resulting in consistent high carbon yields. Moreover, the textile-derived waste. [17] Among them, polypropylene carbon shows exceptional Joule heating performance, which can be employed (PP) fabrics comprise a significant porin various heating applications, resulting in reduced energy consumption tion due to their low cost, hydrophobic compared to conventional heating. Furthermore, decoration of fabric-derived (waterproof) nature, and versatile use in carbon with metal nanoparticles is demonstrated through electroplating, [18] leading to altered surface functionality and further enhanced Joule heating Several PP recycling strategies have performance. This work introduces a scalable method for upcycling of plastic been developed at scale, aiming at "closwaste to functional carbons that can completely retain initial material ing the loop" to minimize waste genarchitectures with controlled shrinkage, providing a viable strategy eration and capitalize on plastic waste for generating value-added products toward electrification of heating cally, mechanical recycling directly reprocesses waste to new products with the same chemical identity, which is typically applicable for single-stream plastic waste. [21,22] Alternatively, chemical recycling can transform plastic waste into different compounds, typically by chemical reac-Plastic pollution represents an impending global threat due to tion, pyrolysis or hydrolysis, for the production of value-added their ecological persistence, which can accumulate and cause materials. [23,24] For example, PP can be depolymerized into propydamage to food production and biological life, [1] leading to dis-lene through the use of an induction-coupled plasma reactor, [25] turbing societal and environmental impacts. [2,3] Aiming to ad-resulting in a high conversion of 78 wt% of gaseous products. dress these challenges and develop a sustainable future, strong Other chemical recycling strategies include converting PP to policies and efforts have been implemented to promote plastics fuels/oils, [26] composed of olefins, aromatics, paraffins, and cycircularity, [4] including banning/limiting single use products, [5,6] cloalkanes, as well as carbonaceous products. [27] For example, extensive economic and infrastructure support for develop-carbon fiber can be prepared through a two-step process of ing recycling and upcycling technologies, [7][8][9] and facilitating crosslinking and carbonization, while carbon nanotubes can be prepared by pressurized catalytic pyrolysis of waste plastics using nickel/cordierite catalysts. [28][29][30][31] We note that the use of these works reported so far primarily focus on material design and innovation, while morphological features of wastes become an overlooked resource. Specifically, during the entire recycling process, plastic wastes often have to first completely lose their morphology features, which are then built back through additional processing steps (e.g., fiber spinning and weaving). In product manufacturing, significant energy and economic costs are associated with processing of plastic materials, [34,35] enabling their ability to achieve desired properties and functionalities, such as fabricating textiles for personal and medical care as well as filtration media. [36][37][38] Therefore, from the perspective of maximized and sustained use of waste as feedstocks, retaining and taking advantage of these pre-existing structural features in final upcycled products is useful, toward directly reducing energy consumption and cost of the recycling process. However, very limited methods have been reported to achieve this important goal. Recently, textiles have been converted to smart materials capable of functioning as wearable heating devices through the Joule heating effect, where electrical resistors generate thermal energy from the passage of electric current. [39,40] These materials have several advantages of uniform heating distribution and precise temperature control, which can be employed in various applications such as intelligent textiles and plane heating elements. [41] Moreover, performance of functional textiles can be further enhanced through incorporating additional electroactive materials, such as metal nanoparticles or conductive agents, whose ions collide with charge carriers when connected to external electrodes to produce heat. [42,43] While various promising systems have been developed, they often require pristine textiles, expensive precursors, and complex processes, which may involve significant challenges for scaling up. It is also important to note that manufacturing efficient Joule heating materials represents a strong need for addressing industrial electrification (heat generation is responsible for over 40% of global carbon emission in the past several years), [44] while additional sustainability-relevant considerations should be taken into account in method and system design, including how to leverage the use of plastic wastes as feedstock materials.

