WO2010031106A1

WO2010031106A1 - Buoyant panel

Info

Publication number: WO2010031106A1
Application number: PCT/AU2009/001131
Authority: WO
Inventors: Kevin Michael O'donnell; Alfred Johannes Biden; Bernard Kent Masters
Original assignee: Kevin Michael O'donnell; Alfred Johannes Biden; Bernard Kent Masters
Priority date: 2008-09-19
Filing date: 2009-09-01
Publication date: 2010-03-25
Also published as: AU2009295248A1; AU2009295248A2

Abstract

The present invention relates to a buoyant panel (1) for use on bodies of water, the pane comprising a buoyant perimeter frame (10) and a perforatable membrane (20) substantiall located therewithin and substantially supported thereby, the frame (10) being constructed o a closed-cell foamed polymeric material having a substantially solid or hollow centre or combination thereof.

Description

BUOYANT PANEL

Field of the Invention

The present invention relates to a buoyant panel for use on bodies of water. In particular, the panel of the present invention finds application in a number of areas including: (i) as an artificial island hosting plants, wherein the plants are useful in water treatment; (ii) as an artificial island hosting plants, wherein the plants are useful in providing bird nesting habitats and/or protective shelter for fish and crustaceans; (Hi) as an artificial island hosting plants, wherein the plants arc used for beautification of the environment; (iv) for evaporation control; and (v) for wave damage control.

Background of the Invention

Floating platforms aτe known to exist in a number of forms and for a number of purposes. Typically, each of these platforms is intended to be used for a specific purpose. Floating platforms have previously been used as planters or as artificial islands.

A number of known floating planters are covered by materials that prevent or restrict plant growth. For example, some include a floatation layer that is manufactured from conventional buoyant foam, such as a foamed plastic. However, this material is not suitable for plant growth and regions of the foam layer must be cut out so thai plants roots can grow through the planter and spread into the water therebeneath. Other background art planters use hollow buoyant pipes as a frame formed around the perimeter of the structure to provide buoyancy. For example, scaled PVC or polyethylene tubes placed around the perimeter of a floating planter are sometimes used to provide buoyancy thereto. This method of providing buoyancy tends to be fragile, in that it is subject to failure by impact from boats and pressure from environmental conditions and furthermore, has limited manufacturing capability. Planters can a] so be constructed from interwoven or spun-bonded structures that contain buoyant components in appropriate positions to provide a degree of stability. Various raan-madc floating structures arc known that do support flora. These structures generally have scaled hollow pipe-framed perimeters and an internal membrane constructed from synthetic or naturally occurring materials stretched therebetween, which support water-tolerant plants or plant containers placed therein or thereon. However, the buoyancy of such a structure is vulnerable in that simple rupturing of the plastic pipe can allow ingress of fluid resulting in the entire structure sinking.

Research has shown that particular water-plants and land-plants can be effective in the purification of contaminated waters. The high surface area of the root system of such plants facilitates the formation of a 'biofilm' at an appropriate position with respect to the waterline, which can dramatically improve the aquatic environment in which the biosphere is situated. This research has also shown that the efficiency of such plants is reliant on a series of factors, including the provision of a cost-effective and stable buoyant structure; an appropriate root support medium; and a containment system. By their form and design, such planted floating planters provide benefits such as water purification, visual beautification and the provision of habitats for birds and protection to fish life.

Some floating platforms have also been used to cover bodies of water in order to prevent excessive water evaporation. When water evaporation occurs, this affects not only the loss of a valuable resource, but also provides a method by which water impurities and water-soluble agents become concentrated in that body of water. Water bodies in warmer climates are subject to heating up under direct exposure to sunlight, thereby promoting the growth of blue-green algae in nutrient rich waters and prohibiting the development of a natural biosphere, where this might otherwise be desirable. In many instances, it is most desirable to achieve both the suppression of water evaporation in combination with the purification of contaminated water.

Water evaporation suppression systems are commercially available. The technology of these systems ranges from the provision of a surface layer of surfactant with and without repelling powders and foamed pellets, through to foils and discs of self-supporting designs being laid onto the water bodies; and shade cloths stretched by elaborate frameworks over the water surface. However, some surface films/powders/pellcts and surface foil applications suffer from instability. This feature contributes to safety issues of such covering systems, particularly the foil cover, when applied directly onto the water surface. Most systems incur high costs and present difficulties with respect to installation and maintenance. Fully impermeable foil systems arc also susceptible to wind lift and sinking under heavy rainfall and/or deposition of sand/dust from dust storms.

Wave action can cause erosion of natural or artificial boundaries of such water bodies, Wave erosion is generally mitigated by the construction on the shore-line of fixed structures, such as rocky batters/slopes or liners. However, such structures are expensive to install and maintain, and may be prone to damage.

The present invention seeks to provide an improved buoyant panel. More particularly, the present invention provides a buoyant panel, which seeks to minimize or ameliorate the disadvantages of the prior art.

Summary of the Invention

According to the present invention, there is provided a buoyant panel for use on a body of water, the panel comprising a buoyant perimeter frame and a perforatable membrane substantially located tberewithin and substantially supported thereby, the frame being constructed of a closed-ceU foamed polymeric material having a substantially solid or hollow centre or a combination thereof.

The buoyant perimeter frame of the buoyant panel substantially provides structural stability and buoyancy for the buoyant panel, as well as support for the perforatable membrane. The major advantage provided by the present invention is that the buoyant perimeter frame- is made to be inherently buoyant through use of the closed-cell foamed polymeric material from which the frame is constructed due to the air trapped within the material during the manufacturing process. While fluid could still enter the material, the material will remain substantially afloat and the perimeter frame is still abJe to substantially support additional weight, such as the perforatable membrane and any load applied thereto.

