Interfaces ◽  
Time Resolved ◽  
Polymer Sample ◽  
Ft Ir ◽  
Atr Spectroscopy ◽  
Poly Propylene

We present an experimental method for measuring diffusion of lubricants (or any highly viscous fluid) in polymers using Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy. Unlike the conventional FT-IR ATR diffusion measurement, in which a polymer sample is sandwiched between the penetrant and an internal reflection element (IRE), in this method, a thin layer of penetrant (for example, a lubricant) is sandwiched between the IRE and the polymer sample. This allows accurate control and measurement of the thickness of the lubricant layer, which, in turn, facilitates subsequent data analysis. The diffusion is studied by monitoring the time-resolved change in absorbance of either a unique polymer or penetrant band. A feature of this new method is that it can provide an estimate of solubility, as well as an estimate of the diffusivity of the penetrant in the polymer. Using this method, we studied the diffusion of mineral oil and a commercial fluorocarbon ether lubricant (Krytox® 143AC‡) in poly(propylene) (PP) film at room temperature. The experimental data was modeled using a Fickian model with impermeable and saturated boundary conditions applied at the IRE/lubricant and lubricant/polymer interfaces, respectively. The diffusivity and solubility of mineral oil in PP were found to be 1.34 ± 0.35 (×10−10) cm2/s and 0.77 ± 0.13 (×10−2) g/g of PP, respectively. The current model was unable to quantitatively describe the diffusion of the Krytox® 143AC in the PP, possibly due to excessive swelling.

scholarly journals Intumescent Polymer Metal Laminates for Fire Protection

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 995 ◽  
Author(s):  
Laura Geoffroy ◽  
Fabienne Samyn ◽  
Maude Jimenez ◽  
Serge Bourbigot
Keyword(s):  
Fire Protection ◽  
Thin Layers ◽  
Intumescent Coatings ◽  
Thin Aluminum ◽  
Thermal Measurements ◽  
Polymer Metal ◽  
Fire Barrier ◽  
Steel Substrates ◽  
Burn Through

Intumescent paints are applied on materials to protect them against fire, but the development of novel chemistries has reached some limits. Recently, the concept of “Polymer Metal Laminates,” consisting of alternating thin aluminum foils and thin epoxy resin layers has been proven efficient against fire, due to the delamination between layers during burning. In this paper, both concepts were considered to design “Intumescent Polymer Metal Laminates” (IPML), i.e., successive thin layers of aluminum foils and intumescent coatings. Three different intumescent coatings were selected to prepare ten-plies IPML glued onto steel substrates. The IPMLs were characterized using optical microscopy, and their efficiency towards fire was evaluated using a burn-through test. Thermal profiles obtained were compared to those obtained for a monolayer of intumescent paint. For two of three coatings, the use of IPML revealed a clear improvement at the beginning of the test, with the slopes of the curves being dramatically decreased. Characterizations (expansion measurements, microscopic analyses, in situ temperature, and thermal measurements) were carried out on the different samples. It is suggested that the polymer metal laminates (PML) design, delays the carbonization of the residue. This work highlighted that design is as important as the chemistry of the formulation, to obtain an effective fire barrier.

Metal – polymer interfaces and their effect on the glass transition of thin polystyrene films

2003 ◽  
Vol 790 ◽  
Author(s):  
J.S. Sharp ◽  
J.A. Forrest
Keyword(s):  
Glass Transition ◽  
Metal Layer ◽  
Interfacial Structure ◽  
Polymer Interfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Polymer Metal ◽  
Sample Preparation Procedure ◽  
Metal Interfaces ◽  
Metal Polymer

ABSTRACTWe present a study of polystyrene-metal interfaces and discuss the relationship between the interfacial structure and anomalies in the measured glass transition temperature (Tg) of thin metal capped polystyrene (PS) films. The PS films used in these studies were coated with an evaporated metal layer of either Aluminum (Al) or gold (Au) and the Tg values were measured with ellipsometry. Uncoated PS films were also measured and these samples showed Tg values that were reduced relative to the bulk value for film thicknesses (h) less than 40 nm. Films coated with Au were shown to have measured Tg values that were the same as the bulk value (Tgbulk=370 K) for all the film thicknesses studied (h ≥ 8nm). The Al coated PS films had measured Tg values that were the same as the uncoated PS films. The observed differences are discussed in terms of the differences in the structure of the metal-polymer interfaces produced during thermal evaporation of the metal layers. A novel sample preparation procedure was developed to enable us to use Atomic Force Microscopy (AFM) to directly measure the structure of the buried polymer-metal interfaces. The measurements performed on these systems support the suggestion that the interfacial structure is different for the two metal-polymer interfaces studied and that these differences may be the cause of the anomalies in the measured Tgs of these samples.

scholarly journals Frequency-dependent scaling behavior of polyvinylidene fluoride/metal composites

