Composite product and manufacture thereof

Abstract

An elongate composite product (10) comprises a polymer material, such as a recycled polymer material, in an 5 elongate cavity (15) between an elongate outer wall (12) and an elongate inner wall (14). The inner wall is manufactured to be deformable outwardly and / or the outer wall is manufactured to be deformable inwardly, in response to contraction of the polymer material in the 10 cavity that occurs when the product is being manufactured and molten polymer material in the cavity cools to an ambient temperature. The deformation reduces the volume of the cavity and minimises voids that would otherwise be in the polymer material in the finished product. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 2020 2020244530 01 Oct 5 10 20 20 24 45 30 0 1 O ct 2 02 0 2 / 3 2020244530 01 20 Figure 3 22 24 10 Figure 4

Description

COMPOSITE PRODUCT AND MANUFACTURE THEREOF FIELD OF THE INVENTION The present invention relates to elongate composite products, such as utility poles for street lighting and traffic management bollards, and to a process for manufacturing the elongate composite product. The present invention relates particularly, although by no means exclusively to the use of recycled polymer material in the composite product. The present invention relates particularly, although by no means exclusively, to a process for manufacturing the composite product using recycled polymer material that would otherwise typically be used as landfill. BACKGROUND OF THE INVENTION The following description of the background of the invention discusses waste polymers. The following description of the background of the invention also discusses manufacturing elongate composite products, such as utility poles for street lighting and traffic management bollards, using polymer material as one of the materials in the composite product. Currently, there is an excess of post-industrial and post- consumer waste polymers. As a consequence, recycled polymer material is a readily available resource for use, for example, in the manufacture of new consumer products, such as new beverage bottles. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 Also, recycled polymer material is useful in the construction industry, which term is understood herein to include industries that produce and use elongate composite products, such as utility poles for street lighting and traffic management bollards. Recycled polymer material can provide required construction strength and is also cost efficient. However, the finished construction industry products made from recycled polymer material are not necessarily aesthetically pleasing, particularly when the products are presenting a finished surface. The optical properties of recycled polymer material and the generally variable composition and mechanical properties of recycled polymer material have typically dictated that construction industry products made from recycled polymer material are more suitable for products requiring compression strength. In addition, there are problems with processing and using polymer material generally and recycled polymer material more specifically in the manufacture of construction industry products such as elongate composite products. These problems include, by way of example, accommodating shrinkage of polymer material as molten polymer material used in the manufacture of elongate composite products cools to ambient temperature. There is therefore a need to be able to re-use waste polymers as recycled polymer material for manufacturing products for the construction industry while also providing aesthetic finished products. In the context of the invention, this need extends particularly to the manufacture of elongate composite products which include recycled polymer material as a component of the products. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 One, although not the only, aim of the present invention is to produce a cost efficient and effective elongate composite product utilising recycled polymer material that is suitable for the construction industry. SUMMARY OF THE INVENTION The present invention is based on a realisation that a particular structure for elongate composite products, such as utility poles for street lighting and traffic management bollards, makes it possible to include polymer material, including but not limited to, recycled polymer material, as a component of the products. The present invention is based on a realisation that it is possible to use waste polymers, in particular but not limited to mixed waste polymer materials, as recycled polymer material in the manufacture of elongate composite products. The term “mixed waste polymer materials” is understood herein to mean a mixture of different waste polymer materials at the end of a recycling separation process that have not previously been separated into single source polymer material categories. Typically, mixed waste polymer materials have very low, if any economic value and are used as land fill. The mixed waste polymer materials may include any two or more of PET, HDPE, LDPE and other polymer materials in consumer and other industry-derived products that are processed in recycling facilities. The invention provides an elongate composite product comprising a polymer material, such as a recycled polymer material, in an elongate cavity between an elongate outer wall and an elongate inner wall, with the inner wall being manufactured to deform outwardly and / or the outer wall 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 being manufactured