Method For Preparing Nanodiamond-containing Thermoplastic Fibers And The Use Of Such Fibers In Yarns And Fabrics

Abstract

The present disclosure relates to methods for preparing nanodiamond-containing thermoplastic fibers and filaments having diamond particles substantially uniformly distributed throughout. The process comprises melt extruding a material comprising a thermoplastic polymer and from about 0.001% to about 0.25% by weight nanosized diamond particles. The present disclosure also relates to yarns and fabrics comprising the nanodiamond-containing thermoplastic fibers or filaments, and to garments comprising these yarns and/or fabrics. Yarns and fabrics comprising nanodiamond-containing thermoplastic fibers and filaments have been found to have enhanced thermal properties, enhanced mechanical properties, and/or enhanced softness.

Description

BACKGROUND

[0001] The disclosure relates to nanodiamond-containing thermoplastic fibers, methods of making nanodiamond-containing thermoplastic fibers, and fabrics and garments comprising nanodiamond-containing thermoplastic fibers. In particular, the disclosure relates to nanodiamond-containing thermoplastic fibers in which nanosized diamond particles are substantially uniformly distributed throughout the fiber, and methods of making such fibers by a melt extrusion process. By substantially uniformly distributing the nanosized diamond particles throughout the fiber, advantages imparted by the diamond particles are consistently obtained. This consistency is of particular importance where, as here, the fibers may be textile fibers configured for use in fabrics and garments.

SUMMARY

[0002] The present disclosure relates, in various embodiments, to methods for preparing a nanodiamond-containing thermoplastic fiber having diamond particles substantially uniformly distributed throughout the fiber. The process comprises melt extruding a material comprising a thermoplastic polymer and from about 0.001% to about 0.25% by weight nanosized diamond particles. The nanosized diamond particles preferably have particle sizes between about 2 nm and about 500 nm, alternatively between about 2 nm and about 10 nm. In some embodiments, the thermoplastic polymer may comprise one or more polyamides, such as one or more polyamides that are generally referred to as nylon. In other embodiments, the thermoplastic polymer may comprise polyester.

[0003] In some embodiments, the process of melt extruding may include at least two steps. One step involves preparing diamond concentrate pellets, i.e. pellets that have a significantly higher concentration of diamond particles than the final nanodiamond-containing thermoplastic fiber. For instance, the diamond concentrate pellets may comprise between about 0.1% to about 10% by weight diamond particles. Another step involves melt extruding a mixture of a thermoplastic polymer and the diamond concentrate pellets such that the diamond particles are substantially uniformly distributed throughout the resulting thermoplastic fiber.

[0004] The present disclosure also relates, in various embodiments, to nanodiamond-containing thermoplastic fibers, such as those having diamond particles substantially uniformly distributed throughout. The nanodiamond-containing thermoplastic fibers may comprise about 99.0% to about 99.9% by weight thermoplastic polymer, about 0.001% to about 0.25% by weight nanosized diamond particles, and about 0.0025% to about 0.02% by weight dispersion agent. The nanosized diamond particles preferably have particle sizes between about 2 nm and about 500 nm, alternatively between about 2 nm and about 10 nm. In some embodiments, the thermoplastic polymer may comprise one or more polyamides, such as one or more polyamides that are generally referred to as nylon. In other embodiments, the thermoplastic polymer may comprise polyester.

[0005] The present disclosure also relates, in various embodiments, to yarns and fabrics comprising the nanodiamond-containing thermoplastic fibers described herein, and to garments comprising these yarns and fabrics. Yarns and fabrics comprising the nanodiamond-containing thermoplastic fibers described herein have been found to have enhanced thermal properties (e.g. coolness), enhanced mechanical properties (e.g. strength, elongation), and enhanced softness.

[0006] For instance, because of the enhanced thermal properties provided by the dispersion of nanodiamonds throughout the fibers, use of these fibers in fabrics may provide the fabrics with an improved ability to transfer body heat away from a wearer, an improved ability to reduce heating due to sunlight, an increased coolness to the touch, and the like. Accordingly, garments comprising the fibers disclosed herein may provide a wearer with a cooling benefit. Moreover, because incorporation of nanodiamonds in accordance with the present disclosure has also been found to increase the strength of the fibers, this cooling effect can be achieved without a sacrifice in the strength and/or durability of the fabric. And because incorporation of nanodiamonds in accordance with the present disclosure has also been found to not significantly decrease the elongation of the fibers (and in some instances to actually increase the elongation of the fibers), this cooling effect can also be achieved without having a significant adverse effect on the mechanical and/or tensile properties of the fabric. It has also been found that incorporation of the fibers disclosed herein may also increase the softness of the fabric.

[0007] The present disclosure also relates, in various embodiments, to a method of increasing the thermal conductivity of a fabric. For instance, it has been found that a fabric comprising the nanodiamond-containing thermoplastic fibers may have at least a 5% higher thermal conductivity than a comparative fabric without the diamond particles.

[0008] The present disclosure also relates, in various embodiments, to a method of increasing the strength of a fabric without producing a substantial decrease in the elongation of the fabric. For instance, it has also surprisingly been found that a fabric comprising the nanodiamond-containing thermoplastic fibers may have at least a 5% higher strength than a comparative fabric without the diamond particles, and an elongation that is within about 3% of that of a comparative fabric without the diamond particles. In some embodiments, it has even been found that both the strength and the elongation of a fabric comprising the nanodiamond-containing thermoplastic fibers may be greater than that of a comparative fabric without the diamond particles.

[0009] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A clear conception of the advantages and features of one or more embodiments will become more readily apparent by reference to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings:

[0011] FIG. 1 is a graphical representation of test results concerning the heating and cooling properties of sample fabrics prepared in accordance with the present disclosure.

[0012] FIG. 2 is a graphical representation of test results concerning the heating and cooling properties of sample fabrics prepared in accordance with the present disclosure.

[0013] FIG. 3 is a graphical representation of test results concerning the heat transfer between a surface and sample fabrics prepared in accordance with the present disclosure.

[0014] FIG. 4 is a graphical representation of test results concerning the softness of sample fabrics prepared in accordance with the present disclosure.

[0015] FIG. 5 is a graphical representation of test results concerning the heating and cooling properties of sample fabrics prepared in accordance with the present disclosure.

[0016] FIG. 6 is a graphical representation of test results concerning the heating and cooling properties of sample fabrics prepared in accordance with the present disclosure.

[0017] FIG. 7 is a graphical representation of test results concerning the tensile properties of sample fabrics prepared in accordance with the present disclosure.

DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure are directed to nanodiamond-containing thermoplastic fibers and methods for making such fibers. The term "fiber" is used throughout this application to refer to fibers of any length, including for example those that may more commonly be referred to as filaments. For instance, the term "fiber" should be understood as including both staple fibers and continuous filaments, as those terms are commonly understood in the textile industry. Accordingly, unless otherwise indicated, the terms "fiber" and "filament" are used interchangeably throughout this specification.

[0019] Embodiments of the nanodiamond-containing thermoplastic fibers comprise between about 95.0% and about 99.9% by weight thermoplastic polymer, alternatively between about 96.0% and about 99.9% by weight thermoplastic polymer, alternatively between about 97.0% and about 99.9% by weight thermoplastic polymer, alternatively between about 98.0% and about 99.9% by weight thermoplastic polymer, alternatively between about 99.0% and about 99.9% by weight thermoplastic polymer, alternatively between about 99.5% and about 99.9% by weight thermoplastic polymer, alternatively between about 99.7% and about 99.9% by weight thermoplastic polymer.