2019 ◽  
Vol 09 (02) ◽  
pp. 1950010
Author(s):  
Maheswar Panda
Keyword(s):  
Polyvinylidene Fluoride ◽  
Dielectric Constants ◽  
Scaling Behavior ◽  
Process Conditions ◽  
Polarization Model ◽  
Metal Composites ◽  
Frequency Dependent ◽  
Alloy Particles ◽  
Polymer Metal ◽  
Experimental Values

The frequency-dependent percolation and scaling behavior of a variety of polymer/metal composites (PMC), based on polyvinylidene fluoride (PVDF) matrix and various types of fillers such as; metal/alloy particles of different sizes, prepared through cold/hot pressing process conditions have undergone investigation. The universal percolation behavior in the vicinity of percolation threshold ([Formula: see text]), i.e., [Formula: see text] and [Formula: see text] is well satisfied, which suggests [Formula: see text] to be independent of frequency, where [Formula: see text] and [Formula: see text] are the effective ac conductivity and effective dielectric constants of the composite and [Formula: see text] is the frequency of applied ac signal. The obtained experimental values of the exponents are consistent with the inter-cluster polarization model ([Formula: see text] and [Formula: see text]), satisfying [Formula: see text]. The widely used percolative equations are well fitted with the experimental results of all PMC at all values of the frequency. The value of [Formula: see text] is found to be independent of frequency of the applied signal, suggesting the studied PMC are real percolating systems. The critical exponents ([Formula: see text] and [Formula: see text]) which characterize the divergence of [Formula: see text] and [Formula: see text] in the vicinity of [Formula: see text] are found to decrease with the increase of frequency. The rate of decrease of ‘[Formula: see text]’ and ‘[Formula: see text]’ with increase of frequency is attributed to the method of preparation, size of the fillers, adhesiveness of polymer/filler and the rate of decrease of [Formula: see text] with frequency (due to the absence of different extents of contributions of various types of conventional polarizations).

Modelling of Extrusion Behaviour of Biopolymer and Composites in Fused Deposition Modelling

2007 ◽  
Vol 334-335 ◽  
pp. 1241-1244 ◽  
Author(s):  
H.S. Ramanath ◽  
M. Chandrasekaran ◽  
Chee Kai Chua ◽  
Kah Fai Leong ◽  
Ketan D. Shah
Keyword(s):  
Fused Deposition Modeling ◽  
Flow Behavior ◽  
Current Model ◽  
Behavior Modeling ◽  
Fused Deposition Modelling ◽  
Fe Model ◽  
Fused Deposition ◽  
X Ray Imaging ◽  
Deposition Modeling ◽  
Experimental Values

Processing of polymers plays an important role in application of polymers in biomedical engineering, for instance in manufacture of scaffolds for tissue engineering applications. Rapid prototyping technologies like fused deposition modeling (FDM) has been widely used in processing polymers for biomedical applications. The present work is focused on modeling of flow behavior in the extrusion liquefier in FDM. A finite element (FE) model of extrusion liquefier was constructed on ANSYS after verification of internal geometry using X-ray imaging. Polycaprolactone (PCL) is used as the base bio polymer for analysis. Experiments were carried out to characterize the physical properties like thermal conductivity, specific heat, viscosity and shear thinning property of PCL. These values were used for behavior modeling in the extrusion liquefier. The thermal and flow behavior in the extrusion liquefier is studied by varying input conditions and analyzing the velocity, pressure drop profiles at various zones of extrusion liquefier. Experimental values of parameters and the simulated flow model showed good correlation. The current model can be extended to predict the flow behavior of PCL/ Hydroxyapatite composites in a FDM head which in turn will reflect on the quality of scaffold constructed using the Biocomposite.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

Early ossicle growth in the regenerating disc of a brittle star

1994 ◽  
Vol 52 ◽  
pp. 364-365
Author(s):  
M. Shlepr ◽  
R. L. Turner
Keyword(s):  
Cell Membrane ◽  
Light Microscopy ◽  
De Novo ◽  
Current Model ◽  
Syncytium Formation ◽  
Brittle Star ◽  
Intracellular Location ◽  
Limited Volume ◽  
Tissue Calcification

Calcification in the echinoderms occurs within a limited-volume cavity enclosed by cytoplasmic extensions of the mineral depositing cells, the sclerocytes. The current model of this process maintains that the sheath formed from these cytoplasmic extensions is syncytial. Prior studies indicate that syncytium formation might be dependent on sclerocyte density and not required for calcification. This model further envisions that ossicles formed de novo nucleate and grow intracellularly until the ossicle effectively outgrows the vacuole. Continued ossicle growth occurs within the sheath but external to the cell membrane. The initial intracellular location has been confirmed only for elements of the echinoid tooth.The regenerating aboral disc integument of ophiophragmus filograneus was used to test the current echinoderm calcification model. This tissue is free of calcite fragments, thus avoiding questions of cellular engulfment, and ossicles are formed de novo. The tissue calcification pattern was followed by light microscopy in both living and fixed preparations.

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