Description:TECHNICAL FIELD
[0001] The present disclosure relates to a field of upcycling of polymers. Moreover, the present disclosure relates to a recyclable polymer and a method of production of the recyclable polymer.
BACKGROUND
Thermoplastic polyolefins (e.g., polyethylene (PE) and polypropylene (PP)) are widely used due to their low cost, lightweight nature, and mechanical durability. The thermoplastic polyolefins find extensive use in packaging, consumer goods, automotive components, and various industrial applications. However, post-use disposal of the thermoplastic polyolefins has become a major environmental concern. The thermoplastic polyolefins persist in landfills, pollute terrestrial and aquatic ecosystems, and contribute to the generation of microplastics and harmful emissions when incinerated. With rising volumes of plastic waste, including used milk pouches, containers, and packaging materials, accumulating in municipal solid waste. The degradation of the thermoplastic polyolefins during their first service life and through repeated recycling further reduces their usability and commercial value, creating an urgent need for advanced upcycling methods.
Conventional recycling technologies primarily focus on mechanical processing, which often leads to a decline in material performance. Recycled polyolefins suffer from reduced tensile strength, brittleness, and a loss in elongation properties. The deterioration results from chain scission and oxidative degradation that occurs during use and remelting. Consequently, most recycled TPOs are downgraded into low-end applications (phenomenon known as downcycling). Chemical recycling alternatives have shown promise but are often energy-intensive, involve complex processes, or yield materials with inconsistent properties. Furthermore, traditional approaches end to produce stiff, glassy materials that lack the flexibility required for many practical uses. The inherent rigidity limits their adoption in applications requiring both toughness and processability. Likewise, some other systems typically lack structural robustness and long-term mechanical resilience.
Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks.
SUMMARY
[0002] The present disclosure provides a recyclable polymer and a method of production of the recyclable polymer. The present disclosure addresses the technical problem of how to efficiently recycle and upcycle post-consumer thermoplastic polyolefin (TPO) waste in a manner that preserves mechanical performance across multiple reprocessing cycles. An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in the prior art and provides an improved recyclable polymer that integrates dynamic covalent networks with reversible ionic crosslinking. The dual crosslinking approach enables the creation of a recyclable and reprocessable polymer network that simultaneously exhibits enhanced mechanical strength and flexibility.
[0003] One or more objectives of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.
[0004] In one aspect, the present disclosure provides a method of production of a recyclable polymer. The method includes melt mixing a recycled polyolefin with a monomer comprising an anhydride group in the presence of an initiator, a co-agent, and an antioxidant to form a grafted polyolefin comprising grafted anhydride moieties. The method further includes melt blending the grafted polyolefin with an ionic crosslinker to form the recyclable polymer having a dual crosslinked network.
The ionic crosslinker comprises multivalent metal ions and hydroxyl groups. The hydroxyl groups form ester bonds with the grafted anhydride moieties and the multivalent metal ions form ionic crosslinks with the grafted polyolefin, and wherein the ester bonds undergo dynamic bond exchange, and the ionic crosslinks exhibit reversible bond formation for reprocessability.
[0005] Incorporation of a dual crosslinking (comprising both dynamic covalent bonds and reversible ionic interactions) enables the formation of a polymer network that is not only structurally robust but also thermally reprocessable. The grafting of anhydride groups onto the recycled polyolefin backbone improves chemical reactivity and compatibility with subsequent crosslinking agents. The use of multivalent metal-based ionic crosslinkers (e.g., zinc gluconate) introduces hydroxyl groups that react with the grafted anhydride moieties to form ester bonds, which are capable of dynamic bond exchange reactions. The dynamic covalent interactions impart reprocessability and mechanical strength to the reversible polymer. Concurrently, the multivalent metal ions engage in reversible ionic bonding with the grafted polyolefin chains, forming a physically crosslinked network that enhances flexibility and toughness. The unique dual network architecture ensures that the mechanical performance of the recyclable polymer, particularly its tensile strength and elongation at break, is preserved or even improved over multiple recycling cycles. Additionally, the method is compatible with standard melt extrusion techniques, making it scalable for industrial implementation without the need for specialised equipment. Further, the method delivers a recyclable polymer with a superior balance of mechanical resilience, flexibility, and processability.
[0006] In another aspect, the present disclosure provides the recyclable polymer.
[0007] The recyclable polymer achieves all the advantages and technical effects of the method of production of the recyclable polymer.
[0008] It is to be appreciated that all the aforementioned implementation forms can be combined. All steps that are performed by the various entities described in the present application, as well as the functionalities described to be performed by the various entities, are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
[0009] Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
[0011] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG.1 is a flowchart illustrating a method of production of a recyclable polymer, in accordance with an embodiment of the present disclosure;
FIG. 2A is a flowchart illustrating a reaction mechanism for the formation of grafted polyolefin, in accordance with an embodiment of the present disclosure;
FIG. 2B is a flowchart illustrating a reaction mechanism for the formation of the recycled polymer, in accordance with an embodiment of the present disclosure;
FIG. 3 is a graphical representation illustrating comparative analysis of the mechanical properties of recycled polymers, in accordance with an embodiment of the present disclosure;
FIG. 4 is a graphical representation illustrating Fourier transform infrared (FTIR) spectroscopy comparison between different recycled polymers, in accordance with an embodiment of the present disclosure; and
FIG. 5 is a graphical representation illustrating a differential scanning calorimetry (DSC) thermal analysis of the recyclable polymers, in accordance with an embodiment of the present disclosure.
[0012] In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION OF EMBODIMENTS
[0013] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
[0014] FIG.1 is a flowchart illustrating a method of production of a recyclable polymer, in accordance with an embodiment of the present disclosure. With reference to FIG. 1, there is shown a flowchart illustrating the method 100 for production of a recyclable polymer. The method 100 includes steps 102 to 104. There is provided the method 100 for production of the recyclable polymer.