[0020] The thermoplastic polymer may be selected from the group consisting of: polyesters (e.g., polyethylene terephthalate (PET)), polypropylene, polycarbonate, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polytrimethylene naphthalate (PTN), polyether ketone (PEK), polyether ether ketone (PEEK), poly(p-phenylene sulfide) (PPS), polyamides (nylon), thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE), and combinations thereof. In some embodiments, for instance, the thermoplastic polymer may comprise polypropylene, polyester, nylon, polybenzimidazole, polyacrylonitrile (acrylics), polyurethane elastomers such as spandex, plant-based polymers such as corn-based polymers, and combinations thereof. In some embodiments the thermoplastic polymer may comprise polyester, nylon, polypropylene, and combinations thereof.

[0021] In some embodiments, the thermoplastic polymer may comprise any of the polyamides that are commonly known as nylon. For instance, in some embodiments the thermoplastic polymer may comprise nylon 6; nylon 6,6; nylon 6,12; nylon 12; nylon 4,6; nylon 6,10; or a combination thereof. In some embodiments, the thermoplastic polymer may comprise nylon 6; nylon 6,6; or a combination thereof. In some embodiments, the thermoplastic polymer may comprise polyester. Nanodiamond-containing thermoplastic fibers comprising nylon, polyester, or a combination thereof may be particularly useful in the preparation of yarns and fabrics for use in making garments and other articles.

[0022] Embodiments of the nanodiamond-containing thermoplastic fibers comprise between about 0.001% and about 0.25% by weight diamond particles, alternatively between about 0.001% and about 0.1% by weight diamond particles, alternatively between about 0.001% and about 0.05% by weight diamond particles, alternatively between about 0.001% and about 0.01% by weight diamond particles, alternatively between about 0.005% and about 0.25% by weight diamond particles, alternatively between about 0.005% and about 0.1% by weight diamond particles, alternatively between about 0.005% and about 0.05% by weight diamond particles, alternatively between about 0.005% and about 0.01% by weight diamond particles, alternatively between 0.01% and about 0.25% by weight diamond particles, alternatively between about 0.01% and about 0.1% by weight diamond particles, alternatively between about 0.01% and about 0.05% by weight diamond particles; alternatively between 0.025% and about 0.25% by weight diamond particles, alternatively between about 0.025% and about 0.1% by weight diamond particles, alternatively between about 0.025% and about 0.05% by weight diamond particles.

[0023] The diamond particles are preferably nanosized, i.e. have particles sizes that may be measured on the nanometer scale. In some embodiments, for example, the diamond particles have particle sizes between about 1 nm and about 500 nm, alternatively between about 1 nm and about 100 nm, alternatively between about 1 nm and about 50 nm, alternatively between about 1 nm and about 25 nm, alternatively between about 1 nm and about 10 nm; alternatively between about 2 nm and about 500 nm, alternatively between about 2 nm and about 100 nm, alternatively between about 2 nm and about 50 nm, alternatively between about 2 nm and about 25 nm, alternatively between about 2 nm and about 10 nm. The incorporation of nanosized diamond particles into the thermoplastic fibers has been found to impart desirable properties without significantly altering the visual appearance, e.g. the color or gloss, of the fiber.

[0024] The nanosized diamond particles may be obtained by any known methods. For instance, the nanosized diamond particles may be obtained by detonation synthesis, the ultrasonic cavitation of graphite, the high energy laser irradiation of graphite, or other known methods. Because the nanosized diamond particles can be hazardous in powder form, the nanosized diamond particles are typically provided in slurry form. For instance, the nanosized diamond particles may be slurried with water or with another solvent, such as ethylene glycol. In some embodiments, the nanosized diamond particles may be surface functionalized. For example, the surfaces of the nanosized diamond particles may be functionalized by treatment with carboxyls, amines, hydroxyls, silanes, anhydrides, acrylates, methacrylates, isocynates, stearic acids, or the like.

[0025] Embodiments of the nanodiamond-containing thermoplastic fibers may also comprise between about 0.001% and about 0.1% by weight dispersion agent, alternatively between about 0.001% and about 0.05% by weight dispersion agent, alternatively between about 0.001% and about 0.03% by weight dispersion agent, alternatively between about 0.001% and about 0.02% by weight dispersion agent; alternatively between about 0.002% and about 0.1% by weight dispersion agent, alternatively between about 0.002% and about 0.05% by weight dispersion agent, alternatively between about 0.002% and about 0.03% by weight dispersion agent, alternatively between about 0.002% and about 0.02% by weight dispersion agent, alternatively between about 0.005% and about 0.1% by weight dispersion agent, alternatively between about 0.005% and about 0.05% by weight dispersion agent, alternatively between about 0.005% and about 0.03% by weight dispersion agent, alternatively between about 0.005% and about 0.02% by weight dispersion agent.

[0026] The dispersion agent may comprise any agent that is capable of aiding the dispersion of the nanosized diamond particles throughout the thermoplastic polymer, such as by preventing agglomeration of the nanosized diamond particles. In some embodiments the dispersion agent may be selected from the group consisting of zinc stearate, calcium stearate, and combinations thereof.

[0027] In some embodiments, the nanodiamond-containing thermoplastic fibers may also comprise one or more additional additives. In some embodiments, these additives may include boron nitride, graphite, graphene, silica, one or more aluminosilicate materials, or a combination thereof. These additives are desirably in the form of particles having particle sizes of less than 10 microns. For example, in some embodiments the additive particles may have particle sizes between about 2 nm and about 5 microns, alternatively between about 4 nm and about 2 microns. Embodiments of the nanodiamond-containing thermoplastic fibers comprise between about 0.001% and about 1.0% by weight of these additives, alternatively between about 0.001% and about 0.5% by weight of these additives, alternatively between about 0.001% and about 0.25% by weight of these additives, alternatively between about 0.05% and about 1.0% by weight of these additives, alternatively between about 0.05% and about 0.5% by weight of these additives, alternatively between about 0.05% and about 0.25% by weight of these additives. In other embodiments, these additives may include nanosized particles of sapphire, ruby, amethyst, aquamarine, turquoise, topaz, tourmaline, emerald, quartz, coral, pearl, peridot, moldavite, platinum, gold, amber, selenite, and combinations thereof.

[0028] Thermoplastic fibers are typically prepared by methods such as melt extrusion, which is used to produce thermoplastic fibers of uniform shape and density. In melt extrusion, a polymer is melted to form a viscous phase (known as the melt) and then forced through one or more orifices (also known as dies). Melt extrusion is a continuous or semi-continuous process. Melt extrusion is typically carried out in an extruder, which comprises a barrel containing one (single screw extruder) or two (twin screw extruder) rotating screws that transport the polymer through the barrel and out of the one or more orifices. The one or more orifices shape the polymer as it exits the barrel. In some applications, such as when materials are being mixed, the use of twin screw extruders may be preferred over the use of a single screw extruder.

[0029] While it is generally known that one can incorporate solid particles into the melt during a melt extruding process, the incorporation of diamond particles into thermoplastic fibers during melt extrusion has given rise to complications. Most significantly, because of the well-known hardness of diamond, the presence of diamond in an extruder can damage the equipment. This is most likely to occur when the diamond particles become concentrated in a particular area of the melt. For instance, high concentrations of diamond particles can damage the barrel walls of the extruder. Moreover, the forcing of diamond particles through the relatively narrow orifice (or orifices) to prepare a fiber (or fibers) can cause damage to the orifice (or orifices). Embodiments of the present disclosure provide a process by which nanodiamond-containing thermoplastic fibers can be prepared by melt-extrusion without causing damage to the extruder.