Converting polyolefin-based materials to carbon products has been previously demonstrated through a sulfonation-based crosslinking reaction followed by pyrolysis, initially developed for the economic production of carbon fiber. [45,46] At elevated temperatures, sulfuric acid can functionalize the polymeric backbone, which eventually leads to intermolecular crosslinking by radicalbased coupling. A subsequent pyrolysis step can directly convert crosslinked PP segments to carbon materials. While there have been reports of transforming surgical masks into carbons for the preparation of anode materials for lithium-ion batteries and environmental remediation sorbents, [31,47] retention of large-scale architectures has been rarely explored. As previously discussed, an ideal upcycling approach should take advantage of existing material architectures and structures to match or exceed their current use and performances. Method development to achieve this goal, accompanied with unlocking the use of waste-derived carbons for Joule heating, can provide an effective solution for addressing two sustainability challenges/needs, including plastic waste management and decarbonized heat generation, toward establishing a carbon-neutral society.

Herein, we report the upcycling of PP-based woven textiles to carbon-based Joule heaters, with product yields up to 59 wt% and a controlled dimensional shrinkage of ≈30% after pyrolysis. This work reports how the crosslinking reaction impacts the chemical composition and material structure of textile fabrics, which is distinct from previous reports of application-focused PP upcycling to carbon products. The resulting carbon structures demonstrate the retention of not only macroscopic shape, but also microscopic fibrous structures with defined pores generated from controlled upcycling process, which represents a key novelty of this work; the ability to retain morphology features after upcycling can also enable their direct use in versatile applications. Furthermore, PP textile derived carbons structures with intricate woven patterns exhibit excellent Joule heating performance, with great potential for the use in electrifying heat process. Different waste precursors with distinct weave patterns are investigated to confirm the robustness and generalizability of our pyrolysisbased upcycling method. Incorporation of textile carbon structures with copper is also demonstrated through a simple electroplating step, showing the opportunity of further improving the performance and economic value of waste-derived materials through a post-processing method, which this concept could be potentially further utilized in future work. Our method for upcycling of polyolefin-based textile waste to functional carbons can be extended and scaled for providing a promising approach to current waste management practices, while simultaneously allowing a new solution for industrial electrification and curtailing the global threat of plastic pollution.

The process of converting PP-based fabrics to structured carbons is depicted in Figure 1a, involving two steps of sulfonation-based crosslinking and carbonization. Briefly, textiles are submerged in concentrated sulfuric acid at elevated temperatures (150 °C), leading to the incorporation of sulfonic acid groups onto the PP backbone followed by homolytic dissociation which forms unsaturated bonds. These functional groups from sulfonation then undergo a series of reactions, which ultimately result in the production of radical species that are capable of crosslinking through coupling reactions, enabling PP to become effective carbon precursors. Once thermally stabilized, crosslinked woven fabrics were exposed to temperatures up to 800 °C under a nitrogen environment to produce the final carbon product through pyrolysis. This approach is simple and scalable, involving the use of low-cost waste materials, PP-based textile waste and sulfuric acid.

