The present disclosure relates to polymer composites and particularly relates to a reinforced thermally conductive polymer composite and a method of manufacturing such polymer composite.

BACKGROUND

Heat sinks are widely used in electrical and electronic equipment to dissipate heat generated during the operation of such equipment. Heat sinks may play a vital role in the development of electric vehicles as heat sinks are needed to dissipate heat from electric motors and a battery management system of an electric vehicle. Further, owing to their installation in the electric vehicle the heat sinks are needed to be lightweight, thermally conductive, but not necessarily electrically insulative. Materials, such as Aluminum nitride and boron nitride are used to manufacture heat sinks. However, considering the high cost of these materials, the overall cost of the product is significantly high.

One of the ways to mitigate this issue is to use Aluminum-based materials and Copper-based materials that are generally used to manufacture heat sinks for a variety of applications because such materials may have high thermal conductivity and are therefore the suitable candidate materials for active heat dissipation applications. For instance, Aluminum-based materials and Copper-based materials are widely used to form cooling components of computing devices. However, owing to their large density, the use of such material is limited for heat dissipation for large-sized components, such as the components used in an electric vehicle. For instance, the part weight of large-sized components becomes high due to a higher density of 8.8 and 2.7 g/cc of Copper and Aluminum, respectively. As a result, the weight of the heat sinks for such large-sized components increases the overall weight of the electric vehicle resulting in the reduction in the performance and range of the electric vehicle. Moreover, the fabrication of such heat sinks may not be easy.

SUMMARY

This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.

The present disclosure relates to the aspects of a thermally conductive polymer and manufacturing thereof. The thermally conductive polymer includes heat-dissipating components dispersed in a synthetic polymer.

In an embodiment of the present disclosure, a thermally conductive polymer composite is disclosed. The thermally conductive polymer may include a plurality of Aluminum flakes, Graphite microparticles, and Graphene nanoparticles and a synthetic polymer formed by an extrusion process.

In another embodiment of the present disclosure, a method of forming the thermally conductive polymer is disclosed. The method may include a step of mixing Graphite microparticles, and Graphene nanoparticle and Aluminum flakes with synthetic polymer using an extrusion process to form the thermally conductive polymer composite.

According to the present subject matter, the thermally conductive polymer composite is lightweight resulting in lesser overall weight of the heat sink making them suitable for use in the electric vehicle. In one example, the use of the thermally conductive polymer composite may enable a weight saving of about 30 to 35% in comparison to convention aluminium materials and about 80% weight saving in comparison to copper-based heat sink or enclosures. Moreover, the thermally conductive polymer composite has high thermal stability that allows for application in components, such as an electric motor that generates a lot of heat during its operation.

To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

Figure 1 illustrates a schematic view of three-dimensional of a block of thermally conductive polymer composite, according to an embodiment of the present disclosure; and
Figure 2 illustrates a method of forming a thermally conductive polymer composite, according to an embodiment of the present disclosure.

Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION OF FIGURES

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.

Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a nonexclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or subsystems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

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 to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

It should be understood at the outset that although illustrative implementations of the embodiments of the present disclosure are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary design and implementation illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

The term “some” as used herein is defined as “none, or one, or more than one, or all.” Accordingly, the terms “none,” “one,” “more than one,” “more than one, but not all” or “all” would all fall under the definition of “some.” The term “some embodiments” may refer to no embodiments or to one embodiment or to several embodiments or to all embodiments. Accordingly, the term “some embodiments” is defined as meaning “no embodiment, or one embodiment, or more than one embodiment, or all embodiments.”

The terminology and structure employed herein is for describing, teaching and illuminating some embodiments and their specific features and elements and does not limit, restrict or reduce the spirit and scope of the claims or their equivalents.

Reference is made herein to some “embodiments.” It should be understood that an embodiment is an example of a possible implementation of any features and/or elements presented in the attached claims. Some embodiments have been described for the purpose of illuminating one or more of the potential ways in which the specific features and/or elements of the attached claims fulfil the requirements of uniqueness, utility and non-obviousness.

Use of the phrases and/or terms such as but not limited to “a first embodiment,” “a further embodiment,” “an alternate embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”, “furthermore embodiment”, “additional embodiment” or variants thereof do NOT necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and/or elements may be described herein in the context of only a single embodiment, or alternatively in the context of more than one embodiment, or further alternatively in the context of all embodiments, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Figure 1 illustrates an enhanced view of the three-dimensional structure of a block 100 of a thermal polymer composite, according to an embodiment of the present disclosure. The thermal polymer composite may be used to make a heat dissipative unit, commonly known as a heat sink. For instance, the thermal polymer composite may be employed as a heat sink for an electric motor, battery packs, and a power management system in an electric vehicle. The thermal polymer composite may be configured to dissipate heat while being electrically insulating to prevent short-circuiting of the electrical components to which the heat sink is attached. The thermal polymer composite is made of different components that has requisite thermal conductivity and electrical insulation that enables the thermal polymer composite to be used as a heat sink.