to deform inwardly, in response to contraction of the polymer material in the cavity that occurs when the product is being manufactured and molten polymer material in the cavity cools to an ambient temperature, to thereby reduce the volume of the cavity and minimise voids that would otherwise be in the polymer material in the finished product. The term “minimise voids that would otherwise be in the cavity in the finished product” is understood herein to mean that the volume of voids in the finished product is at least 70%, typically at least 80%, more typically at least 90% smaller than the void volume that would otherwise have formed due to contraction of the polymer material on cooling without deformation of the inner wall being deformable outwardly and / or the outer wall. Typically, the inner wall is manufactured to be deformable outwardly and the outer wall is manufactured to remain in its original profile in response to contraction of the polymer material in the cavity that occurs as molten polymer material in the cavity cools to the ambient temperature. With this arrangement, the inner wall and not both the inner wall and the outer wall takes up the reduction in the volume in the cavity in the cooling process. As a consequence, the profile and finish of the outer wall may be selected to optimise aesthetic appeal of the elongate composite product. With the arrangement described in the preceding paragraph, the materials and / or the structure of the inner wall and the outer wall are selected so that the inner wall deforms outwardly before the outer wall deforms inwardly in response to contraction of the polymer material in the cavity when the product is being manufactured and molten polymeric material in the cavity cools to the ambient temperature. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 The outer wall and the inner wall may be made from the same materials, with different wall thicknesses, such that the inner wall deforms preferentially. The outer wall and the inner wall may be made from different materials, with the same or different wall thicknesses, with the material of the inner wall being more deformable than the material of the outer material. The profiles of the as-manufactured outer wall and the as- manufactured inner wall, i.e. the profiles before the polymer material is injected into the cavity, may be selected so that the inner wall is more deformable than the outer wall. One relevant factor to the selection of the materials and structure of the inner wall is that the inner wall be able to accommodate deformation to the extent required without there being damage to the structural integrity of the inner wall. The profile of the as-manufactured inner wall may be selected to allow controlled deformation of the inner wall, i.e. deformation without damage to the structural integrity of the inner wall. For example, the as-manufactured inner wall may have a profile that, when viewed in a transverse section, includes convex sections separated by concave sections. This profile may be described as a flower-shaped profile. Generally, a suitable profile is one that has undulations as viewed in a transverse section. It is noted that the invention is not confined to the above arrangement in which the inner wall is manufactured to deform preferentially compared to the outer wall. The 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 invention also extends to the reverse arrangement. The invention also extends to an arrangement in which the inner wall and the outer wall are manufactured to deform. The outer wall may be made from aluminium or any other suitable material. The outer wall may be made form a polymer material. Typically, the outer wall is cylindrical. However, the invention is not confined to cylindrical outer walls. Typically, the outer wall is an extruded wall. However, the invention is not confined to extruded outer walls. The outer wall may include formations, such as ribs, that extend inwardly into the cavity. The formations may be provided to function as reinforcement of the product. The formations may be provided to limit the extent of the outward deformation of the inner wall in response to contraction of the polymer material in the cavity that occurs when the product is being manufactured and molten polymer material in the cavity cools to the ambient temperature. The inner wall may be made from aluminium or any other suitable material. The inner wall may be made form a polymer material. The inner wall may be any suitable profile. Typically, the inner wall is an extruded wall. However, the invention is not confined to extruded inner walls. The present invention also provides an assembly of an elongate outer wall, an elongate inner wall, and a cavity between the wall for use in manufacturing an elongate composite product, with the inner wall being manufactured 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 to deform outwardly and / or the outer wall being manufactured to deform inwardly when molten polymer material is injected into the cavity and fills the cavity and the polymer material contracts in the cavity as the polymer material cools to an ambient temperature to form the elongate composite product, thereby reducing the volume of the cavity and minimising voids that would otherwise be in the polymer material in the elongate composite product at the ambient temperature. The invention also provides a method of manufacturing an elongate composite product that includes: (a) positioning the as-manufactured elongate inner wall described herein within the as-manufactured