[0015] At step 102, the method 100 includes melt mixing a recycled polyolefin with a monomer comprising an anhydride group in the presence of an initiator, a co-agent, and an antioxidant to form a grafted polyolefin comprising grafted anhydride moieties. The initiator is a chemical compound that generates free radicals when subjected to thermal energy during the melt mixing process and initiates the grafting reaction between the recycled polyolefin and the monomer. The initiator functions by decomposing at elevated temperatures to produce reactive radical species that abstract hydrogen atoms from the polyolefin backbone and creating polyolefin-derived macroradicals that serve as active sites for grafting. In an implementation, the initiator may be dicumyl peroxide (DCP), which exhibits appropriate decomposition kinetics at the processing temperature of 180-200°C to provide controlled radical generation without causing excessive polymer degradation. In an example the recycled polyolefin may be post-consumer recycled polypropylene (PP) or polyethylene (PE).
[0016] The co-agent is a reactive monomer that participates in the grafting process by preferentially reacting with polyolefin-derived macroradicals to form more stable and reactive intermediates that subsequently copolymerize with the monomer comprising the anhydride group. The co-agent serves the dual technical function of enhancing grafting efficiency and suppressing chain scission of the recycled polyolefin during melt processing. In some implementations, the co-agent is styrene. The styrene reacts with macroradicals derived from the recycled polyolefin to form copolymer macroradicals comprising styrene units and polyolefin units that exhibit enhanced reactivity toward the anhydride monomer compared to unmodified polyolefin macroradicals.
[0017] The antioxidant is a stabilizing agent that prevents oxidative degradation of the recycled polyolefin during the high-temperature melt mixing process by scavenging free radicals and other reactive oxygen species that may cause unwanted side reactions, chain scission, and polymer deterioration. The antioxidant maintains the structural integrity of the polymer chains while allowing the desired grafting reactions to proceed. In an implementation, the antioxidant is Irganox 1010. Irganox 1010 is a hindered phenolic antioxidant that provides effective thermal stability and radical scavenging capability at the processing temperatures of 180-200°C without interfering with the intended grafting mechanism between the polyolefin, co-agent, and anhydride monomer. In some implementations, the antioxidant may be octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,3',3',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl) tri-p-cresol or combinations thereof.
[0018] Prior to melt mixing, the recycled polyolefin undergoes treatment to meet processing conditions. The recycled polyolefin (e.g., polypropylene (PP) or polyethylene (PE)) is first cleaned with an aqueous detergent solution to remove surface contaminants. The cleaned recycled polyolefin is then subjected to repeated washing in cold water to eliminate detergent residues. In some examples, the cleaned recycled polyolefin is then dried in a vacuum oven at 70°C for six hours to remove moisture that may interfere with the grafting reactions. After drying, the recycled polyolefin is chopped into small pieces to facilitate uniform feeding and mixing in a twin-screw extruder. The twin-screw extruder includes co-rotating conical screws and a recirculation system for controlling material residence time. The twin-screw allows for precise control over processing conditions and material flow. The co-rotating conical screws provide efficient mixing and heat transfer while the recirculation system enables controlled residence time management and ensure uniform distribution of all components throughout the polymer matrix.
[0019] In some examples, the twin-screw extruder operates at a screw speed of 100-150 rpm to provide optimal shear mixing for uniform component distribution while avoiding excessive mechanical degradation of the polymer chains. The processing time is controlled to 1-5 minutes through the recirculation system. The control of processing time allows sufficient time for complete grafting reactions while preventing over-processing.
[0020] During the melt mixing process, a sequence of chemical reactions occurs to form the grafted polyolefin. For example, initially, the dicumyl peroxide initiator decomposes at the processing temperature to generate peroxy radicals, which abstract hydrogen atoms from the recycled polyolefin backbone to create polyolefin-derived macroradicals. The co-agent (e.g., styrene) then preferentially reacts with the polyolefin-derived macroradicals to form copolymer macroradicals comprising styrene units and polyolefin units. The styrene-containing intermediates subsequently react with the monomer through copolymerization that resulting in grafted anhydride moieties attached to the polyolefin backbone.
[0021] Throughout the melt mixing process, parameters are continuously monitored to ensure grafting efficiency. The melt temperature is maintained within the specified range of 180-200°C using temperature controllers and thermocouples positioned at multiple locations along the extruder barrel. The torque and power consumption are monitored to assess the viscosity changes during grafting, while the residence time is controlled through the recirculation system to achieve the desired grafting yield. Irganox 1010 antioxidant prevents oxidative degradation during the high-temperature processing.
[0022] The melt mixing process produces the grafted polyolefin comprising grafted anhydride moieties that are uniformly distributed along the polymer backbone. The styrene-assisted grafting mechanism achieves a grafting yield significantly higher than conventional direct grafting methods, while maintaining a controlled melt flow index (MFI). Following the grafting process, the grafted polyolefin demonstrates increased MFI due to chain scission effects during grafting, but this is subsequently reduced to optimal levels through the styrene co-agent mechanism that suppresses degradation while enhancing grafting efficiency.
[0023] At step 104, the method 100 includes melt blending the grafted polyolefin with an ionic crosslinker to form the recyclable polymer having a dual crosslinked network. The ionic crosslinker is a chemical compound that creates crosslinks between polymer chains through ionic interactions. The ionic crosslinker includes multivalent metal cations that form coordinate bonds or electrostatic interactions with electron-rich sites along polymer backbones. The ionic crosslinker establishes reversible associations that can dissociate and re-form under appropriate conditions.
[0024] The melt blending process is conducted using the twin-screw extruder that includes co-rotating conical screws and a recirculation system for controlling material residence time. The grafted polyolefin is maintained at processing temperature to preserve its molten state and reactivity, while the ionic crosslinker (e.g., zinc gluconate) is fed separately into the twin-screw extruder through a dedicated feeding mechanism to ensure controlled introduction and prevent premature reactions. In an implementation, the preferred composition for melt blending comprises 70-99 weight per cent of the grafted polyolefin and 1 to 30 weight per cent of the ionic crosslinker.
[0025] The thermal and mechanical processing conditions are carefully controlled to achieve optimal crosslinking while maintaining material integrity, with the melt blending conducted at a temperature range of 180 to 200 degrees Celsius, preferably 180 degrees Celsius, which provides sufficient thermal energy for crosslinking reactions without causing thermal degradation of the polymer matrix. The extruder operates at a screw speed of 100 to 150 revolutions per minute that provides adequate distributive and dispersive mixing for uniform distribution of the ionic crosslinker throughout the grafted polyolefin while promoting intimate contact between reactive groups. The processing time is precisely controlled between 1 to 5 minutes through the recirculation system to allow complete crosslinking reactions while preventing over-processing that could degrade the network structure or cause excessive gelation.