In operation, the heat sink can be attached to a surface of the component whose heat is to be dissipated. For instance, the thermal polymer composite may be attached to an outer surface of an electric motor by fasteners. Alternatively, the thermal polymer composite may be glued to the outer surface of the electric motor. In either case, the thermal polymer composite is spread on the surfaces that may generate heat.

The thermal polymer composite may be made of two major components, namely, a synthetic polymer and a mixture of fillers. The synthetic polymer may act as a carrier for the mixture of fillers. Further, the synthetic polymer is configured to bind the mixture of fillers so that the mixture of fillers may efficiently absorb the heat from the component and dissipate the heat to the environment. On the other hand, the mixture of fillers is configured to absorb the heat received by the thermal polymer composite and dissipate the heat to the environment. The mixture of fillers is composed of fillers that enables the mixture of fillers to efficiently remove heat from the surface to which the thermal polymer composite is attached.

For instance, the mixture of fillers may be composed of synthetic polymer 102 that may form a major component of the mixture of fillers. The synthetic polymer 102 is configured to performed two tasks. First, the synthetic polymer 102 binds the fillers of the mixture of fillers together and second, the synthetic polymer 102 allows bonding of the mixture of fillers with the synthetic polymer of the thermal polymer composite.

As may be understood, the synthetic polymer may be used to make both the mixture of fillers and the thermal polymer composite. In one example, the synthetic polymer 102 can be Nylon 6,6 commonly known as Nylon 66. Nylon 66 is used as a synthetic polymer because Nylon 66 has high thermal stability. In other words, Nylon 66 enables the mixture of fillers to sustain a high amount of heat transfer without causing the mixture of fillers or the thermal polymer composite to disintegrate. As a result, the use of such material enables a long operational life of the thermal polymer composite. The synthetic polymer 102 is electrically insulating that may prevent inadvertent short-circuiting of the electrical components.

In an embodiment, the mixture of fillers may include Aluminum in the form of a plurality of Aluminum flakes 104. Aluminum flakes 104, in one example, can be micro-sized powder. The Aluminum flakes 104 forms a second major component of the mixture of fillers. The Aluminum flakes 104 enables the thermally conductive polymer composite to absorb the heat from the electrical component. The Aluminum flakes 104 may have a thermal conductivity in the range of 150 Watts per meter-Kelvin (W/mK). Such a high thermal conductivity of the Aluminum flakes 104 enables a large amount of removal of heat from the electrical components. The Aluminum flakes 104 may have different types of structure within the mixture of fillers. For instance, the Aluminum flakes 104 may have a globular shape as shown in Figure 1 and the Aluminum flakes 104 are spread homogeneously inside the synthetic polymer 102.

The mixture of fillers may include other fillers that may further enhance the thermal conductivity of the mixture of fillers. In one example, the mixture of fillers may include Graphite microparticles 106 dispersed homogeneously inside the block 100 as shown in Figure 1. The Graphite microparticles 106 may be configured to enhance the thermal conductivity of the block 100 along with the Aluminum flakes 102. Graphite being an inexpensive material can be easily processed to produce Graphite microparticles 106.

In one example, Graphite microparticle 106 may be treated thermally and/or chemically to increase the surface area of Graphite microparticles 106. An increase in the surface area of Graphite microparticles 106 results in an increase of the overall surface area of thermally conductive polymer composite to absorb the heat. Therefore, chemically treated Graphite microparticles 106 enables larger absorption of heat. Moreover, Graphite microparticles 106 have higher thermal stability that elevates the thermal absorbing capacity of the thermally conductive polymer composite.

The mixture of fillers may also include fillers that may reinforce the thermally conductive polymer composite while at the same time increases the thermal conductivity. For instance, the mixture of fillers may include Graphene in form of Graphene nanoparticles 108. The structure of the Graphene nanoparticles 108 may elevate the thermal conductivity and strength of the thermally conductive polymer composite. In one example, the Graphene nanoparticles 108 may have a thermal conductivity in the range of about 3000 – 4000 W/mK. Further, a thickness of graphene nanoparticles 108 is between 2-30 Nanometers.

As a result, the Graphene nanoparticles 108 increases the thermal conductivity of the thermally conductive polymer composite. Moreover, the Graphene nanoparticles 108 may have a higher surface area than the Aluminum flakes 104. As a result, the addition of the Graphene nanoparticles 108 further increases the overall surface area of the thermally conductive polymer composite thereby increasing the heat absorbing capability of the thermal polymer composite. Graphene nanoparticles 108 may be formed using a variety of technique, such as chemical vapour deposition, among other examples.

