Multilayer composites comprising a polymeric layer and a continuous fiber reinforced polymeric composite

Abstract

Embodiments of the present disclosure are directed to multilayer composites includes a polymeric layer and a continuous fiber reinforced polymeric composition adjacent to the polymeric layer. The polymeric layer includes a polymer matrix, thermally non-conductive hollow beads, and a thermally conductive material. The thermally non-conductive hollow beads and the thermally conductive material are dispersed in the polymer matrix.

Description

MULTILAYER COMPOSITES COMPRISING A POLYMERIC LAYER AND A CONTINUOUS FIBER REINFORCED POLYMERIC COMPOSITECLAIM OF PRIORITY

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 436,096 bearing Attorney Docket Number 1202224 and filed on December 29, 2022, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] Embodiments of the present disclosure are generally related to multilayer composites, and are specifically related to multilayer composites including a continuous fiber reinforced polymeric composite and a polymeric layer having low thermal inertia.BACKGROUND

[0003] Heat transfer may be classified as active (i.e., heat exchanges) or passive (i.e., heat sinks). Efficient movement of heat from one location to another may be critical to optimal operation of various equipment or instruments. However, after heating, conventional materials may not return to ambient temperature at a desired cooling rate (i.e., relatively quickly).

[0004] Accordingly, a continuous need exists for improved materials capable of returning to ambient temperatures at a desired cooling rate.SUMMARY

[0005] Embodiments of the present disclosure are directed to multilayer composites comprising a polymeric layer and a continuous fiber reinforced polymeric composite, which are capable of returning to ambient temperatures at a desired cooling rate.

[0006] According to one embodiment, a multilayer composite is provided. The multilayer composite comprises a polymeric layer and a continuous fiber reinforced polymeric composition adjacent to the polymeric layer. The polymeric layer comprises a polymer matrix, thermally non-conductive hollow beads, and a thermally conductive material. The thermally non-conductive hollow beads and the thermally conductive material are dispersed in the polymer matrix.

[0007] Additional features and advantages of the embodiments described herein 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 described herein, including the detailed description, which follows and the claims.DRAWINGS

[0008] FIG. 1 is a schematic view of an exemplary multilayer composite, according to one or more embodiments shown and described herein;

[0009] FIG. 2 is a schematic view of another exemplary multilayer composite, according to one or more embodiments shown and described herein;

[0010] FIG. 3 are cross-sectional, schematic views of a comparative multilayer composite and example multilayer composites, according to one or more embodiments shown and described herein;

[0011] FIG. 4 is a plot of time elapsed (x-axis; in min.) versus relative temperature above ambient (y-axis; in °C) of thermocouple probes at 17.0 mm deep in a comparative example composite and example composites, according to one or more embodiments shown and described herein;

[0012] FIG. 5 is a plot of time elapsed (x-axis; in min.) versus relative temperature above ambient (y-axis; in °C) of thermocouple probes at 8.5 mm deep in a comparative example composite and example composites, according to one or more embodiments shown and described herein;

[0013] FIG. 6 is a plot of time elapsed (x-axis; in min.) versus relative temperature above ambient (y-axis; in °C) of thermocouple probes at the top surfaces of a comparative example composite and example composites, according to one or more embodiments shown and described herein;

[0014] FIG. 7 is a plot of time elapsed (x-axis; in min.) versus relative temperature above ambient (y-axis; in °C) of thermocouple probes at 17.0 mm deep in a comparative example composite and example composites, according to one or more embodiments shown and described herein;

[0015] FIG. 8 is a plot of time elapsed (x-axis; in min.) versus relative temperature above ambient (y-axis; in °C) of thermocouple probes at 12.7 mm deep in a comparative example composite and example composites, according to one or more embodiments shown and described herein; and

[0016] FIG. 9 is a plot of time elapsed (x-axis; in min.) versus relative temperature above ambient (y-axis; in °C) of thermocouple probes at 8.5 mm deep in a comparative example composite and example composites, according to one or more embodiments shown and described herein.DETAILED DESCRIPTION

[0017] Reference will now be made in detail to various embodiments of multilayer composites, specifically multilayer composites comprising a polymeric layer and a continuous fiber reinforced polymeric composite adjacent to the polymeric layer, wherein the polymeric layer comprises a polymer matrix, thermally non-conductive hollow beads, and a thermally conductive material, the thermally non-conductive hollow beads and the thermally conductive material being dispersed in the polymer matrix.

[0018] The disclosure 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 subject matter to those skilled in the art.

[0019] Definitions

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in the disclosure herein is for describing particular embodiments only and is not intended to be limiting.

[0021] Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0022] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0023] As used in the specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0024] The term “continuous fiber,” as used herein, refers to a fiber that has a long aspect ratio (length-to-diameter ratio). Due to the long aspect ratio of the continuous fiber, the continuous fiber may be wrapped, woven knitted, braided, arranged to be substantially parallel, or used in a nonwoven fabric. In embodiments, where the continuous fiber are arranged to be substantially parallel, the continuous fibers may span all or substantially all of a dimension of the continuous fiber reinforced polymeric composite. The term “substantially all of a dimension,” as used herein, refers to greater than 75% of a dimension of the continuous fiber reinforced polymeric composite.

[0025] The term “average diameter,” as used herein with respect to the continuous fibers, refers to an average of the diameters of each of the fibers in the plurality of continuous fibers.

[0026] The term “average diameter,” as used herein with respect to the thermally non- conductive hollow beads, refers to an average of the diameters of each bead of the thermally non- conductive hollow beads.

[0027] The term “average length,” as used herein, refers to an average of the lengths of the thermally conductive material.

[0028] The term “average geometrical dimension,” as used herein, refers to an average of the largest dimensions of the thermally conductive material.

[0029] The term “ambient temperature,” as used herein, refers to about 20 °C.

[0030] The term “thermal inertia,” as used herein, refers to the property of a material that expresses the degree of slowness with which its temperature reaches that of the environment. A relatively lower thermal inertia indicates a faster return to equilibrium with the environment. A relatively higher thermal inertia indicates a greater resistance of a material to return to ambient temperature. Thermal inertia is calculated as the square root of the product of volumetric heat capacity and thermal conductivity (i.e., thermal inertia = ^(volumetric heat capacity x thermal conductivity).

