Patent Application
20140099496
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
The disclosed subject matter relates to a composite material comprising a high tenacity fiber reinforced polymer fabric, such as a carbon fiber reinforced polymer, and a polyurea layer coated on at least one surface of the polymer fabric. The disclosed subject matter also relates to reinforcing a substrate, such as a wood, concrete, masonry, steel, or other component, with the composite material.
Earthquakes remain one of nature's deadliest forces. One way in which earthquakes cause damage is the stress they exert on buildings and other structures due to ground shaking and ground rupture. The damage can render buildings and other structures unusable, or at worst, cause their outright, collapse, often resulting in human injury or death. For example, the 2010 earthquake in Haiti caused significant damage or destruction to many homes and to the health care infrastructure, resulting in over 170,000 casualties and affecting over 3 million people.
Furthermore, earthquakes, such as, for example, the 1906 San Francisco earthquake, often initiate associated fire disasters (i.e., “fire following earthquake” disasters). The earthquake-associated fires can significantly contribute to the economic losses and to the loss of life related to the original earthquake event. Regions of northern and southern California that lie along the San Andreas Fault and its various sister faults are primary candidates for a “fire following earthquake” disaster due to their population and infrastructure density. Recent modeling of present-day damage resulting from a “fire following earthquake” disaster of the same magnitude as the 1906 San Francisco earthquake and fire estimated that nearly 10 million residents of northern California would be impacted by economic, social, and mortality factors. The overall economic losses were estimated to be about $150 billion dollars.
In addition to earthquakes and other seismic events, structural damage can also be caused by other natural or non-natural events that exert stresses on buildings and other structures, including, for example, hurricanes, tornados, landslides, flash flooding, tsunamis, and explosions due to warfare or terrorism. Moreover, structural damage can occur even in the absence of a particular catastrophic event. For example, damage to structures can be caused by regular long-term use, long-term exposure to environmental factors, and/or increased use and/or loading of structures due to increasing population demands.
For at least these reasons, various approaches have been made to strengthen structural elements, such as concrete slabs, walls, beams, columns, and foundations. For example, one approach for strengthening new and existing concrete structural elements is by reinforcing them with a variety of steel shapes, such as steel meshes, steel reinforcement bars, and steel grids. However, steel or other suitable metals used for reinforcing these structural elements are subject to corrosion. The products of corrosion result in an expansion of the column of the steel which causes a spalling effect, which can cause a breakup and deterioration of the concrete structure. In addition, while other corrosion-resistant materials have been considered, these materials bring about other difficulties, such as delamination, less ductility, or higher cost.
Accordingly, it is desirable to provide high strength, highly damped, and/or high elasticity composite materials that overcome these and other deficiencies of the prior art.
For example, there is an ongoing need for protection systems to reinforce structures (e.g., buildings and other infrastructure) against damage due to torsion and/or shear and tensile stresses, such as might be experienced, for example, during structural accelerations and displacements, or to strengthen them following such damage. In addition, there is a need for materials that can also protect buildings and other infrastructure from fire damage and/or that can provide other additional protection, such as from ultraviolet radiation, water damage, and/or environmental pollutants, and/or that can provide an insulative effect, e.g., to reduce heating and/or cooling costs in the reinforced structures.
In accordance with various embodiments of the disclosed subject matter, a composite material is provided. The composite material in accordance with some embodiments of the disclosed subject matter includes a high tenacity fiber reinforced polymer fabric and a polyurea coating layer formed on at least one surface of the polymer fabric. The composite material provides significant strength, flexibility, viscous damping, and energy dissipation. In some embodiments, the composite material can also be formed to have additional protecting properties, such as fire resistant properties, UV protective properties, or moisture resistant properties.
The composite material can be used in a variety of applications. For example, the composite material can be used to reinforce structural and/or non-structural substrates to protect them from damage (e.g., due to seismic or wind activity, fire, impact, loading, and/or explosive forces). In another example, the composite material can be used to strengthen structural and/or non-structural substrates following damage by forming the composite material on at least one surface of the substrate (e.g., tightly wrapped around the entire substrate, formed over a crack in the substrate, etc.). In yet another example, the composite material can be used to provide a particular protective property to a substrate, such as UV protection, fire resistance, corrosion resistance, moisture resistance, and/or energy efficiency. In yet another suitable example, the composite material can be used as a stand-alone structure that is strong, stiff, and provides significant damping, while also providing one or more protective properties, such as UV protection, fire resistance, corrosion resistance, moisture resistance, and/or energy-efficiency.
In a more particular example, the composite material can be used to provide energy dissipation and sustainable strength properties to light-frame wood construction, concrete and masonry structures, and/or steel structures to save occupant lives and protect infrastructure during extreme loading events (e.g., an earthquake or human-induced hazards having high impact loads involving ballistics or blast loads). In some embodiments, the composite material can be used for the lightweight design of vehicle components, which would improve safety, performance, and fuel efficiency.
In some embodiments, the disclosed subject matter can provide a protection system that reduces structural accelerations and displacements by combining a high strength/high stillness material with sustainable energy dissipation and ductility. In some embodiments, this protection system can. include a composite material that is tightly wrapped around or applied as a ply to (e.g., adhered to) an exterior lace or surface of a substrate, thereby providing viscoelastic behavior properties that transition to a sustainable elastomeric state by sustaining the interfacial interaction between the composite material and the underlying substrate. The composite material can act as an energy-release valve by providing sustainable energy dissipation and large viscous-type damping during extreme loading events, such as during earthquakes, that minimise structural damage to the substrate. In some embodiments, the composite/substrate system can allow for a change in viscous damping ratio (e.g., the composite/substrate system has a different viscous damping ratio than the substrate alone).
In accordance with some embodiments of the disclosed subject matter, a composite material is provided, the composite material comprising: a substrate; a fiber reinforced polymer fabric layer attached to at least a portion of the substrate; and a polyurea coating layer formed on an exposed surface of the fiber reinforced polymer fabric layer.
In some embodiments, the substrate is one of: wood, masonry, concrete, steel, and a combination thereof.
In some embodiments, the substrate has at least one damaged portion and the fiber reinforced polymer fabric layer and the polyurea coating layer are formed on the at least one damaged portion of the substrate.
In some embodiments, the fiber reinforced polymer fabric layer is a carbon fiber reinforced polymer fabric.
In some embodiments, the polyurea coating layer is formed by applying an elastomeric polyurea-forming component solution to the exposed surface of the fiber reinforced polymer fabric layer, wherein the elastomeric polyurea-forming component solution forms an aromatic polyurea coating layer.
In some embodiments, the polyurea further comprises an additive component, wherein the additive component is at least one of: an ultraviolet (UV) protective additive, a flame retardant, a corrosion protective additive, a moisture resistance additive, and ceramic microspheres.
In accordance with some embodiments, a method for reinforcing a substrate is provided, the method comprising: providing a substrate; attaching a high tenacity fiber reinforced polymer fabric to at least a portion of the substrate; applying a saturant composition to an exposed surface of the high tenacity fiber reinforced polymer fabric, wherein the saturant composition comprises a polymer resin; curing the saturant composition to form a tacky surface; applying an elastomeric polyurea-forming component solution to the tacky surface; and curing the polyurea-forming component solution to form a polyurea coating layer.
In some embodiments, the method further comprises; applying a primer layer to a surface of the substrate; and applying another saturant composition to the primer layer. The primer layer can be used to prepare the substrate and/or assist layers to bond with the substrate. The saturant composition can be used to bond the high tenacity fiber reinforced polymer fabric with the substrate.
In some embodiments, the substrate is one of: wood, masonry, concrete, steel, and a combination thereof.
In some embodiments, the substrate is used in one of: a newly constructed structure and an existing structure.
In some embodiments, the method further comprises performing surface preparation on at least a portion of the substrate, wherein the surface preparation includes at least one of: smoothing the substrate, filling in one or more damaged portions of the substrate with a putty material, and cleaning the substrate.
In some embodiments, the high tenacity fiber reinforced polymer fabric is wrapped around the substrate.
In some embodiments, the polyurea-forming component solution comprises an isocyanate component and a polyamine component, the method further comprising mixing the isocyanate component and the polyamine component prior to applying it to the tacky surface of the saturant to form the polyurea-forming component solution. The polyurea-forming component solution may, in some embodiments, have an excess of the isocyanate component.
In some embodiments, the method further comprises spraying the polyurea-forming component solution on the tacky surface.