[0026] During the melt blending process, two distinct but simultaneous crosslinking mechanisms occur to form the dual crosslinked network characteristic of the recyclable polymer. The primary mechanism involves nucleophilic ring-opening reactions where the hydroxyl groups of the zinc gluconate ionic crosslinker attack the grafted anhydride moieties on the polyolefin backbone, forming ester bonds that create covalent linkages between the ionic crosslinker and the polymer chains. The ester bonds are capable of undergoing transesterification reactions at the processing temperature that establish a dynamic covalent adaptable network that allows for bond exchange and structural rearrangement while maintaining network connectivity. Simultaneously, the multivalent ions present in the ionic crosslinker establish ionic interactions with electron-rich sites along the grafted polyolefin chains, forming reversible ionic crosslinks that contribute to the overall network structure while retaining the ability to dissociate and reform under thermal or mechanical stress, thereby providing the material with both structural integrity and reprocessability.
[0027] The formation of the dual crosslinked network proceeds through the progressive development of both covalent and ionic crosslinks throughout the polymer matrix, with the concentration of ester bonds increasing as the reaction between hydroxyl groups and anhydride moieties continues, while ionic crosslinks develop through the association of multivalent metal ions with the polymer chains. The resulting network structure combines the stability and strength characteristics of covalent bonds with the reversibility and flexibility of ionic interactions, creating a unique hybrid system that provides the recyclable polymer. The process is continuously monitored through real-time measurement of torque, temperature, and power consumption, with torque increases indicating the development of crosslinks and increased viscosity, while temperature control systems maintain processing conditions within the specified range to ensure consistent crosslinking kinetics and optimal network formation.
[0028] The melt blending process results in the production of a recyclable polymer having a dual crosslinked network that exhibits superior mechanical properties compared to conventional recycled polyolefins. The recyclable polymer demonstrates tensile strength of 30 to 35 megapascals and elongation at break of 35 to 50 per cent, which represents a significant achievement in simultaneously enhancing both strength and flexibility characteristics.
[0029] In some implementations, the recyclable polymer may be blended with any virgin or waste polyolefins and filled polyolefins (fillers like silica, carbon black, glass fibre etc). Experimentally, it has been observed that there is a reduction in MFI after the formation of the recycled polymer. The systematic reduction in MFI observed in the recyclable polymer formulations compared to the recycled polyolefins indicates the formation of the crosslinked network structure and enables advanced manufacturing applications, including 3D printing capabilities.
[0030] The controlled reduction in melt flow index to a range (e.g., 6-8 g/10 min) provides rheological properties for 3D printing applications, where the recyclable polymer exhibits superior printability characteristics compared to conventional recycled polyolefins that tend to flow excessively and create dimensional instability during the printing process. The lower MFI value indicates higher melt viscosity and reduced flow behaviour that enables precise extrusion control and layer-by-layer deposition essential for maintaining geometric accuracy and surface quality in 3D printed components. The dual crosslinked network structure of the recyclable polymer provides thixotropic behaviour where the material exhibits controlled flow under the shear conditions present in the 3D printer extruder, while rapidly developing sufficient viscosity upon deposition to maintain shape integrity and prevent layer deformation or sagging during the printing process. The dynamic nature of both the ester bonds and ionic crosslinks allows for temporary network disruption under the processing conditions in the 3D printer hot end and enables smooth extrusion and flow. Further, rapid network reformation occurs upon cooling and solidification that providing excellent interlayer adhesion and structural integrity in the final printed component.
[0031] Further, the optimised melt viscosity range enables enhanced injection molding performance with reduced warpage, improved surface finish, and better mold filling characteristics compared to high-MFI materials that may exhibit excessive flow and poor dimensional control. The dual crosslinked network of the recyclable polymer provides temperature-dependent viscosity control where the material exhibits appropriate flow characteristics at processing temperatures while developing enhanced viscosity upon cooling, enabling complex part geometries and thin-wall applications. Furthermore, the controlled MFI combined with the enhanced mechanical properties including tensile strength of 33 MPa and elongation at break of 48% creates the recyclable polymer that is suitable for demanding structural applications in automotive, packaging, and consumer goods sectors, where the combination of processability, performance, and sustainability provides significant advantages over conventional materials.
[0032] FIG. 2A is flowchart illustrating a reaction mechanism for the formation of grafted polyolefin, in accordance with an embodiment of the present disclosure. FIG. 2A is described in conjunction with FIG. 1. With reference to FIG. 2A, there is shown a flowchart 200A that includes a series of operations from 202A to 204A.
[0033] At operation 202A, the recycled polyolefin backbone represented by the polymer chain with repeating units where R groups indicate the side chains (R = H for polyethylene, R = CH₃ for polypropylene) reacts with including styrene monomer (Ph-vinyl group), maleic anhydride (cyclic anhydride structure), and dicumyl peroxide initiator (represented as Ph-CO-O-O-CO-Ph structure with tertiary carbon centres) to create a first mixture. The styrene serving as the co-agent for enhanced grafting efficiency, maleic anhydride providing the anhydride functionality for subsequent crosslinking, and dicumyl peroxide functions as the thermal radical initiator that decomposes at processing temperatures to generate the reactive species necessary for initiating the grafting mechanism. Further, Irganox 1010 is added to the first mixture at 180 degrees Celsius for 2 mins inside the twin- screw extruder.
[0034] At operation 204A, at 180°C, the peroxide bonds of the dicumyl peroxide undergo homolytic cleavage to generate two cumyloxy radicals (Ph-C(CH₃) ₂-O•). The cumyloxy radicals are highly reactive species that initiate the grafting mechanism by abstracting hydrogen atoms from the post-consumer recycled polyolefin (PCR PO) backbone through a hydrogen abstraction mechanism. The hydrogen abstraction occurs preferentially at tertiary carbon sites in polypropylene or secondary carbon sites in polyethylene that creates polyolefin-derived macroradicals along the polymer backbone. The presence of Irganox 1010 antioxidant prevents unwanted oxidative side reactions and allows the desired grafting reactions to proceed, with the hindered phenolic structure scavenging harmful oxygen radicals that may cause chain scission or thermal degradation during the high-temperature processing.