The buoyant perimeter frame is preferably composed of one or more frame members, used in combination, wherein the frame member comprises a continuously extruded polymer of closed-cell or closed-cell walled hollow tube or a combination thereof. Joining together of the frame members to make the buoyant perimeter frame of the buoyant panel may be achieved by any method known in the art, for example, but not limited to, heat-welding, screwing, riveting and/or stapling together.

One preferred embodiment of the frame member is a rod formed from foamed polyethylene, having a density of from approximately 0.45 g/cm³ to approximately 0.75 g/cm³. More preferably, the density of the rod is from approximately 0.5 g/cm³ to approximately 0.6 g/cm³. The source of polyethylene is most preferably impure recycled plastic, such that it includes other scrap plastics. During manufacture, this material is preferably mixed with a blowing agent, for example, a^odicarbonamide, and the closed- cell foam rod is produced therefrom using standard extrusion techniques.

The effective diameter of the frame member is preferably determined by the amount of buoyancy required for a particular application. A preferred frame member diameter is in the order of between about 30 mm to about 100 mm, while B most preferred diameter is about 50mm.

The buoyant panel may be of any shape, including but not limited to triangular, quadrilateral, pentagonal, hexagonal and octagonal. Generally, the shape of the buoyant panel will have substantially straight sides, since substantially straight rods of the foamed polymeric profile are more readily prepared than curves. Furthermore, straight edged shapes are more readily assembled and used as modular components for being tethered together as described above to form a buoyant structure. In order to provide additional structural stability to the buoyant panel or structure, some embodiments of the present invention further comprise opposite sides of the buoyant perimeter frame being spaced apart by one or more cross-members placed therebetween. These cross-members are typically constructed from the same material as the buoyant frame members. As discussed in detail below, the perforatable membrane may include additional sleeves or pockets to accommodate the one or more cross-member/s.

Artificial islands or, as also referred to herein, Floating Biospheres, can preferably be used for growing vegetation to assist in bioremediation of waterways; to provide habitats for various organisms, including birds; or for beautifying waterways. When used for the bioremediation of waterways, careful selection of plants can result in the formation of bio-films on the roots of such plants, which can dramatically improve the aquatic environment in which the artificial island is situated. The filler medium combinations of the buoyant panel also contribute, due to their large surface area, to the rapid growth of the root system of the plants and also, at the submersed portion, to the formation of bio- film and at the non-submersed portion, to aeration of water from natural circulation. The modular construction of such a buoyant structure allows a large area of the body of water to be covered.

The present invention also preferably provides at .least one buoyant panel, whose buoyancy is variable depending on the composition of the frame and the filler medium in combination with the perforatable membrane used therein. Preferably, a number of buoyant panels may be used in combination as modular units. There are two main types of buoyant panels according to the present invention, namely, Floating Biospheres that are used for growing plants and Floating Covers that are used in evaporation and wave suppression applications. The modular nature of the buoyant panels allows for easy construction of a variety of sizes of Floating Biospheres or Floating Covers, depending on the requirements of the body of water.

In a first preferred aspect, the buoyant panel of the present invention functions as a Floating Biosphere and in particular, provides an artificial island which supports water tolerant plants. In this aspect of the invention, the perforatable membrane is preferably one which is able to be permanently immersed in water without long-term deterioration. The nature and construction of the perforatable membrane may vary depending on the intended use of the buoyant panel of the present invention. Typically, ύie membrane is preferably constructed from a fabric having an open weave to permit plant root penetration. Furthermore, the fabric selected most preferably has the capability of being sewn or welded together by appropriate joining techniques.

In this first aspect, the perforatable membrane is substantially fillable with a filler medium. The filler medium consists substantially of water-resistant materials composed of natural and/or synthetic open cell foam, short fibres or shredded fabrics, plastics pellets/granules or purpose specific polymeric or inorganic particulates and closed cell plastics particulates. The filler medium composed of the different composition materials is selected from being uncoated or coated or a combination thereof. Where the filler medium is coated, polymeric adhesives randomly mixed into a fluffy, pervious but coherent consistency arc preferably used.

The filler medium of the present invention is more preferably provided by one or by a combination of more than one of three types of material, each of which serves a specific function. The three types of material are: a) chips of closed cell foam of polymeric nature of rigid or flexible foam origin; b) chips of open cell foam of polymeric nature of rigid or flexible foam origin; and c) short fibres or shredded fabric of natural fibre or synthetic fibre origin or combination thereof,

Where the filler medium includes chips of dosed cell foam of polymeric nature of rigid or flexible foam origin, the material can contain water-insoluble impurities. The closed cell foam provides additional buoyancy to the buoyancy provided by the- buoyant perimeter frame member, by water displacement at the immersed filler medium portion of the buoyant panel. This material is most preferably, but not limited, to expanded polystyrene. Where the filler medium material includes chips of open cell foam of polymeric nature of rigid or flexible foam origin, the material can further contain water-insoluble impurities. This material predominantly provides structural stability to the filler medium, but also allows for water penetration for the formation of a biofilm on the roots of flora planted on the panel, which as described above, can dramatically improve the aquatic environment in which, the biosphere is situated.

Where the filler medium material includes shredded materials consisting predominantly of short fibres or shredded fabrics of spun-, woven- or pressed fibres of polymeric nature, the material can also contain water-insoluble impurities, soEd plastics granules, particulates or flakes of plastics originating from film, foil or felt. This material allows for water migration and formation of bio-film due to its high aspect ratio of surface area to material volume. Λ non-limiting example of this material is shredded carpet. Such a filler medium material also preferably provides additional buoyancy to the buoyant panel.