In some embodiments, the method further comprises providing an additive component into the polyurea-forming component solution, wherein the additive component is one of: an ultraviolet (UV) protective additive, a flame retardant, a corrosion protective additive, a moisture resistance additive, and ceramic microspheres.
In some embodiments, the polyurea coating layer has a thickness, the method further comprising controlling the thickness of the polyurea coating layer.
In some embodiments, the method further comprises applying the polyurea-forming component solution to form the polyurea coating layer after a given time when the saturant composition on the high tenacity fiber reinforced fabric layer has become tacky and controlling the thickness of the polyurea coating layer. In some embodiments the given time is between about two hours and about five hours.
In some embodiments, the saturant composition is cured for a first time period and wherein the polyurea-forming component solution is cured for a second time period, the method further comprising modifying the first time period and the second lime period to obtain material properties of the polyurea coating layer on the high tenacity fiber reinforced polymer fabric.
In some embodiments, a first component of the polyurea-forming component solution and a second component of the tacky surface of the saturant composition applied to the high tenacity fiber reinforced polymer fabric internet to form a sustainable interface between the polyurea coating layer and the high tenacity fiber reinforced polymer fabric.
In accordance with some embodiments, a method for reinforcing a substrate having damaged portions is provided, the method comprising: forming a polyurea-coated high tenacity fiber reinforced polymer fabric, wherein the forming comprises: providing a high tenacity fiber reinforced polymer fabric; applying a saturant composition to a surface of the high tenacity fiber reinforced polymer fabric, wherein the saturant composition, comprises a polymer resin; curing the saturant composition to form a tacky surface; applying an elastomeric polyurea-forming component solution to the tacky surface; and curing the polyurea-forming component solution to form a polyurea coating layer on the high tenacity fiber reinforced polymer fabric; preparing at least a portion of the substrate for reinforcement prior to positioning the polyurea-coated high tenacity fiber reinforced polymer fabric on the substrate; and attaching the polyurea-coated high tenacity fiber reinforced polymer fabric to at least the damaged portions of the substrate.
In some embodiments, the method further comprises applying a putty to the substrate having damaged portions to create a smooth surface on the substrate.
In some embodiments, the method further comprises applying another saturant composition to an interface between the substrate and the high tenacity fiber reinforced polymer fabric.
In some embodiments, the method further comprises forming the polyurea coating layer of a thickness based at least in part on an assessment of the damaged portion of the substrate.
In some embodiments, the method further comprises forming the polyurea coating layer after a given time when the saturant composition on the high tenacity fiber reinforced fabric layer has become tacky and based at least in part on an assessment of the damaged portion of the substrate.
In some embodiments, at least a first component of the polyurea-forming component solution and a second component of the tacky surface of the saturant composition applied to the high tenacity fiber reinforced polymer fabric interact to form a sustainable interface between the polyurea coating layer and the high tenacity fiber reinforced polymer fabric.
In some embodiments, the method further comprises forming a plurality of polyurea-coated high tenacity fiber reinforced polymer fabrics and attaching each of the plurality of polyurea-coated high tenacity fiber reinforced polymer fabrics to a different portion of the substrate.
The disclosed subject matter will now be described more fully hereinafter with reference to the accompanying examples and drawings, in which representative embodiments are shown. The presently disclosed subject matter can, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art.
Throughout the specification and claims, a given chemical formula or name shall encompass all optical and stereoisomers, as well as racemic mixtures where such isomers and mixtures exist.
While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the disclosed subject matter.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.
Following long-standing patent law convention, the terms “a,” “an,” and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to “an additive” includes a plurality of such additives, and so forth.
Unless otherwise indicated, all numbers expressing quantities of size, amount, elongation percentage, tensile strength, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.
As used herein, the term “about,” when referring to a value or to an amount of size, weight, concentration, time, or percentage is meant to encompass variations of, in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods.
The term “and/or” when used to describe two or more activities, conditions, or outcomes refers to situations wherein both of the listed conditions are included or wherein only one of the two listed conditions are included.
The term “comprising,” which is synonymous with “including,” “containing,” or “characterized by” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. “Comprising” is a term of art used in claim language which means that the named elements are essential, but other elements can be added and still form a construct within the scope of the claim.
As used herein, the phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When the phrase “consists of” appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.
As used herein, the phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.
With respect to the terms “comprising,” “consisting of,” and “consisting essentially of,” where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.
The term “fiber” generally refers to an elongated body the length dimension of which is much greater than the transverse dimensions of width and thickness. The term fiber includes either manufactured or natural monofilament, multifilament, ribbon, strip, staple and other forms of chopped, cut or discontinuous fiber and the like having regular or irregular cross-section. The term “fiber” includes a plurality of any of the foregoing or a combination thereof.
In some embodiments, the cross sections of the fibers may be circular, flat or oblong. They may be irregular or regular multilobal cross-section having one or more regular or irregular lobes projecting from the linear or longitudinal axis of the fibers.
High tenacity fibers are fibers that have high ultimate tensile strength and a high modulus of elasticity (e.g., a high Young's modulus or tensile modulus). High tenacity fibers include, but are not limited to, highly oriented, high molecular weight polyolefin fibers, particularly high modulus polyethylene fibers and polypropylene fibers; aramid fibers; polybenzazole fibers such as polybenzoxazole (PBO) and polybenzothiazole (PBT); polyvinyl alcohol fibers; polyacrylonitrile fibers; liquid crystal copolyester fibers; glass fibers; carbon fibers; basalt or other mineral fibers; as well as rigid rod polymer fibers; and mixtures and blends thereof. In some embodiments, the high tenacity fiber is carbon, fiber, glass fiber (e.g., e-glass or s-glass), aramid (e.g., meta- or para-aramid), liquid crystal copolyester fiber, basalt fiber or a combination thereof.
Fabrics comprising high tenacity fibers can include a network of fibers in the form of a woven, knitted or a non-woven fabric. In some embodiments, at least 50% by weight of the fibers in the fabric are high tenacity fibers. In some embodiments, at least about 75% by weight of the fibers in the fabric are high, tenacity fibers. In some embodiments, substantially all of the fibers in the fabric are high tenacity fibers.
The fabrics of the presently disclosed subject matter can comprise one or more different high tenacity fibers. In some embodiments, the yams in the fabric can be essentially parallel in alignment. In some embodiments, the yarns can be twisted, over-wrapped or entangled. The fabrics of the presently disclosed subject matter can be woven with yarns having different fibers in the warp and weft directions, or in other directions.
As used herein, a “monomer” refers to a molecule that can undergo polymerization, thereby contributing constitutional units (i.e., an atom or group of atoms) to the essential structure of an oligomer or polymer.
An “oligomer” refers to a molecule of intermediate relative molecular mass, the structure of which comprises a small plurality of units (e.g., between about 2 and about 10 repeating units) derived from molecules of lower relative molecular mass.
A “polymer” refers to a molecule comprising a plurality of repeating units derived from smaller molecules (e.g., monomers or oligomers). In some embodiments, the polymer has more than 10 repeating units, more than 25 repeating units, more than 50 repeating units, or more than 100 repeating units. In some embodiments, a polymer can have more than 1,000, more than 5,000, more than 10,000, more than 50,000, more than 100,000 repeating units, or more than 250,000 repeating units.
A “copolymer” refers to a polymer derived from more than one species of monomer.
The term “prepolymer” refers to a monomer, oligomer or short chain polymer with reactive terminal groups (e.g., epoxy, ester, carboxylic acid (or carboxylate), hydroxyl, vinyl, or amine groups) that can react to form a larger (e.g., higher molecular weight) polymer or copolymer. In some embodiments, “short chain polymer” refers to a polymer with 1,000 repeating units or less (e.g., 1,000, 750, 500, 400, 300, 200, 150, 100, 75, 60, 50, 40, or 30 repeating units or less). In some embodiments, a short chain polymer has molecular weight of less than 10,000 g/mol (e.g., less than 10,000, 7,500, 5,000,4,000, 3,000, 2,000, or 1,000 g/mol).
The term “resin” or “polymer resin” as used herein refers to a composition comprising one or more polymeric, oligomeric or monomeric materials that can be hardened by polymerization. Thus, in some embodiments, a resin is a viscous liquid composition that can be polymerized to form a solid. Suitable resins include, but are not limited to, epoxy resins, vinyl ester resins, polyester resins and methylmethacrylate resins.