elongate outer wall described herein and forming a cavity between the walls; (b) injecting a molten polymer material, such as a recycled polymer material, into the cavity and filling the cavity; and (e¢) allowing the molten polymer material to cool to an ambient temperature, with the inner wall and / or the outer wall deforming in response to contraction of polymer material in the cavity that occurs as the molten polymer material cools to the ambient temperature thereby to reduce the volume of the cavity and minimise voids that would otherwise be in the polymer material in the finished product. Step (b) may include drawing at least a partial vacuum from one end of the cavity and injecting molten polymer material into the cavity from the other end. Step (b) may include inserting a nozzle through the cavity from one end of the cavity up to a position proximate the other end of the cavity and progressively withdrawing the nozzle away from the other end while injecting molten polymer material into the cavity. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 The applicant has recognised that mixed waste polymer materials as described herein have different melting points which, in terms of melting and reforming, are not viable using existing industrial equipment. In order to make it possible to use such mixed waste polymer materials, the method may include melting mixed waste polymer materials at a temperature that is selected to at least partially melt a lower or lowest melting point polymer of the mix and leave other polymers in the mix in a solid form and forming an injectable slurry of the mixed waste polymer materials, whereby at least one molten polymer material acts as a binder for the other polymer materials in the mix when the mixture solidifies. Typically, the melting temperature of the mixed waste polymer materials is in a range of 160-260°C, typically 180-250°C. The invention also provides a utility pole for street lighting that includes a post that includes the above- described elongate composite product. The invention also provides a traffic management bollard that includes a post that includes the above-described elongate composite product. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of non-limiting examples, in which: Figure 1 is a transverse cross-sectional view of an embodiment of an assembly of an outer wall and an inner wall separated by a cavity according to the invention that is used in the manufacture the embodiment of the elongate 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 composite product according to the invention shown in Figure 2; Figure 2 is a transverse cross-sectional view of an embodiment of an elongate composite product according to the invention; Figure 3 is a perspective end view of the embodiment of the elongate composite product of Figure 2; Figure 4 is a side view of an upper section of an embodiment of a pole for street lighting in accordance with an embodiment of the invention, with the light pole including a post made from the elongate composite product of Figures 2 and 3; and Figure 5 is a diagrammatic side view of the light pole of Figure 4 illustrating the placement of a junction box of the light pole. DESCRIPTION OF EMBODIMENTS Whilst the following description refers to an elongate composite product in the form of an elongate composite pole for street lighting, it is to be understood that the invention is not confined to this product and extends to other elongate products such as bollards, fence posts, and beams. A known product in the construction industry is a laminate product that includes a pair of spaced-apart flat panels, such as panels made from aluminium, and a layer of a polymer material sandwiched between the panels. The polymer material provides strength and stiffness to the laminate product. In some known forms, the flat panels have a thickness of up to 3.0 mm and skin layers of aluminium as low as 0.21 mm thickness. In some known 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 forms, in percentage terms, the polymer material accounts for 10-18% of the material in the laminate product. The manufacturing process for the laminate product is relatively straightforward. This description of known products is not to be taken as an admission of the common general knowledge in Australia or elsewhere. However, there are problems when constructing an elongate composite product in the form of a pole for street lighting or other applications that includes outer and inner walls and a polymer material in a cavity between the wall as opposed to the above described flat panel laminate product because there are additional structural and manufacturing requirements that need to be taken into consideration. For example, when considering a pole having an outer wall and an inner wall that define a cavity therebetween, with the walls made as cylindrical aluminium extrusions (or extrusions of other suitable materials), of say 7-10 m in length, there are limitations on the minimum wall thicknesses that can be used successfully for the outer wall and the inner wall and this adds cost and materials handling issues. There is also a need to ensure that the cavity between the outer wall and the inner wall is completely filled with the polymer material and that there are at least substantially no voids in the pole, which in practical terms means that the cavity is at least 80%, typically at least 95% filled with polymer material in the finished pole. There are technical barriers to achieving complete cavity filling of such poles, primarily due to polymer material shrinkage upon cooling in situations where the polymer material in injected in a molten form into the cavity. It is estimated that typical polymer materials will shrink in volume by up to 20% when cooling from such a melt. