Method of forming a recyclable fiber reinforced thermoset polymer (FRP) composite material

Abstract

A method of forming a recyclable Fiber Reinforced Thermoset Polymer (FRP) composite material is disclosed. The method includes forming a cleavable imine bond-based hardener. An aromatic compound solution is mixed with a hardener to form the cleavable imine bond-based hardener. The method further includes mixing the cleavable imine bond-based hardener with a resin material and a fiber material 10 to form a homogeneous mixture. The method further includes curing the homogenous mixture form the recyclable FRP composite material.

Description

[0001] “METHOD OF FORMING A RECYCLABLE FIBER REINFORCED THERMOSET POLYMER (FRP) COMPOSITE MATERIAL” TECHNICAL FIELD

[0002]

[0001] The present disclosure relates to a field of fiber reinforced polymer (FRP) composite material. More particularly, the present disclosure relates to a method to form a cleavable recyclable high-performance epoxy thermoset polymer for recycling and renewing of FRP composites for several cycles after usage.

[0003] BACKGROUND OF THE INVENTION

[0004]

[0002] The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0005]

[0003] Fiber Reinforced Thermoset Polymer (FRP) composites generally include thermoset polymers as a primary matrix element because of their high mechanical properties and excellent interfacial bonding properties with fibers. However, such thermoset polymers are infusible and insoluble in nature, which restrict their recyclability or re-processability. Therefore, with growing production and consumption of FRP in several sectors, recycling of such FRP and its disposal based on usage, are some of the biggest challenges. Therefore, there is a requirement to develop a new polymer matrix with thermoset like performance and thermoplastic like recyclability.

[0004] Several recycling techniques are developed to overcome this challenge. However, traditional recycling processes like incineration or elevated temperature burning, pyrolysis, mechanical grinding followed by hot-press, and chemical degradation of polymer matrix via solvents. Such traditional recycling process (for example, mechanical grinding) can only recover partial materials (for example, only fiber can be recovered with degradation of properties). Further, other traditional recycling process (such as, solvent based chemical degradation) shall require a huge amount of solvents to dissolve the used FRP materials, which is costly and also detrimental to environment. Therefore, these recycling processes are not feasible at commercial scale to recover the thermoset polymer due to excessive cost and environmental concerns.

[0006]

[0005] The present disclosure is directed to overcome one or more limitations stated above or any other limitations associated with the prior art.

[0007] SUMMARY OF THE INVENTION

[0008]

[0006] The following presents a simplified summary to provide a basic understanding of some aspects of a recyclable fiber reinforced thermoset polymer (FRP) composite material. This summary is not an extensive overview and is intended to neither identify key or critical elements nor delineate the scope of such elements. Its purpose is to present some concepts of the described features in a simplified form as a prelude to the more detailed description that is presented later.

[0009]

[0007] An exemplary aspect of the disclosure may include a method of forming a recyclable Fiber Reinforced Polymer (FRP) composite material. The method mayinclude forming a cleavable imine bond-based hardener. An aromatic compound solution is mixed with a hardener to form the cleavable imine bond-based hardener. The method may further include mixing the cleavable imine bond-based hardener with a resin material and a fiber material to form a homogeneous mixture. The method may further include curing the homogenous mixture form the recyclable FRP composite material.

[0010]

[0008] Another exemplary aspect of the method may further disclose immersing, based on a usage, the recyclable FRP composite material in a container comprising the hardener. The method may further include heating the immersed recyclable FRP composite material and the hardener to form a recycled resin. The method may further include separating the fiber material from the recycled resin and form a renewed fiber material. The method may further include forming a new cleavable imine bond-based hardener, wherein the aromatic compound solution is mixed with the recycled resin to form the new cleavable imine bond-based hardener. The method may further include mixing the new cleavable imine bond-based hardener with a new resin material and the renewed fiber material to form a new homogeneous mixture. The method may further include curing the new homogenous mixture form another recyclable FRP composite material.