[0031] The term “thermal conductivity,” as used herein, refers to a measure of a material’s ability to conduct heat. The defining equation for thermal conductivity is q = -kAT, where q is the heat flux, k is the thermal conductivity, and AT is the temperature gradient. An alternative is thermal conductivity calculated by multiplying heat capacity by density and by thermal diffusivity (i.e., thermal conductivity = (heat capacity x density) x thermal diffusivity).

[0032] The term “thermal diffusivity,” as used herein, refers to the rate of heat transfer through a medium.

[0033] The term “heat capacity,” as used herein, refers to the number of heat units needed to raise the temperature of the material by one degree.

[0034] The term “volumetric heat capacity,” as used herein, refers to the heat capacity of a material divided by the volume of the material.

[0035] The term “density” as used herein, refers to a material’s mass per unit of volume.

[0036] As discussed hereinabove, heat transfer may be classified as active (i.e., heat exchanges) or passive (i.e., heat sinks). Efficient movement of heat from one location to another may be critical to optimal operation of various equipment or instruments. The object of heat transfer may be to eliminate (i.e., remove) heat from the system and “dump” the heat into the environment. Greater efficiency may be derived by actively using the heat transferred, such as in waste heat recovery units or counter flow heat exchangers. Alternatively, system efficiency may be derived from creating a new equilibrium where at a higher temperature, heat energy is eliminated from the system at the same rate it is input. However, after heating, conventional materials may not return to ambient temperature at a desired cooling rate (i.e., relatively quickly).

[0037] Disclosed herein are multilayer composites, which mitigate the aforementioned problems. Specifically, the multilayer composites comprise a polymeric layer and a continuous fiber reinforced polymeric composite, which are capable of returning to ambient temperature at a desired cooling rate. In particular, the polymeric layer comprises a polymer matrix, thermally non- conductive hollow beads, and a thermally conductive material. The thermally non-conductive hollow beads and the thermally conductive material are dispersed in the polymer matrix. The thermally non-conductive hollow beads help to channel heat through the thermally conductive material, resulting in microchannels of thermally conductive material connecting opposite ends of the polymeric layer. These microchannels impart a low thermal inertia to the polymeric layer and ensure that the multilayer composite, within which the polymeric layer is included, returns to ambient temperature at a desired cooling rate.

[0038] Referring now to FIG. 1, the multilayer composites 100 disclosed herein may generally be described as comprising a polymeric layer 102 and a continuous fiber reinforced polymeric composite 104 adjacent to the polymeric layer 102.

[0039] In embodiments, the multilayer composites may include a substrate layer. Referring now to FIG. 2, in embodiments, a multilayer composite 200 may comprise a polymeric layer 202,a continuous fiber reinforced polymeric composite 204, and a substrate layer 206. The substrate layer 206 may be adjacent to the polymeric layer 202 opposite the continuous fiber reinforced polymeric composite 204.

[0040] Polymeric Laver

[0041] The multilayer composites 100, 200 described herein include polymeric layers 102, 202 having relatively low thermal inertia (e.g., less than or equal to 1200 J / m2K s1 2) to ensure that the multilayer composites 100, 200, after heating, returns to ambient temperature at a desired cooling rate. Additionally, in embodiments, the relatively low thermal inertia of the polymeric layers 102, 202 may reduce the maximum temperature of the multilayer composites 100, 200 during heating.

[0042] Thermal conductivity of a material may be used to understand the heat transferability of a material; the greater the thermal conductivity, the greater the degree of accepting heat from the environment. However, as mentioned hereinabove, thermal conductivity is calculated by multiplying heat capacity by density and by thermal diffusivity. Thus, focusing on thermal conductivity may provide an advantage to high density and high heat capacity material and may not appreciate the potential effectiveness of lightweight materials on improved thermal characteristics. Thermal conductivity does not take into account the ability of a material to release heat from a volume. Accordingly, when considering materials for use in heat-exchange or heatrelease applications, thermal conductivity may not give the user an advantage over alternative materials. As such, thermal inertia may be more prudent to evaluate for these applications.

[0043] In embodiments, the polymeric layers 102, 202 may comprise a thermal inertia from 420 J / m2K s1 2to 1200 J / m2K s1'2. In embodiments, the polymeric layers 102, 202 may comprise a thermal inertia greater than or equal to 420 J / m2K s1'2, greater than or equal to 500 J / m2K s1 / 2, greater than or equal to 580 J / m2K s1 2, greater than or equal to 660 J / m2K s1 2, or even greater than or equal to 720 J / m2K s1'2. In embodiments, the polymeric layers 102, 202 may comprise a thermal inertia less than or equal to 1200 J / m2K s1 / 2, less than or equal to 1100 J / m2K s1 / 2, less than or equal to 1000 I / m2K s1 2, or even less than or equal to 900 J / m2K s1 2. In embodiments, the polymeric layers 102, 202 may comprise a thermal inertia from 420 J / m2K s1'2to 1200 J / m2K s1 2, from 420 J / m2K s1 2to 1100 J / m2K s1 2, from 420 J / m2K s1 2to 1000 J / m2K s1 / 2, from 420 J / m2K s1'2to 900 J / m2K s1'2, from 500 J / m2K s1 2to 1200 J / m2K s1'2, from 500 J / m2K s1 2to 1100J / m2K s1 2, from 500 J / m2K s1 2to 1000 J / m2K s1 / 2, from 500 J / m2K s1 2to 900 J / m2K s1'2, from 580 J7m2K s1 2to 1200 J / m2K s1'2, from 580 J / m2K s1 2to 1100 J / m2K s1 / 2, from 580 J / m2K s1 / 2to 1000 J / m2K s1 / 2, from 580 J / m2K s1'2to 900 J / m2K s1'2, from 660 J7m2K s1'2to 1200 J / m2K s1 / 2, from 660 J / m2K s1'2to 1100 J / m2K s1 / 2, from 660 J / m2K s1'2to 1000 J / m2K s1 / 2, from 660 J7m2K s1 2to 900 J / m2K s1 / 2, from 720 J7m2K s1 / 2to 1200 J / m2K s1 / 2, from 720 J / m2K s1 / 2to 1100 J7m2K s1,2, from 720 J7m2K s1 2to 1000 J / m2K s1'2, or even from 720 J / m2K s1'2to 900 J / m2K s1 / 2, or any and all subranges formed from any of these endpoints.