In one example, the aforementioned fillers 104, 106, and 108 are arranged in a predefined way to provide requisite properties of the block 100, consequently to the thermal polymer composite. For instance, the block 100 may be formed in form of a stack of layers, such that each layer includes Aluminum flakes 104, Graphite microparticles 106, and Graphene nanoparticles 108. In one example, the Graphene nanoparticles 108 may be placed in between the Aluminum flakes 104 and the Graphite microparticles 106 such that the Graphene nanoparticles 108 reinforce the Aluminum flakes 104 and the Graphite microparticles 106. Moreover, the Aluminum flakes 104 are configured to be the main sink for heat transfer, Graphite microparticles 106 as the thermal conductivity network making filler for the Aluminum flakes, and Graphene nanoparticles 108 to further elevate the thermal conductivity.

Further, Aluminum flakes 104 are of significantly wider particle size distribution whereas graphene nanoparticles 108 are a stack of multiple layers, which are delaminated by high shear force applied during the manufacturing of the thermally conductive polymer composite. Delamination results in the homogenous spread of Graphene nanoparticles 108 which reinforces the block 100, consequently the thermal polymer composite.

Furthermore, the thermal conductivity of Graphene nanoparticles 108 can be improved by the expanded graphite microparticles 106. Therefore, Aluminum in the form of flakes 104, graphite microparticles 106, and the Graphene nanoparticles 108 are compounded together through a variety of operation to form the thermally conductive polymer composite. Further, the thermal polymer composite may be manufactured by a variety of method. Exemplary methods of forming the thermal polymer composite are explained with respect to Figure 2 and 3.

Figure 2 illustrates a method 200 of manufacturing the thermal polymer composite. The order in which the method steps are described below is not intended to be construed as a limitation, and any number of the described method steps can be combined in any appropriate order to execute the method or an alternative method. Additionally, individual steps may be deleted from the method without departing from the spirit and scope of the subject matter described herein.

The method 200 can be performed by programmed computing devices, for example, based on instructions retrieved from non-transitory computer-readable media. The computer-readable media can include machine-executable or computer-executable instructions to perform all or portions of the described method. The computer-readable media may be, for example, digital memories, magnetic storage media, such as magnetic disks and magnetic tapes, hard drives, or optically readable data storage media.

The method 200 may begin at step 202 at which the synthetic polymer 102 is combined with Graphite microparticles 106, Graphene nanoparticles 108, and a plurality of Aluminum flakes 104 to form the thermally conductive polymer composite. In one example, the thermally conductive polymer composite can be combined by an extrusion process. The extrusion process may be performed using a screw-type extruder. In the extrusion process, the synthetic polymer 102 is fed by a first feeder far from, but towards a die (at a higher L/D ratio). In one example, the synthetic polymer 102 may be added 60-80% by weight. Further, the synthetic polymer 102 may be fed in the molten state.

At step 204, Graphite microparticles 106, the Graphene nanoparticles 108, and the plurality of Aluminum flakes 104 are mixed together manually in powdery form and fed into a die (not shown) by a second feeder that may be placed near to the die (at lower L/D ratio). The Graphite microparticles 106, the Graphene nanoparticles 108, and the plurality of Aluminum flakes 104 are weighted separately to determine a predetermined composition of the thermally conductive polymer composite. In one example, the Graphite microparticles 106 is mixed 5-10% by weight, Graphene nanoparticles 108 is mixed up to 1% by weight and the plurality of Aluminum flakes 104 is mixed 20-30% by weight.

Finally, at step 206, the powdery mixture of fillers of the Graphite microparticles 106, the Graphene nanoparticles 108, and the plurality of Aluminum flakes 104 are added to the molten synthetic polymer 102 by the screw-type extruder. The mixture is added to the molten synthetic polymer 102 to achieve better mixing and dispersion, especially with significantly high filler loading. Once mixed, the resultant mixture may be heated to a determined temperature and extruded to form the thermally conductive polymer composite. In one example, the temperature of extrusion may be in range of 240 to 265 °Celsius. In addition, the screw speed and torque in the extrusion process may be kept at 500 revolutions per minute (rpm) and 56 Newton-Meter (Nm) respectively. The extruded thermally conductive polymer composite may then be cut into predefined shape and size, such as granules, pellets, among other examples and stored for further use.