[0035] The styrene preferentially reacts with the polyolefin-derived macroradicals before they can undergo competing reactions such as chain scission or reaction with maleic anhydride. When a polyolefin macroradical is formed through hydrogen abstraction, the styrene rapidly adds to this radical site due to its high reactivity and favourable kinetics, forming a more stable styrene-terminated macroradical (polymer-CH₂-CH•-Ph). The addition of styrene is thermodynamically and kinetically favoured because the resulting benzyl-type radical is stabilised by resonance with the aromatic ring, making it much more stable than the original alkyl macroradical on the polyolefin backbone. The formation of the stabilized styrene-terminated macroradicals serves two critical functions: first, it prevents the polyolefin macroradicals from undergoing β-scission reactions that may cause chain degradation and molecular weight reduction.
[0036] Following the formation of styrene-terminated macroradicals, the stabilized radical species undergo copolymerization with maleic anhydride monomer to form the grafted anhydride functionalities along the polymer backbone. The styrene-terminated macroradicals exhibit significantly enhanced reactivity toward maleic anhydride due to the electron-donating nature of the styrene unit and the stability of the benzyl radical, enabling efficient copolymerization under the processing conditions. The copolymerization proceeds through a radical mechanism where the styrene-terminated macroradical attacks the vinyl carbon of maleic anhydride, forming a new C-C bond and creating a maleic anhydride-terminated radical. The newly formed radical can either terminate through combination or disproportionation reactions, or it can react with additional styrene or maleic anhydride units to form short copolymer branches containing both styrene and maleic anhydride units. The alternating tendency between styrene and maleic anhydride due to their different reactivity ratios ensures efficient incorporation of anhydride functionality while the styrene units provide steric stabilisation and enhanced grafting efficiency.
[0037] Further, the grafted polyolefin contains grafted anhydride moieties uniformly distributed along the recycled polyolefin backbone through the styrene-assisted grafting mechanism. The styrene units serve as spacers and stabilising groups that enhance the reactivity of the grafted anhydride moieties toward subsequent crosslinking reactions, while also improving the mechanical properties of the grafted polymer compared to direct maleic anhydride grafting. The anhydride rings retain their reactive character and are available for ring-opening reactions with nucleophiles such as hydroxyl groups, making them ideal for the subsequent crosslinking step with zinc gluconate ionic crosslinker. The processing conditions of 150 rpm for 2 minutes at 180°C ensure complete reaction while the controlled residence time prevents over-processing or degradation, resulting in a grafted polyolefin with optimal grafting yield and maintained molecular weight as evidenced by the controlled melt flow index of 25 g/10 min.
[0038] FIG. 2B is flowchart illustrating a reaction mechanism for the formation of the recycled polymer, in accordance with an embodiment of the present disclosure. FIG. 2B is described in conjunction with elements of FIGs. 1 and 2A. With reference to FIG. 2B, there is shown a flowchart 200B that includes a series of operations from 202B to 204B.
[0039] At operation 202B, the grafted polyolefin 204A undergoes dual crosslinking with a zinc gluconate 206B at processing temperatures of 180-200°C to form the recyclable polymer having a dual crosslinked network. The process begins with the grafted polyolefin containing uniformly distributed grafted anhydride moieties and styrene units along the recycled polyolefin backbone being fed into the twin-screw extruder in molten state, maintaining the reactive anhydride functionality necessary for crosslinking reactions. Simultaneously, zinc gluconate ionic crosslinker is introduced through a separate feeding mechanism, with the gluconate structure containing multiple hydroxyl groups (-OH) coordinated around the central zinc ion (Zn²⁺) 206B. Under the controlled thermal and mechanical conditions of the melt blending process, two distinct but simultaneous crosslinking mechanisms are initiated: the primary mechanism involves nucleophilic ring-opening reactions where the hydroxyl groups of zinc gluconate perform nucleophilic attack on the electrophilic carbonyl carbon atoms of the grafted anhydride rings, causing the five-membered anhydride rings to open and form ester linkages (-COO-) between the ionic crosslinker and the polymer backbone. This ring-opening reaction is thermodynamically favourable due to the relief of ring strain and the formation of stable ester bonds that can undergo transesterification reactions at processing temperatures, creating a dynamic covalent adaptable network. The secondary mechanism involves the establishment of ionic crosslinks through coordination interactions between the multivalent zinc ions (Zn²⁺) and electron-rich sites along the grafted polyolefin chains, including coordination with carbonyl oxygens from both the newly formed ester groups and any remaining anhydride functionalities, as well as π-electron interactions with the aromatic styrene units incorporated during the grafting process. These ionic crosslinks create reversible associations that can dissociate under thermal or mechanical stress and reform when the stress is removed, providing the network with energy dissipation mechanisms and flexibility that complement the structural integrity provided by the covalent ester bonds.
[0040] At operation 204B, the final recyclable polymer structure that results from the complete reaction between the grafted polyolefin and the zinc gluconate three-dimensional network architecture that combines both covalent and ionic crosslinking mechanisms within a unified polymer matrix to achieve unprecedented mechanical performance and recyclability characteristics. The recyclable polymer demonstrates how individual zinc gluconate molecules have reacted with multiple grafted anhydride moieties through the ring-opening esterification reactions, creating covalent crosslinks between adjacent polymer chains while maintaining the coordination of zinc ions with various polar sites throughout the network structure. The ester bonds formed through the nucleophilic ring-opening mechanism are capable of undergoing transesterification reactions at the processing temperatures of 180-200°C, enabling dynamic bond exchange that allows for network rearrangement and stress relaxation while maintaining overall network connectivity, which is the fundamental mechanism that enables reprocessability in the dual crosslinked system. The zinc ions serve as multifunctional crosslinking nodes that not only participate in ester bond formation but also establish ionic crosslinks through coordination bonding with electron-rich sites along the polymer backbone, creating a secondary network of reversible associations that can dissociate to accommodate deformation and reassociate to maintain network integrity. The hybrid network architecture exhibits unique properties where the covalent ester bonds provide load-bearing capacity, dimensional stability, and structural integrity under stress, while the ionic crosslinks contribute flexibility, toughness, and energy dissipation through their ability to undergo reversible association and dissociation without permanent network damage. The three-dimensional crosslinked structure maintains processability and recyclability due to the dynamic nature of both crosslinking modes: the ester bonds undergo bond exchange reactions that allow for network reconfiguration at processing temperatures, while the ionic crosslinks dissociate and reform during thermal processing.