[0044] In addition to low thermal inertia, the polymeric layers 102, 202 may have a relatively low heat capacity (e.g., less than or equal to 1.75 J / gK) such that the multilayer composites 100, 200 have an overall reduced heat capacity. In embodiments, the polymeric layers 102, 202 may comprise a heat capacity from 0.62 J / gK to 1.75 J / gK. In embodiments, the polymeric layers 102, 202 may comprise a heat capacity greater than or equal to 0.62 J / gK, greater than or equal to 0.72 J / gK, or even greater than or equal to 0.82 J / gK. In embodiments, the polymeric layers 102, 202 may comprise a heat capacity less than or equal to 1.75 J / gK, less than or equal to 1.50 J / gK, less than or equal to 1.25 J / gK, or even less than or equal to 1.00 J / gK. In embodiments, the polymeric layers 102, 202 may comprise a heat capacity from 0.62 J / gK to 1.75 J / gK, from 0.62 J / gK to 1.50 J / gK, from 0.62 J / gK to 1.25 J / gK, from 0.62 J / gK to 1.00 J / gK, from 0.72 J / gK to 1.75 J / gK, from 0.72 J / gK to 1.50 J / gK, from 0.72 J / gK to 1.25 J / gK, from 0.72 J / gK to 1.00 J / gK, from 0.82 J / gK to 1.75 J / gK, from 0.82 J / gK to 1.50 J / gK, from 0.82 J / gK to 1.25 J / gK, or even from 0.82 J / gK to 1.00 J / gK, or any and all subranges formed from any of these endpoints.

[0045] In embodiments, the polymeric layers 102, 202 may comprise a density from 1.00 g / cm3to 1.80 g / cm3. In embodiments, the polymeric layers 102, 202 may comprise a density greater than or equal to 1.00 g / cm3, greater than or equal to 1.20 g / cm3, greater than or equal to 1.40 g / cm3, or even greater than or equal to 1.60 g / cm3. In embodiments, the polymeric layers 102, 202 may comprise a density less than or equal to 1.80 g / cm3or even less than or equal to 1.70 g / cm3. In embodiments, the polymeric layers 102, 202 may comprise a density from 1.00 g / cm3to 1.80 g / cm3, from 1.00 g / cm3to 1.70 g / cm3, from 1.20 g / cm3to 1.80 g / cm3, from 1.20 g / cm3to 1.70 g / cm3, from 1.40 g / cm3to 1.80 g / cm3, from 1.40 g / cm3to 1.70 g / cm3, from 1.60 g / cm3to 1.80 g / cm3, or even from 1.60 g / cm3to 1.70 g / cm3, or any and all subranges formed from any of these endpoints.

[0046] In embodiments, the polymeric layers 102, 202 may comprise a volumetric heat capacity from 0.62 J / gK g / cm3to 1.95 J / gK g / cm3. In embodiments, the polymeric layers 102, 202 may comprise a volumetric heat capacity greater than or equal to 0.62 J / gK g / cm3, greater than or equal to 0.80 J / gK g / cm3, greater than or equal to 1.00 J / gK g / cm3, or even greater than or equal to 1.20 J / gK g / cm3. In embodiments, the polymeric layers 102, 202 may comprise a volumetric heat capacity less than or equal to 1.95 J / gK g / cm3, less than or equal to 1.75 J / gK g / cm3, or even less than or equal to 1.55 J / gK g / cm3. In embodiments, the polymeric layers 102, 202 may comprise a volumetric heat capacity from 0.62 J / gK g / cm3to 1.95 J / gK g / cm3, from 0.62 J / gK g / cm3to 1.75 J / gK g / cm3, from 0.62 J / gK g / cm3to 1.55 J / gK g / cm3, from 0.80 J / gK g / cm3to 1.95 J / gK g / cm3, from 0.80 J / gK g / cm3to 1.75 J / gK g / cm3, from 0.80 J / gK g / cm3to 1.55 J / gK g / cm3, from 1.00 J / gK g / cm3to 1.95 J / gK g / cm3, from 1.00 J / gK g / cm3to 1.75 J / gK g / cm3, from 1.00 J / gK g / cm3to 1.55 J / gK g / cm3, from 1.20 J / gK g / cm3to 1.95 J / gK g / cm3, from 1.20 J / gK g / cm3to 1.75 J / gK g / cm3, or even from 1.20 J / gK g / cm3to 1.55 J / gK g / cm3, or any and all subranges formed from any of these endpoints.

[0047] In embodiments, the polymeric layers 102, 202 may comprise a thickness greater than or equal to 0.1 mm, greater than or equal to 0.5 mm, greater than or equal to 1 mm, greater than or equal to 3 mm, or even greater than or equal to 5 mm. In embodiments, the polymeric layers 102, 202 may comprise a thickness less than or equal to 15 mm, less than or equal to 13 mm, or even less than or equal to 10 mm. In embodiments, the polymeric layers 102, 202 may comprise a thickness from 0.1 mm to 15 mm, from 0.1 mm to 13 mm, from 0.1 mm to 10 mm, from 0.5 mm to 15 mm, from 0.5 mm to 13 mm, from 0.5 mm to 10 mm, from 1 mm to 15 mm, from 1 mm to 13 mm, from 1 mm to 10 mm, from 3 mm to 15 mm, from 3 mm to 13 mm, from 3 mm to 10 mm, from 5 mm to 15 mm, from 5 mm to 13 mm, or even from 5 mm to 10 mm, or any and all subranges formed from any of these endpoints.

