# Eco-friendly Conductive biopolymer nanocomposites and Life Cycle Assessment: a review

Rana Farhat, S.A.E. Boyer, A. Burr, M. Batistella, J. Lopez-Cuesta

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Rana Farhat, S.A.E. Boyer, A. Burr, M. Batistella, J. Lopez-Cuesta. Eco-friendly Conductive biopolymer nanocomposites and Life Cycle Assessment: a review. Cleaner Environmental Systems, 2026, 20, pp.100383. 10.1016/j.cesys.2025.100383. hal-05410605

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# Eco-friendly Conductive biopolymer nanocomposites and Life Cycle Assessment: a review

R. Farhat<sup>a,b</sup>, S.A.E. Boyer<sup>a,*</sup> ◆, A. Burr<sup>a</sup>, M. Batistella<sup>b</sup>, J.M. Lopez-Cuesta<sup>b</sup>

## ARTICLE INFO

**Keywords:**

Biopolymers

Nanofillers

Conductive

Additive manufacturing

Life-cycle assessment

## ABSTRACT

Conductive bionanocomposites are attracting growing interest as multifunctional materials. They can meet the requirements of electrical applications while supporting sustainable development. This review summarizes recent research on bionanocomposites made from biopolymer matrices and carbon conductive fillers that can be processed by additive manufacturing. These materials offer several advantages, including reduced dependence on fossil resources, possibility of low-impact processing, minimized risks in case of dissemination, and satisfactory electrical properties with low amounts of conductive fillers. However, despite their "green" label, their actual environmental performance has not been fully demonstrated. Only a limited number of comprehensive Life Cycle Assessments (LCA) are available. This review discusses the potential of these materials, while underscoring the necessity for rigorous environmental analysis. Such assessments are essential to validate their sustainability from a circular economy perspective using LCA.

## 1. Introduction

Over the past decades, the plastics industry has grown at an unprecedented pace. Global production rose from 15 Mt in 1964 to 311 Mt in 2014. It is projected to reach nearly 460 Mt in 2024—representing a thirtyfold increase compared to the 1960s. It is anticipated that the demand for this material will reach 600 Mt by 2035, as its applications continue to expand. However, it is important to note that of the total global plastic production in 2018 (390 Mt), only 1.5 % of these plastics were bio-based and a mere 8 % were recycled. Non-controlled treatment of waste plastics leads to dissemination. This has deleterious consequences for the environment and human health (Plastics Europe, 2024). The effects are due to their rapid accumulation and limited understanding of their persistence (Chamas et al., 2020). As posited by Lau et al. (2020), even immediate action is taken, plastic waste will continue to accumulate in the environment. It is anticipated that hundreds of millions of metric tons (Mt) will build up over the next few decades. In order to address this problem, bioplastics (i.e. bio-based and/or biodegradable plastics) could be excellent candidates. They provide environmentally friendly alternatives to conventional plastics, but their properties are often below expectations. A possible strategy to improve their performances is adding nanoparticles, which are known to enhance

many technological properties of a host polymer matrix (Fu et al., 2019). For example, polymer nanocomposites loaded with conductive nano-materials have experienced considerable growth due to their remarkable electrical, thermal, and mechanical performance. These materials combine lightness and versatility. They have become essential in many technological sectors, including flexible electronics, connected health, energy, and smart sensors. Concurrently, recent advancements in additive manufacturing (AM) have unveiled novel prospects for the development of these nanocomposites. The ability to design complex geometries and integrate functionalities directly into parts gives this approach significant potential for innovation. It also helps reduce material waste. However, beyond technical performance, the issue of environmental sustainability is becoming crucial, particularly in the current context of ecological transition. The introduction of nano-materials, while showing promise, raises concerns about their environmental impact throughout the product life cycle. Life cycle assessment (LCA) is therefore a fundamental tool for objectively assessing these impacts, from production to disposal. Life cycle assessment (LCA) is a methodological framework for estimating and assessing the environmental impacts attributable to the life cycle of a product (Rebitzer et al., 2004). This analysis is subject to the principles and requirements described by the International Organization for Standardization in the

<footnote><sup>a</sup> CEMEF UMR CNRS 7635, Mines Paris PSL, Sophia Antipolis, 06904, France</footnote>

<footnote><sup>b</sup> Polymères Composites et Hybrides (PCH), IMT Mines Alès, Alès Cedex, 30319, France</footnote>

<footnote>* Corresponding author.
E-mail address: severine.boyer@minesparis.psl.eu (S.A.E. Boyer).</footnote>
ISO 14040 and ISO 14044 standards. The LCA process involves four iterative phases: defining the goal and scope, conducting a life cycle inventory analysis (LCIA), carrying out a life cycle impact assessment, and interpreting the results (Jolliet et al., 2015).

In this context of LCA, a number of studies have examined the sustainability of using conductive composites in additive manufacturing. For instance, recent reviews have analyzed the current state of conductive nanocomposites for sustainable applications, highlighting their potential and challenges in terms of material performance (Blachowicz et al., 2023; Jalali et al., 2023; Rahman et al., 2024; Yan et al., 2023). Another study has investigated the life cycle assessment (LCA) of conductive composites (Alvarado et al., 2024). Despite the increasing research on conductive biopolymer nanocomposites and their potential in additive manufacturing, a systematic overview of current knowledge is still limited. In particular, studies addressing environmental aspects through Life Cycle Assessment (LCA) remain scarce. To date there has been no study which has combined the life cycle assessment (LCA) of conductive biopolymer nanocomposites in additive manufacturing processes. This has prompted us to focus specifically on this subject, which is the reason for conducting this work. In order to ensure a comprehensive and transparent review, the present study adopts a structured methodology. This methodology is employed to identify, classify and critically analyze the most relevant work in this emerging field. The subsequent section delineates the research questions, objectives, and methodological approach that guided the present review.

## 2. Research methodology and objectives

The rapid development of conductive biopolymer nanocomposites for additive manufacturing applications has engendered novel prospects for sustainable electronic and structural components. Nevertheless, the environmental implications of such materials remain insufficiently understood. The majority of extant studies concentrate on processing and electrical performance, while only a small number assess the life cycle impacts of these emerging composites. A search on Scopus (www.scopus.com, accessed in July 2025) for the terms 'LCA' and "conductive nanocomposite" yields a mere two documents. However, it should be noted that no results are found when the same search is performed by adding the term "additive manufacturing". This result indicates that studies about additive manufacturing (AM) in the field of life cycle assessment (LCA) are rare in literature. This shows the interest of this review focusing on the association of these topics. The necessity for this review arises from the requirement to provide a comprehensive and structured overview of the state of the art in the domain of conductive bionanocomposites processed via AM. The review will highlight current achievements, methodological limitations, and emerging challenges. The following research questions have been selected for investigation in order to guide this effort.

Research Question 1: What types of conductive biopolymer nanocomposites have been developed for additive manufacturing, and what are their key material and processing characteristics?

Research Question 2: What is the effect of manufacturing parameters and nanofiller types on the functional properties and environmental performance of these composites?

Research Question 3: Poses an inquiry into the methodologies employed in the assessment of the environmental impacts of the subject, and the limitations of these methodologies in the present context.

Research Question 4: How can the Life Cycle Assessment (LCA) approaches be improved or adapted in order to evaluate the sustainability of conductive biopolymer nanocomposites more effectively?

A systematic literature review was conducted to identify and analyze studies on conductive biopolymer nanocomposites and their

environmental assessment. Literature research were extracted from scientific databases, including Scopus. In order to ensure comprehensive coverage, a range of synonymous keywords were employed in various combinations: 'conductive biopolymer', 'bionanocomposite', 'additive manufacturing', '3D printing', 'life cycle assessment', 'life cycle analysis', 'environmental assessment', 'environmental analysis'. The research included peer-reviewed articles published between 2015 and 2025, focused on bionanocomposite materials, particularly those processed by additive manufacturing and/or including an LCA or environmental assessment.

Building on this comprehensive literature search, the present review is organized into a structured synthesis composed of three main parts. The first part is devoted to conductive nanocomposites developed using additive manufacturing, addressing the materials used, the techniques implemented, and the performance achieved. In the second part, following the absence of studies on conductive nanocomposites developed by additive manufacturing, a selection of notable LCAs on biopolymer-based composites and nanofillers will be detailed. We will focus on a better understanding of the sustainability issues associated with their use. Finally, the third part will be devoted to a specific life cycle analysis carried out as part of an ongoing work. The study focuses on conductive nanocomposites with eco-friendly matrices, developed using additive manufacturing to promote environmental sustainability.

This review constitutes a preparatory phase, intended to lay the theoretical and bibliographical foundations necessary for the complete environmental assessment of materials studied. This section will facilitate the integration of bibliographic results including initial data from an ongoing thesis project.

## 3. Conductive biopolymer nanocomposites developed by additive manufacturing

Conductive bionanocomposites have emerged as a promising class of materials. They are attracting increasing scientific attention due to their distinctive properties. These materials show significant potential for applications in high-value domains. Examples include smart scaffolds, functional biomedical implants, and biosensors within the scope of tissue engineering. When combined with three-dimensional (3D) printing technologies, these materials offer a powerful platform for advanced manufacturing, improving both functional performance and design versatility (Distler and Boccaccini, 2020). The additive manufacturing of electrically conductive components has become a strategic area of development. This is especially true in sectors such as telecommunications, wearable health electronics, photovoltaics, and flexible electronic interfaces (Wang et al., 2025; Yin et al., 2024). The mechanical and geometric adaptability of these components has been shown to significantly broaden their application scope. In order to enhance the electrical conductivity of 3D-printed devices, conductive fillers are typically incorporated into biopolymer matrices. These fillers are most commonly carbon-based allotropes. They include graphene, carbon nanotubes (CNTs), carbon (nano)fibers, carbon black and graphite. All are known by their excellent electrical properties and compatibility with additive manufacturing processes (Bajpai and Jain, 2023). The following section presents the main constituents of bionanocomposites (biopolymers and conductive fillers), as well as the various additive manufacturing techniques employed to process these materials.