[0041] FIG. 3 is a graphical representation illustrating comparative analysis of the mechanical properties of recycled polymers, in accordance with an embodiment of the present disclosure. FIG. 3 is described in conjunction with elements of FIGs. 1 , 2A and 2B With reference to FIG. 3, there is shown a graphical representation 300 illustrating the tensile strength of various intermediate formulations used in production of the recycled polymer (for example, the recycled polymer obtained using grafting of post-consumer recycled polypropylene (PCR PP and then melt blending grafted PCR PP with the ionic crosslinker). The tensile strength measured in megapascals (MPa) is represented on the left ordinate axis and the elongation at break is represented on the right ordinate axis. The various intermediate formulations of the recycled polymers and various recycled polymers as labelled along the abscissa axis.
[0042] The graphical representation 300 includes a bar 302 representing tensile strength of PCR PP, a bar 304 representing elongation at break of PCR PP, a bar 306 representing tensile strength of the grafted polyolefin (for example, maleic grafted polypropylene (m'-PCR PP)), a bar 308 representing elongation at break of m'-PCR PP. The graphical representation 300 further includes a bar 310 representing tensile strength of a first recycled polymer. A first recycled polymer includes m'-PCR PP melt blended with 5 wt% of an ionic crosslinker (e.g., zinc gluconate), a bar 312 representing elongation at break of the first recycled polymer. The graphical representation 300 further includes a bar 314 representing tensile strength of a second recycled polymer. The second recycled polymer includes m'-PCR PP melt blended with 10 wt% of ionic crosslinker (e.g., the zinc gluconate). The graphical representation 300 further includes a bar 316 representing elongation at break of the second recycled polymer. Further, the graphical representation 300 further includes a bar 318 representing tensile strength of a third recycled polymer. The recycled polymer includes m'-PCR PP melt blended with 15 wt% of ionic crosslinker (e.g., the zinc gluconate). The graphical representation 300 further includes a 320 representing elongation at break of the second recycled polymer.
[0043] The bar 302 represents the baseline tensile strength of post-consumer recycled polypropylene (PCR PP), demonstrating a tensile strength of approximately 28 MPa. The relatively modest tensile strength exhibited by PCR PP reflects the inherent limitations of mechanically recycled polyolefin materials that have undergone degradation processes during their initial service life, including thermal oxidation, photodegradation, and mechanical stress-induced chain scission that collectively reduce the molecular weight and compromise the structural integrity of the polymer matrix. The value of the tensile strength represents the typical performance characteristics of post-consumer recycled polypropylene that would normally limit its application to low-stress, non-critical applications, highlighting the critical importance of developing chemical modification strategies that can restore and enhance mechanical performance to enable broader utilization of recycled plastic waste streams in demanding engineering applications
[0044] The bar 304 represents the elongation at break of post-consumer recycled polypropylene, showing approximately 100% elongation, which indicates that while the recycled polyolefin reasonable flexibility and ductility characteristics, the combination with the low tensile strength creates a material profile characterised by extensive deformation before failure without adequate load-bearing capacity. The high elongation value demonstrates that the polymer chains retain sufficient mobility to accommodate significant strain, but the lack of effective stress transfer mechanisms and reduced intermolecular interactions result in poor dimensional stability and structural integrity under load.
[0045] The bar 306 represents the tensile strength of the grafted polyolefin, specifically maleic anhydride grafted polypropylene (m'-PCR PP), showing approximately 30 MPa, which demonstrates a measurable improvement over the tensile strength of PCR PP through the introduction of polar anhydride functionalities along the polymer backbone. The strength enhancement results from the styrene-assisted maleic anhydride grafting mechanism that creates additional intermolecular interactions and reduces chain mobility through the formation of polar domains within the predominantly nonpolar polyolefin matrix. The improvement validates the effectiveness of the melt mixing process in chemically modifying the recycled polypropylene structure, with the styrene co-agent playing a critical role in enhancing grafting efficiency while suppressing chain scission that would otherwise compromise mechanical properties.
[0046] The bar 308 represents the elongation at break of the grafted polyolefin (m'-PCR PP), showing approximately 45% elongation, which represents a significant reduction from the baseline PCR PP elongation and demonstrates the typical trade-off between strength enhancement and flexibility reduction that occurs during conventional polymer modification approaches. The elongation reduction results from the introduction of polar anhydride groups that create stronger intermolecular interactions and restrict polymer chain mobility, leading to increased stiffness and reduced ability to accommodate large strains before failure. T highlights a fundamental limitation of traditional grafting approaches where strength improvements are typically achieved at the expense of flexibility and toughness, creating materials that, while stronger, exhibit brittle behaviour that limits their application range.
[0047] The bar 310 represents the tensile strength of the first recycled polymer, which comprises m'-PCR PP melt blended with 5 weight per cent zinc gluconate ionic crosslinker, showing approximately 30 MPa tensile strength that maintains the strength level achieved through maleic anhydride grafting while beginning to establish the dual crosslinked network structure. The tensile strength maintenance with initial ionic crosslinker introduction demonstrates successful integration of zinc gluconate into the polymer matrix without compromising the mechanical benefits achieved through grafting, while the formation of initial ester bonds between anhydride groups and hydroxyl groups begins to create covalent crosslinks that will contribute to enhanced performance at higher concentrations. The result validates the compatibility of the zinc gluconate ionic crosslinker with the grafted polypropylene and confirms that the dual crosslinking mechanism begins to function even at relatively low crosslinker concentrations.