[0048] In embodiments, the polymeric layers 102, 202 may comprise a thick polymeric layer (e.g., from greater than 1 mm to 15 mm), a thin polymeric layer (e.g., from 0.1 mm to 1 mm), or a combination thereof. In embodiments in which the polymeric layers 102, 202 comprises a thick polymeric layer and a thin polymeric layer, the polymeric layers 102, 202 may be considered to be multi-layered.

[0049] In embodiments, the thick polymeric layer may comprise a thickness greater than 1 mm, greater than or equal to 3 mm, or even greater than or equal to 5 mm. In embodiments, the thick polymeric layer may comprise a thickness less than or equal to 15 mm, less than or equal to 13 mm, or even less than or equal to 10 mm. In embodiments, the thick polymeric layer may comprise a thickness from greater than 1 mm to 15 mm, from greater than 1 mm to 13 mm, from greater than 1 mm to 10 mm, from 3 mm to 15 mm, from 3 mm to 13 mm, from 3 mm to 10 mm, from 5 mm to 15 mm, from 5 mm to 13 mm, or even from 5 mm to 10 mm, or any and all subranges formed from any of these endpoints.

[0050] In embodiments, the thin polymeric layer may be a paste that, in addition to having a low thermal inertia, may help adhere opposing layers together. In embodiments, the thin polymeric layer may comprise a thickness greater than or equal to 0.1 mm, greater than or equal to 0.25 mm, or even greater than or equal to 0.5 mm. In embodiments, the thin polymeric layer may comprise a thickness less than or equal to 1 mm or even less than or equal to 0.75 mm. In embodiments, the thin polymeric layer may comprise a thickness from 0.1 mm to 1 mm, from 0.1 mm to 0.75 mm, from 0.25 mm to 1 mm, from 0.25 mm to 0.75 mm, from 0.5 mm to 1 mm, or even from 0.5 mm to 0.75 mm, or any and all subranges formed from any of these endpoints.

[0051] The polymeric layers 102, 202 may comprise a polymer matrix, thermally non- conductive hollow beads, and a thermally conductive material. The thermally non-conductive hollow beads and the thermally conductive material may be dispersed in the polymer matrix.

[0052] In embodiments, to form the polymeric layers 102, 202, the thermally non-conductive hollow beads may be added to and continuously mixed into a homogenous solution of the polymer matrix. The thermally conductive materially may then be sheared into the homogenous solution including the thermally non-conductive hollow beads to form the polymeric layer.

[0053] Polymer Matrix

[0054] In embodiments, the polymer matrix may comprise thermoplastic polymer, thermoset polymer, or a combination thereof. In embodiments, the polymer matrix may comprise the thermoplastic polymer, the thermoplastic polymer comprising polyamides, polyphenylene sulfides, polyetherimides, polysulfones, polyethersulfones, polyetherketones,polyetheretherketones, or a combination thereof. In embodiments, the polymer matrix may comprise the thermoset polymer, the thermoset polymer comprising Bisphenol A epoxy, Bisphenol F epoxy, novolac epoxy, phenolic resin, bismaleimide, benzoxazine, cyanate resin, silicone resin, or a combination thereof.

[0055] In embodiments, the polymer matrix may further comprise one or more additives comprising curing agents of polyamine, anhydride, and polyphenolic.

[0056] Thermally N on-conductive Hollow Beads

[0057] The thermally non-conductive hollow beads provide structure (e g., compression strength) to the polymeric layers 102, 202. Additionally, since the thermally non-conductive beads are hollow, they allow for the polymeric layers 102, 202 to be lightweight. As the average diameter of the thermally non-conductive hollow beads increases (e.g., from 5 microns to 500 microns), the beads generally become lighter, thereby providing lower density and relatively lower thermal inertia to the polymeric layer. The thermally non-conductive hollow beads are also an insulating material such that heat will not move through the beads. Instead, the non-conductive hollow beads help to channel heat through the thermally conductive material.

[0058] In embodiments, the thermally non-conductive hollow beads may comprise hollow glass beads, hollow ceramic beads, or a combination thereof. In embodiments, the thermally non- conductive hollow beads may be spherical. In embodiments, where the thermally non-conductive hollow beads are hollow glass beads, the hollow glass beads may comprise at least 75 wt% glass, at least 80 wt%, at least 85 wt%, at least 90 wt%, at least 95 wt%, or at least 99 wt% glass based on the total weight of the hollow glass beads. In embodiments, the hollow glass beads may consist of glass. In embodiments, where the thermally non-conductive hollow beads are hollow ceramic beads, the hollow ceramic beads may comprise at least 75 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, at least 95 wt%, or at least 99 wt% ceramic based on the total weight of the hollow ceramic beads. In embodiments, the hollow ceramic beads may consist of ceramic.

[0059] In embodiments, the thermally non-conductive hollow beads may be electrically non- conductive. In these or other embodiments, the thermally non-conductive hollow beads may lacka coating or other components that would impart or increase the electrical conductivity of the thermally non-conductive hollow beads.

[0060] In embodiments, the thermally non-conductive hollow beads may have a minimum average diameter (e.g., greater than or equal to 5 microns) to ensure a desired density is achieved. For example, in embodiments, the thermally non-conductive hollow beads may comprise an average diameter from 5 microns to 1000 microns. In embodiments, the thermally non-conductive hollow beads may comprise an average diameter greater than or equal to 5 microns, greater than or equal to 10 microns, or even greater than or equal to 25 microns. In embodiments, the thermally non-conductive hollow beads may comprise an average diameter less than or equal to 1000 microns, less than or equal to 750 microns, less than or equal to 500 microns, less than or equal to 400 microns, less than or equal to 300 microns, less than or equal to 200 microns, less than or equal to 100 microns, or even less than or equal to 50 microns. In embodiments, the thermally non-conductive hollow beads may comprise an average diameter from 5 microns to 1000 microns, from 5 microns to 750 microns, from 5 microns to 500 microns, from 5 microns to 400 microns, from 5 microns to 300 microns, from 5 microns to 200 microns, from 5 microns to 100 microns, from 5 microns to 50 microns, from 10 microns to 1000 microns, from 10 microns to 750 microns, from 10 microns to 500 microns, from 10 microns to 400 microns, from 10 microns to 300 microns, from 10 microns to 200 microns, from 10 microns to 100 microns, from 10 microns to 50 microns, from 25 microns to 1000 microns, from 25 microns to 750 microns, from 25 microns to 500 microns, from 25 microns to 400 microns, from 25 microns to 300 microns, from 25 microns to 200 microns, from 25 microns to 100 microns, or even from 25 microns to 50 microns, or any and all subranges formed from any of these endpoints. In embodiments, the thermally non-conductive hollow beads may comprise a graded aggregate as to average diameter to optimize the fdling ratio.