[0011]

[0009] Another exemplary aspect of the method may further disclose that the immersed recyclable FRP composite material and the hardener, is heated at a first temperature that ranges between 80 °C to 150 °C, to form a recycled resin.

[0012]

[0010] Another exemplary aspect of the method may further disclose that the separating involves dissolving the recyclable FRP composite material into differentamine compounds and hardener at the first temperature ranging between 80 °C to 150 °C.

[0013] [Oil] Another exemplary aspect of the method may further disclose that the recyclable FRP composite material has first mechanical properties, comprising a first tensile strength and a first tensile modulus; and the new recyclable FRP composite material has second mechanical properties, comprising a second tensile strength and a second tensile modulus. A reduction in the second mechanical properties of the new recyclable FRP composite material is less than 10% of the first mechanical properties.

[0014]

[0012] Another exemplary aspect of the method may further disclose that the aromatic compound solution is a vanillin solution.

[0015]

[0013] Another exemplary aspect of the method may further disclose that the hardener is a Triethylenetetramine (TETA) hardener, which is mixed with the vanillin solution to form the cleavable imine bond-based hardener.

[0016]

[0014] Another exemplary aspect of the method may further disclose that the hardener is formed by a reaction between multifunctional amines with hydroxy benzaldehyde compounds at an elevated temperature ranging between 25 °C to 100 °C. The elevated temperature ranges between 60 °C to 100 °C, preferably between 60 °C to 80 °C, and the multifunctional amines are selected from one of: an aliphatic material or an aromatic material.

[0017]

[0015] Another exemplary aspect of the method may further disclose that the resin material is selected from one of: an epoxy resin, a phenolic resin, a polyester resin,a silicone resin, a Melamine-Formaldehyde Resin, a polyimide material, or a thermosetting polyurethane material.

[0018]

[0016] Another exemplary aspect of the method may further disclose that the fiber material is selected from one of: a glass fiber material, a carbon fiber material, an aramid fiber material, or any other fiber material.

[0019]

[0017] Another exemplary aspect of the method may further disclose that the recyclable FRP composite material is formed based on a curing reaction between an epoxy resin, bisphenol A diglycidyl ether, the fiber material, and the cleavable imine bond-based hardener from an elevated temperature ranging between 25 °C to 150 °C.

[0020]

[0018] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

[0021]

[0019] The above summary is provided merely for the purpose of summarizing some example embodiments to provide a basic understanding of some aspects of the disclosure. Accordingly, it will be appreciated that the above-described embodiments are merely examples and should not be construed to narrow the scope or spirit of the disclosure in any way. It will be appreciated that the scope of the disclosure encompasses many potential embodiments in addition to those here summarized, some of which will be further described below.

[0022] OBJECTS OF THE INVENTION

[0020] The main object of the present disclosure is to form a recyclable Fiber Reinforced Thermoset Polymer (FRP) composite material, which shall be directly dissolvable and recyclable when heated with a commercial hardener instead of traditional dissolving methods, such as, with a large amount of solvents. Therefore, the disclosed method shall not require such large amount of solvents and the used FRP composite material may be directly recycled with the commercial hardener, with improved cost efficiency and without impacting the environment.

[0023]

[0021] Another object of the present disclosure is to form a recyclable Fiber Reinforced Thermoset Polymer (FRP) composite material, which shall easily separate the used fibers from the FRP composite material with improved quality, instead of traditional separation methods such as mechanical grinding that produces to low quality fiber extraction from the used FRP composite material. Therefore, the disclosed method shall easily extract the fibers from the used FRP composite material, with improved quality, and cost efficiency compared to traditional recycling methods.