The sulfonation-induced crosslinking reaction was monitored by tracking the PP mass gain over sulfonation time, which is shown in Figure 1b. At shorter reaction times, a steady increase in mass with reaction progression was first observed, followed by a plateau value of ≈54% at ≈16 h. With significantly longer reaction times, minimal increases of mass gain are found which suggests a completed crosslinking reaction. These results can be correlated with changes in the chemical composition of PP textiles by Fourier transform infrared (FTIR) spectroscopy (Figure 1c). The C-H stretch on PP backbones is signified by the characteristic band at 2920 cm -1 , which significantly diminishes following the first 2 h of reaction and becomes nearly absent at 4 h. Additionally, a broad band at ≈3300 cm -1 , corresponding to the -OH stretching is developed, in addition to bands at 1150 to 1000 cm -1 associated with sulfonic acid groups, indicate progression of the functionalization reaction. Moreover, formation of alkenes within the backbone is observed through the increased band intensity at ≈1630 cm -1 . Additional bands from 1700 to 1600 cm -1 can be found in longer reaction times which may indicate the presence of side reactions leading to ketones, aldehydes or carboxylic acids. Furthermore, the progression of PP crosslinking was also tracked through changes in its degree of crystallinity by differential scanning calorimetry (DSC) measurements (Figure 1d and Figure S1, Supporting Information). As functionalization of the PP textile introduces bulky sulfonic acid groups and crosslinked networks, the ability of PP to re-crystallize is severely hindered. As a result, the crystallinity degree of the material can be correlated to the fraction of unreacted sample throughout the sulfonation reaction. By comparing the degree of crystallinity of crosslinked samples to the starting material (≈46%), kinetics of crosslinking reaction can be quantitatively assessed. A complete loss of crystallinity is observed at 8 h, which is consistent with reaction progression from FTIR results. The slightly lower reaction time where a plateau is reached in Figure 1d, compared to mass gain, may indicate crystallinity is disrupted marginally before complete crosslinking is achieved. Furthermore, PP gel fraction was determined by soaking samples following sulfonation in hot xylene for 24 h at 120 °C to extract soluble portions. An insoluble fraction plateau of 87 wt% was observed for a 16 h reaction time and macroscopic shape of the crosslinked textile was maintained following solvent extraction at elevated temperatures (Figure S2, Supporting Information).

Figure 2a shows the microstructure of PP woven fabrics prior to sulfonation through scanning electron microscopy (SEM), with an initial fiber diameter of ≈50 μm. At all sulfonation times, both fibril structures and large-scale woven patterns are completely retained. After 4 h of sulfonation time, the fiber diameter is observed to shrink to 45 μm, which further decreases to 39 μm when extending sulfonation time to 16 and 40 h (Figure 2b-d), associated with increased density of crosslinked PP after reaction. Note that sulfonation does not lead any major structural disruption in this study, which is different from other amorphous polyolefin systems. [50] Sulfonated samples were then washed in acetone to remove byproducts and residual acid and dried prior to the carbonization step. Figure 3a shows the carbon yield of PP textiles as a function of their sulfonation-induced crosslinking time. The neat fabric and textile following 1 h of sulfonation exhibited a complete thermal degradation with no mass retention. PP after 4 h of sulfonation showed a carbon yield of 21 wt%, compared to the mass of starting material, which plateaus at ≈59 wt% after 16 h of reaction time. Thermogravimetric analysis (TGA) results are depicted in Figure S3, Supporting Information, where neat textile exhibits no carbon yield following heating up to 800 °C in a nitrogen environment. In comparison, textile sulfonated for 16 h has a residual mass of 35 wt% that corresponds to a carbon yield of 55 wt% when compared to the initial mass of the textile prior to sulfonation. At low reaction times, insufficient crosslink-ing throughout the PP fiber structure results in significant mass loss during carbonization as sulfonation of PP is a diffusioncontrolled process; sufficient reaction time is required to allow sulfuric acid to fully diffuse through and react with PP fibers. Notably, the sulfonation reaction introduces sulfonic acid groups which impart hydrophilicity to the PP backbone, facilitating acid penetration to further promote crosslinking. As a comparison, a previous study investigated the use of PP-based filaments to prepare 3D structured carbon, [51] through similar sulfonationbased crosslinking and carbonization approach. Investigation of the 3D printed structure's morphology after crosslinking revealed the formation of micron-sized cracks which promoted diffusion of sulfuric acid throughout the structure and subsequently accelerate reaction kinetics. Of note, this crack initiation-propagation mechanism does not occur in the textile system investigated in this work. The distinct behavior can be explained by the significantly smaller textile fiber diameter (50 μm) compared to the wall thickness of the printed parts (0.6 mm). A carbon yield plateau after 16 h of sulfonation time suggests complete crosslinking is achieved, with minimal change at longer sulfonation times. The carbon yield observed here is in good agreement with val-ues reported for the carbonization of several sulfonated PP-based materials, [29,52] while the reaction time necessary for reaching a maximized carbon yield value is longer than previous studies that used PP-based surgical masks as the starting material. [31] This difference can be explained by the textiles fiber diameter of 50 μm, which is nearly double the diameter studied in earlier reports.