The three types of materials described above can be varied in composition ratio in accordance with design functions and requirements of the buoyant panel, whereby each material provides a specific function within the filler medium. The combination preferably enables regulation of the buoyancy, the overall carrying capacity and stability of the buoyant panel, as well as the position of the waterline within lhe panel with respect to the planted flora. The filler medium of the above composition enables the possibility for it to be mixed with plant seeds and/or plant cuttings.

The filler medium material most preferably consists of a mixture of the three types of material as described above, in a ratio of approximately 1:1:1. m this case, the filler medium has a material density of approximately 0.04 kg/1 to approximately 0.07 kg/1, preferably approximately 0.045kg/l, and an open cell void factor (solid volume/void volume) of approximately 0.10 to approximately 0.25, preferably approximately 0.135.

The separation of the individual functions of components of the filler medium allows great flexibility with respect to adapting various embodiments for particular functions. Further, buoyancy of the panel is provided by air trapped throughout the frame and the perfbratable membrane; by the density of the material from which the perimeter frame is constructed; and by the closed cell foam component of the filler medium; and from material used for membrane and membrane filler medium with a density below 1.0 g/cm3.

The filler medium is further preferably predetermined to a volume of twice the frame cavity volume in this embodiment of the invention. When the filler medium is inserted into the perforatablc membrane, the membrane forms a substantially flat configuration ^' being, on average, approximately twice the thickness of the diameter of the buoyant frame profile, i.e. 100 mm when the buoyant frame profile has a diameter of 50 mm.

In this preferred embodiment, the perfbratable membrane which substantially ensures the containment of the filler medium is perforated, whereby dust, water or rain can pass therethrough to prevent the pooling thereof on the surface of the buoyant panel. More preferably, when the membrane is constructed of a perforated mesh, the pores thereof being of a sufficiently small pore size to substantially inhibit or prevent the filler medium passing through the membrane.

Where the membrane is composed of a polymeric woven fabric, the fabric is preferably selected from open mesh, closed mesh or spun-bonded construction, as appropriate for the particular embodiment. One selected fabric construction may be used for the entire membrane or alternatively can be used in combination with others, whereby the sun- cxposcd part of the membrane is adequately UV-stabiliscd and all component parts are suitable for long-term water immersion. A more preferred membrane material is commercially available shadecloth. Sbadecloth, having a 50% shading rating, is most preferred, as it is lightweight and consists of a single weave, and provides a suitable level of porosity to allow water and dust to be washed therethrough, while still retaining the filler medium therein. Since the membrane is exposed to the environment, it is most preferably robust and resistant to degradation. Accordingly, at least the upper surface of the membrane is substantially resistant to cnviroπmenta] degradation, such as UV-degradation and preferably includes stabilizers and absorbers such as, but not limited to, hindered amine light stabilizers and UV absorbers. Commonly used products include various compounds sold by Ciba, such as the Chimassorb^® and Tinuviπ^® ranges of compounds. Non-limiting examples of hindered amine light stabilizers include Tinuvin* 770 (Bis(2,2,6,6,- tctramethyl-4-piperidyl) sebacatc) and Tinuvin^® 783 (Poly[[6-[(1, 1,3,3 - tetramcώylbutyl)aπimo]-l,3,5-uiazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl) irmno]-l,6-hexanediyl[(2,2,6,6-tctramethyl-4"piperidiriyl)imino] Butanedioic acid, dimethylcster, polymer with 4-hydroxy-2,2,6,6-tetramethyl-l-piperidine ethanol). Non-limiting examples of UV absorbers include Turovin⁸¹ 571 (2-(2H-benzotriazol-2-yl)- <5-dodecyl-4-mcthylphenol) and Tinuvin^® 360 (2,2'-methyIene-bis[6~(2H-benzotriazol-2- y))-4-(l,l,3,3-tctramethylbutyl) phenol]).

In a second aspect, the buoyant panel of the present invention functions as a Floating Cover, which can be applied to the water surface for minimising water evaporation or to function as a wave suppressor to reduce wave damage to the land at the edges of a body of water.

Preferably, placing Floating Covers of the present invention on a body of water substantially prevents the water from direct sun exposure and thereby reduces both airflow across the water surface and water temperature, resulting in a significant reduction in water evaporation. The modular nature of such buoyant structures allows a large area of the body of water to be covered.

Preferably further, placement of Floating Covers adjacent to and anchored to, the shore of a clay-lined dam or a reservoir substantially reduces wave damage, which would otherwise cause the clay lining thereof to be washed away. Such buoyant structures are able to cascade down the slope of a water dam, reservoir or channel with the change in water level, thus further protecting the shore line and prevent the clay-lined dam from cracking.

The perfbratablc membrane used for Floating Covers is typically of a flat-mat construction, which construction is preferably in the form of a laminate. In the laminate embodiment, the membrane is the upper surface layer thereof. To the underside of the laminate, there is preferably provided a lower surface layer, which layer is adhered or welded to the upper surface layer. The lower surface layer is more preferably comprised of filler medium, as described above.

In certain preferred embodiments, the choice of material from which the membrane is constructed regulates the degree of suppression of water evaporation. The membrane is preferably able to be permanently immersed in water without long-term deterioration. The membrane material used for the evaporation suppression application is preferably a fabric having bonded-fibre configuration, a plastics or aluminium foil having perforations therein on the upper surface of the laminate to control water and dust permeation and a fabric having open-weave or bonded-fibre configuration forming the lower surface layer. The material chosen most preferably has the capability of being sewn or welded together by appropriate joining techniques.