[0024] EFFECTS / AD VANTAGES OF THE PRESENT INVENTION

[0025]

[0022] One of the advantages of the present disclosure is a simple method to dissolve the recyclable Fiber Reinforced Thermoset Polymer (FRP) composite material directly by the commercial hardener, instead of traditional dissolving methods, such as, via large amount of solvents that were used in the traditional recycling methods.

[0023] Another advantage of the present disclosure is a simple method to separate fibers from the used recyclable Fiber Reinforced Thermoset Polymer (FRP) composite material directly by the commercial hardener, instead of traditional separation methods such as , via mechanical grinding that produces to low quality fiber extraction from the used FRP composite material. Therefore, the disclosed method shall easily extract the fibers from the used FRP composite material, with improved quality, and cost efficiency compared to traditional recycling methods.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027]

[0024] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, explain the disclosed principles.

[0028]

[0025] FIGs. 1A-1B illustrate a reaction scheme for (a) commercial epoxy thermoset and (b) cleavable recyclable epoxy thermoset.

[0029]

[0026] FIG.2 illustrates a FTIR spectra to confirm formation of imine bonds from aldehyde of Vanillin.

[0030]

[0027] FIG. 3 illustrates a recycling process of the epoxy thermoset in hardener.

[0031]

[0028] FIG. 4 illustrates a fabrication of recyclable fiber reinforced thermoset polymer (FRP) composite material.

[0032]

[0029] FIGs. 5A-5B illustrate a recycling process of the recyclable fiber reinforced thermoset polymer (FRP) composite material and re-fabrication of FRP laminates.

[0030] FIG. 6 is a flowchart of a method to form the recyclable fiber reinforced thermoset polymer (FRP) composite material.

[0033] DETAILED DESCRIPTION

[0034]

[0031] Exemplary embodiments are described with reference to the accompanying drawings. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, adaptations, and other implementations are possible without departing from the spirit and scope of the disclosed embodiments. It is intended that the following detailed description be considered as exemplary only, with the true scope and spirit being indicated by the following claims. Additional illustrative embodiments are listed below.

[0035]

[0032] FIGs. 1A-1B illustrates a reaction scheme for (a) commercial epoxy thermoset and (b) cleavable recyclable epoxy thermoset. With reference to FIG. 1 A, there is shown the reaction scheme for a commercial epoxy thermoset. As described above, the present invention relates to the incorporation of cleavable and reversible covalent bonds into the epoxy thermosets to make them re-processible and recyclable for sustainable development of high-performance recyclable FRP composites and the process of fabrication thereof. The term ‘epoxy thermoset’ comprises of a crosslinking reaction product of epoxy resin with a hardener or crosslinking agent, as shown in FIG. 1. The resin material (i.e., the epoxy resin) is selected from one of: an epoxy resin, a phenolic resin, a polyester resin, a siliconeresin, a Melamine-Formaldehyde Resin, a polyimide material, or a thermosetting polyurethane material.

[0036]

[0033] The ‘FRP composite material’ comprises of a discontinuous phase fiber element dispersed in the continuous phase epoxy thermoset matrix. The fiber material (such as the discontinuous phase fiber element) is selected from one of: a glass fiber material, a carbon fiber material, or an aramid fiber material. The process aspects of the invention consist of synthesis of reversible and cleavable hardener from a multifunctional amine compound and followed by curing reaction with a common epoxy resin to form the recyclable thermoset polymer. The multifunctional amines are selected from one of: an aliphatic material or an aromatic material.

[0037]

[0034] This recyclable epoxy system is utilized to fabrication of FRP composite with a synthetic fiber. The invented thermoset based FRP composite exhibited similar performance like commercial epoxy based FRP composites. The most interestingly the present invented thermoset polymer or the matrix element of the FRP composite can be dissolved in amine-based compounds or hardeners of epoxy thermoset. Therefore, both the elements, fiber and thermoset polymer can be completely recovered from the FRP composite and utilized for re-fabrication.