### 3.1. Biopolymers and conductive nanofillers

#### 3.1.1. Biopolymers

Biopolymers are a category of polymers that are bio-based, biodegradable or both (Imre and Pukánszky, 2013). Their classification can be divided into two primary groups: namely, biodegradable and non-biodegradable. In addition, a classification system exists that categorizes them according to their provenance as either bio-based or fossil resource-based (oil or gas) (Niaounakis, 2015). Bio-based polymers are
derived from biomass, which can be categorized into distinct types: corn, potatoes, sugarcane, palm oil, straw and wood (cellulose, hemi-cellulose, etc.). Examples of biopolymers include polysaccharides, proteins and polyesters (Abogmaza et al., 2020; Khalil et al., 2020; Nuryawan et al., 2020). Biodegradable polymers are defined as those that can undergo biodegradation, resulting in the production of carbon dioxide, water, and compost. Biodegradation is a process facilitated by the action of bacteria, algae, and fungi (Ferrari et al., 2022). The most well-known bio-based and biodegradable polymers include polylactic acid (PLA), polyhydroxyalkanoates (PHAs), polybutyl succinate (PBS) and starch. The term 'bio-based and non-biodegradable' is used to describe biopolyethylene (bio-PE), biopolyethylene terephthalate (bio-PET) and biopolyamide (bio-PA), among other substances. Poly-butylene terephthalate (PBAT) and polycaprolactone (PCL) are classified as fossil-based and biodegradable polymers (Matthews et al., 2021). The use of biopolymers offers several advantages, including renewability, biocompatibility, affordability, and reduced carbon release (Fig. 1). Furthermore, a significant benefit of biopolymers is their environmental sustainability (Taib, 2023). The non-toxic, non-carcinogenic, non-thrombogenic nature of biopolymers, coupled with their ease of extraction, renders them a promising material for use in a wide range of applications.

### 3.1.2. Conductive nanofillers

It is evident that polymers characteristically exhibit low conductivity. In order to enhance this property, it is necessary to incorporate conductive fillers into polymer-based materials (Almuallim et al., 2022). Electrical conductivity is a material property that has the potential to provide effective control over the functions of biomaterials. For example, it can be used for drug release control, cell stimulation and tissue repair. It also enables stimulation to restore body functions, the production of bioactuators and the development of in vivo biosensors to monitor tissue regeneration (Distler and Boccaccini, 2020). Nanofillers, which are responsible for conductivity, are classified into three categories: emerging materials (MXenes), carbon-based (CNTs, graphene, carbon black), and metallic fillers (silver nanowires, copper nanowires, gold nanoparticles). They are defined as materials of different chemical nature that have at least one dimension between 1 and 100 nm. They are produced as 0D, 1D, 2D, and 3D nanomaterials (Fig. 2) (Frigione and Lettieri, 2020). 0D nanofillers are characterized by their possession of all three dimensions at the nanometric scale, with examples including nanoparticles and quantum dots. One-dimensional (1D) nanofillers are characterized by two nanometric dimensions and one larger dimension, for example nanotubes or nanowires. 2D nanofillers are characterized by one nanometric dimension and two larger dimensions, for example in the form of nanosheets or nanoplates. As demonstrated in Figs. 2 and 3D nanofillers extend beyond the nanometric dimensions and can represent bulk materials with integrated nanostructures (Qureshi et al., 2024).

The electrical performance of conductive materials is strongly governed by the percolation mechanism (Khan et al., 2021). Electrical percolation occurs when conductive nanofillers form a continuous path throughout the polymer matrix, allowing efficient electron transport. Prior to the incorporation of the electrical filler, the polymer material

exhibits insulating properties. As the filler concentration increases, the electrical conductivity of the material gradually improves until it reaches a limit value known as the electrical percolation threshold. At this point, the material changes from an insulator to a conductor with the formation of conductive paths. Increasing the doping of the conductive material by a specific value has been shown to stabilize the electrical conductivity of the polymer composite material. An additional increase in doping will not result in a substantial enhancement of the material's conductivity. Consequently, a plateau will be observed on the conductivity curve (Fig. 3). The percolation threshold is contingent on the dimensionality, aspect ratio, and dispersion state of the fillers (Qureshi et al., 2024; Zhang et al., 2024).

The combination of biopolymer and nanofiller results in the creation of bionanocomposites. In composite systems composed of an immiscible polymer matrix, a phenomenon known as double electrical percolation has been shown to enhance electrical conductivity. In such structures, the conductive filler and one of the polymer phases form continuous interpenetrating networks that effectively lower the overall percolation threshold and improve charge transport efficiency. The process entails the encapsulation of conductive fillers within a single phase or at the interface of a co-continuous polymer blend. This blend morphology of polymers with fillers confined at the interface is highly versatile. It has the capacity to achieve remarkably low percolation thresholds (Sumita et al., 1991). These nanocomposites find application in a variety of fields, including flexible electronics, energy storage, soft robotics, sensors, printed circuits, antennas and heat dissipation systems (Arroyo and Ryan, 2018; Tazwar et al., 2025). These materials offer significant advantages, especially since they are derived from renewable and biodegradable resources. This reduces dependence on fossil plastics and therefore make their use in electronics particularly relevant. It allows for more environmentally friendly devices, especially for products with a short lifespan or that are difficult to recycle (Bozó et al., 2021). In addition to conductivity, carbon fillers, depending on their aspect ratio, improve rigidity, tensile strength, thermal stability and mechanical durability. These properties are often limited in pure bioplastics. Conductive bioplastics enable the development of multifunctional materials, particularly for electromagnetic shielding (EMI), piezoresistive devices, antistatic components or even printable heating elements (Kong et al., 2023). Many conductive biocomposites can be transformed into filaments for AM, thus facilitating the rapid production of personalized, flexible or integrated electronic parts (Arroyo and Ryan, 2018).

### 3.2. Additive manufacturing

Additive Manufacturing, also known as 3D printing, is a method for creating nD objects with various complex shapes and geometries (Blachowicz et al., 2023). The processes of additive manufacturing are based on a common principle, namely the design of a three-dimensional model using Computer-Aided Design (CAD) software. The file obtained is then transformed into a format compatible with slicing software, which sets all the parameters necessary to ensure the correct printing of the object. These instructions are then transferred to the process machine. Finally, after optimizing the experimental process conditions, the machine commences printing the object layer by layer, until the 3D object is obtained. This object is then removed to move on to the surface finishing stage (González-Henríquez et al., 2019). This phase consists of post-processing steps such as cleaning, surface finishing, heat treatment, removal of support structures, surface coating, electropolishing, ultrasonic finishing and hot isostatic pressing (HIP) (Kantaros et al., 2024). There are many 3D printing methods devoted to polymers and composites, and they are classified as shown in Fig. 4. They can be classified according to two main criteria: deposition methods or material selection (powder, filament etc.). According to ASTM F42, the classification system comprises seven categories: material extrusion (for example FDM), powder bed fusion (SLS), vat photopolymerization (SLA, DLP), binder jetting, material jetting, sheet lamination (LOM), and directed energy

<figure><img src="image_3.png" /><figcaption>Fig. 1. Main characteristics of biopolymers (adapted from (Opriş et al., 2024)).</figcaption></figure>
<figure><img src="image_4.png" /><figcaption>**Fig. 2.** Classification and examples of nanomaterials with 0D, 1D, 2D, and 3D structures (adapted from (Qureshi et al., 2024)).</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>**Fig. 3.** Electrical percolation model (adapted from (Zhang et al., 2024)).</figcaption></figure>

deposition. Fused deposition modeling (FDM) is the most accessible technique. It involves melting and extruding a thermoplastic filament layer by layer. Stereolithography (SLA) and digital light processing (DLP) both rely on the photopolymerization of liquid resin, but DLP uses a digital projector to cure entire layers simultaneously, which speeds up printing. Selective laser sintering (SLS) involves the use of a laser beam to melt polymer powder, allowing for complex geometries without the need for support structures. PolyJet printing projects UV-cured drops of photopolymer resin, enabling the production of high-resolution multi-material parts. Finally, laminated object manufacturing (LOM), otherwise known as lamination, involves the production of parts by the methodical stacking and bonding of thin sheets of material, most commonly paper, polymer, or composite films. The key distinctions between these techniques pertain to the raw material state (filament, resin, powder, or sheet), the energy source (thermal, light, or laser), the surface finish and material compatibility (Nath and Nilufar, 2020). The AM process is distinguished by its rapid implementation, cost-effectiveness and minimal tool requirements. However, it should be noted that profitability can be a limiting factor for consumer products.

This technology offers a number of advantages over conventional manufacturing methods, primarily due to the reduced levels of waste generated (Dul et al., 2022). Its use is appropriate in many areas, such as automotive, jewelry, medical and aerospace engineering (Tiwari et al., 2015). Polymer materials are used extensively in the field of 3D printing. The two main categories of polymer materials used for this purpose are thermoplastics and UV-curable thermosets (also known as photopolymers) (Park et al., 2022).

### 3.3. Overview of 3D printed conductive polymer bionanocomposites research

The versatility of the 3D printing process, encompassing a wide range of materials and equipment, enables the targeted integration of functionalities into a structure developed by AM. A plethora of studies are presented on an annual basis concerning the integration of specific functionalities, such as conductivity, magnetism, integrated circuits, thermal sensing and self-repair, into components (Bekas et al., 2019; Wang et al., 2017; Gojny et al., 2004). The present section is chiefly concerned with the various aspects of materials and manufacturing processes. It focuses on the development of nanocomposites with electrical conduction properties. These properties are achieved through the incorporation of carbon fillers (Table 1).