Since the upper surface layer of the laminate is exposed to the environment, it is most preferably robust and resistant to degradation. Accordingly, at least the upper surface layer is substantially resistant to environmental degradation, such as UV-degradation. Accordingly, the laminate may include stabilizers and absorbers such as, but not limited to, hindered amine light stabilizers and UV-absorbcrs. Commonly used products include various compounds sold by Ciba, such as the Chimassorb® and Tinuvin® ranges of compounds.

In this embodiment of the present invention, the lower surface layer can be made of a variety of materials, such as chips of open cell foam of polymeric nature of rigid or flexible foam origin, which are randomly bonded by a polymeric bonding compound or composition to retain a coherent water pervious structure. The most preferred material, which acts as a "water weight" for the panel and helps prevent the buoyant panel from being lifted off the water surface by wind movement, is polyurethane flexible foam.

The lower surface layer of the laminate of the Floating Cover, which preferably has the same composition ratio and open cell void factor as for the Floating Biosphere, is preferably pre-manufacturcd as a flat sheet, which can be randomly bonded or welded to the upper surface layer. Suitable adhesives, which ensure the integrity of the laminate, can be those as known in the art of adhesives. The adhesive is preferably an adhesive mastic. In some preferred embodiments of the present invention, the adhesive is an ethylene-vinyl acetate adhesive. The thickness of the laminate is preferably approximately half the thickness of the diameter of the frame profile.

Attachment of the perforatable membrane¹ or in its laminate form to the buoyant perimeter frame is achieved by any method known to the skilled addressee. In exemplary embodiments of the present invention, attachment is achieved by the use of sleeves or pockets around the periphery of the membrane/laminate resulting in the frame being substantially encased therewithin. In further embodiments, the membrane/laminate is fixed directly to the buoyant perimeter frame. The closed-cell nature of the frame member allows a fastening means to be inserted into the buoyant perimeter frame without compromising or reducing its buoyancy. Ih some alternative embodiments, the fastening means, for example, a cable tie, may wrap around the outside of the frame.

In some particular embodiments of the Floating Cover, the membrane/laminate is prepared with the membrane extending over the top of the perimeter frame. This extended region may be used to link the membrane/laminate to the frame, for example, by fasteners inserted directly into the perimeter frame, by welding, or by usual methods known to those in the art. The flat-mat membrane/laminates can preferably further include an underlayer, wherein the underlayer may also extend beyond the edge of the membrane/laminates and also be used in the attachment of the membrane/laminates to the perimeter frame. The buoyant panel according to the present invention consists of only a limited number of components and this type of construction permits individual components to be produced separately and then assembled to form a complete panel. This assembly may be performed in a factory or even on site immediately prior to installation on the intended body of water.

The profiles of the buoyant perimeter frame members can be manufactured continuously to selected dimensions and cut to size in accordance with the respective design. The buoyant frame structure can be preassembled or assembled into construction sleeves or pockets within the membrane/laminate. The membrane structure rnay be pre-prepared according to tbe respective design and the laminate prepared prior to final assembly as a buoyant panel. Several examples of various possible design options are possible and these will be discussed further below. The simplicity of the design concept allows for many other geometries should they be required. As discussed above, panels of any shape can be constructed including, but not limited to, triangular, quadrilateral, pentagonal, hexagonal and octagonal.

In preferred embodiments of the present invention, a plurality of buoyant perimeter frame members are joined together to form the buoyant perimeter frame which is substantially leak-proof and inherently buoyant. The buoyant perimeter frame members arc preferably produced from a virgin polyolefin, polyolefm composites or recycled polyoletln/composite composition. The buoyancy of unfilled polyolefin is more preferably enhanced by the incorporation of a closed-cell processing technique commonly known in the art. As noted above, the density of the frame members is most preferably in the range of 0.45 g/cm³ to 0.75 g/cm³, which density provides the required strength of the frame structure. The buoyant frame perimeter members of the present invention can be joined using any known process, including, but not limited to, heat- welding, screwing, riveting or stapling together, without any such process affecting the degree of buoyancy for the construction of a frame structure and any fastening of component to the frame for specific applications, e.g. construction of an installation of panels for the creation of an island or attachment of bird-netting fixtures (see below).

When interconnected, in a modular manner, the buoyant panels can form large Floating Biospheres or Floating Covers, wherein the Floating Biospheres are intended to support various flora, and the Floating Covers are intended to act as evaporation or wave suppression covers. The specific buoyancy capacity and panel stability, being varied by the individual panel designs, further enables the design to be varied by the combination of the construction of the membrane/laminate, whereby individual buoyant panels are configured in specific patterns and functions. Accordingly, it is envisaged that combinations of all of the above discussed applications can be constructed depending on the choice of each of the buoyant panels. It is envisaged that different types of panels could be joined together to provide a multifunctional floating cover.

It is envisaged that the modular panels may be linked using, for example, 5mm diameter ski-rope passed through a hole drilled in the frame and joined to a loop as practiced in the trade of joining ski-ropes. In yet further embodiments of the present invention, it is desirable to have the buoyant panel/s fixed in position on the water or to the bank, in the case of a wave suppression application. As noted previously, due to the nature of the buoyant frame members, it is possible to securely attach ropes, chains or the like to the buoyant panels, which chains or ropes etc. may be used to tie the panel to the bank or to an anchor, to position the panel on the water-

In certain Floating Biosphere embodiments of the present invention, it is desirable to be able to protect the plants planted thereon from predators, such as birds. To achieve this, the buoyant panel further comprises a support structure formed over the buoyant panel by, for example, placing arches formed of a suitable lightweight material from one side of the buoyant panel to another. The arches are preferably constructed from any suitable lightweight material, for example, plastic piping. One suitable type of plastic piping is garden irrigation pipe, having a diameter of approximately 12mm. Fixing this type of piping to the. buoyant frame may be achieved using any suitable means including, but not limited to, barbed connectors, such as those typically used in garden irrigation systems, inserted into holes drilled into the buoyant frame. As noted above, it is possible to form holes in the buoyant frame without compromising its buoyancy. Bird netting or the like can then be installed over the support structure to protect the plants during the initial growing phase on the buoyant panel. The bird netting is removed after the plants have established sufficient root mass that is deemed sufficient to prevent the plants from being pulled out or being substantially damaged by grazing bird populations.