[0038]

[0035] The cleavable and recyclable epoxy thermoset is prepared by curing or crosslinking reaction between an epoxy resin and an imine bond-based hardener at an elevated temperature (from 25 °C to 150 °C).

[0039]

[0036] With reference to FIG. IB, there is shown the reaction scheme for the cleavable recyclable epoxy thermoset. FIG. IB shows the synthesis procedure for cleavable and recyclable epoxy thermoset. The imine bond-based hardener isprepared through reaction between a multifunctional amine compound and a hydroxy benzaldehyde compound at an elevated temperature in the range of 60-100

[0040]

[0037] FIG.2 illustrates a FTIR spectra to confirm formation of imine bonds from aldehyde of Vanillin. FIG. 2 is described in conjunction with elements from FIGs.

[0041] 1A-1B. With reference to FIG. 2, there is shown the FTIR spectra. The formation of imine bond in the hardener is confirmed from the FTIR study as shown in FIG.

[0042] 2. To evaluate the mechanical properties the mixture of the epoxy resin and hardener is poured into a Teflon-based mold, as shown in FIG. 1A, and followed by cured. Comparative tensile properties of a commercial epoxy thermoset of bisphenol A diglycidyl ether and recyclable epoxy of the present invention are given in Table 1. Both the thermosets exhibit similar tensile properties, but the present invented thermoset can be recycled. The invented thermoset can be dissolved in any amine or multifunctional amine compounds, even in the amine-based epoxy hardener itself at an elevated temperature (-100 °C). The dissolved thermoset can be again renewed to recyclable epoxy thermoset by treating with a hydroxy benzaldehyde compound and followed by curing with epoxy resin. The recycling process is shown in FIG. 3.Table 1: Comparative properties of commercial epoxy and recyclable epoxy thermosets.

[0043]

[0044]

[0038] FIG. 3 illustrates a recycling process of the epoxy thermoset in hardener.

[0045] FIG. 3 is described in conjunction with elements from FIGs. 1A-1B and FIG. 2.

[0046] With reference to FIG. 3, there is shown the recycling process of the epoxy thermoset in hardener. The epoxy thermoset is dissolved in amine hardener compounds of epoxy resin including TETA at a temperature around 80-150 °C.

[0047] Then the dissolved resin is treated with a hydroxy benzaldehyde compound like vanillin and followed by curing with bisphenol A diglycidyl ether at 25-120 °C to prepare new recyclable thermoset.

[0048]

[0039] FIG. 4 illustrates a fabrication of recyclable fiber reinforced thermoset polymer (FRP) composite material. FIG. 4 is described in conjunction with elements from FIGs. 1A-1B, FIG. 2 and FIG. 3. With reference to FIG. 4, there isshown the recycling process of the epoxy thermoset in hardener. The FRP composites are fabricated by hand lay-up technique, where synthetic fibers such as glass and carbon are utilized to fabricate FRP laminates with recyclable epoxy thermoset, as shown in FIG. 4. The mixture of epoxy resin and hardener is spread on the fiber layers and cured under hot-press or room temperature and followed by post-curing at 80-150 °C. The commercial epoxy thermoset-based FRP is also fabricated by similar process and compared with the recyclable epoxy-based FRP composite. Comparative tensile properties of commercial and recyclable epoxy thermosets based FRP composites are given in Table 2.

[0049] Table 2: Comparative properties of commercial epoxy and recyclable epoxy FRP composites with glass fiber.

[0050]

[0051]

[0040] Both commercial and recyclable epoxy thermosets based FRP laminates possess similar tensile properties. However, commercial epoxy thermoset based FRP cannot be recyclable, as commercial epoxy thermoset is insoluble andinfusible. Whereas reversible cleavable imine linkage containing epoxy thermoset is recyclable and therefore, the FRP composite is also recyclable. In this case both epoxy thermoset and fiber elements can completely recover from the composite and then can reuse for same purpose.

