Carbon fibre fabrics recovered from end-of-life (EoL) composite products have the potential for reuse in performance applications. However, current recycling methods typically involve extensive cutting and shredding, which breaks the fabrics into short, randomly oriented fragments. This results in low fibre volume fractions and inferior mechanical properties in the recycled composites. A new recycling technique that preserves the original fibre architecture of manufactured samples shows the potential to reduce the down-cycling of carbon fibre materials. In this study, we extend this technique to recycle two types of EoL bicycle components, wheels and frames. We found that woven carbon fibres with narrower fibre tows are more likely to be recycled and reused as intact fabrics due to their greater structural integrity. Moreover, composite designs that combine multiple fibre architectures require post-recycling separation, which reduces efficiency in the recovery of higher-value woven fibres. From an environmental perspective, composites’ polymer cores significantly increase energy consumption and GHG emissions during recycling, offsetting the benefit of fibre recovery. Our findings highlight the importance of reducing multi-format fibre designs for composites and effective pre-recycling separation of core materials to support efficient and sustainable EoL recycling of woven carbon fibres.

The increasing use of carbon fibre-reinforced polymers (CFRP) across aerospace, wind, and automotive sectors is causing an increase in carbon fibre waste. Current recycling methods for CFRPs often lead to reduced material properties of recycled carbon fibre (CF) – a combined effect of various changes to the material introduced by the recycling process. One of these contributing factors is the removal of sizing layer, a common surface treatment for virgin CF, on recycled CFs and the subsequent recycled CFRPs (rCFRPs). This study attempts to de-couple the effect of sizing removal (de-sizing) on the mechanical performance of CFs and their corresponding rCFRPs from the effect of recycling. Original and de-sized virgin CF were analysed through an experimental procedure of manufacturing into composites, recycling, and remanufacturing into rCFRPs. Testing and characterisation were conducted to evaluate tensile and surface properties of fibres as well as flexural properties of composites. We found that de-sizing resulted in reductions in tensile properties of virgin CF, but the combined effect with recycling is not aligned with the degradation experienced by sized CF. The inconclusive result is likely due to the different mechanisms for removing the sizing layer during recycling compared to the de-sizing procedure. Further research is encouraged to analyse pristine un-sized fibres using similar methods and investigate other factors that influence composite properties to provide more insights into the effects of recycling and sizing removal on recycled CF properties.

The growing use of carbon fibre reinforced polymers (CFRP) in the aerospace and wind industries is leading to increases in waste carbon fibres. The current recycling practice for this waste results in significant reductions in material properties. Preserving the reinforcement architecture of carbon fibre has the potential to enhance the mechanical reinforcement capability of the recycled fibre. Nevertheless, the impact of this approach on different woven fibre architectures with varying material characteristics remains unclear. This study presents an observation on applying fibre architecture preservation to the recycling of carbon fibres in two woven fibre architectures, namely twill and satin weaves. Carbon fibres are recycled by a pyrolysis technique and remanufactured into recycled CFRP. Flexural tests indicate increases in the flexural properties of CFRP with twill and satin weaves after recycling, differing from the results for plain weave in a previous study. The results suggest potential influences of weave architectures on the material compositions of the recycled composites, resulting in different flexural properties. Further research is encouraged to investigate the potential correlations and provide deeper insights into the use of this approach to reduce the down-cycling of various types of carbon fibre.

Electrification of automobiles is a crucial step towards achieving net-zero emission targets. This transition, combined with the ongoing trend of lightweighting in the automotive industry, is altering the material composition not only of batteries but also of entire vehicle structures. While the emission reduction benefits of electric vehicles during their use phase are well-documented, the impact of these material and design changes on the overall life cycle environmental performance remains unclear in the fleet level. This paper investigates the interaction between powertrain electrification and vehicle body lightweighting through a System Dynamics model, and their implications on material availability and the energy footprint of the material supply in the U.S.. We find that battery electric vehicles will see an increase in aluminium use in body manufacturing in the short term in support of increased driving range, while potentially reverting to steel-intensive body designs in the longer term as battery technology improves. These changes in material use result in fluctuations in the recycled content and therefore the primary energy demand of the aluminium supply, impacting the life cycle energy and carbon footprint of the automotive industry and beyond. This study stresses the need for dynamic life cycle assessment to analyse the sustainability impacts of these trends and offer insights into managing material selections in the electrification era to improve overall life cycle sustainability performance.

The ongoing transition toward electric vehicles (EVs) is changing materials used for vehicle production, of which the consequences for the environmental performance of EVs are not well understood and managed. We demonstrate that electrification coupled with lightweighting of automobiles will lead to significant changes in the industry's demand not only for battery materials but also for other materials used throughout the entire vehicle. Given the automotive industry's substantial consumption of raw materials, changes in its material demands are expected to trigger volatilities in material prices, consequently impacting the material composition and attractiveness of EVs. In addition, the materials recovered during end-of-life recycling of EVs as the vehicle fleet turns over will impact recycled material supplies both positively and negatively, impacting material availabilities and the economic incentive to engage in recycling. These supply chain impacts will influence material usage and the associated environmental performance of not only the automotive sector but also other metal-heavy industries such as construction. In light of these challenges, we propose the need for new research to understand the dynamic materials impacts of the EV transition that encompasses its implications on EV adoption and fleet life cycle environmental performance. Effectively coordinating the coevolution of material supply chains is crucial for making the sustainable transition to EVs a reality.