[0030] Moreover, in the textile industry, it is of utmost importance that fabrics are able to be prepared with consistent properties. Accordingly, it is important that the yarns, and thus the fibers used to prepare the yarns, have consistent properties. Therefore, when fibers are intended for use in textile applications, the melt-extrusion process should be capable of producing thermoplastic fibers in which the diamond particles are substantially uniformly distributed throughout the fiber, such that the fibers have consistent properties. Embodiments of the present disclosure provide a melt-extrusion process that produces nanodiamond-containing thermoplastic fibers having the diamond particles substantially uniformly distributed throughout the fiber.

[0031] Embodiments of the present disclosure are directed to a method for preparing nanodiamond-containing thermoplastic fibers using a melt extrusion process. In order to achieve the benefits described above, embodiments of the method may comprise a melt extrusion process that is performed in at least two steps. In one step, a diamond concentrate material, such as pellets, may be prepared. In a subsequent step, the diamond concentrate material may be mixed with a thermoplastic polymer and the mixture may be melt extruded to prepare the nanodiamond-containing thermoplastic fiber. Each step is individually described in more detail below.

[0032] As described above, the method for preparing a nanodiamond-containing thermoplastic fiber may comprise a step in which a concentrated diamond composition is prepared. For instance, in some embodiments, the method includes a step for preparing a plurality of diamond concentrate pellets.

[0033] The diamond concentrate pellets comprise a first thermoplastic polymer having nanosized diamond particles present at a greater concentration than in the final fiber. In some embodiments, for instance, the diamond concentrate pellets may comprise between about 0.1% and about 10.0% by weight diamond particles, alternatively between about 0.1% and about 5.0% by weight diamond particles, alternatively between about 0.1% and about 2.0% by weight diamond particles, alternatively between about 0.1% and about 1.0% by weight diamond particles, alternatively between about 0.1% and about 0.5% by weight diamond particles.

[0034] In some embodiments, the first thermoplastic polymer may be selected from the group consisting of: polyesters (e.g., polyethylene terephthalate (PET)), polypropylene, polycarbonate, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polytrimethylene naphthalate (PTN), polyether ketone (PEK), polyether ether ketone (PEEK), poly(p-phenylene sulfide) (PPS), polyamides (nylon), thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE), and combinations thereof. In some embodiments, the first thermoplastic polymer may comprise polypropylene, polyester, nylon, polybenzimidazole, polyacrylonitrile (acrylics), polyurethane elastomers such as spandex, plant-based polymers such as corn-based polymers, and combinations thereof. In some embodiments the first thermoplastic polymer may comprise polyester, nylon, polypropylene, and combinations thereof.

[0035] In some embodiments, the first thermoplastic polymer may comprise any of the polyamides that are commonly known as nylon. For instance, in some embodiments the first thermoplastic polymer may comprise nylon 6; nylon 6,6; nylon 6,12; nylon 12; nylon 4,6; nylon 6,10; or a combination thereof. In some embodiments, the first thermoplastic polymer may comprise nylon 6; nylon 6,6; or a combination thereof. In some embodiments, it may be desirable that the first thermoplastic polymer be nylon 6. Nylon 6 is relatively easy to process and can sustain the heat treatments associated with both the preparation of the diamond concentrate pellets and the preparation of the final fiber.

[0036] In some embodiments, the diamond concentrate pellets may comprise between about 90.0% and about 99.9% by weight of the first thermoplastic polymer, alternatively between about 95.0% and about 99.75% by weight of the first thermoplastic polymer.

[0037] In some embodiments, a dispersion agent may be incorporated into the diamond concentrate pellets. The dispersion agent may comprise any agent that is capable of aiding the dispersion of the nanosized diamond particles throughout the thermoplastic polymer, such as by preventing agglomeration of the nanosized diamond particles. In some embodiments the dispersion agent may be selected from the group consisting of zinc stearate, calcium stearate, and combinations thereof. In some embodiments, the diamond concentrate pellets may comprise between about 0.1% and about 1.0% by weight dispersion agent, alternatively between about 0.1% and about 0.8% by weight dispersion agent, alternatively between about 0.2% and about 0.8% by weight dispersion agent.

[0038] The diamond concentrate pellets may be prepared by mixing the nanosized diamond particles and optionally the dispersion agent with the first thermoplastic polymer and extruding the resulting mixture. For instance the step of preparing the diamond concentrate pellets may comprise heating the first thermoplastic polymer to form a viscous phase, blending the nanodiamond particles and dispersion agent into the viscous phase of the first thermoplastic polymer, and extruding the resulting mixture. The nanodiamond particles may be added to the first thermoplastic polymer in slurry form. The mixture of the first thermoplastic polymer and the nanosized diamond particles may be extruded through an orifice (or orifices) having a diameter (or diameters) within the millimeter range. Diameters within the millimeter range are large enough to provide that the relatively high concentration of nanodiamond in the mixture at this stage does not damage the extrusion equipment.

[0039] The extruded diamond concentrate material may then be divided, or cut, to produce a number of diamond concentrate pellets. The sizes of the diamond concentrate pellets may be selected depending on the manner in which they are mixed with the second thermoplastic polymer in a downstream processing step. In some embodiments, for example, the diamond concentrate pellets may have a diameter between about 0.5 mm and about 5 mm, alternatively between about 1 mm and about 4 mm, alternatively between about 2 mm and about 3 mm. Similarly, in some embodiments the diamond concentrate pellets may have a length between about 1 mm and about 10 mm, alternatively between about 1 mm and about 7 mm, alternatively between about 1 mm and about 5 mm, alternatively between about 1 mm and about 4 mm, alternatively between about 2 mm and about 3 mm. Where additional additives are desired in the final thermoplastic fiber, those additives may also be added to the first thermoplastic polymer during this step.

[0040] As described above, the method may also comprise a step in which the concentrated diamond composition, such as the diamond concentrate pellets, are mixed with a second thermoplastic polymer and melt-extruded to prepare a nanodiamond-containing thermoplastic fiber.

[0041] In some embodiments, the second thermoplastic polymer may be selected from the group consisting of: polyesters (e.g., polyethylene terephthalate (PET)), polypropylene, polycarbonate, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polytrimethylene naphthalate (PTN), polyether ketone (PEK), polyether ether ketone (PEEK), poly(p-phenylene sulfide) (PPS), polyamides (nylon), thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE), and combinations thereof. In some embodiments, the second thermoplastic polymer may comprise polypropylene, polyester, nylon, polybenzimidazole, polyacrylonitrile (acrylics), polyurethane elastomers such as spandex, plant-based polymers such as corn-based polymers, and combinations thereof. In some embodiments the second thermoplastic polymer may comprise polyester, nylon, polypropylene, and combinations thereof.

[0042] In some embodiments, the second thermoplastic polymer may comprise any of the polyamides that are commonly known as nylon. For instance, in some embodiments the second thermoplastic polymer may comprise nylon 6; nylon 6,6; nylon 6,12; nylon 12; nylon 4,6; nylon 6,10; or a combination thereof. In some embodiments, the second thermoplastic polymer may comprise nylon 6; nylon 6,6; or a combination thereof. In some embodiments, it may be desirable that the first thermoplastic polymer be nylon 6,6.

[0043] In some embodiments, the first thermoplastic polymer and the second thermoplastic polymer may be the same. For instance, in some embodiments, the first thermoplastic polymer and the second thermoplastic polymer are nylon 6. In other embodiments, the first thermoplastic polymer and the second thermoplastic polymer are nylon 6, 6. In other embodiments, the first thermoplastic polymer and the second thermoplastic polymer are polyester. In other embodiments, the first thermoplastic polymer and the second thermoplastic polymer are different. For instance, in some embodiments, the first thermoplastic polymer is nylon 6 and the second thermoplastic polymer is nylon 6,6.