[0061] Suitable commercial embodiments of the thermally non-conductive hollow beads are available from Zeeospheres Ceramics, LLC, such as ceramic microspheres grades N-200, N-600, and N-800; under the brand name EXTENDO SPHERES from Sphere One Inc.; or under the brand name E-SPHERES from Envirospheres Pty Ltd.

[0062] Thermally Conductive Material

[0063] The thermally conductive material included in the polymeric layers 102, 202 acts as a conduit to transfer heat that is channeled by the thermally non-conductive hollow beads through and out of the polymeric layers 102, 202, thereby imparting a low thermal inertia to the polymeric layers 102, 202.

[0064] In embodiments, the thermally conductive material may have a regular shape, an irregular shape, or a combination thereof. In embodiments, the shapes may comprise plates, particles, acicular, fibrous, filamentous, tubular, or a combination thereof. In embodiments, the shapes may be of micron size, nano size, or a combination thereof.

[0065] In embodiments, the thermally conductive material may comprise an average length from 10 microns to 500 microns. In embodiments, the thermally conductive material may comprise an average length greater than 10 microns, greater than or equal to 25 microns, greater than or equal to 50 microns, greater than or equal to 75 microns, or even greater than or equal to 100 microns. In embodiments, the thermally conductive material may comprise an average length less than or equal to 500 microns, less than or equal to 400 microns, less than or equal to 300 microns, or even less than or equal to 200 microns. In embodiments, the thermally conductive material may comprise an average length from 10 microns to 500 microns, from 10 microns to 400 microns, from 10 microns to 300 microns, from 10 microns to 200 microns, from 25 microns to 500 microns, from 25 microns to 400 microns, from 25 microns to 300 microns, from 25 microns to 200 microns, from 50 microns to 500 microns, from 50 microns to 400 microns, from 50 microns to 300 microns, from 50 microns to 200 microns, from 75 microns to 500 microns, from 75 microns to 400 microns, from 75 microns to 300 microns, from 75 microns to 200 microns, from 100 microns to 500 microns, from 100 microns to 400 microns, from 100 microns to 300 microns, or even from 100 microns to 200 microns, or any and all subranges formed from any of these endpoints.

[0066] In embodiments, the thermally conductive material may comprise an average geometrical dimension from 1 nm to 800 nm. In embodiments, the thermally conductive material may comprise an average geometrical dimension greater than or equal to 1 nm, greater than or equal to 10 nm, or even greater than or equal to 20 nm. In embodiments, the thermally conductive material may comprise an average geometrical dimension less than or equal to 800 nm, less thanor equal to 500 run, or even less than or equal to 400 nm. In embodiments, the thermally conductive material may comprise an average geometrical dimension from 1 nm to 800 nm, from 1 nm to 500 nm, from 1 nm to 400 nm, from 10 nm to 800 nm, from 10 nm to 500 nm, from 10 nm to 400 nm, from 20 nm to 800 nm, from 20 nm to 500 nm, or even from 20 nm to 400 nm, or any and all subranges formed from any of these endpoints.

[0067] In embodiments, the thermally conductive material may comprise carbon fiber, carbon nanomaterial, silver, copper, aluminum, or a combination thereof. In embodiments, the thermally conductive material may comprise milled carbon fiber. In embodiments, the thermally conductive material may comprise graphene.

[0068] Continuous Fiber Reinforced Polymeric Composite

[0069] The continuous fiber reinforced polymeric composites 104, 204 of the multilayer composites 100, 200 imparts strength and stiffness to the multilayer composites 100, 200.

[0070] In embodiments, the continuous fiber reinforced polymeric composite may comprise a plurality of continuous fibers. In embodiments, the plurality of continuous fibers may be substantially parallel. In embodiments, the plurality of continuous fibers may form a tow, yarn, end, pic, roving, woven fabric, knitted fabric, braided fabric, or non-woven fabric.

[0071] In embodiments, the plurality of continuous fibers may comprise carbon fibers, glass fibers, aramid fibers, basalt fibers, metallic fibers, or a combination thereof. In embodiments, the plurality of continuous fibers may comprise the metallic fibers, the metallic fibers comprising boron, beryllium, aluminum, copper, tungsten, titanium, nickel, stainless steel, and alloys thereof.

[0072] In embodiments, the plurality of continuous fibers may comprise an average diameter greater than or equal to 1 micron, greater than or equal to 5 microns, or even greater than or equal to 7 microns. In embodiments, the plurality of continuous fibers may comprise an average diameter less than or equal to 100 microns, less than or equal to 50 microns, or even less than or equal to 35 microns. In embodiments, the plurality of continuous fibers may comprise an average diameter from 1 micron to 100 microns, from 1 micron to 50 microns, from 1 micron to 35 microns, from 5 microns to 100 microns, from 5 microns to 50 microns, from 5 microns to 35 microns, from7 microns to 100 microns, from 7 microns to 50 microns, or even from 7 microns to 35 microns, or any and all subranges formed from any of these endpoints.