Figure 3b shows the initial macroscopic architecture of neat PP which is retained following conversion to carbon for a sample sulfonated for 16 h. The dimensional shrinkage of macroscopic carbon structures is significant, which has also been reported in literature for polymer-derived carbon. [53] For example, the conversion of acrylate resins to structured carbons through UV-assisted additive manufacturing followed by imidization and carbonization resulted in 45% volumetric shrinkage following crosslinking and 10% following carbonization. [54] Dimensional control over textile-based carbon structures were assessed through a model system of 46 mm by 36 mm samples. It was found that in-plane shrinkage was consistently ≈30%, regardless of initial sample size and geometry. This value is similar to structured carbon prepared through additive manufacturing using polypropylenebased filaments, where shrinkages of 25% were observed in the filament printing directions. [51] Interestingly, the reaction of PP woven fibers from outside in can be visually observed from the SEM images of carbonized textiles in Figure 4a, where carbon fibers obtained from 2 h of sulfonation shows significant distortion and bending compared to their neat or sulfonated counterparts. The cross-section of this weakened fiber is shown in Figure 4e where a hollow core is observed. As the majority of the fiber was susceptible to degradation or decomposition due to insufficient crosslinking, only the shell of the fiber is retained. Following 4 h of reaction, the macroscopic structure is more comparable to the initial woven architecture, though significant warping is again observed (Figure 4b). The cross section is shown in Figure 4f where a hollow fiber is observed, while the thickness of the carbon shell (7.8 μm) has considerably increased compared to 2 h crosslinked counterparts (4.8 μm). Figure 4c,g shows the carbon from textile sulfonated for 16 h exhibiting a woven architecture nearly identical to its precarbonized analogs as well as a cross section with solid cores with diameters of 35.5 μm, showing an ≈30% diameter shrinkage from the neat textile analog. With extended reaction time to 40 h (Figure 4d,h), no significant change can be found in macrostructure and fiber cross sections compared to Figure 4c,g. These results of insufficient sulfonation leading to hollow fibers is consistent with literature for polyolefin-derived carbon fiber. [46,55,56] While textile-derived carbon at low sulfonation times does not yield sufficient crosslinking throughout fiber diameters and maximized carbon yields, fabrication of hollow carbon fibers may impart unique material morphologies and functionalities. [57] For example, the use of cotton-based hollow carbon fibers as supercapacitors was previously reported, [58] which can exhibit excellent electrochemical performance due to their tubular structure, chemical composition, and mesopore morphology. Furthermore, hollow carbon fibers have been shown to act as effective sorbents for water purification, [59] including high oil adsorption capacities up to 32-77 g g -1 in addition to superior selectivity and repeatability compared to a cotton fiber control. Additionally, we also note that woven PPderived carbons exhibit significantly different mechanical properties compared to their polymer precursors, including increased stiffness and brittleness as well as reduced mechanical flexibility. As plastics and carbon have significantly different mechanical properties, this change is anticipated. Furthermore, the complex woven architecture built into PP samples can generate internal stress during the polymer pyrolysis step. Moreover, PP itself is a less ideal carbon precursor compared to polyacrylonitrile, polyethylene, and lignin for preparing strong carbon fiber materials, due to inherent chain scissions that occur during sulfonation-enabled crosslinking process. [51,60] However, our carbon mat prepared from the pyrolysis of PP textiles still shows sufficient mechanical performance for their practical use, As shown in Figure S4, Supporting Information, mechanical deformation of carbons can be achieved without sample damage/failure occurring and can be fully recovered.