[0052]

[0041] FIGs. 5A-5B illustrate a recycling process of the recyclable fiber reinforced thermoset polymer (FRP) composite material and re-fabrication of FRP laminates. FIGs. 5A-5B are described in conjunction with elements from FIGs. 1A-1B, FIG. 2 and FIG. 3. With reference to FIG. 5, there is shown the recycling process of the epoxy thermoset in hardener. The recycling process is shown in Fig.

[0053] 5. As mentioned above that the epoxy thermoset can be dissolved in amine hardener of the epoxy thermoset at an elevated temperature. So, the resin and fiber elements of the FRP laminate can be separated in an amine hardener. The extracted epoxy can be retreated with a hydroxy benzaldehyde compound and followed by mixing with epoxy resin to refabricate FRP composite with recycled fibers. The process can be repeated many times and shows similar mechanical properties as shown in Table 3.

[0054] Table 3: Mechanical property of FRP composite after different cycles of recycling.

[0055]

[0056]

[0057]

[0042] As shown in table 3, the recyclable FRP composite material has first mechanical properties, comprising a first tensile strength (for example, 460±10 Mpa) and a first tensile modulus (for example, 20±l GPa); and the new recyclable FRP composite material has second mechanical properties, comprising a second tensile strength (for example, 410±10 Mpa) and a second tensile modulus (for example, 16.5±1.5 GPa). A reduction in the second mechanical properties of the new recyclable FRP composite material is less than 10% of the first mechanical properties.

[0058]

[0043] FIG. 6 is a flowchart of a method to form the recyclable fiber reinforced thermoset polymer (FRP) composite material. FIG. 6 is described in conjunction with reference from FIGs. 1A-1B, FIG. 2, FIG. 3, FIG. 4, and FIGs. 5A-5B. With reference to FIG. 6, there is shown a flowchart (600) that may correspond to a method to form the recyclable fiber reinforced thermoset polymer (FRP) composite material. Further, for ease of explanation, in the embodiments described below, the method may be implemented by a system, an operator or a manufacturer, as described with reference to Figs. 1A-5B. The method illustrated in the flowchart may start from step (602).

[0059]

[0044] At step (602), a cleavable imine bond-based hardener may be formed, wherein an aromatic compound solution is mixed with a hardener to form the cleavable imine bond-based hardener. In an embodiment, the operator may form the cleavable imine bond-based hardener.

[0045] At step (604), the cleavable imine bond-based hardener may be mixed with a resin material and a fiber material to form a homogeneous mixture. In an embodiment, the operator may mix the cleavable imine bond-based hardener with the resin material.

[0060]

[0046] At step (606), the homogenous mixture may be cured form the recyclable FRP composite material. In an embodiment, the operator may cure the homogeneous mixture to form the recyclable FRP composite material.

[0061]

[0047] The order in which the flowchart (600) is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the flowchart (600) or alternate methods. Additionally, individual blocks may be deleted from the flowchart (600) without departing from the spirit and scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

[0062] EXAMPLES

[0063]

[0048] Example 1: Cleavable and reversible imine bond containing epoxy hardener is synthesized by reaction of a multifunctional amine compound, triethylenetetramine (TETA) with a hydroxy benzaldehyde compound, vanillin. The reaction mixture is refluxed under ethanol or isopropanol solvent.

[0064]

[0049] Example 2: Cleavable and reversible imine bond containing epoxy hardener is synthesized by reaction of a multifunctional amine compound,hexamethylenediamine with a hydroxy benzaldehyde compound, vanillin. The reaction mixture is refluxed under ethanol or isopropanol solvent.

[0065]

[0050] Example 3: Cleavable and reversible imine bond containing epoxy hardener is synthesized by reaction of an aromatic multifunctional amine compound, p-phenylenediamine with a hydroxy benzaldehyde compound, vanillin. The reaction mixture is refluxed under ethanol or isopropanol solvent.