A significant advancement in the field of 3D printing of nanoparticle-reinforced biocomposites is the potential for printing structural components for practical electrical applications. In a recent study, Beniack et al. (Beniak et al., 2022) employed FDM to fabricate various PLA/carbon black composite specimens using a commercial material reinforced with 25 % CB, intended for use in electrical applications. The findings of the study indicated a linear dependence between the electrical resistance of the specimens and their length. This suggests a linear dependence of the material's properties on its dimensions. It was also demonstrated that the processing temperature of the material during fabrication resulted in reduced electrical resistance. Moreover, if the measurement was performed at 80 °C instead of 25 °C, the resistance was higher. A maximum tensile strength of 32.1 MPa was attained. Nevertheless, conductive PLA material achieved only 66 % of the strength of conventional PLA material without carbon black.

Chizari et al. (2016) used the solvent-cast 3D printing method to develop sensors for liquids that exhibited enhanced sensitivity. This result was achieved by optimizing the structural parameters of the

<figure><img src="image_6.png" /><figcaption>**Fig. 4.** Classification of AM techniques based on the type of base materials (3D printing methods figures are taken from (Nath and Nilufar, 2020)).</figcaption></figure>
<table><caption>**Table 1**

Research on conductive bionanocomposites manufactured by AM.</caption><thead><tr><th>Materials</th><th>AM Method</th><th>Results</th><th>Applications</th><th>Main objective</th><th>Ref.</th></tr><tr><th>Biopolymers</th><th>Nanofillers</th><th></th><th></th><th></th><th></th></tr></thead><tbody><tr><td>Polylactic acid (PLA)</td><td>Carbon black (CB)</td><td>Fused deposition modeling (FDM)</td><td>Low voltage electronic applications</td><td>Assess the correlation between geometry, temperature, and electrical performance in conductive PLA/CB materials fabricated via FDM</td><td>Beniak et al. (2022)</td></tr><tr><td>Polylactic acid (PLA)/ Polycaprolactone (PCL)</td><td>Multi-walled carbon nanotube (MWCNT)</td><td>Solvent-cast</td><td>Organic liquid detector</td><td>Investigate how CNT content and filament geometry affect the electrical and sensing performance of 3D-printed CNT/PLA composites</td><td>Chizari et al. (2016)</td></tr><tr><td>Polylactic acid (PLA)/ Graphene nanoplatelet (GNP)</td><td>Carbon black (CB)</td><td>Fused deposition modeling (FDM)</td><td>-</td><td>Explore the relationship between graphene content and the electrical/mechanical performance of 3D-printed PLA/PCL nanocomposites</td><td>Masarra et al. (2022)</td></tr><tr><td>Polylactic acid (PLA)</td><td>Multi-walled carbon nanotube (MWCNT)/Carbon fiber (CF)</td><td>Fused deposition modeling (FDM)</td><td>-</td><td>Analyze the relationship between FDM printing parameters, microstructure, and the coupled mechanical-electrical behavior of PLA/carbon black composites</td><td>(Musenich et al., 2024)</td></tr><tr><td>Poly(L-lactide) (PLLA)/ Thermoplastic polyurethane (TPU)</td><td>Multi-walled carbon nanotube (MWCNT)/t-ZnO</td><td>Selective Laser Sintering (SLS)</td><td>-</td><td>Design bio-based conductive PLA composites with CF and CNT reinforcements to improve electrical and mechanical properties</td><td>(Petrény et al., 2022)</td></tr><tr><td>Polylactic acid (PLA)</td><td>Multi-walled carbon nanotubes (MWCNT)/ graphene nanoplatelet (GNP)</td><td>Fused deposition modeling (FDM)</td><td>EMI shielding devices Electromagnetic compatibility (EMC) systems (Bychanok et al., 2017)</td><td>Design an SLS-printed PLLA/TPU nanocomposite with t-ZnO@MWCNT to improve conductivity and electro-actuated shape memory performance</td><td>Shuai et al. (2024)</td></tr><tr><td>Polylactic acid (PLA)</td><td>Multi-walled carbon nanotubes (MWCNT)</td><td>Fused deposition modeling (FDM)</td><td>-</td><td>Develop FDM-printed PLA composites with GNP and MWCNT fillers to evaluate conductivity, percolation behavior, and suitability for EM applications</td><td>(Spinelli et al., 2019)</td></tr><tr><td>Polylactic acid (PLA)</td><td>Multi-walled carbon nanotubes (MWCNT)</td><td>Fused deposition modeling (FDM)</td><td>Sensors, Health monitoring devices</td><td>Improve the mechanical strength of 3D-printed thermoplastics by reinforcing filaments with CNTs and applying microwave irradiation to strengthen interlayer welds</td><td>(Sweeney et al., 2017)</td></tr><tr><td>Polylactic acid (PLA)</td><td>Multi-walled carbon nanotubes (MWCNT)</td><td>Fused deposition modeling (FDM)</td><td>Sensors, Health monitoring devices</td><td>Investigate the effect of MWCNT content on the mechanical, thermal, electrical, and antibacterial properties of PLA nanocomposites developed using FDM</td><td>(Vidakis et al., 2021)</td></tr></tbody></table>

conductive nanocomposite (CNT/PLA) using 3D printing techniques. The materials were prepared at CNT concentrations of up to 30–40 wt%. It was demonstrated that an electrical conductivity of 2350 S/m was attained with 30 wt% CNT. This value is higher than the considerably lower values reported in other studies (less than $10^{-2}$ S/m (Wei et al., 2015), <100 (Postiglione et al., 2015), <1 (Czyżewski et al., 2009) and ~10 S/m (Leigh et al., 2012). Reported electrical conductivity values for polymer nanocomposites vary considerably, ranging from $10^{-2}$ to 2350 S/m. This discrepancy results from variations in filler type, quantity, dispersion quality, and processing conditions, which significantly affect the formation of conductive pathways. For example, the composite with a conductivity of 2350 S/m contains 30–40 % of well-dispersed carbon nanotubes (Chizari et al., 2016). This, in turn, allowed the formation of a continuous conductive network well above the percolation threshold. In contrast, the graphene/ABS composites with a conductivity less than $10^{-2}$ S/m were based on graphene oxide (GO) with a much lower filler content (≤5.6 wt%) and printed by fused deposition modeling (FDM). Moreover, the solvent casting 3D printing process used by Chizari et al. allows for dense filament deposition at room temperature, while high-temperature extrusion in FDM can introduce microvoids and polymer degradation, further reducing conductivity. These results highlight the strong dependence of electrical performance on filler characteristics and processing methods. Furthermore, the use of hybrid fillers does not result in the same conductivity values as a single filler

type. Composites with poorly dispersed fillers often remain below the percolation threshold. Systems with well-aligned networks or post-processing steps (e.g. annealing) can achieve conductivities several orders of magnitude higher. It is important to note that the conditions and parameters used during the mixing process can also have a significant impact on the results. Therefore, a direct comparison between studies should consider all these parameters. In addition, Chizari et al. reported that the sensor sensitivity depends on the thickness of the deposited filaments. Finer filaments lead to higher sensitivity, especially when combined with moderate interfilament spacing. Consequently, it was determined that the sensor architecture plays a pivotal role in determining its performance. The thin and porous nature of these materials allows for enhanced liquid retention, thereby prolonging the detection effect. In the present study, difficulties were observed in printing at 40 % CNT, attributable to technical issues, including clogged nozzles and fragility.

Masarra et al. (2022) fabricated PLA/PCL matrix nanocomposites loaded with graphene nanoplatelets (GNP) using the FDM method. The results obtained demonstrated an electrical percolation rate of 15 wt% and a rheological percolation of 10 wt%. Samples filled with 20 wt% presented a conductivity of 0.58 S/m. The nanocomposites with 20 and 25 wt% exhibited the capacity to establish an electrical circuit constructed using a voltage generator (5V), an LED and the 3D-printed sample. Maintaining the same voltage (5 V) resulted in the 25 wt%
sample producing a higher light intensity of the LED, attributable to its reduced electrical volume resistivity (Fig. 5). An enhancement of 30 % in Young's modulus was also observed between the 10 % and 25 % graphene samples.

In another recent study, Musenich et al. (2024) used the FDM method to design PLA/carbon black nanocomposites. They experimentally characterized and analytically modeled the structural and piezoresistive behavior of 3D printed anisotropic PLA/CB nanocomposite polymer samples. They built a testing setup to simultaneously measure the mechanical response to uniaxial tensile stress and the corresponding variations in electrical resistance as a function of strain. The results highlighted a significant dependence of the behavior of the samples on the microstructure induced by additive manufacturing. Thus, their behavior depends on the orientation of the 3D printing layers. A further study (Abdalla et al., 2020) was conducted to investigate the effects of varying printing layer thicknesses and orientations on the electron transfer kinetics and resistivity of conductive PLA/CB materials. The findings demonstrated that electrodes printed with a minimum layer thickness of 0.1 mm in the vertical orientation exhibited the highest conductivity. With increasing layer thickness and horizontal printing orientation, the electrode became more resistive. This phenomenon can be attributed to the ability of vertical prints to establish conductive pathways within individual printing layers. These pathways are capable of establishing distinct connections between electrical contact and the interface with the solution (Fig. 6).