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 One option to minimise voids is to inject the molten polymer material at a high pressure and maintain the high pressure during cooling. However, the use of high pressure injection, at for example in excess of 50 MPa as would be required, with thin skinned aluminium extrusions is not feasible. In addition, the required lengths of the aluminium extrusions for light poles and poles for other applications dictates that the cooling time and directional cooling profile (cooling from the farthest point to promote solidification of the poles back to the injection port to ensure complete filling of the cavity) would be technically prohibitive and time consuming. In addition, cooling is preferably completed while the pole is connected to an injection head for molten polymer material so that additional polymer material may be injected as the polymer material shrinks to ensure the cavity is filled completely. This is an issue because the cycle time of the process becomes quite high - approximately 15 minutes, even though the injection time typically is only 1 minute. The embodiments of the elongate composite pole, the precursor assembly of the pole, and the method of manufacturing the pole according to the invention that are described below are effective alternatives to the known elongate composite pole and the known manufacturing process described above. Figures 2 and 3 show an embodiment of an elongate composite pole 10 according to the invention. Figure 1 shows an embodiment of an assembly of two hollow elongate outer and inner walls 12, 14 separated by a 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 cavity 15 according to the invention that is used in the manufacture of the pole shown in Figures 2 and 3. In the embodiment of the method of manufacturing the pole 10 in Figures 2 and 3 described below, the elongate outer and inner walls 12, 14 of the assembly of Figure 1 form respective concentric cylindrical outer and inner walls 12, 14 of the pole 10 of Figures 2 and 3, with the cylindrical profile of the inner wall 14 being the result of controlled deformation of the inner wall 14 in Figure 1, described further below. The thickness of the outer wall 12 preferably is in a range of 1-3 mm. The thickness of the inner wall 14 is preferably in a range 0.5-1 mm. The diameter of the outer wall 12 may be between 75-350 mm, but outer diameters up to 600-700 mm or more are contemplated depending on the use of the pole 10. The cavity 15 between the walls 12, 14 is filled with a polymer material, such as recycled polymer waste 20, as will be described in further detail below. The outer wall 12 includes a plurality of lengthwise- extending corrugations or grooves in an external surface that increase rigidity of the outer wall 12. The corrugations assist in preventing the outer wall 12 from being deformed in response to contraction as the molten polymer material cools to an ambient temperature in the method of manufacturing the pole 10. In addition, the corrugated external surface provides a textured appearance of the assembly 10 that is an aesthetically pleasing appearance. The outer wall 12 includes a plurality of inwardly extending strengthening ribs 16. These ribs also serve the purpose of holding the walls 12, 14 in position relative to each other during the polymer material filling process 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 that is part of the method of manufacturing the pole 10, described below. The outer wall 12 also includes a plurality of anchor lugs 18 which assist in holding together the outer wall 12 and the polymer material as molten polymer material cools in the manufacturing method, and thereby assisting in preventing unwanted buckling. It will be noted that the inner wall 14 in Figure 1 is not cylindrical, although it is noted that it may be cylindrical in other embodiments. Instead, the inner wall 14 in Figure 1 is in the form of a series of convex and concave sections that form an undulating profile, which may be described as “flower-like”, when viewed in the transverse section of Figure 1. The inner wall 14 in Figure 1 is a deformable wall. In use, in the manufacturing method, when the assembly 10 of Figure 1 is filled with a polymer material, such as a mixed waste polymer material, and allowed to cool, the inner wall 14 in Figure 1 deforms outwardly due to contraction of molten polymer material as the molten polymer material cools and forms the more cylindrical profile of the inner wall 14 as shown in Figures 2 and 3, and as will be described further below. It is noted that in the embodiment shown in Figure 1, the inner wall 14 may be any geometric shape which allows the inner wall 14 to deform in a controlled way to the reduce the volume of the cavity 15 in line with the volume change of the solidifying polymer material 20 in the cavity 15. It is also noted that the inner wall 14 in Figure 1 may deform inwardly during injection of the molten polymer material as a consequence of the injection pressure and thereby increase the cavity volume, and then deform 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 outwardly in response to contraction of the polymer material to form the inner wall 14 in the final cooled position shown in Figures 2 and 3. For example, during injection the inner wall 14 in Figure 1 may deform inwardly