[0048] The bar 312 represents the elongation at break of the first recycled polymer containing 5 weight per cent zinc gluconate (showing approximately 35% elongation), which demonstrates the beginning of flexibility restoration that characterises the unique dual crosslinking mechanism developed. While the elongation value remains below the level of PCR PP, the reduction compared to m'-PCR PP is minimal, indicating that the ionic crosslinks formed through zinc ion interactions with the matrix of the recycled polymer begin to provide energy dissipation mechanisms that counteract the stiffening effects of maleic anhydride grafting. It signifies that even at low concentrations of ionic crosslinker begin to establish reversible crosslinks that can dissociate under stress to accommodate deformation, providing the first evidence of the flexibility-enhancing mechanism that will become more pronounced at higher zinc gluconate concentrations.
[0049] The bar 314 represents the tensile strength of the second recycled polymer, which comprises m'-PCR PP melt blended with 10 weight per cent zinc gluconate ionic crosslinker, showing approximately 32 MPa tensile strength that demonstrates continued improvement as the zinc gluconate concentration increases, and the dual crosslinked network becomes more fully developed. The strength enhancement reflects the increased crosslinking density achieved through both ester bond formation between anhydride groups and hydroxyl groups of zinc gluconate, and ionic crosslinks established between zinc ions and electron-rich sites along the polymer backbone, creating a more robust hybrid network structure that effectively distributes stress throughout the polymer matrix.
[0050] The bar 316 represents the elongation at break of the second recycled polymer containing 10 weight per cent zinc gluconate, showing approximately 40% elongation, which demonstrates significant improvement in flexibility compared to the lower concentration formulations and represents substantial recovery of the elongation properties that were compromised during maleic anhydride grafting. The flexibility enhancement indicates that the increased concentration of zinc gluconate provides sufficient ionic crosslinks to create effective energy dissipation mechanisms through reversible association and dissociation of ionic bonds, while the dynamic nature of the ester bonds formed through transesterification reactions allows for stress accommodation and network rearrangement without permanent damage to the crosslinked structure. The result demonstrates that the dual crosslinking mechanism successfully addresses the traditional inverse relationship between strength and flexibility by providing both structural integrity through covalent connectivity and stress accommodation through reversible ionic interactions, creating a material architecture that combines the benefits of both crosslinking modes.
[0051] The bar 318 represents the tensile strength of the third recycled polymer, which comprises m'-PCR PP melt blended with 15 weight per cent zinc gluconate ionic crosslinker, showing approximately 33 MPa tensile strength that represents the optimal performance achieved through the dual crosslinking technology and demonstrates the culmination of the systematic property enhancement strategy. The maximum tensile strength reflects the optimal balance of crosslinking density and network architecture that provides superior load-bearing capability through the fully developed hybrid network combining covalent ester bonds and ionic crosslinks, creating a structure that effectively transfers stress throughout the polymer matrix while maintaining network integrity under high loads.
[0052] The bar 320 represents the elongation at break of the third recycled polymer containing 15 weight percent zinc gluconate, showing approximately 48% elongation, which represents the most remarkable achievement of the dual crosslinking technology by demonstrating that the highest strength formulation simultaneously exhibits the greatest flexibility improvement, completely overcoming the traditional trade-off between strength and elongation observed in conventional polymer systems. The result validates the unique capability of the dual crosslinking mechanism to create a polymer architecture where covalent ester bonds provide structural integrity and load-bearing capacity while ionic crosslinks enable stress accommodation, energy dissipation, and network rearrangement through reversible association and dissociation mechanisms. Advantageously, the combination of dynamic covalent bonds capable of undergoing transesterification reactions and reversible ionic crosslinks creates a hybrid network that exhibits both thermoplastic processability and enhanced mechanical performance, achieving the fundamental objective of developing a recyclable polymer that maintains superior properties through multiple reprocessing cycles. Experimentally its observed, that the recyclable polymer maintains at least 95% of its initial mechanical properties after three reprocessing cycles at temperatures of 180-200 degree Celsius (°C). Further, the recyclable polymer exhibits higher tensile strength and an elongation at break as compared to factionalized polyolefins (i.e., grafted polyolefin (m'-PCR PP)).
[0053] FIG. 4 is a graphical representation illustrating Fourier transform infrared (FTIR) spectroscopy comparison between different recycled polymers, in accordance with an embodiment of the present disclosure. FIG 4 is explained in conjunction with elements from FIGs. 1 to 3. With reference to FIG. 4, there is shown a graphical representation 400 representing Fourier transform infrared (FTIR) spectroscopy comparison between different recycled polymers. The transmittance percentage is represented on the ordinate axis. The wavenumber is measured in centimetres inverse (cm⁻¹) on the abscissa axis. Transmittance percentage quantifies the amount of light that passes through a sample or material, expressed as a percentage of the original light intensity. The wavenumber is defined as the number of wavelengths per unit distance. The graphical representation 400 includes a curve 402 depicting the behaviour of PCR PP, a curve 404 representing grafted PCR PP (m'-PCR PP), and a curve 406 depicting behaviour of the first recycled polymer (as defined in FIG. 3). Further, the graphical representation 400 include a curve 408 depicting the second recycled polymer and a curve 410 depicting the third recycled polymer.
[0054] The curve 402 exhibits characteristic polyolefin absorption patterns including C-H stretching vibrations in the 2800-3000 cm⁻¹ region corresponding to methylene and methyl groups along the polypropylene backbone, C-H bending vibrations around 1450-1500 cm⁻¹, and C-C stretching modes in the fingerprint region below 1300 cm⁻¹. The absence of significant absorption in the carbonyl region (1600-1800 cm⁻¹) and hydroxyl region (3200-3600 cm⁻¹) confirms the essentially non-polar character of the PCR PP.
[0055] The curve 404 exhibits the emergence of a characteristic sharp peak at wavenumber approximately 1780 cm⁻¹ corresponding to the C=O stretching vibration of anhydride groups, providing direct spectroscopic evidence for the successful grafting of maleic anhydride onto the polyolefin backbone. The appearance of this anhydride peak validates the effectiveness of the reactive extrusion process and the styrene co-agent mechanism in promoting efficient grafting while suppressing chain scission, with the peak intensity reflecting the grafting yield achieved through the optimized processing conditions. The curve 404 depicts significance of the addition of maleic anhydride creates the reactive sites necessary for subsequent ester bond formation with the ionic crosslinker, while the preservation of the baseline polyolefin absorption patterns confirms that the polymer backbone structure remains intact throughout the grafting process.