The hardening (or further polymerization) of the resin can also be referred to as “curing.” In some embodiments, the curing requires a polymerisation initiator, e.g., an organic peroxide. In some embodiments, the level of curing is dependent on time and temperature. In some embodiments, “curing” refers to partial curing, e.g., wherein the further polymerization of the resin is allowed to proceed to about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% completion (i.e., leaving about 90, 80, 70, 60, 50, 40, 30, 20, or about 10% unreacted polymerizable groups as compared to the percentage of polymerizable groups present in the resin prior to curing).
The term “tacky” as used herein refers to a partially cured resin, e.g., a resin or saturant wherein some level of polymerization of the original resin has occurred, but wherein there are still unreacted, polymerizable groups available.
The term “polyurea” refers to a polymer comprising multiple urea bonds (i.e., bonds having the structure —NR—C(═O)—NR—, wherein R is H, alkyl, or aryl). Polyureas can be formed by the reaction of isocyanate-terminated prepolymers and amine-containing components (e.g., amine-terminated polymer resins, amine-terminated oligomers, or amine-containing monomers).
The term “isocyanate” refers to the group —N═C═O.
The term “amine” refers to the group —NR′R″, wherein R′ and R″ are independently H, alkyl, or aryl. “Primary amines” are compounds wherein both R′and R″ are H. “Secondary amines” are compounds wherein one of R′ and R″ is H and the other is alkyl or aryl.
As used herein, the term “alkyl” refers to C1-20 inclusive, linear (i.e., “straight-chain”), branched, or cyclic, saturated or at least partially and in some cases fully unsaturated (i.e., alkenyl and alkynyl) hydrocarbon chains, including for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, ethenyl, propenyl, butenyl, pentenyl, bexenyl, octenyl, butadienyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, and allenyl groups. “Branched” refers to an alkyl group in which a lower alkyl group, such as methyl, ethyl or propyl, is attached to a linear alkyl chain. “Lower alkyl” refers to an alkyl group having 1 to about 8 carbon atoms (i.e., a C1-8 alkyl), e.g., 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms. “Higher alkyl” refers to an alkyl group having about 10 to about 20 carbon atoms, e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms. In certain embodiments, “alkyl” refers, in particular, to C1-8 straight-chain alkyls. In other embodiments, “alkyl” refers, in particular, to C1-8 branched-chain alkyls.
Alkyl groups can optionally be substituted with one or more alkyl group substituents, which can be the same or different. The term “alkyl group substituent” includes but is not limited to alkyl, halo, arylamino, acyl, hydroxyl, aryloxyl, alkoxyl, alkylthio, arylthio, aralkyloxyl, aralkylthio, carboxyl, alkoxycarbonyl, oxo, and cycloalkyl. There can be optionally inserted along the alkyl chain one or more oxygen, sulfur or substituted or unsubstituted nitrogen atoms, wherein the nitrogen substituent is hydrogen, lower alkyl (also referred to herein as “alkylaminoalkyl”), or aryl.
The term “aryl” is used herein to refer to an aromatic substituent which can be a single aromatic ring or multiple aromatic rings which are fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety. The common linking group can also be a carbonyl as in benzophenone or oxygen as in diphenylether or nitrogen in diphenylamine. The aromatic ring(s) can include phenyl, naphthyl, biphenyl, diphenylether, diphenylamine and benzophenone among others. In particular embodiments, the terra “aryl” means a cyclic aromatic comprising about 5 to about 10 carbon, atoms, including 5- and 6-membered hydrocarbon and heterocyclic aromatic rings,
The aryl group can be optionally substituted with one or more aryl group substituents which can be the same or different, where “aryl group substituent” includes alkyl, aryl, aralkyl, hydroxy, alkoxyl, aryloxy, aralkoxyl, carboxy, acyl, halo, nitro, alkoxycarbonyl, aryloxycarbonyl, aralkoxycarbonyl, acyloxyl, acylamino, arcylamino, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, arylthio, alkylation, alkylene and —NR′R″, where R′ and R″ can be each independently hydrogen, alkyl, aryl and aralkyl.
Specific examples of aryl groups include but are not limited to cyclopentadienyl, phenyl, furan, thiophene, pyrrole, pyran, pyridine, imidazole, isothiazole, isoxazole, pyrazole, pyrazine, pyrimidine, and the like.
The term “microspheres” refers to particles having at least one dimension less than about 1000 microns. In some, but not all, embodiments, microspheres are essentially spherical and have a diameter of less than about 1000, 750, 500, 400, 300, 200, 100, 75, 50, 25, 10, 5, or 1 microns, in some embodiments, microspheres can be irregular in shape, or have a rod-like, disc, or cubic shape.
Generally speaking, the disclosed subject matter provides a composite material that includes a high tenacity fiber reinforced polymer fabric and a polyurea coating layer formed on the high tenacity fiber reinforced polymer fabric. The composite material can be formed on any suitable substrate (e.g., wood, reinforced concrete, steel, any other suitable substrate, and/or any combination thereof). The composite material provides a material that integrates viscoelastic behavioral properties via sustainable interfacial interaction between the composite material and the underlying substrate.
The composite material can be used in a variety of applications. For example, the composite material can be used to reinforce structural and/or non-structural substrates to protect them from damage (e.g., due to seismic activity, fire, impact, loading, and/or explosive forces). In another example, the composite material can be used to strengthen structural and/or non-structural substrates following damage by forming the composite material on at least one surface of the substrate (e.g., tightly wrapped around the entire substrate, formed over a crack in the substrate, etc.). In yet another example, the composite material can be used to provide a particular protective property to a substrate, such as UV protection, fire resistance, corrosion resistance, moisture resistance, and/or energy efficiency.
In a more particular embodiment, the disclosed subject matter can provide a protection system that reduces structural accelerations and displacements by combining a high strength/high stiffness material with sustainable energy dissipation and ductility. In some embodiments, this protection system can include a composite material that is tightly wrapped around or applied as a ply (e.g., adhered to) an exterior face or surface of a substrate, thereby providing viscoelastic behavior properties that transition to a sustainable elastomeric state by sustaining the interfacial interaction between the composite material and the underlying substrate. The composite material can act as an energy-release valve by providing sustainable energy dissipation and large viscous-type damping during extreme loading events, such as during earthquakes, that minimize structural damage to the substrate. In some embodiments, the composite/substrate system can allow for a change in viscous damping ratio (e.g., the composite/substrate system has a different viscous damping ratio than the substrate alone).
In another suitable embodiment, the composite material of the disclosed subject matter can be used to construct a stand-alone structure having high strength, high stiffness, and provides significant damping. In addition, the composite material can provide one or more protective properties, such as UV protection, fire resistance, corrosion resistance, moisture resistance, and or energy-efficiency. For example, the composite material can be used to manufacture automotive parts, spotting goods equipment, and bicycle frames, among others. In a more particular example, each of these parts or structures may have a desirable set of properties, such as a damping ratio greater than a given percentage. As explained hereinbelow, the composite material can be modified by varying curing times and/or varying the thickness of the polyurea coating layer to achieve particular properties.
As described herein, the composite material can include a layer of high tenacity fiber reinforced polymer (FRP) and a layer of elastomeric polyurea formed on the layer of high tenacity fiber reinforced polymer. In a more particular embodiment, a high tenacity fiber reinforced polymer fabric can be attached to a substrate using a first saturant composition, a second saturant can be applied to the exposed surface of the high tenacity fiber reinforced polymer fabric and cured until forming a tacky surface, and an elastomeric polyurea can be formed on the tacky surface. Use of the polyurea coating layer can increase ductility and energy dissipation by about 100% in a composite as compared to that of the relatively stiff and brittle FRP alone.
In some embodiments, the properties of the composite material can be described as a function of time-related (tc) and volume-fraction (hp) polymeric properties. For example, it has been determined that time-related factors in the preparation of the composite material (e.g., time factors related to the reaction of the precursors of the polyurea layer and the precursors of the polymer of the FRP) can affect the viscous properties and/or elongation percentage of the FRP and/or composite as a whole, thereby enabling the strength of the resulting load-bearing composite to be sustained at large deformations.
For example, as described herein, studies of the disclosed composites and of composite-wrapped wood-frame structures indicate that wrapping substrates with the presently disclosed composite material can synergistically confine the substrate and provide a continuous load path, for example, between the foundation of the wrapped wood-frame structure and its roof. Moreover, no de-bonding was exhibited between the individual composite wrap constituents or between the wrap and the wood frame substrate. Accordingly, the interaction, or synergy, of the exterior composite tight-wrap and the frame can be used to replace the interaction of an exterior wood sheathing diaphragm and the frame, for example, via the fasteners typically used in traditional wood structures. The integration of large viscous-type damping can preclude reliance on the hysteretic damping of the shear wall fasteners, which can pull through or withdraw from the framing during ground motions, or the minimal viscous damping that is ordinarily provided by structural and non-structural components in traditional wood structures.