[0073] In embodiments, the plurality of continuous fibers may comprise an average length greater than or equal to 5 centimeter (“cm”), greater than or equal to 7 cm, greater than or equal to 10 cm, greater than or equal to 15 cm, or even greater than or equal to 20 cm. Those skilled in the art will appreciate that the maximum length of the continuous fibers may be determined by various considerations, including but not limited to, the orientation, use, and arrangement of the continuous fibers

[0074] In embodiments, the continuous fiber reinforced polymeric composite may comprise a polymeric material. In embodiments, the polymeric material may comprise thermoplastic polymer, thermoset polymer, or a combination thereof within which the continuous fibers are placed. In embodiments, the continuous fiber reinforced polymeric composite may comprise the thermoplastic polymer, the thermoplastic polymer comprising polyamides, polyphenylene sulfides, polyetherimides, polysulfones, polyethersulfones, polyetherketones, polyetheretherketones, or a combination thereof. In embodiments, the continuous fiber reinforced polymeric composite may comprise the thermoset polymer, the thermoset polymer comprising Bisphenol A epoxy, Bisphenol F epoxy, novolac epoxy, phenolic resin, bismaleimide, benzoxazine, cyanate resin, silicone resin, or a combination thereof.

[0075] In embodiments, the polymeric material of the continuous fiber reinforced polymeric composite may be the same as the polymer matrix employed in the polymer layer of the multilayer composite. In embodiments, the polymeric material of the continuous fiber reinforced polymeric composite may include the thermally conductive material. In embodiments, the polymeric material of the continuous fiber reinforced polymeric composite may include the thermally non- conductive hollow beads. In embodiments, the polymeric material of the continuous fiber reinforced polymeric composite may include the thermally conductive material and the thermally non-conductive hollow beads. In embodiments, the continuous fiber reinforced polymeric composite may further comprise one or more additives comprising curing agents of polyamine, anhydride, and polyphenolic.

[0076] Depending on the desired fiber arrangement of the continuous fiber reinforced polymeric composite, various methods may be used to prepare the continuous fiber reinforced polymeric composite. In embodiments, a continuous fiber can be immersed and pulled through a bath of polymeric material and wrapped around a mandrel. The mandrel turns while the fiber is held in tension and moved from one end of the mandrel to the other and back and forth until a sufficient thickness of fiber reinforced polymer is added to the mandrel. The fiber, polymeric material, and mandrel are heated to consolidate and cure the resultant composite which is then pulled off the mandrel. In other embodiments, continuous fiber may be strung through a guiding system to arrange them in parallel to each other. The continuous fibers are then pulled through a handling system that may include spreading, pre-heating, and a melt impregnation die geometry, where they are combined with polymeric material, for example, from a single or twin screw extruder arranged perpendicular to the fiber direction. In other embodiments, for example, where the continuous fibers are in a fabric (e.g., woven fabric or nonwoven fabric), layers of the fabric may be stacked and individual layers of fabric or the stack of fabric layers may be wetted out with the polymeric material.

[0077] Substrate Laver

[0078] Referring to FIG. 2. when used in combination with a substrate layer 206, the polymeric layer 202 and the continuous fiber reinforced polymeric composite 204 may, after heating, help return multilayer composite 200 to ambient temperature at a desired cooling rate and may help reduce the maximum temperature of the multilayer composite 200 as compared to conventional materials. In embodiments, multilayer composite 200 may comprise an article used in an engine, microprocessor chip, electronic device, electric motor, heat sink system, and radiator.

[0079] In embodiments, the substrate layer 206 may comprise a heat insulating material. For example, in embodiments, substrate layer 206 may comprise steel, aluminum, copper, brass, bronze, titanium, nickel, glass, ceramic, or a combination thereof.

[0080] In embodiments, the substrate layer 206 may comprise a thickness from 1 mm to 15 mm, from 1 mm to 10 mm, from 5 mm to 15 mm, or even from 5 mm to 10 mm, or any and all subranges formed from any of these endpoints.

[0081] Processing

[0082] In embodiments, the multi-layer composite may be formed by molding, extrusion, and other known fabrication processes into forms that may be useful in the production of heat exchangers and heat sinks, including plates, rods, and pipes.

[0083] EXAMPLES

[0084] Referring now to FIG. 3, comparative example composite Cl and example composites E1-E3 are shown. Each composite was formed with dimensions of 25.4 mm x 50.8 mm x 50.8 mm. The composites in FIG. 3 include one or more of a steel layer 302, a continuous fiber reinforced polymeric composite 304, and a polymeric layer 306.

[0085] Example 1 - Continuous Fiber Reinforced Polymeric Composite: To form a continuous fiber reinforced polymeric composite, 150 g of Bisphenol F epoxy (thermoset polymer) and 43.2 g of isophorone diamine (IPDA) (epoxy curing agent) were mixed to form a homogenous solution.7.8 g of milled carbon fibers were sheared into the homogenous solution including the hollow ceramic spheres to form a thermally conductive liquid resin. 45 layers of carbon fiber twill woven fabric (continuous fiber) of dimensions 254 mm x 254 mm were prepared for a composite layup. The layers were placed on a polyethylene board one layer at a time and then rolled with 4 g to 5 g of the pre-mixed thermally conductive liquid resin. Once fully wet out and stacked, the layers were covered with a polyethylene sheet and consolidated and hardened under vacuum in an oven at 48.9 °C overnight. The polyethylene sheeting was removed and the composite sheet was postcured for 2.0 hr at 71.1 °C, 1.0 hr at 104.4 °C, 1.0 hr at 137.8 °C, and 2.5 hr at 148.9 °C (300 °F). The resulting continuous fiber reinforced polymeric composite was machined with a surface grinder into individual 50.8 mm x 50.8 mm pieces at 12.3 mm thick.

[0086] Example 2 - Thin Polymeric Layer: To form a thin polymeric layer, 50 g of Bisphenol F epoxy (thermoset polymer) and 14.4 g of isophorone diamine (IPDA) (epoxy curing agent) were mixed to form a homogenous solution. 96 g of hollow ceramic spheres (Zeeospheres N-800 from Zeeospheres Ceramics, LLC) were added and continuously mixed into the homogenous solution.3.9 g of milled carbon fibers were sheared into the homogenous solution including the hollow ceramic spheres to form a viscous thin polymeric layer.17SUBSTITUTE SHEET (RULE 26)

[0087] Example 3 - Thick Polymeric Layer '. To form a thick polymeric layer, 50 g of Bisphenol F epoxy (thermoset polymer) and 14.4 g of isophorone diamine (IPDA) (epoxy curing agent) were mixed to form a homogenous solution. 64.4 g of Zeeospheres N-800 from Zeeospheres Ceramics, LLC (thermally non-conductive hollow beads) were added and continuously mixed into the homogenous solution. 2.6 g of milled carbon fibers were sheared into the homogenous solution including the Zeeospheres N-800 to form a thick polymeric layer.