[0056] The curve 406 shows the beginning of anhydride peak reduction at wavenumber depicted by a region 412, indicating partial consumption of anhydride groups through ring-opening reactions with hydroxyl groups of zinc gluconate, while simultaneously exhibiting the emergence of absorption an ester region around 414 (approximately at 1740 cm⁻¹) corresponding to C=O stretching of newly formed ester bonds. The broadening of absorption in a hydroxyl region (3200-3600 cm⁻¹) reflects the incorporation of the zinc gluconate with its multiple hydroxyl functionalities, while changes in the fingerprint region indicate the establishment of ionic interactions between zinc ions and the polymer matrix. The curve 406 provides direct evidence for the dual crosslinking mechanism initiation, with the simultaneous formation of covalent ester bonds and ionic crosslinks beginning to create the hybrid network structure that will provide enhanced mechanical properties.
[0057] The curve 408 curve exhibits further reduction in the anhydride peak intensity compared to the first recycled polymer, indicating greater consumption of anhydride groups through increased crosslinking reactions, while the ester region 414 shows enhanced intensity reflecting the formation of additional ester bonds between anhydride moieties and hydroxyl groups of zinc gluconate. The hydroxyl region displays broader and more intense absorption due to the higher concentration of zinc gluconate, while the fingerprint region shows increasing complexity indicative of more extensive ionic crosslink formation and network development. The curve 408 demonstrates that increasing zinc gluconate concentration leads to more complete utilisation of grafted anhydride sites and enhanced ionic crosslink density, creating a more robust dual crosslinked network that correlates with the observed mechanical property improvements, including increased tensile strength and restored flexibility.
[0058] The curve 410 shows near-complete reduction or elimination of the anhydride peak in the region 412, indicating essentially complete consumption of anhydride groups through crosslinking reactions, while the ester peak in the ester region 414 exhibits maximum intensity, reflecting extensive ester bond formation throughout the polymer matrix. The hydroxyl region exhibits the broadest and most intense absorption due to the optimal zinc gluconate concentration, while the fingerprint region shows the most complex absorption pattern indicative of fully developed ionic crosslinks and complete network formation.
[0059] FIG. 5 is a graphical representation illustrating a differential scanning calorimetry (DSC) thermal analysis of the recyclable polymers, in accordance with an embodiment of the present disclosure. FIG. 5 is explained in conjunction with FIGs. 1 to 4. With reference to FIG. 5, there is shown a graphical representation 500 that illustrates the differential scanning calorimetry (DSC) thermal analysis of the recyclable polymer formulations. The graphical representation 500 includes a curve 502 depicting behaviour of PCR PP, a curve 504 depicting behaviour of the first recycled polymer (as defined in FIG. 3). Further, the graphical representation 500 include a curve 506 depicting the second recycled polymer (as defined in FIG.3) and a curve 508 depicting the third recycled polymer (as defined in FIG 3).
[0060] The heat flow measured in watts per gram (W/g) is represented on the ordinate axis, while the temperature measured in degrees Celsius (°C) is shown on the abscissa axis. The differential scanning calorimetry (DSC) is a thermal analysis technique used to measure heat flow associated with crystallisation and melting transitions in the recyclable polymer. DSC is employed to evaluate the crystallisation behaviour, melting characteristics, and thermal processability of the various dual crosslinked polymer formulations.
[0061] As the temperature changes during cooling and heating cycles, variations in heat flow indicate exothermic crystallisation events and endothermic melting transitions corresponding to polymer chain rearrangement, crystal formation, and network relaxation processes influenced by the dual crosslinking mechanism. The upper region represents exothermic crystallisation peaks occurring during the cooling cycle that demonstrate how the dual crosslinked network affects nucleation kinetics and crystal growth efficiency, while the lower region displays endothermic melting transitions during the heating cycle that reveal modifications in crystal structure and melting behaviour resulting from the covalent ester bonds and ionic crosslinks.
[0062] The curve 502 represents the crystallisation peak of post-consumer recycled polypropylene (PCR PE) occurring at approximately 115°C during the cooling cycle, exhibiting the highest intensity among all formulations and demonstrating the characteristic thermal behaviour of unmodified polypropylene chains. revealing a dual peak structure that provides important insights into the composition and heterogeneity of real-world recycled plastic waste streams. The smaller crystallization peak occurring at approximately 115°C corresponds to PCR PE) impurities present within the predominantly polypropylene matrix, while the larger and more prominent crystallization peak at approximately 125°C represents the crystallization of the PCR PP that constitutes the majority of the recycled material. The dual peak structure demonstrates that the PCR PP is not 100% pure polypropylene but rather contains minor polyethylene impurities i.e. PE that are commonly found in mixed post-consumer plastic waste streams due to incomplete sorting and contamination during collection and processing. The sharp, well-defined exothermic peak indicates rapid and efficient crystallisation kinetics typical of linear polypropylene chains that can readily rearrange into ordered crystalline structures without interference from crosslinking networks or chemical modifications. The maximum peak intensity reflects complete crystallisation with minimal restrictions on polymer chain mobility, allowing for optimal nucleation and crystal growth processes that result in well-developed crystalline domains.
[0063] The identification of both PCR PE and PCR PP crystallization peaks in the curve 502 demonstrates a critical advantage of the dual crosslinking approach, as the styrene-assisted maleic anhydride grafting mechanism and subsequent zinc gluconate crosslinking can effectively functionalize and crosslink both polyethylene and polypropylene components within the mixed waste stream. The grafting chemistry is applicable to both polymer types since the radical initiation and styrene co-agent mechanisms can abstract hydrogen atoms from both PCR PE having secondary carbons and PCR PP having tertiary carbons backbones, enabling uniform functionalization across the mixed polyolefin composition. The subsequent crosslinking with the zinc gluconate ionic creates a compatible network that bridges between the different polyolefin phases, effectively compatibilizing the PCR PE and PCR PP components through the dual crosslinked network structure.