In addition to the general information summarized in Table 1 and the above explanations, AM parameters play a crucial role in determining the electrical performance of printed bionanocomposites. Printing orientation significantly impacts the formation of conductive pathways. Samples printed parallel to the current measurement direction generally exhibit higher conductivity due to improved filler alignment and reduced interfacial resistance between layers. Layer thickness is another key factor. Thinner layers enhance interlayer bonding and promote a more continuous conductive network, whereas thicker layers increase void formation and reduce charge transfer efficiency. Similarly, the printing temperature strongly influences filler dispersion within the polymer matrix. Higher temperatures improve matrix fluidity and filler mobility, leading to better percolation. However, excessive temperatures may induce polymer degradation or filler aggregation. Therefore, optimizing printing orientation, layer thickness and temperature is essential for achieving enhanced electrical properties in AM-based bio-nanocomposites (Glogowsky et al., 2024; Naboulsi et al., 2025; Pentek et al., 2020).

In a study by Petrény et al. (2022), PLA-based conductive composites were developed using the FDM method with various conductive fillers (namely carbon fiber (CF), multi-walled carbon nanotubes (MWCNT)

with a view to environmental sustainability. The findings demonstrated that the incorporation of carbon fibers into the polymer matrix enhanced the dispersion of carbon nanotubes (CNTs). The conductivity of CNT-CF reinforced hybrid composites was found to be considerably higher than that of CNT-only composites, a phenomenon attributable to the incorporation of 30 wt% CF. With the incorporation of 0.5 and 0.75 wt% CNTs, a substantial improvement in conductivity was observed, reaching levels that were twice those of the CF-only composite (35.5 S/m). The micro and nanometric hybrid reinforcement causes an increase in viscosity, which adversely impacts the processing stage. Incorporating 10 wt% of a lactic acid-based oligomeric plasticizer into the hybrid composites improved printability and mechanical performance. Specifically, it enhanced ductility, tensile strength, and elongation at break. The addition resulted in only a slight reduction in electrical conductivity. This study highlights the potential of replacing traditional, non-biodegradable conductive plastics with bio-sourced and printable alternatives. This opens up new prospects for green electronics, particularly in printed sensors, disposable smart devices, and low-power applications.

In the study by Shuai et al. (2024) a nanocomposite was fabricated by selective laser sintering (SLS). The material was based on a poly (L-lactic acid)/thermoplastic polyurethane (PLLA/TPU) matrix and reinforced with t-ZnO(zinc oxide tetrapod)@-MWCNT. The aim of this study was to construct a conductive network that would enhance the electro-actuated shape memory properties. The results demonstrated that 40 wt% of the interconnected MWCNTs formed a 3D conductive network within the matrix without significant aggregation, which enhanced the electrical and thermal properties of the matrix. The t-ZnO@MWCNT assembly exhibited superior electro-actuated shape memory properties. It is important to note that, in the SLS process, the starting materials are in the form of powder particles typically ranging from 60 to 100 µm. When additional nanoscale particles are introduced, such as MWCNTs or ZnO, they tend to adhere to the surface of the larger polymer powder particles due to surface energy effects. This distribution promotes more homogeneous dispersion during processing and facilitates the formation of a percolated network. Moreover, unlike melt-processing techniques, the SLS process does not involve shear forces, which helps preserve the morphology of nanostructures. This feature is particularly advantageous for maintaining the functional integrity of the nanofillers and enhancing their effectiveness in forming conductive pathways.

Spinelli et al. (2019) employed the FDM method to study conductive composites. They investigated PLA/GNP and PLA/MWCNT binaries, as well as PLA/GNP/MWCNT ternary systems. The ternary composite had a GNP/MWCNT ratio of 50/50, with filler contents from 0 to 12 wt%. At the highest filler content (i.e., 12 wt%), the electrical conductivity of the

<figure><img src="image_7.png" /><figcaption>Fig. 5. (a) The variation of the volume electrical resistivity of the composites as a function of the percentage of graphene; (b) The electrical circuit connected using the 3D-printed PLA/PCL/GNP (25 wt%) (Masarra et al., 2022).</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>Fig. 6. Comparison of horizontal and vertical prints of 0.1 and 0.4 mm layer thickness and the different conductive paths formed in the print layers (Abdalla et al., 2020).</figcaption></figure>

MWCNT, GNP, and multiphase composites was measured to be 4.54 S/m, 6.27 S/m, and 0.95 S/m, respectively. The electrical percolation threshold was found to be in the range of [3–6] wt% for the PLA/GNP and PLA/GNP/MWCNT composite and was [1.5–3] wt% for PLA/MWCNT. The electrical percolation results agreed with the rheological percolation thresholds. This has rendered these composites promising candidates for the fabrication of 3D printed conductive devices for electromagnetic (EM) applications.

Vidakis et al. (2021) conducted a study on the fabrication of PLA/MWCNT nanocomposites via fused deposition modeling (FDM). The composites were reinforced with multi-walled carbon nanotubes at loadings of 0.5, 1.0, 2.5, and 5.0 wt%. The investigation focused on assessing the influence of these nanoscale fillers on the mechanical, thermal, electrical, thermomechanical, and antibacterial properties of the fabricated nanocomposites. The findings demonstrated that the maximum electrical conductivity (10 S/m) was attained at a 5 wt% concentration of MWCNT in cross-layer direction. It is interesting to note that the conductivity values measured in cross-layer were higher than those of the through-layer. This difference is due to the nature of the FFF 3D printing process, which leads to an "anisotropic" character to the electrical properties of the final nanocomposites; the FFF induced a kind of 1D shear-induced crystallization. In this study, it was established that an increase in tensile strength and elastic modulus occurred for 1.0, 2.5 and 5.0 wt% filler in comparison with unfilled polymer. Higher concentrations (2.5 wt% and 5.0 wt%) did not demonstrate any additional improvement. The most significant enhancements were observed at 1.0 wt% filler, with a 34% increase in tensile strength and a 33% increase in elastic modulus. Regarding the outcomes of the bending test, it was evident that the samples with 2.5 wt% MWCNT and 5 wt% MWCNT loading exhibited the highest bending stress. They showed a 49% increase in bending strength and a 43% increase in flexural modulus.

Based on the results presented, the employment of conductive nanoparticles within biopolymer matrices has resulted in the demonstration of substantial benefits in a broad spectrum of applications for bionanocomposites. However, the health effects of nanoparticle exposure and the environmental risks associated with nanoparticle production and use are less well established (Kumah et al., 2023). This may result in a reduction of benefits and a compromise to the overall sustainability of bionanocomposites (Kim and Fthenakis, 2013). Consequently, a life cycle assessment is imperative to evaluate their environmental impacts, thereby facilitating the adjustment of synthesis methods and the identification of solutions to minimize their hazardousness. Although extensive research has been conducted on these conductive bionanocomposites produced by additive manufacturing, no study has yet assessed their environmental impacts using life cycle assessment (LCA). To address this gap, in section 2, the focus will be on the LCA carbonaceous conductive nanoparticles. A comparison of these nanoparticles will be made to ascertain their impact on the sustainability of the final bionanocomposites materials.

Also, an overview of studies on bionanocomposites in general will be presented. Although these studies do not yet cover conductive bionanocomposites produced by additive manufacturing, they shed light on

the potential environmental implications of similar materials and processes discussed in this Section 1.

# 4. LCA on biopolymer-based nanocomposites

## 4.1. LCA on conductive carbon nanofillers

Nanofillers can affect the durability of conductive nanocomposites. Their environmental assessment helps identify the most suitable filler that balances performance and sustainability. In this context, a search on Scopus with together the terms ‘LCA’ and ‘Nanoparticles’ in the title, abstract and keywords returns approximately 365 documents since 2010 (www.scopus.com, accessed in July 2025). A considerable body of research has been dedicated to the analysis of nanoparticles using the LCA approach. However, there is a paucity of literature that directly compares the environmental impact of different conductive carbon nanofillers and their composites. This study therefore presents an innovative contribution to the field. In order to achieve the objectives, the analysis was limited to conductive carbon nanoparticles, namely graphene, carbon nanotubes (CNT) and carbon black (CB). The figure below (Fig. 7) presents the LCA results on the impact indicators of non-renewable energy use (a) and greenhouse gas emissions (b) for different types of conductive nanoparticles. The selection of these two impact indicators is predicated on the fact that they are the most frequently published (particularly through streamlined LCA) and easy to interpret by decision-makers. Consequently, a focus on them allows for maximum comparability with other studies in the field. Furthermore, within a LCA of manufactured products, the production phase is frequently identified as the primary contributor to environmental impacts. The predominant consequences of this phase are typically characterized by greenhouse gas emissions and primary energy consumption. The focus on these metrics enables the rapid identification of the most impactful stages. The results indicated that, among the nanomaterials examined, carbon nanotubes (CNTs) exhibited the most significant environmental impact, with graphene ranking second, and carbon black demonstrating the least environmental impact. This information is of particular use to researchers and manufacturers involved in the design of conductive nanocomposites. This enables informed decision-making processes when selecting conductive fillers, incorporating considerations beyond mere technical performance into the decision-making framework. Therefore, depending on the project’s priorities — whether the goal is to maximize conductivity or minimize environmental impact — it is possible to find the right balance between efficiency and sustainability. This approach is expected to focus research on the development of safer materials and the creation of more environmentally friendly technologies.