Once the thermally conductive polymer composite is formed, the thermally conductive polymer composite may undergo casting process, such as injection moulding/compression moulding process to form the heat sink. Heat sink prepared through injection moulding/compression moulding may have better surface finish than conventionally manufactured metal heat sink through casting or machining. Further, post processing needed in conventional manufacturing of metal-based heat sinks/enclosure such as machining, cleaning, surface treatment etc can be eliminated if the polymer composite based heat sinks are manufactured through, injection/compression moulding processes.

As would be gathered, the thermal polymer composite of the present disclosure has less weight owing to the use of Graphite and Graphene. Further, the thermal polymer composite uses inexpensive materials, such as Graphite thereby reducing the overall cost of the heat sink. Moreover, the thermal polymer composite can have customized by varying the composition of the thermally conductive polymer composite.

While specific language has been used to describe the present disclosure, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment.

WE CLAIM

A thermally conductive polymer composite comprising:
a synthetic polymer (102);
Graphite microparticles (106);
Graphene nanoparticles (108); and
a plurality of Aluminum flakes (104), wherein the synthetic polymer (102), the Graphite microparticles (106), and Graphene nanoparticles (108) are combined by an extrusion process form the thermally conductive polymer composite.

2. The thermally conductive polymer composite as claimed in claim 1, wherein the synthetic polymer (102) is mixed 60-80% by weight, the Graphite microparticles (106) is mixed 5-10% by weight, Graphene nanoparticles (108) is mixed up to 1% by weight and the plurality of Aluminum flakes (104) is mixed 20-30% by weight.

3. The thermally conductive polymer composite as claimed in claim 1, wherein a temperature of the extrusion process is in a range of 240 to 265 °C.

4. The thermally conductive polymer composite as claimed in claim 1, wherein the extrusion process is a screw extrusion process and a screw speed and torque in the extrusion process is kept at 500 revolutions per minute (rpm) and 56 Newton-Meter (Nm) respectively.

5. The thermally conductive polymer composite as claimed in claim 1, wherein the synthetic polymer (102) is Nylon 66.

6. The thermally conductive polymer composite as claimed in claim 1, wherein thermal conductivity of Graphene nanoparticles (108) is in range of 3000 to 4000 Watts per meter-Kelvin (W/mK), thermal conductivity of graphite micro particles is in the range of 10 to 70 (W/mK) and thermal conductivity of Aluminum flakes (104) is about 100-150 (W/mK).

7. The thermally conductive polymer composite as claimed in claim 1, wherein the Aluminium particles are spherical or oblong shape and having size between 10-150 micron.

8. The thermally conductive polymer composite as claimed in claim 1, wherein a thickness of graphene nanoparticles is between 2-30 Nanometers.

9. The thermally conductive polymer composite as claimed in claim 1, wherein graphene nanoparticles may be used in the form of multilayers of 5-20 layers.

10. A method of making a thermally conductive polymer composite comprising:
feeding a synthetic polymer (102) through a first feeder into a die;
mixing a mixture of Graphite microparticles (106), Graphene nanoparticles (108) and Aluminium flakes (104) and feeding the mixture through a second feeder into the die; and
extruding the mixture and the synthetic polymer (102) through the die to form the thermally conductive polymer composite.

11. The method as claimed in claim 1, wherein the synthetic polymer (102) is mixed 60-80% by weight, the Graphite microparticles (106) is mixed 5-10% by weight, Graphene nanoparticles (108) is mixed up to 1% by weight and the plurality of Aluminum flakes (104) is mixed 20-30% by weight.

12. The method as claimed in claim 9, wherein the synthetic polymer (102) is Nylon 66.

13. The method as claimed in claim 9, wherein the temperature of the extrusion process may be in a range of 240 to 265 °C.

14. The method as claimed in claim 9, wherein the extrusion process is a screw extrusion process and a screw speed and torque in the extrusion process is kept at 500 revolutions per minute (rpm) and 56 Newton-Meter (Nm) respectively.

15. The method as claimed in claim 9, wherein thermal conductivity of Graphene nanoparticles (108) is in range of 3000 to 4000 Watts per meter-Kelvin (W/mK), thermal conductivity of graphite micro particles is in the range of 10 to 70 (W/mK) and thermal conductivity of Aluminum flakes (104) is about 150 (W/mK).

16. The method as claimed in claim 9, wherein the Aluminium particles are spherical or oblong shape and having size between 10-150 micron.

17. The method as claimed in claim 9, wherein a thickness of graphene nanoparticles is between 2-30 Nanometers.

18. A thermally conductive polymer composite as claimed in any of the proceeding claims, wherein the thermally conductive polymer composite may be used for making light weight heat sinks.

19. A thermally conductive polymer composite as claimed in any of the proceeding claims, wherein the thermally conductive polymer composite may be used for making light weight electronics enclosure.