Preferably, the buoyant structure of the present invention is easy to install, plant with flora and maintain. The materials from which the buoyant structure is made are preferably eco-friendly (i.e. to water, flora and fauna), long-lasting and potentially recoverable, when the structure is no longer required or when it reaches the end of its useful life.

Description of the Drawings.

Other features and advantages of one or more preferred embodiments of the present invention will be readily apparent to one of ordinary skill in the art from the following written description with reference to, and used in conjunction with, the accompanying drawings.

Figure 1 shows cross-sections of various embodiments of the buoyant perimeter frame member of the present invention.

Figure 2 shows a cross-section of a flat-mat membrane/laminate embodiment of the present invention.

Figure 3 illustrates exemplary embodiments used as components of the perforatable membrane/laminate of the present invention: A. woven open mesh fabric; B. spun- bonded (fused fibre) short fibre fabric; and C. perforated plastic- or Aluminium (Al)-foil. Figure 4 illustrates an exemplary embodiment of the buoyant panel according to Example 1, end-on view (A) and plan view (B).

Figure 5 illustrates exemplary embodiments of the buoyant panel according to Example 2:_a Floating Biosphere embodiment is shown in end-on view (Λ) and in plan view (B); and a Floating Cover embodiment is shown in plan view (C) and in cross-section through D-D' (D) as identified in (C).

Figure 6 illustrates an exemplary embodiment of the buoyant panel according to Example 3, end-on (A), plan (B) and side-on (C) views.

Figure 7 illustrates an exemplary embodiment of the buoyant panel according to Example 4, end-on (A), plan (B) and side-on (C) views.

Figure 8 illustrates an exemplary embodiment of the buoyant panel according to Example 5, end-on (A), plan (B) and sidc-on (C) views.

Figure 9 illustrates an exemplary embodiment of a disassembled buoyant panel according to Example 6, the buoyant frame is shown in plan view (A) and end-on view (B), and the perforatable membrane is shown in plan view (C) and end-on view (D).

Figure 10 illustrates an exemplary embodiment of an assembled buoyant panel according to Example 6, plan view (A) and end-on view (B).

Figure 11 illustrates an exemplary embodiment of a disassembled buoyant panel according to Example 9, the perforatable membrane is shown in plan view,, (A), and the buoyant frame is shown in plan view (B).

Detailed Description of the Invention Referring to all the drawings wherein like reference numerals designate like or corresponding parts throughout the several views. The following description refers to the specific, illustrated embodiments of the present invention and is m no way intended to limit the scope of the present invention to those specific, illustrated embodiments.

An assembled view of an embodiment of the buoyant panel 1 is shown in Figure 5. The buoyant panel 1 for use on a body of water comprises a buoyant perimeter frame 10 and a perforatablc membrane 20 substantially located therewithal and substantially supported thereby, the frame 10 beiαg constructed of a closed-cell foamed polymeric material having a substantially soJid or hollow centre ox a combination thereof.

Referring to Figure 1, the cross-section of a number of different possible profiles for the buoyant perimeter frame 10 is shown, which may be solid (A, B, C) or hollow with foamed walls (D, E₅ F).

In certain embodiments of the present invention, the membrane/laminate 20 may comprise an integrally bonded flat mat Figure 2 shows an exemplary flat mat laminate 20 comprising a lower surface layer of bonded filler medium 100 and an upper surface layer 200 consisting of a UV-stabilised foil having perforations 205 of adequate strength to retain and support the bonded filler medium 100.

Figure 3 schematically illustrates three non-limiting examples of the types of materials that may be used for the membrane: A. woven open mesh fabric; B. spun-bonded (fused fibre) short fibre fabric; and C. perforated plastic- or Al-foil.

In the case of the embodiment of the invention illustrated in Figure 2, the membrane is an integral component. Several examples of various possible design options are shown in

Figures 4 to 10 and these will be discussed further below. The simplicity of the design concept allows for many other geometries should they be required. In particular, the invention is not to be limited to the .quadrilateral-shaped panels illustrated herein.

Buoyant panels of any shape can be constructed including, but not limited to, triangular, pentagonal, hexagonal and octagonal. Specific embodiments and applications of the present invention will now be discussed in detail by reference to the accompanying example. This discussion is in no way intended to limit the scope of the invention.