Several studies have been conducted on the life cycle assessment of nanofillers (Dong et al., 2021; Khanna et al., 2008) and biopolymers separately (Petchprayul et al., 2012; Vink and Davies, 2015). However, the existing literature on the LCA of conductive nanocomposites is limited. As mentioned in the methodology part, a Scopus search with the terms ‘LCA’ and ‘conductive nanocomposite’ yields only two
<figure><img src="image_9.png" /><figcaption>Fig. 7. Greenhouse gas emissions (a) and Non-renewable energy use (b) for conductive carbon fillers. Data was collected from references in Table 2.</figcaption></figure>

documents (Johnston et al., 2024; Pizza et al., 2014). Moreover, no articles are obtained when the same search is performed adding the term “additive manufacturing”. This result also indicates that studies on the impact of additive manufacturing in the field of life cycle assessment (LCA) are scarce in the literature, despite the potential benefits of these new manufacturing techniques (Carroccio et al., 2022). In view of the absence of studies on conductive nanocomposites developed by AM, a selection of notable LCAs on biopolymer-based composites and nanofillers will be detailed in the next section. Historically, early studies focused on nanocomposites based on non-green matrices, as reviewed in the article by Carroccio et al. (2022) who also discussed LCAs on green nanocomposites. Prior to the publication of Carroccio et al., a Scopus search for articles containing both “LCA” and ‘nanocomposites’ in the title, abstract, or keywords returned fewer than 50 documents. This number decreased further after refining the search. At present, the same search retrieves 84 documents (www.scopus.com, accessed in July 2025), which demonstrates the mounting interest in environmental implications, particularly in the domain of polymer nanocomposites.

## 4.2. Overview of LCA biopolymer-based nanocomposites

Biopolymer nanocomposites offer a number of significant advantages, including enhanced physical, structural, and functional properties, while being environmentally sustainable, affordable, biodegradable, non-toxic, and biocompatible (Ali et al., 2023; Balart et al., 2021). The aforementioned factors have resulted in an elevated societal concern for the environment, thereby rendering ecological and sustainable issues more pertinent than ever before. As a result, materials are designed with their entire life cycle in mind, from production to disposal. It's also important to consider their environmental impact throughout this process. Using renewable resources instead of synthetic ones to make eco-friendly polymer nanocomposites requires to address plastic waste issues. These materials are renewable, biodegradable, and environmentally friendly. Consequently, they can, under certain controlled conditions, be degraded or disposed of at the end of their life with reduced environmental impact (Annu et al., 2024). A life cycle assessment (LCA) is the most appropriate method for assessing the environmental impact of nanocomposites. A selection of notable LCA studies on nanocomposites has been reviewed. The reviewed papers are listed in Table 3, along with additional useful information, such as the product/application for which the nanocomposites are intended, system boundaries, end-of-life options, and the impact categories analyzed in the original study.

Twelve studies have been dedicated to LCAs of biopolymer-based nanocomposites, demonstrating a growing interest in bioplastic systems and their environmental impact over fossil-based plastics. Bala et al. (2022) compared the environmental impact of polyethylene (PE) and polypropylene (PP) plastic films with films made of polylactic acid (PLA) and PLA reinforced with nanoclays (PLA + NC). They found that

<figure><img src="image_10.png" /><figcaption>Table 2</figcaption></figure>

Energy consumption and greenhouse gas emissions to produce different types of nanoparticles.

<table><thead><tr><th>Nanofiller</th><th>Non-renewable energy use (MJ.kg<sup>-1</sup>)</th><th>Ref.</th></tr></thead><tbody><tr><td rowspan="4">CNT</td><td>4.09 10<sup>5</sup></td><td>Teah et al. (2020)</td></tr><tr><td>3.1 10<sup>4</sup></td><td>Gavankar et al. (2015)</td></tr><tr><td>6.55 10<sup>3</sup></td><td>Teah et al. (2020)</td></tr><tr><td>2145</td><td>Roes et al. (2010)</td></tr><tr><td rowspan="6">Graphene</td><td>215</td><td>Roes et al. (2010)</td></tr><tr><td>1879</td><td>Pizza et al. (2014)</td></tr><tr><td>1100</td><td>Arvidsson et al. (2018)</td></tr><tr><td>490</td><td>Cossutta et al. (2017)</td></tr><tr><td>470</td><td>Pizza et al. (2014)</td></tr><tr><td>300</td><td>Cossutta et al. (2017)</td></tr><tr><td rowspan="2">CB</td><td>89</td><td>Ecoinvent Database V2.2</td></tr><tr><td>88</td><td>Voll and Kleinschmit (2010)</td></tr></tbody></table>

<table><thead><tr><th>Nanofiller</th><th>Greenhouse Gas Emissions (kgCO<sub>2</sub>-eq./kg)</th><th>Ref.</th></tr></thead><tbody><tr><td rowspan="4">CNT</td><td>1.53 10<sup>5</sup></td><td>Gavankar et al. (2015)</td></tr><tr><td>2.85 10<sup>4</sup></td><td>Teah et al. (2020)</td></tr><tr><td>4.8 10<sup>2</sup></td><td>Teah et al. (2020)</td></tr><tr><td>110</td><td>Roes et al. (2010)</td></tr><tr><td rowspan="5">Graphene</td><td>11</td><td>Roes et al. (2010)</td></tr><tr><td>6</td><td>Singh et al. (2008)</td></tr><tr><td>146</td><td>Cossutta et al. (2017)</td></tr><tr><td>86</td><td>Cossutta et al. (2017)</td></tr><tr><td>3.4</td><td>Papanikolaou et al. (2019)</td></tr><tr><td>CB</td><td>2.36</td><td>Lin et al. (2017)</td></tr></tbody></table>

PLA + NC reduces the climate impact by 45 % compared to PE, 39 % compared to PP, and 2 % compared to PLA. From the perspective of fossil resource consumption, PLA + NC uses 46 % fewer fossil resources than PE. However, compared to PP and PE, PLA-based nanocomposites have a higher impact on land use and water consumption. It has been demonstrated that the incineration of PLA and PLA + NC is more environmentally friendly than composting, as composting generates methane emission, a potent greenhouse gas. Another study (Garraín et al., 2007) compared oil-based films (made of PP and PA6) with biodegradable films consisting of a blend of PLA and modified starch. The green nanocomposite showed better performance in almost all impact categories.

In an application outside of packaging, the life cycle assessment (LCA) of nanocomposites for a road bike pedal body was studied by Hernández-Díaz et al. (2021). They focused on a comparative study of the environmental impact of glass fiber-reinforced PA6 composites and PLA/SGW wood composites. It is estimated that the use of the bio-based composite has led to a reduction in carbon footprint and energy consumption of over 40 %. This finding indicates that the fabrication of a bio-based composite pedal body is evidently more environmentally sustainable than the production of synthetic alternatives.
<table><caption>**Table 3**
Overview of LCA Studies on bionanocomposites: Materials, Production, and main features of the LCA analyzes.</caption><thead><tr><th colspan="2">Materials</th><th rowspan="2">Product/ Application</th><th rowspan="2">LCA software/ Database</th><th rowspan="2">System boundaries</th><th rowspan="2">End of life (b)</th><th rowspan="2">Impact categories (c)</th><th rowspan="2">Main objective</th><th rowspan="2">Ref.</th></tr><tr><th>Biopolymer (s)</th><th>Nanoparticles (a)</th></tr></thead><tbody><tr><td colspan="9"><strong>PLA-based composites</strong></td></tr><tr><td>PLA</td><td>Clay</td><td>Packaging bakery fresh products</td><td>Gabi software and databases</td><td>Cradle-to-grave</td><td>I</td><td>C; R.f; L; W</td><td>Perform a LCA comparing conventional plastic films (PE, PP) with PLA and PLA/nanoclay composites</td><td>Bala et al. (2022)</td></tr><tr><td>PLA</td><td>Starch</td><td>Food packaging</td><td>SimaPro v7.0./ Bibliographic information</td><td>Cradle-to-grave</td><td>I, L, C</td><td>F; G; A; E</td><td>Compare the environmental performance of PP and PA6 with films made of PLA and modified starch</td><td>Garraín et al. (2007)</td></tr><tr><td>PLA/PHBV</td><td>GNP; MWCNT</td><td>Multifunctional packaging</td><td>OpenLCA v2.0.2/ Ecoinvent v3.2.</td><td>Cradle-to-grave</td><td>A.c, O</td><td>C.f; Et.W; HT; nc; FMR.d</td><td>Assess the ecological footprint of PLA/PHBV-nanocomposites by comparing different end-of-life scenarios</td><td>Dos Anjos et al. (2024)</td></tr><tr><td>PLA</td><td>Clay</td><td>Packaging of ready-to-eat fresh fruit</td><td>SimaPro 8™/ Ecoinvent 3</td><td>Cradle-to-grave</td><td>I; L; C</td><td>H; E.q; C; R</td><td>Compare the environmental impacts of PLA-nanoclay and PET packaging</td><td>Lorite et al. (2017)</td></tr><tr><td>PLA</td><td>Clay</td><td>Food packaging</td><td>SolidWorks 2020/ Litterature</td><td>Cradle-to-grave</td><td>C</td><td>G; E.c</td><td>Evaluate the environmental performance of PLA versus oil-based plastics and assess how end-of-life management affects its sustainability</td><td>Oliver-Ortega et al. (2021)</td></tr><tr><td>PLA</td><td>ChNF</td><td>Food container/ Packaging</td><td>SimaPro7.3.3/ Ecoinvent v2</td><td>Cradle-to-grave</td><td>C; T; L</td><td>C; A; E; E.w; P; OF; OL.d; HT. c; HT.nc; Et.W; L; I</td><td>Evaluate the sustainability of PLA/chitin nanocomposites and explore ways to improve their environmental performance for packaging use</td><td>Cinelli P. et al. (2017)</td></tr><tr><td>PLA</td><td>CNC</td><td>-</td><td>SimaPro 7.2/ Ecoinvent v2</td><td>Cradle-to-grave</td><td>C</td><td>CR; C; Rd; OL. d; E.t; A; E; L; MFF; H; E.q; R. c</td><td>Assess the sustainability of PLA/CNC/limonene films compared to PLA/OMMT/ ATBC composites</td><td>Petrucci et al. (2018)</td></tr><tr><td colspan="9"><strong>PHB-based composites</strong></td></tr><tr><td>PHB</td><td>Clay</td><td>Cathode ray tube monitor housing; Internal car panels</td><td>-</td><td>Cradle-to-grave</td><td>C</td><td>C; NREU</td><td>Assess the environmental performance of PHB/OMMT composites compared to traditional plastics</td><td>Pietrini et al. (2007)</td></tr><tr><td colspan="9"><strong>PA11-based composites</strong></td></tr><tr><td>PA11</td><td>SGW</td><td>Road cycling pedal body</td><td>Solid works/Data base of the sustainability module of Solid works</td><td>Cradle-to-grave</td><td>-</td><td>C.f; E.c</td><td>Evaluate the sustainability of PLA/SGW composites versus PA6 glass fiber composites</td><td>Hernández-Díaz et al. (2021)</td></tr><tr><td colspan="9"><strong>Epoxy-based composites</strong></td></tr><tr><td>Epoxy resin</td><td>GNP; CNC</td><td>Cosmetic; Structural applications</td><td>-</td><td>-</td><td>-</td><td>A.d; A; E; OL. d; OF; C</td><td>Evaluate the environmental sustainability of nano-reinforced bio-based resins relative to conventional epoxy systems</td><td>Tserpes et al. (2023)</td></tr><tr><td colspan="9"><strong>PU-based composites</strong></td></tr><tr><td>PU</td><td>Hemp fibers</td><td>-</td><td>OpenLCA v1.10/ Ecoinvent v3.7</td><td>Cradle-to-grave</td><td>-</td><td>A.d; A.dff; A; E; Et.W; G; HT. nc; MA.e;</td><td>Assess the environmental impact of hemp and silica fillers in bio-based PUR composites</td><td>Recupido et al. (2023)</td></tr><tr><td colspan="9"><strong>Starch-based composites</strong></td></tr><tr><td>Mango kernel starch (MKS)</td><td>SNC</td><td>-</td><td>SimaPro v.9.1.1/ Ecoinvent database v.3.7.1+ litterature</td><td>Cradle-to-grave</td><td>-</td><td>C; NREU; E.w; TA;</td><td>Evaluate the environmental sustainability of MKS/SNC biopolymer films versus LDPE through an ex-ante LCA</td><td>Müller-Carneiro et al. (2023)</td></tr></tbody></table>