[0044] The nanodiamond-containing thermoplastic fibers may be prepared by mixing the diamond concentrate pellets with the second thermoplastic polymer and extruding the resulting mixture. For instance the step of preparing the thermoplastic fibers may comprise heating the second thermoplastic polymer to form a viscous phase, blending the nanodiamond concentrate pellets into the viscous phase of the second thermoplastic polymer, and extruding the resulting mixture. Alternatively, the step of preparing the thermoplastic fibers may comprise feeding the diamond concentrate pellets and pellets of the second thermoplastic polymer into an extruder and then heating the mixture of pellets such that the first and second thermoplastic polymers form a viscous phase in which the diamond particles are dispersed. Desirably, the pellets of the second thermoplastic polymer and the diamond concentrate pellets are separately fed into the extruder in carefully controlled quantities to produce a nanodiamond-containing thermoplastic fiber that contains a predetermined concentration of diamond.

[0045] The extrusion may be controlled to produce a continuous nanodiamond-containing thermoplastic filament. Alternatively, the extruded material may be divided, or cut, to produce fibers having a controlled length, such as staple fibers. Often many filaments or fibers are produced simultaneously and are combined to prepare a yarn.

[0046] Each fiber may have a wide range of diameters. In some embodiments, the fiber may have a diameter in the micron range (e.g., between 1 .mu.m and 100 .mu.m). For instance, in some embodiments, the fiber may have a diameter in the range of about 2 .mu.m to about 50 .mu.m, alternatively about 3 .mu.m to about 30 .mu.m, alternatively about 5 .mu.m to about 20 .mu.m, alternatively about 5 .mu.m to about 15 .mu.m, alternatively about 7 .mu.m to about 11 .mu.m, alternatively about 9 .mu.m. The length of the fiber may be selected depending on the desired end-use of the fiber. Because the present disclosure provides for the extrusion of continuous filaments, the length of the fibers produced from the present disclosure is virtually unlimited.

[0047] The fibers may also be extruded to have a desired cross-section (such as by using one or more orifices that are designed to produce the desired cross-section). For instance, in some embodiments, the fibers may have a circular cross-section or a substantially circular cross-section. In other embodiments, the fibers may have a cross-section of a different shape, including for example, a triangular cross-section, an oval cross-section, a serrated cross-section, a lobal cross-section, and the like. Moreover, in some embodiments, the fibers may be extruded so that the center of the fiber is hollow.

[0048] The fibers may also be prepared so as to have a wide range of linear mass densities (e.g. fineness), which is conventionally measured in terms of denier per filament (dpf). In some embodiments, for instance, the fibers may be very fine, having linear mass densities within the microdenier range (less than 1 dpf). For instance, in some embodiments the fibers may have a linear mass density between about 0.4 and 1.0 dpf, alternatively between about 0.5 and 1.0 dpf, alternatively between 0.6 and 1.0 dpf, alternatively between 0.7 and 1.0 dpf. In other embodiments, the fibers may have a linear mass density greater than 1.0 dpf.

[0049] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure may be converted into yarns using conventional techniques. For example, nanodiamond-containing filaments may be spun together to prepare a yarn. Alternatively, nanodiamond-containing staple fibers may be blended to prepare a yarn. In many applications, it may be desirable that the yarns comprise the nanodiamond-containing thermoplastic fibers in combination with one or more other common textile materials. Common textile materials refer to those natural fibers, cellulosic fibers, and synthetic fibers of the sort that are generally known for use in the textile industry. For example, common textile materials include, but are not limited to, cotton, flax, silk, wool, ramie, polyester, nylon, rayon, spandex, plant-based fibers such as corn-based fibers, hemp, jute, polypropylene, polybenzimidazole, acetate, acrylics, and combinations thereof.

[0050] For instance, nanodiamond-containing filaments may be spun with one or more other textile filaments using conventional yarn-making processes to prepare a substantially uniform yarn. The number of each type of filament that is spun into the yarn may be selected so as to produce a yarn having a desired combination of properties. The spinning may occur by any known method, including, for example, open-end spinning, ring spinning, or air jet spinning.

[0051] Alternatively, nanodiamond-containing staple fibers and staple fibers of one or more other textile materials may be blended, such as in an intimate blend, to produce a substantially uniform yarn. In some embodiments, the intimate blend is prepared by introducing the desired proportions of each fiber into the "opening" step of the yarn-making process. The opening step of the yarn-making process typically involves a process that is configured to open up or separate the clumps of fibers for processing, typically through a combination of air and mechanical actions. The yarn-making process generally continues with the "carding" step, in which the fibers are rendered substantially parallel, forming a ropelike strand. This ropelike strand is then usually subjected to a desired amount of drawing and/or twisting to provide a yarn filament having a desired degree of tightness. The final step in the process is the "spinning" step, which spins the yarn filaments together to form the yarn. The spinning may occur by any known method, including, for example, open-end spinning, ring spinning, or air jet spinning.

[0052] As will be appreciated, the nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure may be blended with one or more other textile materials for a variety of reasons. For instance, in some embodiments, the nanodiamond-containing thermoplastic fibers may be combined with low price textile materials to save costs. In other embodiments, the nanodiamond-containing thermoplastic fibers may be combined with low moisture absorption / moisture regain yarns (for example, polyester) for quick drying applications.

[0053] It is also an object of the present disclosure to provide fabrics that are prepared with yarn that comprises the nanodiamond-containing thermoplastic fibers of the present disclosure. These fabrics may be configured for use in the production of garments and other articles. The incorporation of nanodiamond-containing thermoplastic fibers may provide fabrics that are characterized by enhanced properties, including, for example, an improved cooling effect (e.g. by improving the heat transfer away from a wearer), improved strength, improved elongation, improved softness, and combinations thereof.

[0054] The nanodiamond-containing thermoplastic fibers may be used in the production of woven fabrics, knitted fabrics, and other non-woven fabrics. In preparing various non-woven fabrics, for example, staple fibers can be used to make hydroentangled, needle punched substrates. Alternatively, spun-bond, melt-blown non-woven fabrics can be made directly where the polymer is impregnated with nanodiamond. The nanodiamond-based materials can also include membranes, films and sheets made of any of the thermoplastic materials described herein. Such membranes, films and sheets can be used in apparel items such as jackets and shoes.

[0055] In many embodiments, the fabrics may comprise the nanodiamond-containing yarns of embodiments of the present disclosure in combination with conventional yarns, such as those that are prepared from common textile materials. In woven fabrics, for example, the nanodiamond-containing thermoplastic fibers may be used in the warp yarns, the fill yarns, or both. Moreover, a desired and controlled amount of nanodiamond-containing yarn may be introduced into the warp, the fill, or both using a conventional alternating pick technique.

[0056] In some embodiments, it may be desirable to configure the fabric so that the yarn comprising the nanodiamond-containing fiber is predominantly exposed on the back surface of the fabric, i.e. the surface of the fabric that is configured to be in contact with a wearer when made into a garment. This may provide the garment with an enhanced ability to transfer heat away from the wearer and to the outer surface of the fabric. In a woven fabric, for example, this may be achieved by incorporating the nanodiamond-containing fibers only in the fill or only in the warp, depending on which of the two is predominantly exposed on the back surface of the fabric.

[0057] Similarly, in some embodiments, fabrics comprising the nanodiamond-containing thermoplastic fibers may be used as an inner layer of a multi-layer garment. For instance, in footwear applications, the fabrics comprising the nanodiamond-containing thermoplastic fibers may be used as an inner layer in order to transfer heat from a wearer's foot to the outside of the footwear.