To understand how the nanoscale morphology and potential pore textures of textile-derived carbon change as a function of sulfonation time, nitrogen physisorption measurements were carried out at 77 K. During the carbonization step, partial decomposition results in evolution of gaseous products, inducing porosity of derived carbons as well as increasing their surface areas. The nitrogen adsorption-desorption isotherms are shown in Figure 5a, including PP textile-derived carbon samples with var-ied sulfonation times (2, 4, and 8 h), which all exhibit a type IV isotherm characteristic of mesopores within the carbon framework. After 2 h of sulfonation reaction, a surface area of 546 m 2 g -1 and a pore volume of 1.7 cm 3 g -1 was observed, in ad-dition to a uniform pore size distribution centered at 10.8 nm (Figure 5b). A defined pore size distribution is also observed fol-lowing 4 and 8 h of sulfonation, though the averaged pore size increases to 19 nm and continues to increase in the width of pore size distribution with increasing reaction time. For longer sulfonation times (including 12, 16 and 40 h), no defined mesopores are observed with surface areas ranging from 328 to 510 m 2 g -1 (Figure S5, Supporting Information). With greater degrees of crosslinking, solid carbon fibers are developed with the absence of mesopores.

Carbon-based materials have demonstrated excellent Joule heating performance for their potential use in industrial electrification, due to their advantages of electrical conductivity as well as high temperature thermal stability. [61,62] In this work, electric heating performances of woven PP derived carbon fabrics were examined. A model system (length = 27 mm, width = 18 mm, thickness = 1.4 mm) was prepared through sulfonation-induced crosslinking at 150 °C for 16 h and carbonizing at 1100 °C, which exhibited an identical surface morphology to samples carbonized at 800 °C (Figure S6, Supporting Information). Woven PP-derived carbon mats were attached to a DC power source and maximum equilibration temperatures were tracked as a function of voltage (Figure 6a) and power (Figure 6b). The electrical resistance was found to be 2.50 Ω•m at 25 °C. Following application of electrical power, waste-derived carbons rapidly heat to maximum temperature, with 8, 14, and 28 W resulting in temperatures of 183, 465, and 854 °C, respectively. The steady-state temperature has a quadratic relationship with respect to applied voltage and a linear relationship with respect to power, consistent with Joule's law. We note that performing quantitative comparison about Joule heating performance between this work and other published studies might be challenging, since the efficiency is highly dependent on sample size and geometry, contributed to the total electrical resistance of the sample. Additionally, with increasing sample temperature upon Joule heating (especially above 500 °C under ambient environment), the electrical conductivity of carbons might also be changed due to possible oxidation as well as convection and radiation losses which may play a more significant role. However, one noteworthy advantage in this work is that the PP textile waste-derived carbons have a much wider range of electric heating temperatures compared to conventional polymer composites reinforced with carbon materials. [63] This is www.advancedsciencenews.com due to the significantly better thermal stability of carbon than that of polymers. The time-dependence of maximum temperatures were investigated under various voltages (Figure 6c), demonstrating rapid heating to maximum equilibration temperature and cooling down to room temperature within 30 s. A potential application of textile-derived carbon as electric heating elements is shown in Figure 6d, which can boil water at 8 W; such use can be further extended to extreme conditions, including melting metal species within seconds at 37 W (Figure 6e).

To further investigate how the initial textile structure impacts the resulting carbon's properties, the Joule heating performance at three carbon mat lengths were probed in Figure S7, Supporting Information. It was found that all sample sizes had a quadratic relationship of temperature to applied voltage, with smaller carbon mats reaching higher temperatures under the same voltage compared to their longer analogs. This result is anticipated as at the given voltage, the amount of heat generation is typically in an inverse relationship with total electrical resistance of the samples, which increases with increasing the sample size.