<footnote>(a) Modified Starch (Starch); Stone-ground wood fibres (SGW); Graphene nanoplatelets (GNP); Multi-wall carbon nanotube (MWCNT); Chitin Nanofibrils (ChNF); Starch nanocrystals (SNC); Cellulose nanocrystals (CNC).</footnote>

<footnote>(b) Incineration (I); Land filling (L); Composting (C); Aerobic composting (A.c); Open dumping (O); Thermo-valorization (T).</footnote>

<footnote>(c) Climate Change (C); Resource use fossils (R.f); Land use (L); Water use (W); Fossil energy depletion (F); Global warming (G); Acidification (A); Terrestrial acidification (TA); Eutrophication (E); Carbon footprint (C.f); Energy consumption (E.c); Freshwater Ecotoxicity (Et.W); Human Toxicity, non-carcinogenic effects (HT. nc); Human Toxicity, cancer (HT.c); Fossil, Mineral & Renewable Resources depletion (FMR.d); Abiotic depletion (A.d); Abiotic depletion fossil fuels (A.dff); Marine aquatic ecotoxicity (MA.e); Ozone layer depletion (OL.d); Photochemical oxidation (PC.o); Terrestrial ecotoxicity (T.et); Human Health (H); Ecosystem quality (E.q); Resources (R); Resources consumption (R.c); Eutrophication, freshwater (E.w); Particulate matter (P); Photochemical ozone formation (OF); Ionizing radiation (I); Non Renewable Energy Use (NREU); Total Energy Use (TEU); Carcinogens, Respiratory organics, Respiratory Inorganics (CR); (RI); Radiation (Rd); Ecotoxicity (E.t); Minerals and Fossil Fuels (MFF).</footnote>
In a recent study, Dos Anjos et al. (dos Anjos et al., 2024) evaluated the ecological footprint of PLA/PHBV carbonaceous materials hybrid nanocomposites intended for biodegradable and antimicrobial packaging applications. They examined two end-of-life scenarios: aerobic composting and open-air disposal. The latter scenario was deemed to be the most pessimistic. Their findings revealed that the stage of production which has the most significant impact on carbon footprint is that of PLA/PHBV production, accounting for 80 % of the total impact. The ecotoxicity of freshwater systems was predominantly dictated by the two end-of-life scenarios (exceeding 90 %). Human Toxicity, non-carcinogenic effects (HT.nc) were exacerbated by open-air disposal, surpassing the contribution of the extrusion processing stage ($8.9 \times 10^{-8}$ CTUh*/kg of the blend). The impacts related to Fossil, Mineral & Renewable Resources depletion (FMR.d) were found to be less dependent on the end-of-life scenario. Extrusion was identified as the primary contributor to the FMR.d impact (>91 %, $3.6 \times 10^{-5}$ kg Sb* eq/kg of the blend). In the present study, the authors confirmed that a life cycle in which PLA/PHBV-based hybrid nanocomposites undergo aerobic biodegradation at the end of their service life could be highly eco-efficient. This approach helps minimize harmful emissions to ecosystems and human health.

*CTUh: Comparative Toxic Unit for humans; * Sb: Antimony.

Recupido et al. (2023) carried out a study to examine the potential environmental impacts of the production and functionalization methods of hemp and silica fillers used in bio-based polyurethane (PUR) composite solutions. The study revealed that SiO₂ particles exhibited the highest relative impact in all categories (GWP, EP, ADP, etc.) compared to other fillers, with more than twice the impact of phenolated nano-hemp.

Various studies on green nanocomposites refer to applications in the packaging sector, in which the use of sustainable polymers can lead to immediate advantages. LCA of nanocomposites for packaging of ready-to-eat fresh fruit was investigated, among others, by Lorite et al. (2017). A comparative study was conducted of PLA-nanoclay-based nanocomposite (PLA/NC) and conventional PET-based packaging. Their findings indicated that the packaging manufacturing stage was the largest contributor to environmental impact. This way mainly due to high energy consumption and emissions. Material production and transportation were identified as the second most significant contributors. Even though PLA is bio-based and widely regarded as environmentally friendly, the production of PLA/NC requires more energy than PET, resulting in a greater impact on climate change. However, packaging composed of poly-lactic acid (PLA) (PLA/NC) exhibited lower impacts on human health (e.g., reduced carcinogenic and non-carcinogenic effects) but higher impacts on ecosystem quality (e.g., aquatic eutrophication and land occupation). The conclusion drawn was that the current waste treatment scenario showed a slight preference for PET. For PLA, 20 % was composted, 40 % incinerated, and 40 % landfilled. For PET, 60 % was incinerated and 40 % landfilled. The advantage of PET was attributed to its higher energy recovery from incineration. However, under an ideal scenario where PLA is fully composted, it would become significantly more environmentally friendly than PET. The findings of this study indicate that poly-lactic acid (PLA) packaging has the potential to serve as a sustainable alternative, especially in the context of composting at the conclusion of its lifecycle. In addition, PLA packaging has been demonstrated to play a role in the reduction of food waste through its capacity to prolong shelf life.

A similar conclusion was reached by Olivier-Ortega et al. (Oliver-Ortega et al., 2021). The investigation revealed that PET exhibited the highest energy consumption, followed by HDPE and PP. PLA materials demonstrated a reduced energy consumption, attributable to their raw material production requiring less energy than that of petroleum-based polymers. Preliminary LCA results indicate that PLA nanocomposites present a more sustainable alternative to oil-based plastics. It is anticipated that this sustainability benefit will be amplified if PLA recycling is integrated into waste management strategies. The

LCA suggested that PLA has a lower environmental footprint in certain aspects. However, its impact on global warming potential (GWP) and other environmental factors largely depends on how it is managed at the end of its life cycle.

Cinelli et al. (2017) also highlighted the environmental advantages of green polymer nanocomposites (PNCs) in packaging through a preliminary LCA analysis of PLA blends incorporating chitin nanofibrils. LCA analysis showed that the production of chitin nanofibrils (CN) requires a lot of water and chemicals (HCl, NaOH). To make the nanocomposite more eco-friendly, recycling the solvents and chemicals used in the production of CN would be a good alternative. The use of renewable resources (PLA and chitin) and the ability to produce a compostable product at an industrial scale are major environmental advantages, making these materials more competitive than oil-based plastics.

Muller-Carneiro et al. (Müller-Carneiro et al., 2023) studied the ex-ante life cycle assessment of a biopolymer film made from mango kernel starch (MKS) and reinforced with starch nanocrystals (SNC). The results obtained were compared to low-density polyethylene (LDPE). It was demonstrated that the industrial production of MKS and starch nanocrystals (SNC) generates the majority of environmental impacts, mainly due to steam and acid consumption. The analysis covered three modeling scenarios (M1–M3): M1 considered mango seeds as waste, M2 treated seeds as by-products of mango pulping, and M3 involved film production by extrusion. Four improvement scenarios (P1–P4), including modifications to system boundaries, production techniques, and process improvements, were also examined. The results led to the conclusions shown in Table 4. Compared to LDPE, MKS films consume less non-renewable energy but have higher impacts in terms of climate change, freshwater eutrophication, and soil acidification. MKS films show promises for enhancement, particularly in terms of yield improvement and process optimization. However, it still faces challenges in competing with LDPE in certain impact categories. This ex-ante LCA study has facilitated the assessment of the environmental sustainability of new biopolymers from the outset of the R&D process.