[0066]

[0051] Example 4: The cleavable and recyclable epoxy thermoset is prepared by curing or crosslinking reaction between an epoxy resin, bisphenol A diglycidyl ether and an imine bond-based hardener at room temperature (25-30 °C).

[0067]

[0052] Example 5: The cleavable and recyclable epoxy thermoset is prepared by curing or crosslinking reaction between an epoxy resin, bisphenol A diglycidyl ether and an imine bond-based hardener at 100 °C.

[0068]

[0053] Example 6: The cleavable and recyclable epoxy thermoset is prepared by curing or crosslinking reaction between an epoxy resin, bisphenol A diglycidyl ether and an imine bond-based hardener at 120 °C.

[0069]

[0054] Example 7: The cleavable and recyclable epoxy thermoset is prepared by curing or crosslinking reaction between an epoxy resin, bisphenol A diglycidyl ether and an imine bond-based hardener at 150 °C.

[0070]

[0055] Example 8: The cleavable and recyclable epoxy thermoset based FRP composites are fabricated by hand lay-up technique using glass and carbon fibers at room temperature to 150 °C.

[0056] Example 9: The cleavable and recyclable epoxy thermoset based FRP composites are fabricated by hand lay-up technique using glass and carbon fibers at a temperature range 80-120 °C using hot-press.

[0071]

[0057] Example 10: The cleavable epoxy thermoset is recycled through dissolving the thermoset into different amine compounds like ethylenediamine, TETA, and the like, at a temperature around 100 °C. The dissolved resin is treated with a hydroxy benzaldehyde compound, vanillin and followed by curing with bisphenol A diglycidyl ether to prepare new recyclable thermoset.

[0072]

[0058] Example 11: FRP composites are recycled through immersing the composites into different amine compounds like ethylenediamine, TETA, and the like, at a temperature around 100 °C. Fibers are extracted from the solution and cleaned with water followed by drying at oven for further reuse. The dissolved matrix is treated with a hydroxy benzaldehyde compound, vanillin and followed by mixing with bisphenol A diglycidyl ether to prepare new recyclable matrix. Then recycled fibers and matrix are again reassembled to fabricate recycled FRP by same hand lay-up technique. The recycling process is repeated several cycles.

[0073]

[0001] The illustrated steps are set out to explain the exemplary embodiments shown, and it may be anticipated that ongoing technological development will change the way particular functions are performed. These examples are presented herein for purposes of illustration, and not limitation. Further, the boundaries of the functional building blocks have been arbitrarily defined herein for the convenienceof the description. Alternative boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0074]

[0002] The foregoing method descriptions and the process flow diagrams are provided merely as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As may be appreciated by one of skill in the art the order of steps in the foregoing embodiments may be performed in any order. Words such as “thereafter,” “then,” “next,” and the like, are not intended to limit the order of the steps; these words are simply used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an” or “the” is not to be construed as limiting the element to the singular.

[0075]

[0003] Various embodiments of the present invention are described with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure may satisfy applicable legal requirements. The term “or” is used herein in both the alternative and conjunctive sense, unless otherwise indicated. The terms “illustrative,” “example,” and “exemplary” are used to be examples with no indication of quality level. Like numbers refer to like elements throughout.

[0076]

[0004] The phrases “in an embodiment,” “in one embodiment,” “according to one embodiment,” and the like generally mean that the feature, structure, or characteristic following the phrase may be included in at least one embodiment ofthe present disclosure and may be included in more than one embodiment of the present disclosure (importantly, such phrases do not necessarily refer to the same embodiment).

[0077]

[0005] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0078]

[0006] If the specification states a component or feature “can,” “may,” “could,” “should,” “would,” “preferably,” “possibly,” “typically,” “optionally,” “for example,” “often,” or “might” (or other such language) be included or have a characteristic, that component or feature is not required to be included or to have the characteristic. Such component or feature may be optionally included in some embodiments, or it may be excluded.