Moreover, two additional textiles were converted to carbon mats with different weave patterns compared to the model system. Images of the additional neat and textile-derived carbons as well as SEM micrographs of the carbons confirm each textile's distinct woven architecture are shown in Figure S8, Supporting Information. Sample shrinkage following carbonization of the additional textiles was observed to be consistent with the model system (≈70% dimensional retention). The Joule heating performance of the three textile-derived carbons with identical dimensions were then probed in Figure S9, Supporting Information, which shows the time-dependence of maximum temperatures at two applied voltages. It was found that at an applied voltage of 3 V, the two additional textiles (124 and 128 °C) reached slightly higher maximum equilibration temperatures compared to the model system (117 °C). Furthermore, at 4 V a similar trend is observed where the two additional textiles reach maximum temperatures of 198 and 201 °C, respectively, whereas the model system reaches 183 °C. This indicates the initial textile structure can have an influence on the resulting carbon's Joule heating performance, though this impact is relatively limited and can primarily be attributed to the total electrical resistance of samples. With rapid, well-controlled heating-cooling which require low energy consumption relative to other electric heating devices, these waste-derived carbon structures hold great potential for use in several practical applications, including electrifying of industrial and commercial heating systems. [64] It is also important to note that in comparison to commercial Joule heating materials, such as fiberglass cloth, plastic waste offers a significantly more cost-effective raw material for the preparation of efficient electric heating systems. Moreover, this approach streamlines the recycling process for the utilization of textile waste as shown in the processing scheme in Figure S10, Supporting Information. Rather than requiring various steps including shredding, washing, milling, float-sink separation, mechanical/thermal drying, extrusion, and several additional processes to convert back to textile fibers, this robust process is a facile two-step pathway to prepare highly functional materials, while retaining morphological features from waste resources. Furthermore, the use of polyolefin wastes as precursors for fabricating Joule heaters enables a lowcost approach, with increased economic competitiveness com- www.advsustainsys.com pared to commercial products; we note the typical price for plastic textile is several cents (USD) per feet, while market price of fiberglass cloth-based Joule heaters are typically in the range of several dollars (USD) per feet.

To further functionalize the textile-derived carbon and allow their enhanced use, a simple electroplating process was performed using a copper anode and a copper sulfate electroplating solution as shown in the inset in Figure 7a. We note this additional step could lead to altered material functionality and performance, broadening their applications in different areas. For establishing materials circularity, enabling the versatile use of waste-derived materials is highly desired, [65] which could further increase their economic and sustainability value. [66] Through varying deposition time, a linear relationship of mass gain versus deposition time is observed, increasing from 8 wt% after 20 min to 86 wt% after 400 min (Figure 7a). The controlled metal deposition rate for surface functionalization allows for a facile strategy to produce woven carbon fiber-metal composites. Following 1 and 3 h of deposition time, with mass gains of 18 and 42%, the degree of functionalization can be visually observed through images of the carbon in Figure 7b. These values can be correlated to TGA results under air which result in a final mass of 24 and 53% following decomposition of carbon (Figure S11, Supporting Information). Here, we note that electrodeposition voltage could play an important role in controlling the growth of metal layers in the process. Specifically, increasing applied voltage can lead to a higher rate constant of the growth of metal layer thickness, [67] in addition to further hindering the oxidation of electrodeposited metal oxidation, [68,69] which is important for controlling the conductivity of resulting composites. In our work, we found 1 V is sufficient for electrodeposition of Cu particles on woven textilewaste derived carbon fibers. The copper functionalization of the woven architecture can be further probed through SEM as seen in Figure 7c to determine the extent of electroplating reaction. The copper first forms crystal domains throughout the fiber following 1 h, and after extending electroplating time to 3 h, nearly the entire carbon structure is covered by copper particles. The map of elemental composition can be observed through energy-dispersive X-ray (EDX) spectroscopy in Figure 7d, where copper is shown in green. Figure 7e shows X-ray diffraction results of the neat carbon, with broad (002) and (101) peaks and an interlayer distance of 3.1 Å, as well as the carbon following electrodeposition after 1 and 3 h. The 1 h electroplated sample featured characteristic Cu peaks at 43.2° and 50.4°, corresponding to (111) and (200) reflections. After 3 h of electrodeposition, both the (111) and ( 200) Cu reflections increased in intensity in addition to the formation of a peak at 28.4° corresponding to a Cu 2 O (110) reflection. This indicates the deposited copper may be oxidized with longer deposition times. Through this well-controlled functionalization strategy, woven carbon fiber is shown to be easily decorated with metal particles which can lead to customizable material properties.