PLA-based systems remain a subject of interest for life cycle assessment studies. In the article by Petrucci et al. (2018), a study of the environmental impacts of extruded plastic films based on PLA modified with cellulose nanocrystals (CNC) and limonene as a natural plasticizer was conducted. This formulation was compared to another based on PLA plasticized with Acetyl Tributyl Citrate (ATBC) and reinforced with organo-modified montmorillonite (OMMT). An analysis of the impact of CNC revealed that, although it comes from renewable resources, its chemical extraction requires substantial energy and chemicals (sulfuric acid, NaOH, etc.). This process therefore increases the environmental impact. The addition of only 1 % CNC in PLA resulted in a notable environmental impact. The main contributors to the environmental impact were related to PLA production (66.1 %) and CNC extraction (33.9 %). The most significant impact categories were as follows: fossil

<table><caption>**Table 4**
Summary of the scenarios studied and the environmental impacts.</caption><thead><tr><td>Scenarios</td><td>Description</td><td>Main environmental impact</td><td>Impact reduction compared to the pristine LDPE value</td></tr></thead><tbody><tr><td>P1</td><td>Elimination of the oxidation inhibition step in MKS production</td><td>Non-renewable Energy use (NREU)</td><td>-9 %</td></tr><tr><td>P2</td><td>Replacement of H<sub>3</sub>PO<sub>4</sub> and HCl with H<sub>2</sub>SO<sub>4</sub></td><td>Freshwater eutrophication (FE)</td><td>-30 %</td></tr><tr><td>P3</td><td>Improved performance for MKS and SNC production</td><td>Climate change (CC)</td><td>-22 to -26 %</td></tr><tr><td>P4</td><td>Improvements Combination (P1+P2+P3)</td><td>NREU + FE + CC + Terrestrial acidification (TA)</td><td>-29 to -40 %</td></tr></tbody></table>
fuel consumption (70.12 % of the total impact), respiratory inorganics (34.23 %), and land use (19.23 %). It was found that the end-of-life composting stage was efficacious in reducing the overall environmental impact by 12.9 %. PLA/CNC/limonene films had a slightly lower environmental impact (0.454 Pt) than PLA/OMMT/ATBC films (0.465 Pt). CNC-based films exhibited superior performance regarding fossil fuel consumption and land use. However, they demonstrated suboptimal performance in terms of climate change and ecotoxicity. The PLA/CNC/limonene blend represented a compelling alternative to the conventional PLA/OMMT/ATBC composition, demonstrating marginally superior environmental performance. It was concluded that PLA modified with CNC could be a viable solution for biodegradable packaging. However, it was also determined that further optimization of the CNC extraction process would be necessary to reduce its impact.

In the study by Pietrini et al. (2007), the life cycle of Poly-HydroxyButyrate (PHB)-based nanocomposites reinforced with organo-modified clays (OMMT) was analyzed. The study focused on cathode ray tube (CRT) monitor housings (typically made from high-impact polystyrene (HIPS)) and automotive panels (usually made from glass fiber-reinforced polypropylene (PP-GF)). The study concluded that PHB-OMMT composites have a lower environmental impact than HIPS in both cases. However, in the context of automotive panels, the use of PHB composites did not result in any discernible environmental benefits. The increased weight of vehicles resulted in higher fuel consumption, thereby reducing their competitive advantage. The study concluded that PHB is a viable alternative for CRT monitor housing. However, it is not recommended for automotive applications and also for high energy consuming devices, where weight and power are of paramount importance.

In the study by Tserpes et al. (2023), the environmental impact of a bio-based resin reinforced with graphene nanoplatelets (GNPs) and cellulose nanocrystals (CNCs) was compared to that of a reference resin. The findings indicated that bio-based resin exhibited superior environmental sustainability in comparison to conventional epoxy resins, except for its photochemical ozone creation and global warming potential. The incorporation of GNPs and CNCs did not result in a substantial enhancement of the GWP of the bio-based resin. The life cycle analysis (LCA) confirmed that the nano-reinforced bio-based resin is more environmentally sustainable than commercial epoxy resins.

The studies mentioned above have demonstrated the strong potential of green nanocomposites in various fields, thereby confirming their ecological benefits compared to their non-bio counterparts. However, as mentioned, no studies of the LCA have been conducted on conductive bionanocomposites manufactured by additive manufacturing processes. It is therefore essential to examine whether combining carbon-based conductive fillers with biopolymer matrices can truly create more sustainable materials for electrical applications. These materials are increasingly presented as eco-friendly alternatives to conventional composites. Nevertheless, the overall environmental implications of these phenomena remain to be explored. The particulars of this issue are discussed in Section 3.

## 5. Preliminary LCA analysis

This review features a study on the LCA of conductive bio-nanocomposites. We critically examine whether conductive bio-nanocomposites manufactured by additive manufacturing are truly environmentally friendly, beyond their mere 'green' label. PLA, frequently employed as a biopolymer matrix, is widely regarded as a sustainable option due to its renewable origin and biodegradability. However, the overall environmental impact of this polymer and its composites depends on many factors, including the use of agricultural resources, the industrial processes required for its production, and end-of-life management. Although compostable, PLA only degrades effectively under specific industrial conditions but not easily in non-controlled ones such as these encountered for marine litter. Should it

be landfilled or incinerated, the ecological benefits can be significantly reduced. In a similar way, carbon-based conductive fillers, such as carbon black, carbon nanotubes, or graphene, can achieve electrical conductivity at low concentrations, which limits material usage. However, the manufacturing process for these products is often energy-intensive. It can involve the use of toxic substances, and some require a lot of water which raises questions about their environmental impact over the entire life cycle. The quantity used is a key parameter: at low doses, the ecological balance of the material can be preserved, but higher concentrations risk are compromising this advantage. Finally, while additive manufacturing is efficient and generates minimal waste by nature, it is important to consider its environmental impact. This aspect involves a multifaceted approach. It includes managing printing time by using thicker layers and optimizing infill to reduce material and energy use. It also involves adopting renewable energy to power printers and recycling thermoplastics used in FFF. These strategies help mitigate resource depletion and waste generation (Sola et al., 2024). Therefore, while these materials exhibit strong potential for sustainable applications, only a complete life cycle analysis (LCA) will confirm their true environmental performance. A study is underway to verify the potential of such products. A first part of the study aims to compare environmental impact of the production of two biopolymers used as matrix components of bionanocomposites: polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT). This review also presents a comparative analysis of two conductive fillers: carbon black (CB) and graphene (see histograms, Figs. 8–9 and Table 5).

The LCA was performed to evaluate the eco-footprint of biopolymers (PLA, PBAT) and conductive fillers (CB and graphene). In particular, cradle-to-gate LCAs were carried out using OpenLCA v2.4.1 software. The goal of this study is to provide a first estimation of the environmental performance. Ecoinvent v3.11 database was used to support the life cycle inventory (LCI) and impact assessment (LCIA). Literature data were also employed to address the data limitations of the Ecoinvent datasets. PBAT production data were obtained from (Luo et al., 2024). Production data for the PLA was recovered from the Ecoinvent database. Graphene data were obtained from (Arvidsson et al., 2014), where the ultrasonication method was used to its production. Data on carbon black (CB) was retrieved from the Ecoinvent database, where it was produced

<figure><img src="image_11.png" /><figcaption>**Fig. 8.** Comparative analysis of the environmental impacts of PLA and PBAT production. Note that the values are in % and normalized to the most impactful material; FU = 1 kg of material; System boundaries = Cradle to gate; Database = Ecoinvent v3.11.</figcaption></figure>
<figure><img src="image_12.png" /><figcaption>**Fig. 9.** Comparative analysis of the environmental impacts of Graphene and carbon black production. Note that the values are in % and normalized to the most impactful material; FU = 1 kg of material; System boundaries = cradle to gate; Database = Ecoinvent v3.11.</figcaption></figure>