[0058] In addition to garments, the fabrics described herein may also be used as technical fabrics where thermal management is desirable, for example in accessories such as backpacks and in seats such as automotive seats, office chairs, and the like.

Sample Yarns

[0059] In order to demonstrate the various advantages provided by the use of embodiments of the presently disclosed nanodiamond-containing thermoplastic fibers in yarns and fabrics, three sample partially oriented yarns (POY) were prepared. A control sample (Control Sample) yarn was prepared of nylon 6,6 filaments having no diamond. The first experimental sample (Experimental Sample 1) yarn was prepared of nylon 6,6 filaments having 0.0125% by weight nanodiamond particles. The second experimental sample (Experimental Sample 2) yarn was prepared of nylon 6,6 filaments having 0.025% by weight nanodiamond particles. Each of the sample yarns comprised 34 filaments and had a denier of about 95 [Note that the denier of a yarn is different from the filament deniers described above].

[0060] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide yarns with enhanced strength. For example, the sample yarns described above were tested using a STATIMAT ME+ Tensile Tester. The Tensile Tester was programmed with the following test parameters: test method: standard tensile test; gauge length: 200 mm; test speed: 400 mm/min; pretension: 0.5 cN/tex; load cell: 10 N. Using the Tensile Tester, the sample yarns were elongated at a constant rate of extension until failure of the yarn, i.e., breakage. As each of the sample yarns is elongated, a load cell measured the force placed on the yarn. The force required to cause failure of each yarn indicates the strength of the yarn. Each sample yarn was tested in this manner eight times.

[0061] The results of this testing are shown in Table 1. Notably, the inclusion of nanodiamond particles in the yarn of Experimental Sample 1 gave rise to an average increase of about 1% in the strength of the yarn over the Control Sample. The inclusion of nanodiamond particles in the yarn of Experimental Sample 2 gave rise to an average increase of about 3% in the strength of the yarn over the Control Sample. The strength results were also normalized to account for the small variations in the sizes of the yarns. Accordingly, Table 1 also identifies the average strength of each sample in grams per denier, GPD (the average strength for each sample being converted to grams and divided by the average denier of the sample).

[0062] Embodiments of the nanodiamond-containing thermoplastic fibers disclosed herein have been found to provide a yarn with at least a 1% increase in strength compared to that of a yarn prepared from the thermoplastic polymer without the nanodiamond, alternatively at least a 2% increase in strength, alternatively at least a 3% increase in strength, alternatively at least a 4% increase in strength, alternatively at least a 5% increase in strength, alternatively at least a 6% increase in strength, alternatively at least a 7% increase in strength, alternatively at least a 8% increase in strength. This increase in strength renders the nanodiamond-containing thermoplastic fibers and yarns especially suitable in the preparation of fabrics for garments and other articles where a combination of thermal management and strength is desirable.

[0063] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have also been found to provide yarns with enhanced elongation. For example, the sample yarns described above were tested using a STATIMAT ME+ Tensile Tester. The Tensile Tester was programmed with the following test parameters: test method: standard tensile test; gauge length: 200 mm; test speed: 400 mm/min; pretension: 0.5 cN/tex; load cell: 10 N. Using the Tensile Tester, the sample yarns were elongated at a constant rate of extension until failure of the yarn, i.e., breakage. The degree of elongation at failure was measured as the elongation of the yarn. Each sample yarn was tested in this manner eight times. The results of this testing are shown in Table 1. Notably, the inclusion of nanodiamond particles in the yarn of Experimental Sample 1 gave rise to an average increase of about 4% in the elongation of the yarn over the Control Sample. The inclusion of nanodiamond particles in the yarn of Experimental Sample 2 gave rise to a small average increase in the elongation of the yarn over the Control Sample.

[0064] Surprisingly, embodiments of the nanodiamond-containing thermoplastic fibers disclosed herein have been found to provide a yarn with a significant increase in strength, such as those described above, without a corresponding significant decrease in elongation. In some embodiments, for example, the elongation of yarns prepared from nanodiamond-containing thermoplastic fibers disclosed herein may be within about 3% of that of a yarn prepared from the thermoplastic polymer without the nanodiamond, alternatively within about 2%, alternatively within about 1%. In some embodiments, the increase in strength may surprisingly be accompanied by an increase in elongation. For example, some embodiments of the yarns prepared from nanodiamond-containing thermoplastic fibers disclosed herein may have at least a 1% increase in elongation compared to that of a yarn prepared from the thermoplastic polymer fibers without the nanodiamond, alternatively at least a 2% increase in elongation, alternatively at least a 3% increase in elongation, alternatively at least a 4% increase in elongation, alternatively at least a 5% increase in elongation.

[0065] Each sample yarn was also tested by a draw-force test on a Dynamic Thermal Analyzer (Dynafil), which measures the orientation of the filaments. As shown in Table 1, it was found that inclusion of the nanodiamond did not have a significant effect on the results. Each sample yarn was also tested to determine whether inclusion of the nanodiamond had an effect on the evenness in the yarn diameter. As shown in Table 1, each sample yarn was found to have a Uster percentage value of less than 1.0 (a result less than 1.0 is generally considered a favorable result). Accordingly, inclusion of the nanodiamond was found to not have a significant effect on the evenness of the yarn.

TABLE-US-00001 TABLE 1 Control Experimental Experimental Samples Sample Sample 1 Sample 2 Denier 96.1875 95.85 95.3 Filament 34 34 34 Dynafil (cN) 96.3075 94.2875 98.61286 Elongation min (%) 75.15 78.62625 75.03429 Elongation max (%) 79.27625 82.1125 79.15 Elongation (%) AVG 77.1075 80.29 77.17429 Strength min (cN) 379.0488 383.9125 391.0586 Strength max (cN) 398.3738 401.1988 406.6843 Strength (cN) AVG 388.9263 392.5 399.3386 GPD 4.043418 4.09494 4.190331 Uster % 0.70625 0.735 0.83

[0066] In order to further demonstrate the various advantages provided by use of embodiments of the presently disclosed nanodiamond-containing thermoplastic fibers in yarns and fabrics, a number of sample fabrics were prepared.

Sample Knitted Fabrics

[0067] Control and experimental knitted fabrics were prepared and subjected to a variety of testing. A control knitted fabric sample was prepared by knitting a fabric, using conventional techniques, from a textured yarn made up of nylon 6,6 fibers having no diamond content. An experimental knitted fabric sample (also referred to as the experimental fabric or the first experimental fabric) was prepared by knitting a fabric, using the same conventional techniques, from a textured yarn made up of nylon 6,6 filaments having 0.025% by weight nanodiamond particles.

Thermal Conductivity

[0068] Both the control and the experimental fabric were tested using the Hot Disk Transient Plane Source Technique (TPS 2500 S, Thermtest). This method provides an absolute method for the measurement of thermal conductivity as low as 0.005 W/mK. The thermal conductivity of each sample was measured five times and the results of the five tests were averaged. The average thermal conductivity of the control sample was 0.0862 W/mK. The average thermal conductivity of the experimental sample was 0.0915 W/mK. Accordingly, the inclusion of nanodiamond particles in the fibers of the experimental sample gave rise to an increase of about 6% in thermal conductivity of the fabric.