The use of recycled carbon fibres (rCF) in carbon fibre reinforced polymer (CFRP) is attracting interest for automotive applications due to the economic benefits and lower carbon footprint during production over virgin carbon fibres. However, the mechanical performance of recycled CFRP (rCFRP) is currently significantly lower compared with virgin CFRP (vCFRP), due to a loss of fibre reinforcement architecture. This necessitates a thicker and heavier part design potentially deteriorating rCFRP’s cost and carbon emission benefits. This study investigates the effects of fibre architecture preservation during recycling of carbon fibres on the life cycle environmental performance of rCFRP applied to a vehicle roof panel, based on experimentally determined mechanical properties. Experimental results show that rCFRPs with preserved unidirectional and woven fibre architectures have average flexural properties at least 4 times higher than those of current rCFRP with unpreserved fibre architecture, which enables reduction of thickness and mass by 36%-41% and 13%, respectively. A Life Cycle Assessment found that a hypothetical rCFRP roof panel with preserved plain woven rCF reduces the life cycle global warming potential (GWP) by 26% and 11% compared to vCFRP and the current rCFRP, respectively, when used in gasoline vehicle. While in a battery electric vehicle, the GWP reductions expand to 54% and 23%. Similar GWP reduction benefits are determined when unidirectional rCF is used in the rCFRP roof panel. Compared with steel and aluminium counterparts, the rCFRP roof panels with preserved fibre architectures have lower GWP in both the cradle-to-gate and use phases. This paper demonstrates that the recycling approach with fibre architecture preservation offers great opportunities to improve the mechanical and environmental performances of rCFRP for use in the automotive industry.

Purpose The rising of the sharing economy (SE) has lowered the barrier of purchase price to accessing many different products, thus changing the consumer decision paradigm. This paper addresses the challenge of assessing the life cycle impacts of SE systems in the context of this new consumer decision-making process. The paper proposes a methodological framework to integrate consumer preferences into the Dynamic Life Cycle Assessment (dynamic-LCA) of SE systems. Methods In the proposed consumer preference integrated dynamic-LCA (C-DLCA) methodological framework, system dynamics (SD) is used to combine consumer preference and the principal method, dynamic-LCA, which follows the ISO 14040 LCA framework. Choice-based conjoint analysis (CBCA) is chosen as the stated preference tool to measure consumer preference based on SE alternatives, attributes and attribute levels. CBCA integrates discrete choice experiments (DCE) and conjoint analysis features. Random utility theory is selected to interpret the CBCA results by employing multinomial logistics as the estimation procedure to derive the utilities. Derived utilities are connected in iterative modelling in the SD and LCA. Dynamic-LCA results are determined based on dynamic process inventory and DCE outcomes and then interpreted aligned with the SD policy scenarios. Results and discussion The C-DLCA framework is applied to assess the GHG changes of the transition to car-based shared mobility in roundtrips to work in the USA. Carpooling and ridesourcing are selected as the shared mobility alternatives based on different occupancy behaviours. Powertrain system and body style are employed as the fleet technology attributes and the latter as an endogenous variable. Dynamic-LCA results are generated considering the high battery electrical vehicle (BEV) adoption as the policy scenario, and results are measured against a service-based functional unit, passenger-kilometre. The model outcomes show a significant reduction in aggregated personal mobility-related dynamic-GHG emissions by transitioning to car-based shared mobility. In contrast to the use phase GHG emissions, the production phase emissions show an increase. The results highlight the importance of integrating consumer preference and temporality in the SE environmental assessments. Conclusions The proposed C-DLCA framework is the first approach to combine consumer preferences, SD and LCA in a single formulation. The structured and practical integration of conjoint analysis, SD and LCA methods added some standardisation to the dynamic-LCAs of the SE systems, and the applicability is demonstrated. The C-DLCA framework is a fundamental structure to connect consumer preferences and temporal effects in LCAs that is expandable based on research scope.

Recycled carbon fibre reinforced polymer (rCFRP) is attracting interest for automotive applications but has reduced mechanical properties due to a loss of intact fibre architecture. This study investigates the effects of fibre architecture preservation during recycling of carbon fibres on the mechanical and life cycle environmental performances of rCFRP applied to a vehicle roof panel. Results show that rCFRPs with preserved unidirectional and woven fibre architectures have average flexural properties at least 4 times higher than those of current rCFRP with unpreserved fibre architecture. A hypothetical rCFRP roof panel with preserved plain woven rCF reduces the life cycle greenhouse gas emissions by 11% and 23% compared to the current rCFRP, respectively, when used in gasoline vehicle and battery electric vehicle. This paper demonstrates that the recycling approach with fibre architecture preservation offers great opportunities to improve the mechanical and environmental performances of rCFRP for use in the automotive industry.