In another example, as described herein, the disclosed composites can be applied to reinforced concrete beams, shear walls, and other structures. More particularly, a structure or structural element can be retrofitted with the composite material. A damaged structural element having multiple cracks such that the after-test load capacity dropped to approximately 40% of its peak value can be retrofitted with the composite material. Upon forming the composite material over portions of the damaged, structural element, the reinforced structural element recovered its original load capacity and received a significant increase in the ductility of the structural element. The ductility of the composite material formed on the structural element allows the structural element to experience large deformations. That is, the energy after the formation of cracks can be readily dissipated, thus inhibiting the formation of new crack surfaces and inhibiting further damage from occurring.
In some embodiments, the composite material wrapped around a substrate can reduce accelerations and elastic displacements in wrapped substrates up until their peak loading stress via an increase in strength, stiffness and viscous properties. During extreme loading, where an unwrapped substrate would have been loaded inelastically and beyond its maximum strength, the composite wrap can provide, in some embodiments, a “sustainable negative stiffness” to help minimize damages by inducing a viscous damping mechanism to stabilize crack substrate growth (by invoking stable crack energy release) and dissipate strain energy, allowing the wrapped substrate to sustain a high level of strength. Models of the viscoelastic behavior of the wrapped substrates can be developed based, for example, on existing nonlinear constitutive material models formulated on continuum mechanics theory. See, e.g., Attard, T. L. et al., J. of Eng. Mechanics, ASCE, 134(10), 881 (2008), which is incorporated by reference herein in its entirety.
In some embodiments, the disclosed subject matter provides a composite comprising a fabric that is coated on at least one surface with a coating layer comprising an elastomeric polyurea, where the fabric is a high tenacity fiber reinforced by a polymer matrix (sometimes referred to herein as a fiber reinforced polymer (FRP) fabric). The composite is sometimes referred to herein as CarbonFlex.
Referring to
It should be noted that the composite can be formed without a substrate. That is, the composite can be used to construct a stand-alone structure. Alternatively, the composite can be formed without a substrate and at a later time, attached to a substrate.
In some embodiments, substrate 100 may be damaged and include cracks, pits, chips, and/or grooves in the surface of substrate 100. To provide a uniform and/or a smooth surface, substrate 100 can be prepared by using a putty material. As shown in
It should be noted that putty material 105 applied to substrate 100 may not be used for a newly constructed structure or substrate that is generally undamaged.
In some embodiments, substrate 100 (and its prepared surface) can be in contact with a primer 110 and a first saturant composition 120. Primer 110 can be also in contact with one side of a high tenacity fiber reinforced polymer fabric 130 (e.g., the high tenacity fiber fabric with the polymeric matrix formed by curing of, for example, the first saturant composition 120). Attachment of the fiber reinforced polymer fabric 104 can be performed such that during curing of the polymer matrix in fabric 130 an interaction or bonding (e.g., covalent bonding) takes place between the polymeric components of primer 110, saturant composition 120, and/or the fiber reinforced polymer fabric 130. For example, primer 110 and/or first saturant composition 120 can improve the bonding of the high tenacity fiber reinforced polymer fabric 130 with substrate 100. In another example, primer 110 can improve the bonding of first saturant composition 120 with substrate 100. In yet another example, a predetermined amount of time may elapse before forming additional layers to allow the high tenacity fiber reinforced polymer fabric 130 to bond or interact with substrate 100.
In some embodiments, the exposed side of the fiber reinforced polymer fabric 130 can be in contact with a polyurea coating layer 150, at interface 135. More particularly, a second saturant composition 140 cats be applied to the exposed surface of the fiber reinforced polymer fabric 130. When a tacky surface is formed by at least partially curing the second saturant composition 140 for a given period of time (e.g., about two hours to five hours), a polyurea coating layer 150 can be formed on the high tenacity fiber reinforced polymer fabric 130. Polymeric components from both fiber reinforced polymer fabric 130 with second saturant composition 140 and polyurea coating layer 140 can interact (e.g., via covalent bonding) at interface 135 to prevent separation, of fiber reinforced polymer fabric 130 and polyurea coating layer 140 following complete curing of the composite. It should also be noted that, curing the second saturant composition can, in some embodiments, cure the first saturant composition applied between substrate 100 and fiber reinforced polymer fabric 130.
It should be noted that the thickness of the polyurea coating layer 150 can be varied based on the desired properties of the composite-coated substrate. It should also be noted that the properties of the composite (e.g., viscous damping properties versus stiffness properties) can generally be modified by modifying time-related (tc) and volume-fraction (hp) polymeric properties. For example, the time related to the reaction of the precursors of the polyurea coating layer 150 and the polymer of the fiber reinforced polymer fabric 130 can affect the viscous properties and/or elongation percentage of the composite as a whole.
In some embodiments, if desired, an additive layer 110 can be formed on one side of the polyurea coating layer 108. Additive layer 110 can contain, for example, ceramic microspheres or an additional protectant layer (e.g., a moisture resistance layer, a UV protective layer, a corrosion, resistance layer, a flame retardant layer, etc), in some embodiments, optional additive layer 110 is absent.
Accordingly, the interaction, or synergy, of various components within the primer layer 110, the first saturant composition layer 120, the fiber reinforced polymer fabric layer 130, the second saturant composition layer 140, the polyurea coating layer 150, and/or the additive layer 160 form the composite having desirable strength, stiffness, and damping properties. The strength, stiffness, and damping properties of the composite can be modified based on time-related (tc) and volume-fraction (hp) polymeric properties. For example, time-related factors in the preparation of the composite material (e.g., the time to ewe the second saturant composition, which creates an interaction between components of the polyurea coating layer 150 and the precursors of the polymer of the fiber reinforced polymer fabric layer 130) can affect the viscous properties and/or elongation percentage of the composite, thereby enabling the strength of the resulting load-bearing composite to be sustained at large deformations.
As described above, the composite or composite material can be used in a variety of applications. For example, the composite can be used to wrap substrates including buildings, building components and other structures and parts or elements thereof in order to reinforce the substrates following damage or to prevent damage from occurring in the future. The composite can also be used to provide reinforcing inserts for building materials. For example, in addition to being used as a wrap for concrete structures, materials comprising the composite can be embedded within the concrete structure. In some embodiments, the composite materials can be used as a wrap for armored vehicles, such as military transport or weapons vehicles. Additional uses also include protective clothing (e.g., bullet proof vests and the like) or bio-medical applications, such as in the fabrication of prosthetics or parts for prosthetics. Even further, the composite can be used in high-vibration or high impact or shock load applications, such as bicycles, helmets, etc. For example, the composite material can be formed around a foam core to impart impact, resistance properties to the foam core.
In some embodiments, the composite can be used as a building material itself. For example, the composite can be used to construct bicycle frames, automotive pans, and/or protective clothing. In a more particular example, the composite can be used for the lightweight design and manufacturing of vehicle components, which would, improve safety, performance, and fuel efficiency.
It should be noted that, for the polyurea coating layer, any suitable elastomeric polyurea can be used. The polyurea can be selected based, on any suitable factors including, but not limited to, cost, abrasion resistance, flexibility, chemical resistance, toxicity/volatility of chemicals given off by the polyurea over time, UV resistance, moisture resistance, and the like. In some embodiments, the polyurea has an elongation (i.e., an elongation at break) of at least about 100%. In some embodiments, the polyurea can have an elongation of about 600% or more. In some embodiments, the polyurea has a tensile strength of between about 1500 and about 2000 pounds per square inch (psi) (e.g., about 1500, about 1600, about 1700, about 1800, about 1900, or about 2000 psi). The properties of many polyureas are known in the art and/or can be measured by techniques known in the art, such as ASTM D412.