[0069] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide a fabric with enhanced thermal conductivity. Embodiments of the fabrics prepared with nanodiamond-containing thermoplastic fibers disclosed herein have at least a 2% increase in thermal conductivity compared to that of a fabric prepared with the thermoplastic polymer lacking the nanodiamond, alternatively at least a 3% increase in thermal conductivity, alternatively at least a 4% increase in thermal conductivity, alternatively at least a 5% increase in thermal conductivity, alternatively at least a 6% increase in thermal conductivity, alternatively at least a 7% increase in thermal conductivity, alternatively at least a 8% increase in thermal conductivity, alternatively at least a 9% increase in thermal conductivity, alternatively at least a 10% increase in thermal conductivity. This increase in thermal conductivity renders the nanodiamond-containing thermoplastic fibers especially suitable in the preparation of fabrics for garments and other articles where thermal management is desirable.

Heating and Cooling Properties

[0070] The control and experimental knitted fabrics were also subjected to a study of the rate at which each fabric heats up and cools down when exposed to a halogen lamp, which is designed to mimic natural sunlight. In this study, one side of each of the control and experimental knitted fabric samples was exposed to a 500 W halogen lamp at a distance of 50 cm. The temperature of each fabric sample was measured with a FLIRT620 Infrared (IR) camera. Specifically, the IR camera was located on the opposite side of the fabric samples as the halogen lamp. In this way, the IR camera measured the temperature of the side of the fabric that was not directly exposed to the light from the halogen lamp.

[0071] Each of the control and experimental knitted fabric samples was exposed to the halogen lamp for 15 minutes. After 15 minutes of exposure, the halogen lamp was removed and the samples were allowed to cool for 15 minutes. Temperature measurements were taken at three substantially identical spots on each sample fabric and the temperature at the three spots was averaged for each of the control and the experimental sample fabrics. The results of this test are shown in FIG. 1. As can be seen from FIG. 1, the nanodiamond-containing experimental fabric had a lower rate of heating and a greater rate of cooling than the control sample. For instance, the experimental sample was found to have an average temperature during the hearing stage that was 0.26.degree. C. lower than the control sample. Similarly, the experimental sample was found to have an average temperature during the cooling stage that was 0.23.degree. C. lower than the control sample. Accordingly, the nanodiamond-containing fabric may improve the cooling effect of a garment due to its decreased rate of heating and increased rate of cooling. Moreover, substantially identical portions of the experimental and sample fabrics differed by as much as 1.70.degree. C. (i.e. a portion of the experimental fabric was 1.70.degree. C. lower than the control) during the heating stage and by as much as 1.78.degree. C. (i.e. a portion of the experimental fabric was 1.78.degree. C. lower than the control) during the cooling stage. Accordingly, the difference in heating and cooling rates for portions of the fabric samples was quite substantial even within the relatively short fifteen minute testing stages.

[0072] Each of the control and experimental knitted fabric samples was also exposed to the halogen lamp for 12 hours in order to study the resulting temperature increase of each sample over an extended period of time. The results of this test are shown in FIG. 2. As can be seen from FIG. 2, after about 1 hour, there was about a 1.1.degree. C. difference between the experimental sample and the control sample (i.e., the experimental fabric was about 1.1.degree. C. lower than the control fabric). After about 3 hours, this difference had increased to about 1.9.degree. C. A difference of about 2.0.degree. C. was reached after about 6 hours. Accordingly, the cooling effect provided by the nanodiamond-containing fabrics of the present disclosure may be quite significant.

[0073] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide a fabric with enhanced coolness when subjected to sunlight (or mimicked sunlight as used in the above testing). For instance, when subjected to sunlight (or mimicked sunlight as used in the above testing), embodiments of the fabrics prepared with nanodiamond-containing thermoplastic fibers disclosed herein may provide at least a 1.0.degree. C. reduction in temperature compared to that of a fabric prepared with the thermoplastic polymer lacking the nanodiamond, alternatively at least a 1.5.degree. C. reduction in temperature, alternatively at least a 1.7.degree. C. reduction in temperature, alternatively at least a 1.9.degree. C. reduction in temperature, alternatively at least a 2.0.degree. C. reduction in temperature. This enhanced coolness renders the nanodiamond-containing thermoplastic fibers especially suitable in the preparation of fabrics for garments and other articles where thermal management is desirable.

Cool Touch Properties

[0074] For additional testing, a second experimental sample knitted fabric was prepared by knitting a fabric, using the same conventional techniques described previously, from a textured yarn made up of nylon 6,6 filaments having 0.0125% by weight nanodiamond particles. Each of the first experimental fabric (made up of nylon 6,6 filaments having 0.025% by weight nanodiamond particles), the second experimental fabric, and the control fabric were tested in a Fabric Touch Tester (FTT, SDS ATLAS M293), which measured the heat transfer properties of each of the sample fabrics. Specifically, the Fabric Touch Tester measured the thermal maximum flux, or Q-max, which is the maximum energy transmitted during compression. Because it generally relates to the heat transfer that occurs between a person's skin and a fabric, the Q-max can be used to provide a general indication of how cool a fabric will feel to the touch. Specifically, the greater the Q-max value of a fabric, the cooler that fabric will feel to the touch. The Q-max results (in units of W/m.sup.2) of the sample fabrics are shown in FIG. 3. As seen from FIG. 3, the first experimental sample fabric (identified as Textured ND.sub.2) had a Q-max that is about 14% greater than the control sample and the second experimental sample fabric (identified as Textured ND.sub.1) had a Q-max that is about 4% greater than the control sample.

[0075] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide a fabric with enhanced cool touch properties. Embodiments of the fabrics prepared with nanodiamond-containing thermoplastic fibers disclosed herein may have at least a 4% increase in Q-max compared to that of a fabric prepared with the thermoplastic polymer lacking the nanodiamond, alternatively at least a 6% increase in Q-max, alternatively at least an 8% increase in Q-max, alternatively at least a 10% increase in Q-max, alternatively at least a 12% increase in Q-max. This enhanced coolness renders the nanodiamond-containing thermoplastic fibers especially suitable in the preparation of fabrics for garments and other articles where thermal management is desirable.

Softness

[0076] The Fabric Touch Tester was also used to measure the surface friction coefficient of the samples. The surface friction coefficient of a fabric provides an indication of how soft a material feels to the touch. The surface friction coefficient results are shown in FIG. 4. As seen from FIG. 4, the first experimental sample fabric (identified as ND.sub.2) had a surface friction coefficient that was about 13% lower than the control sample fabric. Similarly, the second experimental sample fabric (identified as ND.sub.1) had a surface friction coefficient that was about 16% lower than the control sample fabric.

[0077] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide a fabric with enhanced softness. Because the nanosized diamond particles may act as rolling elements on the surface of the fabric, they serve to reduce friction between the surface of the fabric and a contacting surface. This may provide the fabric with an enhanced smoothness and/or softness to the touch. Embodiments of the fabrics prepared with nanodiamond-containing thermoplastic fibers disclosed herein may have at least a 5% increase in softness (i.e., at least a 5% decrease in surface friction coefficient) compared to that of a fabric prepared with the thermoplastic polymer lacking the nanodiamond, alternatively at least a 7% increase in softness, alternatively at least a 10% increase in softness, alternatively at least a 12% increase in softness, alternatively at least a 15% increase in softness. This enhanced softness renders the nanodiamond-containing thermoplastic fibers especially suitable in the preparation of fabrics for garments and other articles where enhanced comfort is desirable.