[0064] The curve 504 depicts reduced peak intensity compared to the PCR PP while maintaining similar crystallisation temperature, indicating that the initial formation of the dual crosslinked network begins to restrict polymer chain mobility and crystallisation efficiency. The decreased crystallisation intensity reflects the establishment of both ester bonds between grafted anhydride moieties and hydroxyl groups of zinc gluconate, and ionic crosslinks between zinc ions and the polymer matrix, creating physical constraints that impede the chain rearrangement necessary for optimal crystal formation. Despite the reduced intensity, the maintenance of crystallisation temperature suggests that the fundamental nucleation mechanisms remain intact, while the crosslinking network provides controlled restriction rather than complete inhibition of crystallisation processes. The modified crystallisation behaviour demonstrates that even relatively low concentrations of ionic crosslinker begin to establish network structures that influence thermal transitions while preserving the essential crystallisation capability necessary for maintaining processability and mechanical integrity of the recyclable polymer material.
[0065] The curve 506 represents that during the cooling cycle region, the second recycled polymer exhibits a substantially reduced crystallization peak intensity compared to the PCR PE, with the peak appearing at approximately the same temperature at around 115°C but with markedly diminished heat release, indicating that the dual crosslinked network formed through ester bonds and ionic crosslinks creates significant restrictions on polymer chain mobility and crystallization efficiency. The reduced crystallization intensity reflects the interference of the crosslinking network with the chain rearrangement processes necessary for crystal formation, where both the covalent ester bonds formed between zinc gluconate hydroxyl groups and grafted anhydride moieties, and the ionic crosslinks established through zinc ion coordination, create physical constraints that impede the nucleation and growth of crystalline domains. During the heating cycle, the second recyclable polymer shows a corresponding reduction in melting peak intensity at approximately 165°C, along with noticeable peak broadening that signifies increased structural heterogeneity within the polymer matrix due to the presence of crosslinked regions with varying degrees of network density and crystal perfection.
[0066] The curve 508 depicts the crystallisation behaviour during the cooling cycle, showing the most dramatic reduction in peak intensity, indicating that the highest zinc gluconate concentration creates the most extensive crosslinking network that substantially restricts crystallisation processes through both covalent and ionic crosslinking mechanisms. The severely reduced crystallization peak reflects the comprehensive network structure where the increased concentration of zinc gluconate provides more crosslinking sites for ester bond formation with grafted anhydride moieties, while the higher density of zinc ions establishes more extensive ionic crosslinks throughout the polymer matrix, creating a highly constrained system that significantly impedes polymer chain mobility necessary for crystal formation. The melting behaviour in the heating cycle exhibits the broadest and least intense melting endotherm, with substantial peak broadening that indicates a distribution of melting temperatures rather than a single sharp transition, suggesting that the extensive crosslinking network creates regions with varying degrees of structural constraint and crystal organisation. The thermal profile for the third recycled polymer correlates directly with its superior mechanical properties, including the highest tensile strength (e.g., 33 MPa) and optimal elongation at break (e.g., 48%), where the reduced crystallinity provides enhanced flexibility and toughness while the extensive crosslinking network maintains structural integrity and load-bearing capacity.
[0067] Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.
, Claims:CLAIMS
We claim:
1. A method (100) of production of a recyclable polymer, the method comprising:
melt mixing a recycled polyolefin with a monomer comprising an anhydride group in the presence of an initiator, a co-agent, and an antioxidant to form a grafted polyolefin comprising grafted anhydride moieties; and
melt blending the grafted polyolefin with an ionic crosslinker to form the recyclable polymer having a dual crosslinked network,
wherein the ionic crosslinker comprises multivalent metal ions and hydroxyl groups,
wherein the hydroxyl groups form ester bonds with the grafted anhydride moieties and the multivalent metal ions form ionic crosslinks with the grafted polyolefin, and wherein the ester bonds undergo dynamic bond exchange, and the ionic crosslinks exhibit reversible bond formation for reprocessability.
2. The method (100) as claimed in claim 1, wherein the co-agent is styrene.
3. The method (100) as claimed in claim 2, wherein the styrene reacts with macroradicals of the recycled polyolefin to form copolymer macroradicals comprising styrene units and polyolefin units, and wherein the copolymer macroradicals subsequently react with the monomer.
4. The method (100) as claimed in claim 3, wherein the copolymer macroradicals comprising the styrene units exhibit preferential reactivity toward the monomer and provide suppression of chain scission of the recycled polyolefin.
5. The method (100) as claimed in claim 1, wherein the recycled polyolefin is selected from the group consisting of post-consumer recycled polypropylene (PP), post-consumer recycled polyethylene (PE), and blends thereof.
6. The method (100) as claimed in claim 1, wherein the melt blending is performed at a temperature of 180-200 degree Celsius (°C), a screw speed of 100-150 revolution per minute (rpm), for a time period of 1-5 minutes.
7. The method (100) as claimed in claim 1, wherein the ionic crosslinker is selected from the group consisting of magnesium gluconate, calcium gluconate, zinc gluconate.
8. The method (100) as claimed in claim 7, wherein the ionic crosslinker is zinc gluconate.
9. The method (100) as claimed in claim 1, wherein the antioxidant is selected from Irganox 1010, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl) tri-p-cresol or combinations thereof.
10. A recyclable polymer comprising:
a grafted polyolefin having grafted anhydride moieties; and
an ionic crosslinker comprising multivalent metal ions and
hydroxyl groups,
wherein the grafted polyolefin and the ionic crosslinker form the recyclable polymer having a dual crosslinked network,
wherein the dual crosslinked network comprises ester bonds formed between the hydroxyl groups and the grafted anhydride moieties and ionic crosslinks formed between the multivalent metal ions and the grafted polyolefin,
wherein the ester bonds undergo dynamic bond exchange, and the ionic crosslinks exhibit reversible bond formation for reprocessability of the recyclable polymer.
11. The recyclable polymer as claimed in claim 10, wherein the grafted polyolefin comprises a recycled polyolefin, a monomer, an initiator, a co-agent, and an antioxidant.
12. The recyclable polymer as claimed in claim 10, wherein the recyclable polymer comprises 70-99 weight percentage (wt%) of the grafted polyolefin and 1-30 weight percentage (wt%) of the ionic crosslinker.