and thereby increase the cavity volume by up to 10-20% and then the inner wall 14 in Figure 1 may deform outwardly during cooling and reduce the cavity volume by more than 10-20%. As the external face of the outer wall 12 of the pole 10 is an exposed face, i.e. the presentation face, and needs to remain aesthetically pleasing, the inner wall 14 is configured to deform preferentially to accommodate for the volume decrease of the polymer material as the material cools and thereby minimise the volume of voids in the polymer material. The above-mentioned embodiment of the method of manufacturing the pole 10 of Figures 2 and 3 includes the following steps: (a) positioning the inner wall 14 in Figure 1 within the outer wall 12 in Figure 1, for example by relative sliding movement of the walls 12, 14, with the cavity 15 separating the walls 12, 14, as shown in Figure 1; (b) injecting a molten polymer material into the cavity 15; and (ec) allowing the molten polymer material 20 in the cavity 15 to cool to an ambient temperature, with the inner wall 14 in Figure 1 deforming outwardly in response to contraction of the polymer material 20 in the cavity 15 that occurs as the molten polymer material cools to the ambient temperature, thereby reducing the volume of the cavity 15 and forming the profile of the inner wall 14 as shown in Figures 2 and 3, and minimising voids that would otherwise be in the polymer material in the pole 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 10. In an embodiment, the manufacturing method includes using vacuum-assisted injection of the polymer material into the cavity 15. The at least partial vacuum in the cavity 15 assists faster flow of molten polymer material into the cavity 15 in the filling process and minimises formation of voids in the polymer material 20. In this method, the cavity 15 between the outer and the inner walls 12, 14 is first evacuated to a high vacuum before injection. In embodiments, the pressure used will be approximately 20- 100 mbar. This pressure can be achieved by a standard high-volume vacuum pump in generally under 5-10s. In the above method, the molten polymer material 20 solidifies from the back of the outer wall 12 of the pole 10 towards the centre. Subsequent shrinkage of the polymer material 20 in turn pulls the inner wall 14 radially outwardly thereby preventing the formation of voids and characteristic sink funnels in the polymer material in the cavity 15. If no more molten polymer material 20 is required to be injected into the cavity 15, then the pole 10 can be removed from the injection head, thereby significantly reducing the cycle time as compared to the above-described pre-existing methods. It has been recognised that cooling the molten polymer material 20 requires even, i.e. uniform, heat transfer from the outer wall 12 across the area of the outer wall 12 to prevent distortion of the outer wall 12. Even heat transfer may be achieved by way of example, by forced air (convection) fans, water spray, or immersing the product 10 in a cooling liquid, such as water. Advantageously, the method ensures complete filling of the 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 cavity 15 and ensures that full polymer material / wall contact is maintained throughout the pole 10. The radial thickness of the cavity 15 of the polymer material can range between 10 mm for smaller poles, up to 100 mm thick for larger poles, although it will be appreciated that these measurements may alter dependent on the type of installation. Advantageously, the outer wall 12 is essentially placed in a state of compression as the polymer material 20 cools, thereby increasing the tensile load the outer wall 12 can withstand. The use of aluminium for the profiles of the outer wall 12 advantageously also provides UV protection for the pole 10. Further, the aluminium may be anodized for corrosion protection. Existing paints utilised in current steel street poles in the ground contact zone can be readily replicated. It is note that, aluminium is not the only possible material for the outer wall 12. Figure 4 illustrates one embodiment of a product according to the invention that includes the above-described pole 10. The product is a street light 24 and the pole 10 is used as the post component of the street light 24. Figure 5 illustrates the location and installation of a junction box 24 and cover 26 in the pole 10 of the street light 24. It is envisaged that the pole 10 be produced as a complete structure and the junction access point be routed into the pole. The use of a polymer material between the outer and the inner walls 14, 16 adds strength to the pole and provides resistance to the walls buckling. It will also be appreciated that the present invention 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 provides an opportunity to take advantage of a widely available resource of post-industrial and post-consumer waste polymers that otherwise may be discarded. Many modifications may be made to the embodiment of the pole of the present invention shown in the Figures without departing from the spirit and scope of the invention. By way of example, whilst the pole shown in Figures 1-3 includes an inner wall 14 that deforms outwardly in response to contraction during cooling of molten polymer material while the outer wall 12 remains in its original profile, the present invention is not so limited and extends to the reverse arrangement and to arrangements in which there is deformation of the outer wall 12 and the inner wall 14. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20