Consumer Testing

[0078] A consumer-based study was conducted to further test whether the nanodiamond-containing knitted fabrics are perceived to be cooler and/or softer than the nylon knitted control fabrics by potential consumers. Specifically, the first experimental sample knitted fabric, which was made up of nylon 6,6 filaments having 0.025% by weight nanodiamond particles, was compared against the control sample knitted fabric, which was made up of nylon 6,6 filaments with no nanodiamond content. Sixteen persons were invited to blind evaluate the two fabrics by touch and feel. 66% of the persons in the study found the nanodiamond-containing experimental fabric to feel cooler to the touch than the control fabric. 54% of the persons in the study found the nanodiamond-containing experimental fabric to feel softer than the control fabric. Thus, the consumer-based study confirms that the increases in coolness and softness are significant from a commercial standpoint.

Glass Transition and Melting Temperature

[0079] The experimental knitted fabrics were also tested to determine whether the introduction of the nanodiamonds into the thermoplastic polymer fibers impacted certain properties of the fibers that may be relevant within the fabric- and/or garment-making industries. Specifically, the first experimental sample knitted fabric, which was made up of nylon 6,6 filaments having 0.025% by weight nanodiamond particles, and the control sample knitted fabric, which was made up of nylon 6,6 filaments with no nanodiamond content, were tested to determine glass transition temperatures and melting temperatures. The testing was performed using a differential scanning calorimeter (DSC 6000, Perkin Elmer Precisely). The glass transition temperature and the melting temperatures of the experimental fabric and the control fabric were found to be similar. Accordingly, the nanodiamond-containing fibers are considered suitable to make yarns, fabrics, and garments.

Sample Woven Fabrics

[0080] Control and experimental woven fabrics were also prepared and subjected to a variety of testing. A control fabric sample was prepared by weaving a fabric, using conventional techniques, with a textured yarn made up of nylon 6,6 fibers having no diamond content. An experimental fabric sample was prepared by weaving a fabric, using the same conventional techniques, with a textured yarn made up of nylon 6,6 filaments having 0.025% by weight nanodiamond particles. Specifically, each of the control and experimental fabrics were prepared as a 3/1 right hand twill having a warp*weft density (i.e., ends per inch*picks per inch) of 60*44. The warp of each fabric was made up of conventional cotton yarns. The weft of each fabric was made up of 2/70/34 textured nylon yarns. Specifically, the weft of the control fabric was made up of textured nylon 6,6 yarns, the yarns being made up of nylon 6,6 filaments having no diamond. The weft of the experimental fabric was made up of textured nanodiamond-containing nylon 6,6 yarns, the yarns being made up of nylon 6,6 filaments containing about 0.025% by weight nanodiamond. Accordingly, each of the fabrics was made up of (a) about 72% cotton and (b) about 28% nylon (control) or nanodiamond-containing nylon (experimental).

Heating and Cooling Properties

[0081] The control and experimental woven fabrics were subjected to a study of the rate at which each fabric heats up and cools down when exposed to a halogen lamp, which is designed to mimic natural sunlight. In this study, one side of each of the control and experimental woven fabric samples was exposed to a 500 W halogen lamp at a distance of 50 cm. The temperature of each fabric sample was measured with a FLIRT620 Infrared (IR) camera. Specifically, the IR camera was located on the opposite side of the fabric samples as the halogen lamp. In this way, the IR camera measured the temperature of the side of the fabric that was not directly exposed to the light from the halogen lamp.

[0082] Each of the control and experimental woven fabric samples was exposed to the halogen lamp for 15 minutes. After 15 minutes of exposure, the halogen lamp was removed and the samples were allowed to cool for 15 minutes. Temperature measurements were taken at three substantially identical spots on each sample fabric and the temperature at the three spots was averaged for each of the control and the experimental sample fabrics. The results of this test are shown in FIG. 5. As can be seen from FIG. 5, the nanodiamond-containing experimental fabric had a lower rate of heating and a greater rate of cooling than the control sample. For instance, the experimental sample was found to have an average temperature during the hearing stage that was 0.37.degree. C. lower than the control sample. Similarly, the experimental sample was found to have an average temperature during the cooling stage that was 0.14.degree. C. lower than the control sample. Accordingly, the nanodiamond-containing fabric may improve the cooling effect of a garment due to its decreased rate of heating and increased rate of cooling. Moreover, substantially identical portions of the experimental and sample fabrics differed by as much as 0.90.degree. C. (i.e. a portion of the experimental fabric was 0.90.degree. C. lower than the control) during the heating stage. Accordingly, the difference in heating rates for portions of the fabric samples was substantial even within the relatively short fifteen minute stage.

[0083] Each of the control and experimental woven fabric samples was also exposed to the halogen lamp for 12 hours in order to study the resulting temperature increase of each sample over an extended period of time. The results of this test are shown in FIG. 6. As can be seen from FIG. 6, after about 1 hour, there was about a 1.0.degree. C. difference between the experimental sample and the control sample (i.e., the experimental fabric was about 1.0.degree. C. lower than the control fabric). After about 3 hours, this difference had increased to about 1.9.degree. C. A difference of about 2.0.degree. C. was reached after about 6 hours. Accordingly, the cooling effect provided by the nanodiamond-containing fabrics of the present disclosure may be quite significant.

[0084] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide a fabric with enhanced coolness when subjected to sunlight (or mimicked sunlight as used in the above testing). For instance, when subjected to sunlight (or mimicked sunlight as used in the above testing), embodiments of fabrics prepared with nanodiamond-containing thermoplastic fibers disclosed herein may provide at least a 1.0.degree. C. reduction in temperature compared to that of a fabric prepared with the thermoplastic polymer lacking the nanodiamond, alternatively at least a 1.5.degree. C. reduction in temperature, alternatively at least a 1.7.degree. C. reduction in temperature, alternatively at least a 1.9.degree. C. reduction in temperature, alternatively at least a 2.0.degree. C. reduction in temperature. This enhanced coolness renders the nanodiamond-containing thermoplastic fibers especially suitable in the preparation of fabrics for garments and other articles where thermal management is desirable.

Consumer Testing

[0085] A consumer-based study was conducted to test whether the nanodiamond-containing woven fabric is perceived to be cooler and/or softer than the woven control fabric by potential consumers. Specifically, the experimental woven fabric was compared against the control woven fabric. Sixteen persons were invited to blind evaluate the two fabrics by touch and feel. 67% of the persons in the study found the nanodiamond-containing experimental fabric to feel cooler to the touch than the control fabric. 73% of the persons in the study found the nanodiamond-containing experimental fabric to feel softer than the control fabric. Thus, the consumer-based study demonstrates that the nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure provide woven fabrics having commercially significant increases in coolness and softness.

Tensile Strength

[0086] The control and experimental woven fabrics were subjected to a study in order to determine whether the incorporation of nanodiamond had an effect on the tensile properties of the fabric. Both the control and the experimental woven fabrics were tested using the ASTM 5035 testing method with an Instron 3384 machine. The rate of testing was set to 12 inches/minute, the gauge length to 3 inches, the load cell to 5 kN, and the fiber direction to Fill. The results of the testing are shown in Table 2 and graphically in FIG. 6. As is evident, the experimental sample (containing nanodiamond) exhibited higher load and strain as compared to the control sample.

TABLE-US-00002 TABLE 2 Extension at Maximum Maximum Load Load (kgf) (mm) Nylon 94.31 97.63 ND 109.76 100.18 % 26.38 2.61

[0087] As can be seen from Table 2, the nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide a fabric with enhanced tensile strength (about 16%) and elongation (about 3%).

[0088] The nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to provide a fabric with enhanced tensile strength. Embodiments of the fabrics prepared with nanodiamond-containing thermoplastic fibers disclosed herein may have at least a 5% increase in tensile strength compared to that of a fabric prepared with the thermoplastic polymer lacking the nanodiamond, alternatively at least a 7% increase in tensile strength, alternatively at least a 10% increase in tensile strength, alternatively at least a 12% increase in tensile strength, alternatively at least a 15% increase in tensile strength. This enhanced tensile strength renders the nanodiamond-containing thermoplastic fibers especially suitable in the preparation of fabrics for garments and other articles where enhanced strength is desirable.