[0088] Referring now to Table 1, properties of the formed thick polymeric layer and common materials are shown. Note that the properties of the common materials were extracted from tables of standard engineering properties. Thermal inertia was calculated. As exemplified, although the thick polymeric layer did not express behaviors traditionally associated with high thermal conductivity, the thick polymeric layer had a relatively low thermal inertia as compared to the common materials. Although not measured, one skilled in the art would appreciate that the thin polymeric layer would similarly have a relatively low thermal inertia as compared to the common materials.

[0089] Table 1

[0090] Example 4 - Comparative Example Composite Cl. To form comparative example composite Cl, a 50.8 mm x 50.8 mm 316 stainless steel bar was cut and precision milled to 25.4 mm thick.

[0091] Example 5 - Example Composite EE To form exampl e composite E 1 , a 50.8 mm x 50.8 mm 316 stainless steel bar was cut and precision milled to 17.0 mm thick. A piece of continuous fiber reinforced polymer composite of Example 1 was precision milled to 8.5 mm thick and then affixed to the surface of the steel layer with the thin polymeric layer (about 0.5 mm) of Example 2. The completed system was cured for 1.5 hrs at 71.1 °C, 1.0 hr at 93.3 °C, 1.0 hr at 115.6 °C, 1.0 hr at 137.8 °C, and 1.5 hrs at 176.7 °C.

[0092] Example 6 -Example Composite E2 To form example composite E2, a 50.8 mm x 50.8 mm 316 stainless steel bar was cut and precision milled to 12.7 mm thick. A piece of continuous fiber reinforced polymer composition of Example 1 was precision milled to 12.7 mm thick and then affixed to the surface of the steel layer with the thin polymeric layer (about 0.5 mm) of Example 2 and cured with the same heat cycle as Example 5.

[0093] Example 7 -Example Composite E3: To form example composite E3, a 50.8 mm x 50.8 mm 316 stainless steel bar was cut and precision milled to 8.4 mm thick. The steel layer was placed in a polyethylene fixture, leaving one of the 50.8 mm x 50.8 mm surfaces exposed. The thick polymeric layer of Example 3 was cast into the polyethylene fixture onto the surface of the steel bar and allowed to cure overnight at 48.9 °C. The polyethylene fixture was removed and the system was post-cured for 1.0 hr at 71.1 °C, 1.0 hr at 104.4 °C, 1.0 hr at 137.8 °C, and 1.5 hr at 148.9 °C. The cured thick polymeric layer was then precision milled to a thickness of 8.6 mm, resulting in a bonded bi-layer system 17.0 mm. A piece of continuous fiber reinforced polymeric composite of Example 1 was precision milled to 8.5 mm thick and affixed to the surface of the thick polymeric layer with the thin polymeric layer of Example 2 and cured with the same heat cycle from Example 5.

[0094] Example 8 - Heating: Three 3.2 mm holes were drilled into the top surfaces TSci, TSEI, TSE2, TSE3 of each of comparative example composite Cl and example composites El, E2, and E3: a first hole 8.5 mm deep, a second hole at 12.7 mm deep, and a third hole 17.0 mm deep. A thermocouple wire probe was placed at the bottom of each of hole and each was sealed with epoxy to hold the probes in place. A thermocouple probe was also placed at the top surfaces TSci, TSEI, TSE2, TSE3 of each of comparative example composite Cl and example composites E1 -E3.

[0095] Referring now to FIGS. 4-6, the composites were each subjected to direct heating on the bottom surface opposite the top surfaces TSci, TSEI, TSE2, TSE3 by a hot plate set at 149 °C for 4 minutes.

[0096] FIG. 4 shows the readings of the thermocouple probes at 17.0 mm. As shown, the rates of heating (i.e., slope of curves) and the maximum temperatures reached at a depth of 17.0 mm was relatively consistent among the composites as all of the probes were either within or adjacent to the steel layer.

[0097] FIG. 5 shows the readings of the thermocouple probes at 8.5 mm. As shown, comparative example composite Cl and example composite El had similar rates of heating and maximum temperatures as the probes at this depth in both composites were either within or adjacent to the steel layer. Example composite E2 showed a decrease in rate of heating and maximum temperature reached as compared to comparative example composite Cl and example composite El as the probe at this depth was within the continuous fiber reinforced polymeric composite. Example composite E3 showed an even greater decrease in rate of heating and maximum temperature reached as compared to example composite E2 as the probe at this depth was either within or adjacent to the polymeric layer.

[0098] FIG. 6 shows the readings of the thermocouple probes at the top surfaces, which had similar trends as those shown in FIG. 5. In particular, example composites E1-E3 had decreased rates of heating and maximum temperatures as compared to comparative example composite Cl, due to the decreased mass of the steel layer. Example composite E3 had the lowest rate of heating and maximum temperature. The temperature of steel layer was not increased significantly (i.e., equal to or greater than the difference of temperature observed in other layers) in example composites E1-E3, which included a continuous fiber reinforced polymeric composite and a polymeric layer. Therefore, these layers were not thermally insulating the steel layer. Rather, as exemplified in FIGS. 4-6, a composite including continuous fiber reinforced polymeric composite and a polymeric layer having relatively low thermal inertia as described herein have a reduced overall heat capacity.

[0099] Example 9 - Heating and Cooling: Thermocouple probes were placed in comparative example composite Cl and example composites E1-E3 as described with respect to Example 8.

[0100] Referring now to FIGS. 7-9, the composites were each subjected to direct heating on the bottom surface opposite the top surfaces TSci, TSEI, TSE2, TSE3 by a hot plate set at 149 °C for 60 seconds, removed from the hot plate, and set on a room temperature (22.2 °C) steel surface.