Claims

CLAIMS 1. An elongate composite product comprising a polymer material, such as a recycled polymer material, in an elongate cavity between an elongate outer wall and an elongate inner wall, with the inner wall being manufactured to deform outwardly and / or the outer wall being manufactured to deform inwardly, in response to contraction of the polymer material in the cavity that occurs when the product is being manufactured and molten polymer material in the cavity cools to an ambient temperature, to thereby reduce the volume of the cavity and minimise voids that would otherwise be in the polymer material in the finished product.

2. The composite product defined in claim 1 wherein the inner wall is manufactured to be deformable outwardly and the outer wall is manufactured to remain in its original profile in response to contraction of polymer material in the cavity that occurs when the product is being manufactured and molten polymer material in the cavity cools to the ambient temperature.

3. The composite product defined in claim 2 wherein the materials and / or the structure of the inner wall and the outer wall are selected so that the inner wall deforms outwardly before the outer wall deforms inwardly in response to contraction of the polymer material in the cavity that occurs when the product is being manufactured and molten polymeric material in the cavity cools to the ambient temperature.

4. The composite product defined in claim 2 or claim 3 wherein the outer wall and the inner wall are made from the same materials, with different wall thicknesses, such that the inner wall deforms preferentially. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 5. The composite product defined in claim 2 or claim 3 wherein the outer wall and the inner wall are made from different materials, with the same or different wall thicknesses, with the material of the inner wall being more deformable than the material.

6. The composite product defined in any one of claims 2 to 5 wherein the profiles of the as-manufactured outer wall and the as-manufactured inner wall, i.e. the profiles before the polymer material is injected into the cavity, are selected so that the inner wall is more deformable than the outer wall.

7. The composite product defined in any one of claims 2 to 6 wherein the profile of the as-manufactured inner wall is selected to allow controlled deformation of the inner wall.

8. The composite product defined in any one of claims 2 to 7 wherein the profile of the as-manufactured inner wall, when viewed as a transverse section, includes convex sections separated by concave sections which may be described as a flower-shaped profile.

9. The composite product defined in claim 1 wherein the outer wall is manufactured to be deformable inwardly and the inner wall is manufactured to remain in its original profile in response to contraction of polymer material in the cavity that occurs when the product is being manufactured and molten polymer material in the cavity cools to the ambient temperature.

10. The composite product defined in claim 1 wherein the outer wall and the inner wall are manufactured to be deformable inwardly and outwardly respectively in response to contraction of polymer material in the cavity that occurs when the product is being manufactured and molten 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 polymer material in the cavity cools to the ambient temperature.

11. The composite product defined in any one of the preceding claims wherein the outer wall is made from aluminium or any other suitable material, such as a polymer material.

12. The composite product defined in any one of the preceding claims wherein the outer wall cylindrical.

13. The composite product defined in any one of the preceding claims wherein the outer wall is an extruded wall.

14. The composite product defined in any one of the preceding claims wherein the outer wall includes formations, such as ribs, that extend inwardly into the cavity and are provided to function as reinforcement of the product and / or to limit the extent of the outward deformation of the inner wall and / or the extent of the inward deformation of the outer wall in response to contraction of polymer material in the cavity that occurs when the product is being manufactured and molten polymer material in the cavity cools to the ambient temperature.

15. The composite product defined in any one of the preceding claims wherein the inner wall is made from aluminium or any other suitable material, such as a polymer material.

16. The composite product defined in any one of the preceding claims wherein the inner wall is an extruded wall.

17. A method of manufacturing an elongate composite product that includes: 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 (a) positioning the as-manufactured elongate inner wall defined in any one of the preceding claims within the as-manufactured elongate outer wall defined in any one of the preceding claims and forming a cavity between the walls; (b) injecting a molten polymer material, such as a recycled polymer material, into the cavity; and (ec) allowing the molten polymer material to cool to an ambient temperature, with the inner wall and / or the outer wall deforming in response to contraction of polymer material in the cavity that occurs as the molten polymer material cools to the ambient temperature thereby to reduce the volume of the cavity and minimise voids that would otherwise be in the polymer material in the finished product.

18. The method defined in claim 17 wherein step (b) includes drawing a partial vacuum from one end of the cavity and injecting molten polymer material into the cavity from the other end.

19. The method defined in claim 17 wherein step (b) inserting a nozzle through the cavity from one end of the cavity up to a position proximate the other end of the cavity and progressively withdrawing the nozzle away from the other end while injecting molten polymer material into the cavity.

20. The method defined in any one of claims 17 to 19 includes forming the molten polymer material by melting mixed waste polymer materials at a temperature that is selected to at least partially melt a lowest melting point polymer of the mix and leave other polymers in the mix in a solid form and forming an injectable slurry of the mixed waste polymer materials, whereby at least one molten polymer material acts as a binder for the other polymer materials in the mix when the mixture solidifies. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20 21. A utility pole for street lighting includes a post that includes the elongate composite product defined in any one of claims 1 to 16.

22. A traffic management bollard includes a post that includes the elongate composite product defined in any one of claims 1 to 16.

23. An assembly of an elongate outer wall, an elongate inner wall, and a cavity between the wall for use in manufacturing an elongate composite product, with the inner wall being manufactured to deform outwardly and / or the outer wall being manufactured to deform inwardly when molten polymer material is injected into the cavity and fills the cavity and the polymer material contracts in the cavity as the polymer material cools to an ambient temperature to form the elongate composite product, thereby reducing the volume of the cavity and minimising voids that would otherwise be in the polymer material in the elongate composite product at the ambient temperature. 16629660_1 (GHMatters) P112169.AU.1 1 / 10 / 20

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