Polyureas suitable for use in the disclosed subject matter can be prepared by mixing (e.g., reacting or polymerizing) isocyanates and amines. In some embodiments, the isocyanate is a di-isocyanate-terminated prepolymer (i.e., a compound having the formula O═C═N—R—N═C═O, wherein R can comprise aliphatic or aromatic groups and can be polymeric or non-polymeric). For example, in some embodiments, the isocyanate can be a compound based on the structure of methylene biphenyl diisocyanate. Thus, in some embodiments, the isocyanate includes, but is not limited to, 4,4′,-diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate (PPDI), m-phenylene diisocyanate (MPDI), toluene diisocyanate (TDI), or a mixture thereof. Suitable isocyanates can also comprise backbones based on polyethers. Additional examples of suitable isocyanates are described in, for example, U.S. Pat. No. 5,415,499, which is hereby incorporated by reference herein in its entirety.
Typically the amine-containing component comprises at least two reactive amine groups. The reactive amine groups can be primary or secondary amines. In some embodiments, the amine-containing component comprises an amine-terminated prepolymer, such as an amine-terminated polymer resin and/or a monomeric aliphatic or aromatic polyamine (e.g., a diamine, triamine, tetraamine, etc.). Exemplary amine-terminated polymer resins include blends comprising polyoxyalkylene di- and/or triamines and aromatic polyamines, such as diethyltoluenediamine and dimethylthiotoluenediamine (DMTDA). In some embodiments, the polyurea can include an amine-containing component such as, but not limited to, amine-terminated polypropylene glycols (e.g., JEFFAMINE® D2000 and JEFFAMINE® T5000, available from Huntsman Corporation, The Woodlands, Texas, United States of America), diethyltoluenediamine (i.e., ETHACURE® 100, available from Albemarle Corporation, Baton Rouge, La., United States of America), or a diamine comprising sec-butyl groups (e.g., UNILINK 4200™, Dorf Ketal Chemicals LLC, Stafford, Tex., United States of America). The amine-terminated compounds suitable for use in the present subject matter generally have a mean functionality of about 2.0 to 3.0 and an average molecular weight of about 150 to 6000. Additional examples of suitable amine-containing components are described in, for example, U.S. Pat. No. 5,415,499, which is incorporated by reference herein in its entirety.
Thus, in some embodiments, the polyurea layer is provided by mixing and reacting an isocyanate-terminated compound or polymer with an amine-terminated polymer and/or an aliphatic or aromatic diamine compound and then essentially immediately applying the resultant reacting mixture to the surface (e.g., of the fabric) to be coated. The mixing of the two reactants can be effected directly within a spray gun used to apply the mixture (i.e., impingement mixing). Of course, mixtures of suitable isocyanate-terminated compounds and mixtures of suitable amine-terminated compounds can be used. In some embodiments, a slight excess of isocyanate equivalents can be used. For example, the components can be mixed such that there are slightly more reactive isocyanate groups than reactive amine groups. In some embodiments, there is between about a 1% and about a 10% excess of isocyanate equivalents. In some embodiments, there is about a 5% excess of isocyanate equivalents.
It should be noted that providing an isocyanate-rich polyurea layer (e.g.., a 5%-rich isocyanate) can, in some embodiments, enhance the molecular reactivity between a component of the polyurea layer and a component of the fiber reinforced polymer layer. It should also be noted that providing an isocyanate-rich polyurea layer can, in some embodiments, create non-contaminated state, thereby creating a no-slip condition between the polyurea layer and the fiber reinforced polymer layer.
In some embodiments, the polyurea is aromatic. Accordingly, in some embodiments, either or both of the isocyanate and amine components comprise an aromatic moiety.
In some embodiments, the polyurea is a fire-resistant polyurea. Use of a fire-resistant polyurea can provide fire-resistive properties to the composite material and to substrates reinforced with the composite material. For example, use of a fire-resistant polyurea can reduce the intensity of heat to the polyurea and to the composite material and/or reduce toxic outgassing. In some embodiments, the fire-resistant polyurea is also intumescent. Accordingly, in some embodiments, the composite combines in a single reinforcing material, high strength, high energy dissipation, and fire-resistivity.
Fire resistant properties of polyureas or other materials can be tested by methods known in the art, such as for example, ASTM E84-05 (Standard Test Method for Surface Burning Characteristics of Materials). In some embodiments, the polyurea has a flame spread classification of about 50 or less and/or a smoke developed classification of about 200 or less as measured using ASTM E84-05. In some embodiments, the polyurea has a flame spread classification of about 20 and/or a smoke developed classification of about 115. In some embodiments, the polyurea is the polyurea sold as System 550D-FR by Quantum Coatings (Edmonton, Alberta, Canada).
In some embodiments, various additives can be included in the polyurea layer. For example, the additives can be added to either the isocyanate reactants and/or the amine reactants when the polyurea is prepared. Additives include, for example, organic and inorganic colorants or dyes, UV protective agents, adhesion promoters, fillers, and other processing aids or enhancers.
UV protective agents can include light stabilizers, UV absorbers, and antioxidants. Examples of suitable light stabilizers include hindered amines, such as bis-(1, 2,2,6,6-pentamethyl-4-piperidinyl)sebacate and bis-(2,2,6,6-tetramenthyl-4-piperidyl)sebacate.
UV absorbers can protect against photodegradation by competing with the polyurea for absorption of ultraviolet light. In some embodiments, the UV absorber has broad absorption over the UV range from about 290 nm to about 400 nm. Suitable UV absorbers can include, but are not limited to, triazines, benzoxazinones, benzotriazoles, benzophenones, benzoates, formamidines, cinnamates/propenoates, aromatic propanediones, benzimidazoles, cycloaliphatic ketones, formanilides (including oxamides), cyanoacrylates, benzopyranones, and mixtures thereof.
Antioxidants, on the other hand, can interrupt the degradation process in different ways according to their structure. The major classifications of antioxidants are primary antioxidants and secondary antioxidants. Primary antioxidants, such as sterically hindered phenols, react rapidly with peroxy radicals to break the degradation cycle. Secondary antioxidants, such as arylamines, are more reactive toward oxygen-centered radicals than are hindered phenols. The secondary antioxidants react with hydroperoxide to yield non-radical non-reactive products, and are frequently called hydroperoxide decomposers. Multifunctional antioxidants, such as hindered amine stabilizers (“HAS”), combine the functions of primary and secondary antioxidants.
Examples of adhesion promoters include, but are not limited to, titanates and zirconates, as well as various organofunctional silanes (especially the amino-functional silanes). Examples of useful fillers include, but are not limited to, zinc oxide (“ZnO”), barium sulfate, calcium oxide, calcium carbonate, and silica, as well as any salts and oxides thereof. Additional fillers and/or additives also include, but are not limited to, foaming agents, glass, ceramic, and/or plastic microspheres, and various metals.
The various additives are generally present (individually or as a whole) at less than about 10% by weight of the total polyurea composition. In some embodiments, the polyurea layer contains about 5% by weight or less of one or more additives. In some embodiments, the polyurea layer contains about 1% by weight or less of one or more additives.
In some embodiments, the properties of the composite can be controlled by controlling the thickness of the polyurea coating layer. Controlling the thickness of the coating layer can alter the volume fraction of elastomeric polyurea in the composite as a whole. Typically, the polyurea coating layer is thicker than the fabric (e.g., at least about 5, 10, 20, 30, 40, 50, 100, 250, or 500 times thicker than the fabric when the fabric thickness is measured before the application of the saturant). In some embodiments, the coating layer has a thickness of between about 1/16th of an inch (i.e., about 0.0625 inches) and about ⅛th of an inch (i.e., 0.125 inches). Accordingly, in some embodiments, the coating layer has a thickness of about 0.0625, about 0.0675, about 0.0725, about 0.0775, about 0.0825, about 0.0875, about 0.0925, about 0.0975, or about 0.125 inches. In contrast, the fabric typically has a thickness of less than about 0.01 inches. In some embodiments, the fabric has a thickness (prior to the addition and curing of saturant composition) of between about 0.0013 inches and about 0,0065 inches (e.g., about 0,0013, about 0.0017, about 0.0021, about 0.0025, about 0.0029, about 0.0033, about 0.0037, about 0.0041, about 0.0045, about 0.0049, about 0.0053, about 0.0057, about 0.0061, or about 0.0065 inches).
The fabrics of the presently disclosed composites comprise a network of high tenacity fibers. The fabric can be woven, knitted, or non-woven. In some embodiments, the high tenacity fibers are uni-directional such that the fibers are generally aligned in a parallel fashion. In some embodiments, the high tenacity fibers are bi-directional such that the fibers are aligned in both parallel and perpendicular directions.