Examples

Example 1 - illustrated in Figure 4

The buoyant perimeter frame 10 is assembled from a selected profile, as illustrated in Figure 4, of strong and rigid configuration. The perimeter frame JO is stabilised with a CTOss-member 12 midway along the frame length. The membrane 20 is selected from suitable material as shown in Figure 3 and wrapped around the length of the frame 10 and then jointed to form a tube. The membrane is then stretched and separated from the upper side of the structure and a profile bar 14 is inserted midway along the width of the perimeter frame 10 to form a slight apex to the membrane,- as shown in Figure 4A. The filler medium is inserted to a predetermined fill volume from the top end of the structure and the membrane is then sewn up to form a complete enclosure,

Example 2 - illustrated in Figure 5

Version 1 (Figure 5A and 5B)

The buoyant frame 10 is assembled from a selected profile, as illustrated in Figure 1, of strong and rigid configuration of approximately equal length to width ratio. The membrane 20 is selected from suitable material as shown in Figure 3 and which is sewn up to form a fxllable pillow. The upper surface and the lower surfaces of the membrane may be made from different material types. The filler medium is inserted to the predetermined fill volume at the opening of the pillow and the pillow is then sewn up to form a complete membrane 20, The membrane 20 is stretched and fastened by cable ties 30 or plastic hooks to the buoyant perimeter frame 10 with as small a gap between the membrane 20 and frame 10 as possible. The fastening is positioned to achieve a uniform and stable structure. Version Z

In this non-illustrated version, the buoyant perimeter frame is enlarged by extending its length to two or three tiroes its width. The panel extension is accomplished by producing two or three membranes of equal size. The profiles of the buoyant frame are extended to an appropriate length. Cross-members are affixed at the end of each section to the frame structure. Version 2 has the advantage of providing greater stability due to the fact that it provides a larger area per panel and can be installed as interlocking patterns.

Version 3 (Figure 5C and 5D) The buoyant frame 10 is assembled from a selected profile, as illustrated in Figure 1, of strong and rigid configuration of approximately equal length to width ratio. A flat panel is prepared as illustrated in Figure 2, wherein the membrane/lamin-ite 100 is prepared with the membrane 200 extending past the edge of the laminate as shown in the cross- sectional view of Figure 5D. This extended region 202 is positioned over the top of the perimeter frame 10 and is used to link the membrane/laminate 100 to the frame 10 by welding.

Example 3 - illustrated in Figure 6

Two planes of membrane of selected material, as shown in Figure 3, are sewn up as per structure design as a pillow with sleeves for the insertion of the transverse perimeter frame members 1OT and cross-members 12 from a pre-cut selected profile as shown, in Figure 1. The membrane 20 has initial side opening slots. The membrane material may be of different material type for the two sides of the pillow. The cross-members 12 and transverse frame members IGT arc inserted into the sleeves of the membrane 20. The filler medium is inserted to a predetermined fill volume at the opening of the pillow and. the pillow is then sewn up to form a complete membrane 20. The longitudinal perimeter frame members .1OT are then fastened to the transverse frame members 1OL and cross-members 12 to form the buoyant panel 1.

Example 4 - illustrated in Figure 7 The membrane of selected material, as shown in Figure 3, is sewn up to form a pillow.

The membrane material may be of different material type for the two sides of the pillow.

The buoyant perimeter frame 10 is assembled from a pre-cut selected profile as shown inFigure 1 of strong and rigid configuration. The frame 10 is then inserted into the membrane pillow. The filler medium is inserted to a predetermined fill volume at the opening of the pillow and the pillow is then sewn up to form a complete buoyant panel 1 with the perimeter frame 10- within the membrane 20. The fill factor can be chosen to produce a flat structure or a bulged structure. Cable ties 30 can be used to control the bulge of the structure.

Example S - illustrated in Figure 8

Two planes of membrane of selected material as shown in Figure 3 are sewn up as per structure design to form a longitudinal pillow with an opening at the long end of the pillow. The upper and lower surfaces of the membrane may be of different material types. The filler medium is inserted to a predetermined fill volume at the opening of the pillow and the pillow is then sewn up to form a complete membrane 20. This process can be a continuous operation and then cut to unit length. The longitudinal perimeter frame members 1OL from pre-cut selected profile, as shown in Figure 1, are iastened along the length of the pillow with cable ties 30 or plastics hooks. Transverse perimeter frame members 1OT and cross-members 12 are then fastened at determined spacings to the longitudinal perimeter frame members 10L to form the complete buoyant panel 1.

Example 6 - illustrated in Figures 9 and 10 Version 1: The buoyant perimeter frame 10 is assembled of selected profile, as shown in Figure 1 , of ^■ strong and rigid configuration. The perimeter frame 10 is stabilised with a cross-member 12 midway along the frame length. A furlher stabilising rod 14 is welded in the middle of the frame 10 in length direction. The membrane 20 is a bonded flat mat, such as shown in Figure 2 and is prepared to the size of trie frame with overlap and recesses at the frame junctions (Figure 9C). The flat mat, positioned with the membrane to the upper side, is then stretched and wrapped with overlap round the perimeter frame 10 and fastened by appropriate fastening techniques, such as cable ties 30, adhesive or thermal welding. The flat-mat design may also consist of foam sheet being bonded to a woven or spun-bonded fabric. In this instance the design provides less evaporation suppression, but the ability to be planted with appropriate flora.

Version 2:

The buoyant perimeter frame is assembled of selected profile, as shown in Figure 1, of strong and rigid configuration. The perimeter frame is identical to the frame of Figure 11 B. The membrane 20 is a bonded flat mat, such as shown in Figure 2 is prepared to the size of the perimeter frame 10, or the sections of the frame, with overlap and recesses at the frame junctions. The flat mat, positioned with membrane to the upper side, is then laid into the frame section with foil overlap fastened by appropriate fastening techniques such as cable ties 30, adhesive or thermal welding.