The impact of copper electrodeposition on the resulting carbon's properties was assessed through water contact angle measurements. A shift in surface functionality can be observed in Figure 8a where the textile-derived carbon initially exhibits a highly hydrophobic surface (143°), which first decreases in hydrophobic character (120°) and then begins to display a very slight hydrophilic nature (87°) following electrodeposition for 1 and 3 h, respectively. To understand how the decoration of copper nanoparticles affects the Joule heating performance of the woven carbon, the maximum temperature of electroplated samples was determined under 2 V and compared to the carbon analog in Figure 8b. It was found that the 1 h electroplated sample reached a maximum temperature of 80 °C, showing a 9 °C improvement compared to the neat carbon. The 3 h electroplated sample exhibited a significantly improved Joule heating performance, rapidly reaching a maximum temperature of 177 °C, which can then be cooled down to room temperature after the removal of electrical current. With tailorable surface behaviors and further enhanced Joule heating capabilities, the broad applicability and functionality of textile-derived carbon is demonstrated.

With the continuously increasing scale of plastics waste generation, industrially viable strategies for waste management are needed to lessen their societal and environmental impacts as well as add value to these immense waste streams. To take advantage of the pre-existing features within waste feedstocks and exploit the energy costs associated with initial processing, this work demonstrates the upcycling of PP-based textile waste to carbon electric heating elements through direct pyrolysis. This facile process leads to carbon mats that retain initial macroscopic structure, with reproduceable carbon yields ≈59% and dimensional shrinkage ≈30%. These upcycled products can be directly used for various end applications without the need of additional processing steps. In addition to retaining macroscopic architectures, the resulting carbon also exhibits microscopic fibrous structures with tunable, defined pores which are generated during the carbonization process. The excellent Joule heating performance of these carbon fibers with intricate woven patterns is investigated and demonstrated with the heating of water and melting of metals. These textile carbon structures can also be functionalized

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with metal particles through electroplating to further promote electro-thermal properties; the concept of further modification of waste-derived products can be broadly employed in various systems to further increase their economic and sustainability benefits. This simple upcycling strategy for converting PP fabrics to high performance carbon Joule heaters provides a promising method to not only utilize plastic waste streams, but also take advantage of the existing morphologic features of waste feedstocks for the production of value-added functional materials toward industrial electrification and decarbonization.

Conversion of Textile Fabric to Structured Carbon: Woven PP fabrics were cut into desired dimensions (length = 38 mm, width = 26 mm). Three PP fabrics were obtained from JoAnn's Fabric and Crafts, where the first was used as a model system and referred to as textile 1, while the two additional fabrics were referred to as textile 2 and 3, respectively. The textiles were introduced into a 400 mL glass beaker, and submerged in 75 mL of concentrated sulfuric acid (98%; purchased from Sigma Aldrich). To ensure the woven PP remained fully submerged throughout the reaction, a watch glass was positioned on top of PP samples. The reaction ves-sel was then heated to 150 °C for varying amounts of time. Following the sulfonation-induced crosslinking reaction, samples were then allowed to cool down to room temperature, removed from the reaction vessel and washed with deionized (DI) water (Millipore Sigma Milli-Q IQ 7003) and acetone (obtained from Sigma Aldrich) five times to remove byprod-ucts and residual sulfuric acid. Samples were then vacuum dried at 50 °C overnight and placed in an MTI Corporation OTF-1200× tube furnace for carbonization under nitrogen atmosphere with a rate of 1 °C min -1 to 600 °C and 5 °C min -1 to 800 °C. Electroplating to further functionalize PP woven-derived carbons was performed in 250 mL beakers with aqueous electrolyte solutions of 0.01 m CuSO (Sigma Aldrich) in DI water. The solution pH value was adjusted to 1.8 by adding H SO (98%). A series of deposition times were conducted at room temperature without stirring with a deposition voltage of 1 V. Following this, samples were rinsed with DI water and vacuum dried under nitrogen atmosphere.