It should be noted that any suitable high tenacity fiber or combination of fibers can be used. For example, in some embodiments, the high tenacity fiber is carbon fiber, glass fiber (e.g., e-glass or s-glass), aramid (e.g., meta- or para-aramid), liquid crystal copolyester fiber, basalt fiber, or any suitable combination thereof. In some embodiments, the high tenacity fiber includes carbon fiber and the fabric comprises a carbon fiber reinforced polymer (CFRP) fabric. CFRPs are relatively inexpensive compared to other FRPs and have excellent strength and durability. More particularly, suitable high tenacity fiber fabrics include, but are not limited to, MBrace® cloths, commercially available from BASF Construction Chemicals, LLC (Shakopee, Minn., United States of America).
High tenacity fiber fabrics are generally reinforced by a thermosetting polymer matrix based on a polymeric resin, such as, but not limited to, epoxy resins, vinyl ester resins, and polyester resins. In some embodiments, the disclosed composites comprise a carbon fiber reinforced polymer (CFRP) fabric reinforced with a polymer matrix based on an epoxy resin.
The fabric can be obtained with at least some polymeric resin pre-embedded (or pre-impregnated) in the fabric and then treated further to cause curing of the resin when desired. Alternatively, the fabric can be obtained free of polymeric resin and the polymeric resin can be applied as part of a saturant composition. Accordingly, in some embodiments, the presently disclosed composite comprises a CFRP fabric that has been treated with a mixture (e.g., a saturant composition) comprising a polymeric resin (e.g., an epoxy, vinyl ester, or polyester resin). The mixture can also include additional chemicals or additives, as desired, such as to promote the curing of the resin (e.g., polymerization initiators or curing accelerators) and/or a diluent. Additional additives can further include one or more of a filler, a colorant, a UV protectant, a viscosity modifier, a defoaming agent, and a surface drying agent or the like.
Typically, epoxy resins can include an epoxy-terminated prepolymer (e.g., an epoxy-terminated monomer, oligomer, or short chain polymer) and a hardener comprising a polyamine (e.g., triethylenetetramine). Epoxy-terminated prepolymers can be prepared, for example, from the reaction of epichlorohydrin and bisphenol A. Thus, suitable epoxy resins include, but are not limited to, glycidyl ethers of polyvalent phenols such as bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, phenolic novolak epoxy resins, cresol novolak epoxy resins, brominated bisphenol A epoxy resins, and brominated phenolic novolak epoxy resins; glycidyl esters such as diglycidyl phthalale, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, and benzoic acid, or dimer acid glycidyl esters; heterocyclic epoxy resins such as 1,3-diglycidyl-5,5-dimethylhydantoin and trigiydicyl isocyanurate; and alicyclic epoxy resins such as naphthalene-based epoxy resins and 2,2′,4,4′-tetraglycidoxybiphenyl. These epoxy resins can be used either singly or as a mixture of two or more particular resins.
In some embodiments, the epoxy resin is provided as part of a saturant composition or compositions comprising, for example, Bisphenol A epoxy resin, alkyl glycidyl ether, amorphous silica, isophoronediamine, benzyl alcohol, and salicylic acid. In some embodiments, the epoxy resin is provided as part of a commercially available MBrace® Saturant, such as MBrace® Saturant LTC (available from BASF Construction Chemicals, LLC; Shakopee, Minn., United States of America).
Vinyl ester resins typically include an epoxy resin and a monocarboxylic acid. Examples of monocarboxylic acids include, but are not limited to, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, sorbitanic acid, acrylic dimers, monomethyl malate, monopropyl malate, monobutyl malate, mono(2-ethylhexyl)malate and the like.
Polyester resins can be prepared by the reaction of a di- or polycarboxylic acid and a polyvalent alcohol (i.e., a polyol, a compound comprising at least two hydroxyl groups). Polycarboxylic acids include, but are not limited to, fumalic acid, maleic anhydride, maleic acid, itaconic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, adipic acid and sebacic acid. Polyvalent alcohols include, but are not limited to, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, cyclohexane-1,4-dimethanol, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A.
In some embodiments, the polymer matrix reinforced fabric (e.g., the cured FRP in the absence of the polyurea coating layer) has an ultimate tensile strength of at least about 145 ksi (1.0 GPa) and a tensile modulus of at least about 20,000 ksi (138 GPa) measured in the direction along the length of the fabric. In some embodiments, the fabric has an ultimate tensile strength of at least about 500 ksi (3.45 GPa) and a tensile modulus of at least about 30,000 ksi (207 GPa). In some embodiments, the fabric has an ultimate tensile strength of at least about 550 ksi (3.79 GPa) and a tensile modulus of at least about 33,000 ksi (228 GPa). In some embodiments, the fabric has an ultimate tensile strength of between about 1.90 GPa and about 5,74 GPa (e.g., about 1.90, 2.40, 2.90, 3.40, 3.90, 4.40, 4.90, 5.40, or about 5.74 GPa) with elongation percentages varying between about 0.5% and 2.0% (e.g., about 0.5, 1.0, 1.5, or about 2.0 %) beyond, yield. In some embodiments, the fabric has an ultimate tensile strength per unit width of about 3.575 kips per inch (per ply). In some embodiments, the fabric has an ultimate modulus of about 214.5 kips per inch (per ply per unit width). Tensile properties can be measured by any suitable approach known in the art, such as, for example, ASTM D3039.
By combining the FRP fabric with the elastomeric polyurea layer, the elastic and inelastic properties and viscous properties of the composite material, as a whole can be significantly enhanced, in some embodiments, the composite has an elongation of about 100% or more (e.g., about 100%, about 150%, about 200%, about 250%, about 300%, or about 400% or more). In some embodiments, the composite has an elongation of about 600%.
In addition to providing a combination of strength and energy dissipation, the
presently disclosed composites can be free of carcinogenic toxicity. By “free of carcinogenic toxicity,” it is meant that the composites are essentially free of volatile carcinogenic chemicals and, if used in long-term proximity to humans, such as when the composite is used as a wrap for a building or as protective clothing, the humans exposed to the composite do not experience a statistical increase in cancer incidence compared to humans not exposed to the composite.
In some embodiments, in addition to the FRP fabric and the at least one polyurea coating layer, the composite can include additional components. For example, the composite can include a FRP fabric that is coated on both sides with a polyurea coating layer. Additionally or alternatively, the composite can be coated with an adhesive, e.g., to enhance the attachment, of the composite to various other materials.
In some embodiments, the composite can further include microspheres, such as ceramic microspheres, that are embedded into the polyurea coating layer or added in a separate layer on a surface of the polyurea coating layer (e.g., on the surface of the polyurea coating layer not in contact with the FRP fabric). For example, ceramic microspheres can add additional insulating properties to the composite material. Accordingly, in some embodiments, the composite can be used to increase the energy efficiency rating of a structure, for example, a wood-constructed home. In some embodiments, the use of a composite comprising ceramic microspheres can increase the energy efficiency of a structure from about 2 to about 4 times (e.g., about 2, 3, or 4 times) that of the corresponding structure where the composite is not used.
As shown, method 200 begins by providing a substrate at 210. It should be noted that the composite material in accordance with the disclosed subject matter can be used with any suitable substrate. Suitable substrates can include, but are not limited to, wood, masonry (e.g., brick, stone, stucco, tile), concrete (including concrete reinforced with steel or other metal), steel, or combinations thereof. Alternatively, as shown, in embodiments described herein, a suitable substrate can be a loam (e.g., expanded polystyrene, expanded polyurethane, etc). It should also be noted that, the substrate can be any suitable shape (e.g., a wall, a beam, a slab, a bar, a column, a rod, a support strut) or size. For example, in some embodiments, the substrate is a building component intended for use in new construction of a house or other building (e.g., an office building, a hospital, a school, a store, a power plant, an airport, etc.), a bridge, a roadway, a dam, a tunnel, a retaining wall, a dock, or a wharf.
At 220, a first saturant composition can be applied to the surface of the substrate prior to attaching the high tenacity fiber reinforced polymer fabric. Upon applying the first saturant composition at 220, a high tenacity fiber reinforced polymer fabric can be attached to at least a portion of the substrate at 230. As described previously, any suitable high tenacity fiber fabric can be used. For example, in some embodiments, the fabric can include at least some carbon fibers, in a more particular embodiment, the high, tenacity fiber reinforced polymer fabric is a carbon fiber reinforced polymer fabric.
