Patent Application
20130160638
Fibers and structures formed therefrom have proven to be acceptable for various applications. Such fibers and structures formed therefrom are nevertheless susceptible to improvements that may enhance the overall performance of the fiber and structure formed therefrom. Therefore, a need exists in the art for improved fibers and structures formed therefrom that advance the art.
In one aspect, a fiber includes at least a first portion extending axially and including a shear thickening fluid. The fiber further includes at least a second portion radially outward from the first portion. The second portion extends axially and radially encompasses the first portion over a length thereof. The shear thickening fluid may, for example, include particles suspended in a liquid phase. In a number of embodiments, the particles include at least one of an oxide, calcium carbonate or a polymer. For example, the particles may be Si02.
In a number of embodiments, the second portion includes at least one polymer. The at least one polymer of the second portion may, for example, be processible from a melt phase. In a number of embodiments, the at least one polymer of the second portion is a nylon, a polyester, a polypropylene, or a polyethylene.
The second portion may, for example, include an abrasion resistant material. In a number of embodiments, the abrasion resistant material is an abrasion resistant polymer. The fiber may further include a third portion extending axially and positioned radially inward of the first portion. The third portion may, for example, include a material having a higher strength than the second portion. The third portion may, for example, include at least one of a high-strength polymeric material or a metallic material.
In another aspect, a material includes a plurality of fibers. As described above, each of the plurality of fibers includes at least a first portion extending axially and including a shear thickening fluid. Each of the plurality of fibers further includes at least a second portion radially outward from the first portion. The second portion extends axially and radially encompasses the first portion over a length thereof.
In a further aspect, a fabric includes a plurality of fibers. As described above, each of the plurality of fibers includes at least a first portion extending axially and including a shear thickening fluid. Each of the plurality of fibers further includes at least a second portion radially outward from the first portion. The second portion extends axially and radially encompasses the first portion over a length thereof. The plurality of fibers may, for example, be woven into the fabric. The plurality of fibers may also be nonwoven. The plurality of fibers may, for example, be arranged in a unidirectional manner or in a random manner.
In still a further aspect, a ballistic panel includes at least one layer of a material including a plurality of fibers. As described above, each of the plurality of fibers includes at least a first portion extending axially and including a shear thickening fluid. Each of the plurality of fibers further includes at least a second portion radially outward from the first portion. The second portion extends axially and radially encompasses the first portion over a length thereof.
The present invention, along with the attributes and attendant advantages thereof, will best be appreciated and understood in view of the following detailed description taken in conjunction with the accompanying drawings.
As used herein and in the appended claims, the singular forms “a,” “an”, and “the” include plural references unless the content clearly dictates otherwise. Thus, for example, reference to “a fiber” includes a plurality of such fibers and equivalents thereof known to those skilled in the art, and so forth, and reference to “the fiber” is a reference to one or more such fibers and equivalents thereof known to those skilled in the art, and so forth.
In a number of embodiments of fibers hereof, a fiber 1 includes at least a first portion or layer 2 of a shear thickening fluid as illustrated in
In a number of embodiments, a sheath (second portion 4) and core (first portion 2) fiber is extruded wherein the sheath of second layer 4 is formed from one or more polymers such as nylon 6, nylon 6,6 polyester, polypropylene, polyethylene (for example, an ultra-high-molecular-weight polyethylene such as DYNEEMA®, available from DSM, of Heelen, Netherlands) SPECTRA® available from Honeywell, Inc.) and/or other polymers and the core of the fiber is a dilatant or shear thickening fluid (STF). In a number of embodiments, the polymer or polymers of second portion 4 are processed/extruded from a melt phase.
Fibers hereof can include other portions or layers. For example, multiple layers of shear thickening fluids encompassed by, for example, polymer layers in a generally alternating concentric fashion.
STF suitable for use herein can, for example, be formed as particles suspended in a liquid phase/solvent (for example, an organic solvent or an aqueous solvent). The particles used can be made of various materials, including, but not limited to, Si02 (silica) or other oxides, Si02 or other oxides with a polymer (for example, polyethylene glycol), calcium carbonate, or polymers, such as polystyrene, polymethylmethacrylate, polyisobutenes (for example, OPPANOL®, available from BASF Aktiengesellschaft of Ludwigshafen, Germany), or other polymers from emulsion polymerization. The particles can be stabilized in solution or dispersed by charge, Brownian motion, adsorbed surfactants, and adsorbed or grafted polymers, polyelectrolytes, polyampholytes, or oligomers. Particle shapes include spherical particles, elliptical particles, or disk-like or clay particles. The particles may be synthetic and/or naturally occurring minerals. Also, the particles can be either monodisperse, bidisperse, or polydisperse in size and shape. In a number of embodiments, particles having a particle size less than, for example, 100 microns may be used in forming STFs for use herein.