[0079]

[0007] In some example embodiments, certain ones of the operations herein may be modified or further amplified as described below. Moreover, in some embodiments additional optional operations may also be included. It should be appreciated that each of the modifications, optional additions or amplifications described herein may be included with the operations herein either alone or in combination with any others among the features described herein.

[0080]

[0008] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of teachings presented in the foregoing descriptions and the associated drawings. Although the figures only show certain components of theapparatus and systems described herein, it is understood that various other components may be used in conjunction with the supply management system. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, the steps in the method described above may not necessarily occur in the order depicted in the accompanying diagrams, and in some cases one or more of the steps depicted may occur substantially simultaneously, or additional steps may be involved. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

I / We Claim:

1. A method of forming a recyclable Fiber Reinforced Thermoset Polymer (FRP) composite material, the method comprising:forming a cleavable imine bond-based hardener, wherein an aromatic compound solution is mixed with a hardener to form the cleavable imine bond-based hardener;mixing the cleavable imine bond-based hardener with a resin material and a fiber material to form a homogeneous mixture; andcuring the homogenous mixture form the recyclable FRP composite material.

2. The method as claimed in claim 1, the method further comprising:immersing, based on a usage, the recyclable FRP composite material in a container comprising the hardener ;heating the immersed recyclable FRP composite material and the hardener to form a recycled resin;separating the fiber material from the recycled resin and form a renewed fiber material;forming a new cleavable imine bond-based hardener, wherein the aromatic compound solution is mixed with the recycled resin to form the new cleavable imine bond-based hardener;mixing the new cleavable imine bond-based hardener with a new resin material and the renewed fiber material to form a new homogeneous mixture; andcuring the new homogenous mixture form another recyclable Fiber Reinforced Thermoset Polymer composite material.

3. The method as claimed in claim 2, wherein the immersed recyclable FRP composite material and the hardener, is heated at a first temperature that ranges between 80 °C to 150 °C, to form the recycled resin.

4. The method as claimed in claim 2, the separating involves dissolving the recyclable FRP composite material into different amine compounds and hardener at a first temperature ranging between 80 °C to 150 °C.

5. The method as claimed in claim 2, wherein,the recyclable FRP composite material has first mechanical properties, comprising a first tensile strength and a first tensile modulus; andthe another recyclable FRP composite material has second mechanical properties, comprising a second tensile strength and a second tensile modulus, wherein a reduction in the second mechanical properties of the another recyclable FRP composite material is less than 10% of the first mechanical properties.

6. The method as claimed in claim 1, wherein the aromatic compound solution is a vanillin solution.

7. The method as claimed in claim 6, wherein the hardener is a Triethylenetetramine (TETA) hardener, which is mixed with the vanillin solution to form the cleavable imine bond-based hardener.

8. The method as claimed in claim 1, wherein the hardener is formed by a reaction between multifunctional amines with hydroxy benzaldehyde compounds at an elevated temperature ranging between 25 °C to 100 °C.

9. The method as claimed in claim 8, wherein the elevated temperature ranges between 60 °C to 80 °C.

10. The method as claimed in claim 8, wherein the multifunctional amines are selected from one of: an aliphatic material or an aromatic material.

11. The method as claimed in claim 1, wherein the resin material is selected from one of: an epoxy resin, a phenolic resin, a polyester resin, a silicone resin, a Melamine-Formaldehyde Resin, a polyimide material, or a thermosetting polyurethane material.

12. The method as claimed in claim 1, wherein the fiber material is selected from one of: a glass fiber material, a carbon fiber material, or an aramid fiber material.

13. The method as claimed in claim 1, where the recyclable FRP composite material is formed based on a curing reaction between an epoxy resin, bisphenol A diglycidyl ether, the fiber material, and the cleavable imine bond-based hardener from an elevated temperature ranging between 25 °C to 150 °C.

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