Attaching the high tenacity fiber reinforced polymer fabric to the substrate can be done by any suitable method. For example, the high tenacity fiber reinforced, polymer fabric can be attached to the substrate surface by stapling or nailing. In another suitable embodiment, the attaching can be performed by coating at least a portion of a surface of the substrate with a primer composition and/or the first saturant composition to provide a coated substrate and contacting the coated substrate with the high tenacity fiber fabric. The primer composition and/or the first saturant composition can comprise an adhesive and/or a polymer resin that can interact (e.g., via covalent bonding or non-covalent bonding) with the high tenacity fiber reinforced polymer fabric and, in some cases, the second saturant composition that is applied to the fabric after the fabric is contacted to the coated surface.
It should be noted that any suitable polymer resin can be used in the primer or the saturant composition. Suitable polymer resins for use in the primer can include, but are not limited to, epoxy resins, vinyl ester resins, polyester resins, and methylmethacrylate resins. If a primer comprising a polymer resin is used, it can be the same resin or type of resin as the polymer resin in the saturant composition (the polymer resin in 230) or it can be a different type of polymer resin. Accordingly, in some embodiments, the polymer resin in the saturant and the polymer resin in the primer can both be epoxy resins.
At 240, a second saturant composition can be applied to an exposed surface of the fabric. As described above, the second saturant composition, can comprise an adhesive and/or a polymer resin that can interact (e.g., via covalent bonding or non-covalent bonding) with the high tenacity fiber reinforced polymer fabric. After the saturant is applied to an exposed surface of the fabric (e.g., by painting or spraying) at 240, it can be cured, at 250 for a suitable period of time to provide a tacky surface (a tacky outer surface to the fabric). It should be noted that the time to cure the second saturant composition can be varied based on the chemical composition of the saturant, temperature, and/or humidity. In some embodiments, the second saturant composition can be cured for between about 2 hours and about 3 hours (e.g., about 120, 130, 140, 150,160, 170, or about 180 minutes). In some embodiments, the saturant composition can be partially cured. In some embodiments, the second saturant composition can be cured as long as about live hours.
When the saturant is partially cured at 250, an elastomeric polyurea-forming component solution can be applied to the tacky surface at 260. Applying the polyurea-forming component solution while the surface is tacky can allow for interaction (e.g., covalent or non-covalent bonding) between the chemicals or components in the polyurea-forming component solution and the resin or other components in the saturant composition. This interaction during preparation can allow for sustained interfacial interaction, between the polyurea coating layer and the fiber reinforced polymer fabric layer when, for example, the reinforced substrate is subjected to various stresses or events. In some embodiments, the elastomeric polyurea-forming solution can be sprayed or brushed onto the tacky surface.
In some embodiments, the polyurea-forming component solution comprises materials that form an aromatic polyurea layer. In some embodiments, the polyurea layer is fire-resistant. For example, the polyurea layer can have a flame spread classification as determined using ASTM E84-05 of about 50 or less (e.g., about 50, about 40, about 30, or about 20 or less). In some embodiments, the polyurea layer can have a smoke developed classification, of about 200 or less (e.g., about 200, about 180, about 160, about 140, or about 120 or less) as measured by ASTM E84-05. In some embodiments, the polyurea layer has a flame spread classification of about 20 and a smoke developed classification of about 115. In some embodiments, the fire-resistant polyurea layer is intumescent. A suitable fire-resistant, intumescent polyurea includes, for example, the polyurea sold as System 550D-FR by Quantum Coatings (Edmonton, Alberta, Canada).
In some embodiments, the polyurea-forming component solution comprises a first component that is an isocyanate (e.g., an isocyanate prepolymer) and a second component comprising an amine (e.g., an amine-terminated prepolymer). In some embodiments, the isocyanate is a di-isocyanate-terminated prepolymer (i.e., a compound having the formula O═C═N—R—N═C═O, wherein R can comprise aliphatic or aromatic groups and can be polymeric or non-polymeric). For example, in some embodiments, the isocyanate can be a compound based on the structure of methylene diphenyl diisocyanate. Thus, in some embodiments, the isocyanate includes, but is not limited to, 4,4′-diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate (PPDI), m-phenylene diisocyanate (MPDI), toluene diisocyanate (TDI), or a mixture thereof. Suitable isocyantes can also comprise backbones based on polyethers. Additional, examples of suitable isocyanates are described in, for example, U.S. Pat. No. 3,415,499, which is hereby incorporated by reference herein in its entirety.
The amine-terminated prepolymer can comprise at least two reactive amine groups. The reactive amine groups can be primary or secondary amines. In some embodiments, the amine-terminated prepolymer comprises an amine-terminated polymer resin and/or monomeric aliphatic or aromatic polyamine (e.g., a diamine, triamine, tetraamine, etc.). Exemplary amine-terminated polymer resins can include blends comprising polyoxyalkylene di- and/or triamines and aromatic polyamines, such as diethyltoluenediamine and dimethylthiotoluenediamine (DMTDA). In some embodiments, the polyurea can include an amine-containing component, such as, but not limited to, amine-terminated polypropylene glycols (e.g., JEFFAMINE® D2000 and JEFFAMINE® T5000, available from Huntsman Corporation, The Woodlands, Tex., United States of America), diethyltoluenediamine (i.e., ETHACURE® 100, available from Albemarle Corporation, Baton Rouge, La., United States of America), or a diamine comprising sec-butyl groups (e.g., UNILINK 4200™, Dorf Ketal Chemicals LLC, Stafford, Tex., United States of America), The amine-terminated compounds suitable for use in the present subject matter generally have a mean functionality of about 2.0 to 3.0 and an average molecular weight of about 150 to 6000. Additional examples of suitable amine-terminated prepolymers are described in, for example, U.S. Pat. No. 5,415,499.
The components of the polyurea-forming component solution can be typically mixed immediately prior to application to the tacky surface. For example, the components can be mixed in a spray gun as they are being sprayed. In some embodiments, the components of the polyurea-forming component solution can be mixed in a ratio where there is a slight excess of isocyanate equivalents (i.e., reactive isocyanate groups). In some embodiments, the components can be mixed such that there is between an about 1% and an about 10% excess of isocyanate equivalents (e.g., an about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% excess of isocyanate equivalents). In some embodiments, there is a 5% excess of isocyanate equivalents. In some embodiments, the use of a slight excess of isocyanate can enhance interaction of the polyurea layer with the fiber reinforced polymer fabric, due to interaction of the isocyanate component from the polyurea-forming solution with unreacted polymeric groups in the saturant of the fiber reinforced polymer fabric.
In some embodiments, the polyurea-forming component solution can comprise one or more additives to enhance the functionality or appearance of the reinforced substrate, in some embodiments, the polyurea-forming component solution can comprise a UV protective additive, such as, but not limited to an organic pigment. In some embodiments, the polyurea-forming component solution can comprise between about 1% and about 10% by volume of the UV protective additive (e.g., about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9% or about 10%). In some embodiments, the polyurea-forming component solution can comprise about 5% by volume of the UV protective additive.
Following application of the polyurea-forming component solution, the polyurea component solution can be allowed to cure to form a coating layer at 270. It should be noted that some polyureas can cure relatively rapidly. In some embodiments, the polyurea component solution can be allowed to cure for about 1 to 5 minutes (e.g., about 60, 90, 120, 150, 180, 210, 240, 270, or 300 seconds) and while the polyurea is still tacky, an additive is applied to the coating layer (e.g., to the exposed surface of the coating layer). In some embodiments, the additive comprises ceramic microspheres.
As described herein, properties of the composite (e.g., viscous damping properties, strength properties, and/or stiffness properties) can be modified by controlling the thickness of the polyurea coating layer. Controlling the thickness of the polyurea coating layer can alter the volume fraction of elastomeric polyurea in the composite, which can alter the properties of the resulting composite. In another example, the time related to the reaction between polyurea coating layer and the polymer of the fiber reinforced polymer fabric can affect the viscous properties of the resulting composite. Accordingly, when presented with particular material specifications (e.g., an installation requires a highly damped material), the composite can be made to accommodate such specifications.
In some embodiments, the approach for reinforcing substrates can be applied to a previously constructed structure and, more particularly, an already damaged structure. Referring to
As shown, method 300 begins by providing a substrate having damaged portions at 310. In some embodiments, the substrate can be already present in a previously constructed building or other structure. In some embodiments, the previously constructed building or other structure can be a building or other structure that has been damaged due to a catastrophic event, such as an earthquake, a fire, a tornado, a hurricane, a typhoon, flooding, or an explosion. Alternatively, in some embodiments, the building or other structure is present in a region where there is an increased likelihood of such an event. For example, the building or structure can be located near a fault line, near the coastline, in a war zone, and/or be a building or structure having an increased risk of a terrorist attack, such as a building of economic or government importance or a building related to high population density events (e.g., sporting arenas, theaters, etc.).