The solvents or liquid phases used to form the STFs can, for example, be aqueous in nature (i.e. water with or without added salts, such as sodium chloride, and buffers to control pH) for electrostatically stabilized or polymer stabilized particles, or organic (such as ethylene glycol, polyethylene glycol, ethanol etc.), or silicon based (such as silicon oils, phenyltrimethicone). The liquid phase can also be composed of compatible mixtures of liquids, and may, for example, include free surfactants, polymers, and oligomers. The liquids should be environmentally stable so that they remain integral to the fabric and suspended particles during service.
The particles are suspended in the liquid to produce a fluid that has shear thickening properties. Shear thickening does not require a dilatant response, that is, it may not be associated with an increase in volume such as often observed in dry powders or sometimes in suspensions of larger particles (greater than 100 microns).
The fibers, yarns, fabrics (for example, woven fabrics or nonwoven fabrics), materials and/or articles hereof provide a number of advantages over fibers coated or impregnated with a dilatant or an STF. For example, the STF is contained in fluid form in the core of the fibers hereof. STF applied in a secondary operation such as coating or impregnation is not contained. By containing the STF in the fibers hereof, the STF is much more robust and stable and less likely to evaporate and/or degrade under higher temperature conditions (for example, at ambient summer temperatures or higher temperatures). Containing the STF in the fiber also provides more uniformity and consistency of the STF than current methods which involve application processes such as coating and/or impregnating. Coating and impregnation methods are, for example, susceptible to variations in thickness and coverage uniformity. Containing the STF in the fiber will also improve the overall durability of the STF, including its abrasion resistance, as compared to STFs applied to fibers in a secondary operation. Energy dissipation may, however, be further improved via coating or impregnating the exterior of fabrics hereof with an STF to enhance inter-fiber friction.
Fabrics formed from fibers hereof can, for example, be used to mitigate blunt force trauma in a ballistic vest when impacted by a projectile (bullet, spike, blade, etc). Fibers hereof can also be used to mitigate impact damage in other applications (for example, in hardhats, in advanced combat helmets (ACH), in shielding for machinery etc.).
As described above, body armor 10 includes ballistic panel assemblies or ballistic resistant panel assemblies that provide resistance to, for example, edged weapons, sharp objects, and ballistic threats. As illustrated with dashed lines in, for example,
In the embodiment of
As illustrated in
Adjacent to layer 232 is a layer 234 including, for example, a plurality of plies of, for example, an aramid fabric. In one embodiment, layer 234 included, for example, multiple plies of TWARON® woven fabric available from Teijin Aramid BV of Amhem, The Netherlands. TWARON material is a very strong, light para-aramid (poly-paraphenylene terephthalamide), which has a high tensile strength and is thermally stable. TWARON fabrics also exhibit high impact and chemical resistance. No adhesive was used between the plies of TWARON fabric in layer 234. Without limitation to any particular mechanism of operation, it is believed that the projectile or bullet is stopped within layer 234 as a result, at least in part, of elongation and breakage of the high tensile strength fibers of the TWARON fabric.
Adjacent to layer 234 is a layer 236 including, for example, a fabric formed from fibers 1 that forms the back, inner or wear face of subassembly 230. Layer 236 can, for example, be a single-ply layer or a multi-ply layer of such a fabric material with no adhesive between the plies thereof. The diameter and/or other parameter of the fibers can be varied or optimized to achieve desired results via application of established engineering principles. Layer 236 can operate, at least in part, to limit deformation of the wear face of subassembly 230 upon a ballistic strike thereto to limit the amount of blunt force trauma experienced by a user of vest 20. In that regard (and, once again, without limitation to any particular mechanism of operation,), layer 236 can, for example, operate to distribute rearward propagating force from the projectile or bullet over the surface area thereof and assists in limiting backface deformation or backface signature (BFS) as defined in Section 3.8 of NIJ Standard-0101.06. In that regard, the allowable BFS is the greatest extent of indentation in a backing material caused by a nonperforating impact on tested armor. As set forth in Section 3.9 of NIJ Standard-0101.06, the backing material is a homogeneous block of nonhardening, oil-based modeling clay placed in contact with the back of the armor panel during ballistic testing.
The foregoing description and accompanying drawings set forth the preferred embodiments of the invention at the present time. Various modifications, additions and alternative designs will, of course, become apparent to those skilled in the art in light of the foregoing teachings without departing from the scope of the invention. The scope of the invention is indicated by the following claims rather than by the foregoing description. All changes and variations that fall within the meaning and range of equivalency of the claims are to be embraced within their scope.
| Number | Date | Country | |
|---|---|---|---|
| 61535041 | Sep 2011 | US |