Example 7 - illustrated in Figure 6

The buoyant perimeter frame 10 in this instance is constructed of a circular closed-cell extruded profile as Figure 1Λ, with a diameter size of 50mm. The core consists, in this instance, of LLDPE rccyclates originating from 'agricultural foil', 'silage wrap' or 'industrial shrink wrap'. The profile is produced continuously by extrusion, whilst mixed with a blowing agent common to the art of producing closed cell extruded products of LLDPE type polymers. The preferred blowing of the profile in this instance is to produce a profile with a density of 0.45 kg/L. The buoyant perimeter frame members 10, and cross-members 12, are cut to lengths of 2 x 5.4 m and 4 x 1.8 m and recessed at their ends to facilitate maximum contact jointing. The members 10 are joined by thermal fusion, to form a substantially rectangular frame, after being inserted into sleeves within the membrane 20-

The membrane 20 in this instance consists of a woven fabric as shown in Figure 3A, close weave shade cloth of commercial grade with a density of approximately 220 g/m², preferably light coloured and UV stabilised to provide long-term water exposure and permeation, stability and sun exposure. The membrane 20 is cut to size to fit the inside dimension of the buoyant perimeter frame 10, i.e. 2.0 m x 5,6 m providing allowance for sleeve stitching. The membrane fabric is stitched to form a pillow as described in Example 3 for retaining (i) the filler medium inside the pillow-like membrane; and (H) the cross-members 12 inside the sleeves. The membrane 20 has cut-outs to coincide with the junctions of the perimeter frame 10 (Figure HA). After assembly, the pillow is stitched to form the membrane 20.

The filler medium consists in this instance of a mixture of the three types of material as described above in a ratio of 1:1:1. The filler medium has a material density of 0.075 kg/L and an open cell void factor (solid volume/void volume) of 0.25. The filler medium is predetermined to a volume of twice the perimeter frame 10 cavity volume. When the filler medium is inserted into the membrane pillow and distributed the resultant membrane 20 forms a flat configuration being in average approximately twice the thickness of the diameter of the frame profile, i.e. 100 mm.

The filled and completely sealed membrane 20 is secured to the buoyant perimeter frame 10 by insertion of the transverse perimeter frame members 1OT in the outer slots of the membrane 20 prior to welding the longitudinal perimeter frame members 1OL and cross-members 12.

This buoyant panel 1 is suitable to be applied to the body of water. The panel 1 is suitable to be planted with plants either by incorporating the seeds into the filler medium, sowing the seed evenly on top of the membrane or inserting plant cuttings or established plants through the shade mesh into the filler medium.

The buoyant panel 1 constructed according to this Example has the following dimensions and properties:

Area of complete single panel: 9.720 m² Mass of complete single panel: 71,091 kg

Length of frame profile: 18.000 m Area of membrane fabric: 22.400 in²

Volume of filler medium: 860 L.

The buoyant panel 1 of this Example has a buoyancy to produce the following characteristics:

Total carry capacity per single panel: 229.0 kg

Specific carry capacity: 23.6 kg/m²

% Immersion without payload: 23.7%. Up-lift resistance (unplanted): 25.0 kg/m².

Example 8 - illustrated in Figures 9 and 10

The buoyant perimeter frame 10 in this instance is constructed of a circular closed-cell extruded profile as Figure IA, with a diameter size of 50 mm. The core consists, in this instance, of LLDPE recyclates originating from 'agricultural foil', 'silage wrap' or 'industrial shrink wrap'. The profile is produced continuously by extrusion whilst mixed with a blowing agent common to the art of producing closed-cell extruded products of LLDPE type polymers. The preferred blowing of the profile in this instance is to produce a profile with a density of 0.45 kg/L. The members of the buoyant perimeter frame 10, profile bar 14 and cross-member 12, are cut to a lengths of 3 x 5.4 m and 3 x 1.8 m and recessed at their cods to facilitate best contact jointing. The members arc joined by thermal fusion to form a substantially rectangular frame 10.

The membrane 20 in this instance consists of a polyethylene foil, 100 microns thick, preferably light coloured and UV-stabilised to provide long-term water exposure, stability and sun exposure. The membrane is perforated with 10mm¹ diameter circular air vents at a rate of 25m^'2. A foam sheet of 20mm thickness consisting of granules of polyureihane foam, polystyrene granules m the ratio of 3 to 1 bonded together with a polymeric binder heat bonded to the polyethylene film membrane to form the membrane 20. The membrane 20 is cut to size to fit the design of the buoyant perimeter frame 10

(i.e. 5.6 m x 2.0 m). The membrane 20 is recessed on the comers and at the fastening points of the frame member 10 as shown in Figure 9C to facilitate the overlapping of the membrane 20 around the buoyant perimeter frame 10. The membrane 20 is positioned on top of the assembled frame 10, with the membrane 20 being on the opposite side of the frame 10, and secured to the frame 10 by lapping the out$ide flaps of the membrane 20 around the perimeter frame members 10. The securing of the membrane 20 in this instance is by fastening the flaps (not shown) to the membrane 20 witih commercially available UV-stabilised plastic cable ties 30 in spacing' s gap to ensure permanent fixture of the membrane 20 to the perimeter frame 10 as shown in Figure 1 OA.

Area of complete single panel: 9.7 m²

Mass of complete single panel: 29.0 kg Length of frame profile: 18.0 m

Area of membrane fabric: 19.5 m²

Volume of filler medium: 200 L.

Total carry capacity per single panel: 18.0 kg Specific carry capacity: 1.8 kg/m²

Up-lift resistance (implanted): 22.0 kg/m².

Example 9 -Typical method of preparing a buoyant panel (See Figure 11). Buoyant Frame

A semi-rigid buoyant perimeter frame 10 is .produced from rods of recycled polyethylene and other suitable polyolefin scrap plastics by conventional extrusion techniques and formed into a 50mm diameter circular cross-section using a sizing die former. A blowing agent (azodicarbarnide) is incorporated into the extrusion of the plastic mixture to produce a closed-cell foamed rod. The bulk density of the rod is 0.65 g/cm³.