[0089] Despite these increases in the strength of the fabrics, the nanodiamond-containing thermoplastic fibers of embodiments of the present disclosure have been found to not significantly affect the elongation properties of the fabric. For example, the elongation properties of embodiments of fabrics prepared with nanodiamond-containing thermoplastic fibers may be within about .+-.4% of the elongation properties of a fabric prepared with the thermoplastic fibers lacking the nanodiamond, alternatively within about .+-.3%, alternatively within about .+-.2.5%, alternatively within about .+-.2%, alternatively within about .+-.1.5%, alternatively within about .+-.1%. Surprisingly, in some embodiments, the incorporation of nanodiamond may even result in a fabric having enhanced elongation properties. For instance, embodiments of the fabrics prepared with nanodiamond-containing thermoplastic fibers disclosed herein may have at least a 0.5% increase in elongation compared to that of a fabric prepared with the thermoplastic fiber lacking the nanodiamond, alternatively at least a 1% increase in elongation, alternatively at least a 1.5% increase in elongation, alternatively at least a 2% increase in elongation, alternatively at least a 2.5% increase in elongation.

[0090] It can be seen that the described embodiments provide a unique and novel nanodiamond-containing thermoplastic fiber, method of making a nanodiamond-containing thermoplastic fiber, and fabric comprising a nanodiamond-containing thermoplastic fiber that have a number of advantages over those in the art. While there is shown and described herein certain specific structures embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.

Claims

1. A method for preparing a nanodiamond-containing thermoplastic fiber comprising: melt extruding a material comprising at least 98.0% by weight thermoplastic polymer, and from about 0.001% to about 0.25% by weight diamond particles having particle sizes between about 2 and about 500 nm; to produce a fiber having diamond particles substantially uniformly distributed throughout the fiber.

2. The method of claim 1, wherein the nanodiamond-containing thermoplastic fiber contains from about 0.005% to about 0.100% by weight diamond particles.

3. The method of claim 1, wherein the thermoplastic polymer is selected from the group consisting of: polyesters, polypropylene, polycarbonate, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polytrimethylene naphthalate (PTN), polyether ketone (PEK), polyether ether ketone (PEEK), poly(p-phenylene sulfide) (PPS), polyamides (nylon), thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE), and combinations thereof.

4. The method of claim 1, wherein the thermoplastic polymer comprises one or more polyamides.

5. The method of claim 4, wherein the thermoplastic polymer comprises nylon 6,6; nylon 6; or a combination thereof.

6. The method of claim 1, wherein the diamond particles have particle sizes between about 2 nm and about 10 nm.

7. The method of claim 1, wherein the melt extruding comprises at least the following two steps: a. preparing diamond concentrate pellets comprising a first thermoplastic polymer, about 0.1% to about 10% by weight diamond particles, and about 0.1% to about 1% by weight dispersion agent; and b. preparing the nanodiamond-containing thermoplastic fiber by melt extruding a mixture of a second thermoplastic polymer and the diamond concentrate pellets prepared in step (a).

8. The method of claim 7, wherein the second thermoplastic polymer is a polyamide.

9. The method of claim 8, wherein the first thermoplastic polymer is a polyamide.

10. The method of claim 9, wherein the first thermoplastic fiber is nylon 6 and the second thermoplastic polymer is nylon 6,6.

11. The method of claim 7, wherein the first thermoplastic polymer and the second thermoplastic polymer differ from one another.

12. The method of claim 7, wherein the first thermoplastic polymer and the second thermoplastic polymer are the same.

13. The method of claim 7, wherein the dispersion agent comprises zinc stearate, calcium stearate, or a mixture thereof.

14. The method of claim 7, wherein step (a) comprises heating the first thermoplastic polymer to form a viscous phase, blending the nanodiamond particles and dispersion agent into the first thermoplastic polymer, and extruding the resulting mixture.

15. The method of claim 7, wherein step (b) comprises feeding pellets of the second thermoplastic polymer and the diamond concentrate pellets into an extruder in controlled quantities to produce a nanodiamond-containing thermoplastic fiber that contains a predetermined concentration of nanodiamond.

16. The method of claim 1, wherein incorporation of the diamond particles produces at least a 5% increase in the thermal conductivity of the fiber in contrast to the fiber without the diamond particles.

17. The method of claim 1, wherein incorporation of the diamond particles produces a substantial increase in the strength of the fiber over the fiber without the diamond particles, without producing a substantial decrease in elongation.

18. A nanodiamond-containing thermoplastic fiber comprising: about 99.0% to about 99.9% by weight thermoplastic polymer; about 0.001% to about 0.25% by weight diamond particles, the diamond particles having particle sizes between about 2 and about 500 nm; about 0.002% to about 0.02% by weight dispersion agent.

19. The nanodiamond-containing thermoplastic fiber of claim 18, wherein the thermoplastic polymer is nylon.

20. The nanodiamond-containing thermoplastic fiber of claim 18, wherein the dispersion agent comprises zinc stearate, calcium stearate, or a mixture thereof.

21. The nanodiamond-containing thermoplastic fiber of claim 18, wherein the nanodiamond-containing thermoplastic fiber comprises about 0.005% to about 0.100% by weight diamond particles.

22. The nanodiamond-containing thermoplastic fiber of claim 21, wherein the diamond particles have particle sizes between about 2 nm and about 10 nm.

23. The nanodiamond-containing thermoplastic fiber of claim 18, wherein the nanodiamond-containing thermoplastic fiber has at least a 5% higher thermal conductivity than a fiber containing only the thermoplastic polymer.

24. The nanodiamond-containing thermoplastic fiber of claim 18, wherein the nanodiamond-containing thermoplastic fiber has at least a 4% higher strength than that of a fiber containing only the thermoplastic polymer and an elongation that is within about 2% of that of the fiber containing only the thermoplastic polymer.

25. The nanodiamond-containing thermoplastic fiber of claim 18, further comprising about 0.001% to about 0.25% by weight sub-micron particles of boron nitride, graphite, graphene, silica, one or more aluminosilicates, or a combination thereof.

26. A fabric comprising the nanodiamond-containing thermoplastic fiber of claim 18.

27. A garment comprising the fabric of claim 26, the garment being configured to provide transfer heat away from a wearer's body.

28. A method of increasing the thermal conductivity of a fabric comprising: preparing a fiber having at least 98.0% by weight thermoplastic polymer, and from about 0.005% to about 0.100% by weight diamond particles having particle sizes between about 2 and about 500 nm, wherein the diamond particles are substantially uniformly distributed throughout the fiber; incorporating the fiber into a yarn; and preparing a fabric that comprises the yarn; wherein incorporation of the diamond particles in the fabric produces at least a 5% increase in the thermal conductivity of the fabric in contrast to the fabric without the diamond particles.

29. A method of increasing the strength of a fabric without a significant loss in the elongation of the fabric, comprising: preparing a fiber having at least 98.0% by weight thermoplastic polymer, and from about 0.005% to about 0.100% by weight diamond particles having particle sizes between about 2 and about 500 nm, wherein the diamond particles are substantially uniformly distributed throughout the fiber; incorporating the fiber into a yarn; and preparing a fabric that comprises the yarn; wherein incorporation of the diamond particles in the fabric produces a substantial increase in the strength of the fabric in contrast to the fabric without the diamond particles, without producing a substantial decrease in elongation of the fabric.