[0101] FIG. 7 shows the readings of the thermocouple probes at 17.0 mm. FIG. 8 shows the readings of the thermocouple probes at 12.7 mm. FIG. 9 shows the readings of the thermocouple probes at 8.5 mm. Similar to the results shown in FIGS. 4-6, probes within or adjacent to the steel layer demonstrated similar behavior. Probes embedded in the continuous fiber reinforced polymeric composite or the polymeric layer demonstrated a reduction in heating rate as well as maximum temperature reached as compared to the probes within or adjacent to the steel layer. Once removed from the hot plate (i.e., after 60 seconds), comparative example composite Cl reached an equilibrium throughout the composite and proceeded to decrease at a uniform rate, regardless of probe depth. In each of example composites E1-E3, this trend was not observed as the various layers have differing heat capacities and, thus, did not reach the same maximum temperatures.

[0102] Example composite E3 exhibited the lowest maximum temperature and quickest decrease in temperature at each probe location. As exemplified in FIGS. 7-9, a composite including continuous fiber reinforced polymeric composite and a polymeric layer having a low thermal inertia as described herein has a reduced overall heat capacity and is capable of returning to ambient temperature at a desired cooling rate.

[0103] It will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

[0104] What is claimed is:

Claims

CLAIMS1. A multilayer composite comprising: a polymeric layer; and a continuous fiber reinforced polymeric composite adjacent to the polymeric layer; wherein the polymeric layer comprises a polymer matrix, thermally non-conductive hollow beads, and a thermally conductive material, the thermally non-conductive hollow beads and the thermally conductive material being dispersed in the polymer matrix.

2. The multilayer composite of claim 1, wherein the thermally non-conductive hollow beads comprise an average diameter from 5 microns to 1000 microns.3 The multilayer composite of any of the previous claims, where in the thermally non- conductive hollow beads comprise hollow glass beads, hollow ceramic beads, or a combination thereof.

4. The multilayer composite of any of the previous claims, wherein the thermally conductive material comprises an average length from 10 microns to 500 microns.

5. The multilayer composite of any of claims 1-3, wherein the thermally conductive material comprises an average geometrical dimension from 1 nm to 800 nm.

6. The multilayer composite of any of the previous claims, wherein the thermally conductive material comprises carbon fiber, carbon nanomaterial, silver, copper, aluminum, or a combination thereof.

7. The multilayer composite of claim 6, wherein the thermally conductive material comprises milled carbon fiber.

8. The multilayer composite of claim 6 or claim 7, wherein the thermally conductive material comprises graphene.

9. The multilayer composite of any of the previous claims, wherein the polymer matrix comprises thermoplastic polymer, thermoset polymer, or a combination thereof.

10. The multilayer composite of claim 9, wherein the polymer matrix comprises the thermoplastic polymer, the thermoplastic polymer comprising polyamides, polyphenylene sulfides, polyetherimides, polysulfones, polyethersulfones, polyetherketones, polyetheretherketones, or a combination thereof.

11. The multilayer composite of claim 9 or claim 10, wherein the polymer matrix comprises the thermoset polymer, the thermoset polymer comprising Bisphenol A epoxy, Bisphenol F epoxy, novolac epoxy, phenolic resin, bismaleimide, benzoxazine, cyanate resin, silicone resin, or a combination thereof.

12. The multilayer composite of any of the previous claims, wherein the polymer matrix further comprises one or more additives comprising curing agents of polyamine, anhydride, and polyphenolic.

13. The multilayer composite of any of the previous claims, wherein the continuous fiber reinforced polymeric composite comprises a plurality of continuous fibers.

14. The multilayer composite of claim 13, wherein the plurality of continuous fibers are substantially parallel.

15. The multilayer composite of claim 13 or claim 14, wherein the plurality of continuous fibers form a tow, yarn, end, pic, roving, woven fabric, knitted fabric, braided fabric, or non-woven fabric.

16. The multilayer composite of any of claims 13-15, wherein the plurality of continuous fibers comprises carbon fibers, glass fibers, aramid fibers, basalt fibers, metallic fibers, or a combination thereof.

17. The multilayer composite of claim 16, wherein the plurality of continuous fibers comprises the metallic fibers, the metallic fibers comprising boron, beryllium, aluminum, copper, tungsten, titanium, nickel, stainless steel, and alloys thereof.

18. The multilayer composite of any of the previous claims, wherein the plurality of continuous fibers comprises an average diameter from 1 micron to 100 microns, from 5 microns to 50 microns, or from 7 microns to 35 microns.

19. The multilayer-composite of any of the previous claims, wherein the polymeric layer comprises a thickness from 0.1 mm to 15 mm.

20. The multilayer composite of any of the previous claims, wherein the polymeric layer comprises a thick polymeric layer, the thick polymeric layer having a thickness from greater than 1 mm to 15 mm.

21. The multilayer composite of any of the previous claims, wherein the polymeric layer comprises a thin polymeric layer, the thin polymeric layer having a thickness from 0.1 mm to 1 mm.

22. The multilayer composite of any of the previous claims, wherein the multilayer composite further comprises a substrate layer adjacent to the polymeric layer opposite the continuous fiber reinforced polymeric composite.

23. The multilayer composite of claim 22, wherein the substrate layer comprises steel, aluminum, copper, brass, bronze, titanium, nickel, glass, ceramic, or a combination thereof.

24. The multilayer composite of claim 22 or claim 23, wherein the substrate layer comprises a thickness from 1 mm to 15 mm.

25. The multilayer composite of any of the previous claims, wherein the polymeric layer comprises a thermal inertia from 420 J / m2K s1 / 2to 1200 J / m2K s1 2.

26. The multilayer composite of any of the previous claims, wherein the polymeric layer comprises a heat capacity from 0.62 J / gK to 1.75 J / gK.

27. The multilayer composite of any of the previous claims, wherein the polymeric layer comprises a density from 1.00 g / cm3to 1.80 g / cm3.

28. The multilayer composite of any of the previous claims, wherein the polymeric layer comprises a volumetric heat capacity from 0.62 J / gK g / cm3to 1.95 J / gK g / cm3.

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