Rods are cut to the desired lengths of 2.7τn for the longitudinal perimeter frame members 1OL of the panel and 0.8m for the transverse perimeter frame members 1OT and cross-members 12. During assembly, the rods are heat welded together using a conventional plastics butt-welding technique. A clamping frame is used to maintain pressure on the welded joints until they cool.

Membrane

A filler-retaining membrane 20 comprised of lightweight commercial shadecloth (50% shade factor) is separately fabricated. A 2.7m length of 1.8m wide shadecloth is folded over itself with an overlap of 100mm. The overlap is formed on the top of the membrane. The material is then sewn into a pattern to produce two sleeves or pockets on the long side of the panel and four sleeves across the panel to produce three sections of equal size. Each section has an opening formed by the overlapping shadecloth. Sections of the sleeves axe cut away to form open sections to allow heat welding of the frame as shown in Figure 1 IA.

Filler Medium

A mixture of three components is used for the filler medium:

50% by volume of chips of expanded polystyrene.

25% by volume of chips of polyurethane (PU) flexible foam.

25% by volume of shredded carpet.

The three components are mixed together to form a homogeneous blend prior to inserting into the inner membrane bag consisting of biodegradable plastics foil. The bag is heat sealed after insertion of filler.

Assembly of Buoyant Panel Assembly consists of inserting the pre-cut rods into the sleeves of the shade cloth membrane 20 in the configuration shown in Figure 1 IB. While being held in a clamping frame, the transverse perimeter frame members 1OT and cross-members 12 are heat welded to the inside of the longitudinal perimeter frame members 10L. Clamps are used to provide pressure on the heat welded joints until the weld has cooled and set. An 8 mm hole 16 is drilled vertically through the centre of the longitudinal perimeter frame members 1 OL opposite each heat weld. The purpose of the holes 16 is to permit tethering of the panels at the time of installation.

A filler bag is placed in each section of the panel by inserting through the opening of the shadecloth pillow sleeve. Filler is then manipulated to achieve approximately equal thickness across the whole panel section. Plastic canoe clips, or the like, are pushed through the two overlapping pieces of shadecloth (pillow sleeve) to effect closure. The filling operation may take place at the time of assembly or subsequently at the site of the installation. The filler bag must be perforated after the pillow membrane 20 is closed, to allow ingress of water, the perforating process preferably taking place during the installation of the panels.

The earlier disadvantages detailed in relation to previously known buoyant panels can be minimized Or at least substantially ameliorated by the present invention.

Accordingly, in various embodiments, the panel of the present invention finds application in a number of areas including: (i) as artificial islands hosting plants, wherein the plants are useful in water treatment; (ii) as artificial islands hosting plants, wherein the plants are useful in providing bird nesting habitats and/or protective shelter for fish and crustaceans; (Hi) as artificial islands hosting plants, wherein the plants are used for beautification of the environment; (iv) for evaporation control; and (v) for wave damage control.

Where the terms "comprise", "comprises", comprised" or "comprising" are used in this specification, they arc to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.

Whenever a range is given in the specification, for example, a composition or concentration range, all intermediate ranges and sub-ranges, as well as all individual values included in the ranges given are intended to be included in the disclosure.

One of ordinary skill in the art will appreciate that materials and methods, other than those specifically exemplified can be employed in the practice of the invention without resort to undue experimentation. All art-known functional equivalents, of any such materials and methods arc intended to be included in this invention. The terms and expressions which nave been employed are used as terms of description and not of limitation, and there is no intention that in the use of such teτms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by examples, preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

Claims

The Claims defining the invention are as follows:

1. A buoyant panel for use on a body of water, the panel comprising a buoyant perimeter frame and a perforatable membrane substantially located therewithin and substantially supported thereby, the frame being constructed of a closed-cell foamed polymeric material having a substantially solid or hollow centre or a combination thereof.

2. The buoyant panel of claim 1, wherein the membrane is a pillow-like structure and comprises filler medium within the membrane.

3. The buoyant panel of claim 1 or 2, wherein the buoyant perimeter frame member is constructed from foamed polyethylene or composites of polyethylene.

4. The buoyant panel of claim 3, wherein the buoyant perimeter frame member has density of approximately 0.45 g/cm³ to approximately 0.75 g/ora³.

5. The buoyant panel of any one of claims 1 to 4, wherein the membrane comprises a porous and/or woven matrix.

6. The buoyant panel of any one of claims 1 to 5, wherein the membrane is shadecloth.

7. The buoyant panel of claim 1 , wherein the membrane is of a flat-mat construction and comprises filler medium adhered to the membrane.

8. The buoyant panel of claim 1 , wherein the flat-mat construction is in the form of a laminate comprising an upper surface layer and a lower surface layer, wherein the lower surface layer is adhered or welded to the upper surface layer.

9. The buoyant panel of claim 8, wherein the buoyant perimeter frame member is constructed from foamed polyethylene or composites of polyethylene.

10. The buoyant panel of claim 9, wherein the buoyant perimeter frame member has density of approximately 0.45 g/cτn³to approximately 0.75 g/cm³.

11. The buoyant panel of any one of claims 1 to 10, wherein the filler medium is selected from any one or more of the following: (i) Bonded or Non-bonded closed-cell Foam Chip; (ii) Bonded or Non-bonded open-cell Foam Chip; and (iϋ) Shredded Fabric/Carpet and/or Plastics Granules/Flakes.

12. A floating biosphere comprising at least one buoyant panel according to any one of claims 1 to 6 or claim 11.

13. A floating biosphere according to claim 12 comprising a plurality of buoyant panels.

14. A floating evaporation suppression panel comprising at least one buoyant panel according to any one of claims 7 to 11, wherein the filler medium is bonded by an adhesive to retain a coherent water pervious structure.