In some embodiments, the previously constructed building can be damaged or be suspected of having damage due to normal wear and tear and/or related to age. For example, concrete is relatively alkaline, preventing the corrosion, of any reinforcing metal bar's present within concrete structures. Over time, however, concrete can become neutralized due to the action of carbon dioxide in the air. Once the concrete becomes neutralized, the metal bars can become susceptible to corrosion and an increase in volume, causing cracks in the structure. In some embodiments, the concrete is already cracked, and the metal bars are susceptible to corrosion. In some embodiments, older structures can become candidates for damage because the use of the structure changes over time. For example, bridges can become candidates of damage due to increases in traffic above levels accounted for during the design of the bridge. In such an embodiment the building or other structure can be 10 or more years old (e.g., 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 or more years old).
Alternatively, in some embodiments, the building or other structure can be newly constructed (e.g., within the last 10, 5, 4, 3, or 2 years) such that the reinforcement is performed to prevent damage, in some embodiments, the newly constructed building or other structure is a structure built within, the last 12 months.
In some embodiments, the building or other structure is under construction or the substrate is intended for use in future construction.
With a substrate having damaged portions (or suspected damage due to, for example, wear and tear), the substrate can be prepared at 320. This can include, for example, selecting the substrate and preparing it by one or more of cleaning the surface of the substrate, smoothing the surface of the substrate, and filling in cracks, pits, chips, and/or grooves in the surface of the substrate prior to attaching the fabric. Cleaning can be done by any suitable method, such as power washing or any other method to remove surface dirt and/or other non-substrate matter. In some embodiments, providing the substrate can comprise filling in and/or smoothing out the surface of the substrate with a putty material. Smoothing can be performed by sanding or any other suitable method. Cracks, pits, chips, grooves or other indentations or disfigurements in the surface of the substrate can be filled in with any suitable material, such as, but not limited to wood filler, cement, concrete, or mortar. Generally, the fill material should be such that it does not interfere with the attachment of the fabric. Thus, in some embodiments, the fill material is a material that can interact (e.g., via covalent or non-covalent bonds) with a polymer resin applied to the surface of the substrate as part of a primer for attaching the high tenacity fiber fabric, or with a polymeric component present in or added to (e.g., in a saturant) the high tenacity fiber fabric.
Steps 330 through 380 of
In some embodiments, the substrate can be reinforced by attaching a previously prepared composite to the substrate, wherein the previously prepared composite includes a high tenacity fiber reinforced polymer fabric and a polyurea coating layer. Thus, in some embodiments, the method of reinforcing the substrate comprises preparing a composite material and attaching the composite material to the substrate. The previously prepared composite material can be attached to the substrate via any suitable method, such as, but not limited to, stapling or nailing the composite material to the substrate and/or adhering the composite material to the substrate via an adhesive and/or polymeric resin coated on the substrate and/or on the composite material.
It should be noted that reinforcing a substrate (e.g., a wood home, a reinforced concrete bridge, a steel structure, an automobile, an aircraft structure, etc.) inhibits or reduces damage to the substrate due to seismic activity (e.g., earthquakes), fire, and/or explosive forces (e.g., due to ballistics). In some embodiments, reinforcing the substrate can also provide resistance to water damage (e.g., due to mechanical stresses from flash flooding or by reducing mold or other damage due to water saturation into the substrate), environmental pollutants and/or sun damage. In some embodiments, the protective properties can relate, at least in part, to a specific additive (e.g., a UV protectant, a flame retardant, moisture resistance, etc) added to the fiber reinforced polymer fabric or the polyurea layer. In some embodiments, the protective property is related to the chemical composition of the fiber reinforced polymer fabric and/or the polyurea layer. For example, polyureas can be moisture and/or mold resistant. In some embodiments, such as when a microsphere additive is used, the reinforcing can provide an insulative effect to the substrate, thereby making the reinforced substrate a more energy efficient building material than the non-reinforced substrate. In some embodiments, the reinforcing can increase the energy efficiency to between about 2 and 4 times (e.g., about 2,3, or 4 times) that of the non-reinforced substrate.
The following examples further illustrate some embodiments of the present invention, but should not be consented as in any way limiting the scope.
Tensile Composite Coupon Results
Coupons of composite were prepared using MBrace® FRP cloth (about 0.068 inch thick×about 1 inch wide: available from BASF Construction Chemicals, LLC, Shakopee, Minn., United States of America) saturated with a saturant prepared, by mixing a composition comprising Bisphenol A epoxy resin, alkyl glycidyl ether, and amorphous silica with a composition comprising isophoronediamine, benzyl alcohol, and salicylic acid; and coated with a non-fire resistant polyurea-forming composition. Coupons were prepared with two different polyurea layer thicknesses (e.g., either about one eighth of an inch thick or about one sixteenth, of an inch, thick), providing final composite dimensions of about 0.19 in. thick×about 1 in. wide or about 0.32 in. thick×about 1 in. wide.
Torsion Results of Composite Wrapped Wood
conducted on a white pine wood rod that 12 inches long and ½ of an inch in diameter. In this embodiment, the rod was wrapped with a polyurea coated ( 1/16 inch) CFRP composite according to above-described method of the disclosed subject matter. As shown in
Bending Results of Composite Wrapped Wood
Three 2×4 wood beams of white pine, each with a 28 inch span, were subjected to wood beam bending studies. Each of the wood beams was prepared differently—as shown in
Similarly,
Turning to
As indicated,
It should be noted that the 2×V beam shown by curve 940 depicts an elastic-plastic like region after the final strength drop. Accordingly, curing time and polyurea volume fractions can be tailored to design the tight-wrap to satisfy specific structural performance demands.
In addition, a comparison of the load-deflection curves of the 1×V and 2×V beams in
Simulations of Acceleration and Hysteresis in Wrapped Wood Structure
As shown in
For comparison,
Retrofitting a Steel Reinforced Concrete Composite Beam (SRCC)
As described herein, the approach for reinforcing substrates can be applied to a previously constructed structure and, more particularly, to an already damaged structure.
As shown in
Retrofitting a Seismic Damaged Reinforced Concrete Shear Wall
Similar to the above-mentioned example, the approach for reinforcing substrates can be applied to a previously constructed structure and, more particularly, to an already damaged structure. In this example, a reinforced concrete shear wall was damaged under a cyclic load. The cyclic testing resulted in severe damage to the reinforced concrete shear wall that included a three millimeter wide cross-crack and concrete crush at two of the bottom comers of the wall. The after-test load capacity of the wall dropped to approximately 40% of its peak value.
As shown in portion 1210 of
Turning to
Viscous Damping and Impact Resistance of Composite Wrapped Substrates
In this example, foam core substrates were used, where one foam core substrate was wrapped only with a carbon fiber reinforced polymer fabric and one foam core substrate was wrapped with a polyurea-coated carbon fiber reinforced polymer composite of the disclosed subject matter. These foam core substrates were then subjected to impact resistance testing, where a high loading speed (a shock load) or 4 meters per second was used.
As shown in
Turning to
As shown, when comparing the results between the steel beam substrate that was wrapped only with a carbon fiber reinforced polymer fabric and the steel beam substrate that was wrapped with a polyurea-coated carbon fiber reinforced polymer composite of the disclosed subject matter, the polyurea-coated carbon fiber reinforced polymer composite provides viscous-type damping to minimize vibrations during the testing.
Damping Ratio of the Composite
It should be noted that, in some embodiments, the properties of the composite material can be modified by varying time-related (tc) and volume-fraction (hp) polymeric properties. For example, as shown in
Turning to
As shown in
In this example, these tests were conducted with the polyurea-coated carbon fiber reinforced polymer composite by itself. This can, for example, remove any contributing effects from the thin steel beam. As shown in
Similar to
Accordingly, high strength and high elasticity composite materials and methods of reinforcing substrates with the same are provided.
Although, the invention has been described and illustrated in the foregoing illustrative embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementation of the invention can be made without departing from the spirit and scope of the invention, which is only limited by the claims which follow. Features of the disclosed embodiments can be combined and rearranged in various ways.
This application claims the benefit of U.S. Provisional Patent Application No. 61/420,159, filed Dec. 6,2010, which is hereby incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US11/63581 | 12/6/2011 | WO | 00 | 12/23/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61420159 | Dec 2010 | US |