Characterization: The change in chemical composition of PP textile samples as a function of sulfonation time was investigated through Fourier transform infrared (FTIR) spectroscopy using a Thermo Nicolet 6700 FTIR with an attenuated total reflection accessory (Smart iTR ATR). The scan range was 4000-600 cm -1 with an average of 32 scans and a resolution of 4 cm -1 . Mass gain throughout the sulfonation reaction was monitored, where the final weight of a sample following washing and drying steps was compared to the starting counterpart. The extent of crosslinking was monitored through gel fraction measurements where samples were stirred in hot xylene for 24 h at 120 °C and the insoluble fraction was determined by the change in mass. Differential scanning calorimetry (DSC) was conducted with a TA Instruments Discovery 250 with an initial heating rate of 10 °C min -1 up to 200 °C to erase thermal history, followed by cooling to 20 °C with a rate of 5 °C min -1 , and then back to 200 °C. Trios soft-ware was used for data analysis. The change in degree of crystallinity was monitored by comparing the endothermic melting peak of a crosslinked sample to the theoretical reference enthalpy of PP (209 J g -1 ) in order to track the progression of the sulfonation reaction. [48] Dimensional shrinkage and carbon yield were determined by comparing critical dimensions and masses of final carbon structures to initial textile fabrics.

The morphological changes of textile structures throughout conversion to carbon structures was examined using scanning electron microscopy (SEM) with a Zeiss Ultra 60 field-emission SEM and an accelerating voltage of 15 kV, and elemental composition was also probed through energydispersive X-ray (EDX) spectroscopy. The pore textures of carbon structures were characterized through nitrogen physisorption measurements at 77K with a Micromeritics Tristar II 3020. Surface areas were obtained using the Brunauer-Emmett-Teller analysis and pore size distributions www.advsustainsys.com were determined by non-local density functional theory (NLDFT) with a carbon slit model. Joule heating performance of derived carbon products was investigated with a model system (length = 27 mm, width = 18 mm, thickness = 1.4 mm) by connecting samples to a DC power supply (obtained from Dr. Meter). To compare the impact of different weave patterns on Joule heating performance, dimensions were kept consistent between different textiles. To investigate the impact of mat size, width (20 mm) and thickness (1.4 mm) were kept consistent whereas sample length was varied from 8, 18, and 27 mm. The voltage was incrementally increased, and the temperature of the carbon structure was monitored with a thermocouple (Proster K-type). The electrical resistance of samples was also determined at various conditions through Ohm's law. Furthermore, Joule heating time behavior was investigated at several applied voltages to determine the time required to reach a maximum temperature and time to cool down to room temperature. Water contact angle measurements were performed with a Contact Angle Goniometer and Contact Angle software (Ossila). Thermogravimetric analysis (TGA) experiments were carried out with a TA Instruments Discovery Series TGA 550 where samples were heated with a ramp rate of 10 °C min -1 under air atmosphere. A Rigaku SmartLab X-ray diffractometer with monochromatic Cu K radiation (wavelength of 154.06 pm) was used for X-ray diffraction (XRD) measurements with a 2 range from 5° to 70° with a scan speed of 4° min -1 .