<table><caption>**Table 5**
LCA results of PLA, PBAT, Graphene and CB.</caption><thead><tr><th rowspan="2">Impact category</th><th rowspan="2">Reference unit</th><th colspan="4">Result</th></tr><tr><th>PLA</th><th>PBAT</th><th>CB</th><th>Graphene</th></tr></thead><tbody><tr><td>Acidification: terrestrial</td><td>kg SO<sub>2</sub>-Eq</td><td>0.015</td><td>0.012</td><td>0.006</td><td>0.024</td></tr><tr><td>Climate change</td><td>kg SO<sub>2</sub>-Eq</td><td>3.878</td><td>6.277</td><td>2.474</td><td>12.389</td></tr><tr><td>Ecotoxicity: freshwater</td><td>kg 1,4-DCB-Eq</td><td>0.164</td><td>0.256</td><td>0.051</td><td>0.581</td></tr><tr><td>Ecotoxicity: marine</td><td>kg 1,4-DCB-Eq</td><td>0.207</td><td>0.337</td><td>0.066</td><td>0.756</td></tr><tr><td>Ecotoxicity: terrestrial</td><td>kg 1,4-DCB-Eq</td><td>6.392</td><td>9.004</td><td>1.468</td><td>19.167</td></tr><tr><td>Energy resources: non-renewable, fossil</td><td>kg oil-Eq</td><td>0.736</td><td>2.095</td><td>1.798</td><td>8.402</td></tr><tr><td>Eutrophication: freshwater</td><td>kg P-Eq</td><td>0.001</td><td>0.001</td><td>0.0001</td><td>0.005</td></tr><tr><td>Eutrophication: marine</td><td>kg N-Eq</td><td>0.005</td><td>0.0002</td><td>3.6 E-5</td><td>0.0004</td></tr><tr><td>Human toxicity: carcinogenic</td><td>kg 1,4-DCB-Eq</td><td>0.397</td><td>0.658</td><td>0.258</td><td>2.025</td></tr><tr><td>Human toxicity: non-carcinogenic</td><td>kg 1,4-DCB-Eq</td><td>3.365</td><td>4.817</td><td>0.993</td><td>10.978</td></tr><tr><td>Ionizing radiation</td><td>kBq Co-60-Eq</td><td>0.169</td><td>0.405</td><td>0.017</td><td>0.425</td></tr><tr><td>Land use</td><td>m<sup>2</sup>*a crop-Eq</td><td>2.202</td><td>0.091</td><td>0.015</td><td>0.173</td></tr><tr><td>Material resources: metals/minerals</td><td>kg Cu-Eq</td><td>0.023</td><td>0.041</td><td>0.018</td><td>0.343</td></tr><tr><td>Ozone depletion</td><td>kg CFC-11-Eq</td><td>1.104</td><td>5.8372 E-5</td><td>2.23 E-7</td><td>2.2 E-6</td></tr><tr><td>Particulate matter formation</td><td>kg PM2.5-Eq</td><td>0.006</td><td>0.004</td><td>0.003</td><td>0.09</td></tr><tr><td>Photochemical oxidant formation: human health</td><td>kg NO<sub>x</sub>-Eq</td><td>0.007</td><td>0.008</td><td>0.004</td><td>0.028</td></tr><tr><td>Photochemical oxidant formation: terrestrial ecosystems</td><td>kg NO<sub>x</sub>-Eq</td><td>0.007</td><td>0.009</td><td>0.005</td><td>0.034</td></tr><tr><td>Water use</td><td>m<sup>3</sup></td><td>0.054</td><td>0.130</td><td>0.004</td><td>0.089</td></tr></tbody></table>

using the furnace black process. The functional unit (FU) corresponds to the production of 1 kg of material. The ReCiPe 2016 v1.03 midpoint (H) method was selected for the calculation of the impact indicator values. 18 impact categories are mentioned (see Table 5), which can lead to 3 endpoint categories: damage to human health, to ecosystems, and to resource availability (ReCiPe, 2016).

The preliminary study has a narrow focus due to the partial system boundary, the uncertainty of data from experiments or literature, and process variability that was not considered.

In addition, according to the Ecoinvent database, data uncertainty is assessed using a pedigree matrix that considers several quality indicators, including reliability, completeness, temporal, geographical, and technological representativeness.

Each criteria is rated from 1 (highest quality) to 5 (lowest quality), reflecting the degree of confidence in the underlying inventory data (Weidema and Wesnæs, 1996). For our case, our Ecoinvent data have a criteria 1 for all indicators. For data retrieved from the literature no information is given on the quality. Consequently, the results should be interpreted as indicative and provide a basis for more detailed and comprehensive LCA studies. The results of the calculation of impacts are presented in the histograms. They are normalized as a percentage relative to the most impactful material for an uncertainty of given impact.

For the polymers, PBAT demonstrates for most indicators a higher environmental impact than PLA. This predominance is largely attributable to PBAT's fossil-based origin, which requires energy-intensive industrial chemical synthesis and the use of hazardous substances. These processes are associated with substantial greenhouse gas emissions, particularly CO<sub>2</sub>, as well as other pollutants. Conversely, PLA, being bio-based, generally exhibits reduced impacts in categories directly linked to fossil resource depletion and carbon emissions. However, its performance is less favorable in impact categories such as terrestrial acidification, land occupation, marine eutrophication, and fine particulate matter formation. These effects are derived from the agricultural production of feedstocks (e.g. corn or sugarcane) necessary for the manufacturing of PLA. This process involves the application of fertilizers and pesticides, intensive land use, and emissions from agricultural machinery and biomass processing.

Regarding conductive fillers, graphene has a particularly significant impact on all environmental indicators. This is ascribed to the need of a significant amount of energy to synthesize graphene, to the use of chemicals and to a low yield. Hence, knowing the environmental contribution of each component will enable to optimize composite formulation regarding desired properties and reduced carbon footprint. Despite the fact that nanofillers are typically utilized in minimal amounts, it is imperative to ascertain their substantial impact on the composite. The review by Donia et al. (Donia and Carbone, 2019) explored the issue of the prolonged use of nanoparticles (NPs) and its inevitable impact on the environment. It was hypothesized that the impact would be contingent not solely on the properties of the substances in question but also on the method of disposal and the physical and biochemical characteristics of the disposal site. These parameters are ultimately determinative of the bioaccumulation of nanoparticles and their ecotoxicity. Despite the numerous applications of NP, their deleterious effects on human and environmental health, especially in the long term. The potential risks they pose mean that NP ecotoxicity remains inadequately understood and requires further research.

These LCA findings align with the trends outlined in Section 2, where previous LCA studies on bionanocomposites revealed that the environmental benefits of biopolymers may be offset by the impacts associated with nanofiller production and agricultural feedstocks. Our results confirm that PLA generally performs better than fossil-based PBAT in global warming and resource depletion indicators, while showing higher impacts in land occupation and eutrophication. These findings are consistent with the research conducted by (Oliver-Ortega et al., 2021; Bala et al., 2022), presented in Section 2. In addition, the significant contribution of graphene aligns with the findings of (Arvidsson et al.,
2014) who reported high energy demands and limited yields for nano-material synthesis. Furthermore, this study directly builds upon the technological context introduced in Section 1, where conductive bio-nanocomposites produced via additive manufacturing were discussed as promising materials for flexible electronics and sensing applications. The current LCA results provide a necessary environmental perspective to complement these technological insights, emphasizing that the sustainability of additive manufacturing depends not only on the printing efficiency but also on the upstream material impacts. By integrating environmental assessment into both the literature review and the broader technological framework, this section strengthens the overall narrative of the review. It highlights the importance of integrating an LCA, considering all stages of material production according to their origin to the end of product life to design ecological conductive bio-nanocomposites by additive manufacturing.

## 6. Conclusion

The primary objective of this review was to investigate the sustainability of conductive bionanocomposites produced by additive manufacturing, by examining the environmental implications of using different conductive carbon nanofillers and biopolymer matrices. A comprehensive literature review was conducted for the purpose of identifying current knowledge gaps and challenges in relation to the life cycle assessment (LCA) of nanoparticles, biopolymers and bio-nanocomposites. The results of this review demonstrate that conductive bionanocomposites, based on biopolymer and nanofillers, produced by additive manufacturing, represent a promising avenue for the development of innovative and ecofriendly materials. Their technical performance, particularly in terms of electrical conductivity, can be achieved with reduced quantities of nanomaterials, which constitutes both a functional and environmental advantage. However, this commitment to sustainability must be contextualized. The analysis of their environmental impact cannot be confined to the bio-sourced origin of polymers or their low filler content. The basis for such a system must be a comprehensive life cycle assessment, incorporating production processes, energy consumption, waste management, and the end-of-life of the materials. In this regard, it is imperative to critically examine the actual biological origin of biopolymers, as their environmental impact is contingent on the type of biomass utilized, its cultivation method, and the industrial processes implemented. Furthermore, the methods used to synthesize or functionalize nanofillers (e.g. chemical treatment, pyrolysis, sonication, etc.) can have a significant influence on the environmental impact and toxicity profile of the resulting composite. It is also crucial to recognize the importance of sustainability in additive manufacturing for the development of conductive nanocomposites. While this method offers clear advantages, particularly for small series and complex geometries, life cycle assessment (LCA) studies on conductive composites produced using this technique remain insufficient. Consequently, this review underscores the imperative for sustained LCA-based research to facilitate the development of genuinely sustainable conductive bionanocomposites. In this regard, a doctoral research project (project's acronym MOLIERE) is currently underway to conduct a LCA of a PLA/PBAT conductive composites manufactured using fused deposition modelling (FDM). The project aims to address these issues mentioned in this review and to propose strategies for reducing environmental impacts. Complementary, this article shows that gaps in environmental knowledge remain to be filled in the context of industrial deployments. This remains a significant challenge in terms of data, as these hiatus are highly diverse and driven, for instance, by socio-ecological and geopolitical objectives, particularly those related to the securing and the strategic management of critical raw materials. To make progress, future research should aim to generate more robust pristine data, standardize assessment protocols and test these materials under realistic industrial conditions. In addition, integrating eco-design approaches and optimizing additive manufacturing parameters appear

essential to bear sustainable industrial adoption.

## CRediT authorship contribution statement

**R. Farhat:** Writing – review & editing, Writing – original draft, Visualization, Methodology, Investigation, Formal analysis, Conceptualization. **S.A.E. Boyer:** Writing – review & editing, Visualization, Validation, Supervision, Project administration, Methodology, Investigation, Funding acquisition, Conceptualization. **A. Burr:** Visualization, Validation, Supervision, Methodology, Investigation, Conceptualization. **M. Batistella:** Visualization, Validation, Supervision, Methodology, Investigation, Conceptualization. **J.M. Lopez-Cuesta:** Visualization, Validation, Supervision, Methodology, Investigation, Funding acquisition, Conceptualization.

## Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Acknowledgements

2023 Doctorate of Excellence: Future & Disruptions Research Program jointly supported by the Institut Mines Télécom (IMT), the Mines-Télécom Foundation, the Carnot Institute “Telecom & Digital Society” (TSN), and the Carnot Institute M.I.N.E.S. Funding is coming from Carnot Institute M.I.N.E.S ELECTRE Project « Electrifier les usages (transports, chauffage, climatisation, procédés industriels ...) pour atteindre les objectifs ambitieux de réduction des émissions de GES ».

## Data availability

Data will be made available on request.

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