The quality of resistance spot welds is critical to the structural integrity of components manufactured using the process. This paper analyses the effect of electrode misalignment, referred to as electrode tilt, on the quality of resistance spot welds and their relationship. The weld quality is represented by the diameter of the weld nugget as is standard in industry. Principal Component Analysis (PCA) was used to reduce the dimensionality of the dynamic resistance signal and extract features to be used in a linear regression model for the prediction of nugget diameter. This paper found that increased misalignment of the electrodes reduced the peak resistance of the welding process resulting in smaller nugget diameters and therefore a lower weld quality.

The selective laser sintering (SLS) process generates waste polymer powders, which can be recycled as feedstock for producing injection-molded components. Recycling this powder has implications on the life cycle modeling of the SLS product, as well as the subsequent injection-molded component. This study investigates the life cycle primary energy demand (PED) and global warming potential (GWP) of an automotive fuel-line clip produced with recycled polyamide 12 (PA12) from an SLS process in comparison to the conventional polyamide 66 (PA66) counterpart, based on real-world industry data. In addition, the life cycle PED and GWP of an SLS part are examined, with and without recycling PA12 from the SLS process. The results indicate a strong dependence on the approach to evaluate the environmental burden of waste PA12 from the SLS process (cut-off, mass-based allocation, economic allocation, and substitution). Compared with the PA66 fuel-line clip, the recycled PA12 (rPA12) clip reduces the life cycle GWP by up to 26% (cut-off) or increases by up to 68% (mass-based allocation). For the SLS part, recycling PA12 powder provides a 42% reduction to its life cycle GWP (mass-based allocation). Finally, from an expanded two-part system perspective, the recycling of PA12 from the SLS process provides an 8% reduction in life cycle GWP. Similar trends are shown for the life cycle PED profiles. This study demonstrates the importance of recycling additive manufacturing (AM) wastes within a broader cascading system to improve the environmental performance of AM and the circular economy across industrial systems.

Carbon fibre has a high mechanical reinforcement capability associated with fibre architectures. However, it is significantly down-cycled in the current recycling practice as a result of a loss of fibre architecture. Without the use of chopping/shredding process, the architecture of carbon fibre can be preserved, but the surface cleanliness of recycled carbon fibre (rCF) is not clear. In this study, an investigation is carried out on the surface quality of architecture-preserved rCF obtained from multiple layers of a carbon fibre reinforced polymer (CFRP). Carbon fibre woven fabrics are manufactured into CFRP, recycled using a pyrolysis technique, and inspected using visual and microscopic techniques. The results indicate a good preservation of fibre architecture in all five layers of CFRP. Nonetheless, the residue from the pyrolysis of resin is increased in the internal layers (4th and 5th) of rCF in comparison to the external layers (1st to 3rd). The results suggest that fibre architecture preservation has a potential to reduce the down-cycling of carbon fibre, but the impact is limited in internal fibre layers due to reduced fibre surface cleanliness. The insights from this study provide a further understanding on the approach to reduce the down-cycling of carbon fibre and move the carbon fibre industry towards circular economy.

In recent years, Mobility as a Service (MaaS) modes, such as carpooling (CP) and ridesourcing (RS), are gaining popularity. Although studies have explored the greenhouse gas (GHG) emissions of different MaaS modes, the integration of different powertrain systems and car body styles in MaaS fleets have not been assessed in detail. This research analysed the full life cycle GHG impacts of MaaS fleet changes employing passenger-kilometre as the functional unit. Higher occupancy mode, CP, is shown to produce the lowest GHG emissions (up to 23% compared to a private car) irrespective of the powertrain system or car body style changes in the fleets. Results highlighted that the use of electric vehicles with sedan body type instead of SUVs has better potential to reduce GHG emissions (at least 57% compared to the current fleet) in RS. Results have also shown the higher GHG emissions of larger (comfort) vehicle models used in RS mode, an 11-382% increase compared to mid-sized sedans and SUVs. BEV sedan and SUV larger vehicles in the RS fleet have shown higher GHG emissions than ICEV sedan PCs. This study has shown the importance of electrifying the RS fleet, especially the larger vehicles, and increasing net occupancy to reduce GHG emissions. The study has also highlighted electric sedans as the least GHG emitting technology combination in the MaaS fleets.

Recycled carbon fibre (rCF) is a potential material for sustainable vehicle lightweighting but its realistic environmental impacts are still unclear. In this study, a Life Cycle Assessment (LCA) investigates the primary energy demand (PED) and global warming potential (GWP) of using rCF reinforced Polyamide 66 (PA66) for a side-view mirror bracket, in comparison with its conventional cast aluminium counterpart. Results indicate that using rCF+PA66 with 40wt% rCF in the US can achieve around 13% and 34% reduction in the PED/GWP of the cradle-to-gate phases and the use phase, respectively. Scenario analysis is also carried out to understand the impact of geographical setting and fibre content in rCF+PA66. It shows that replacing aluminium with 40wt% rCF+PA66 in the EU saves 31.5% and 29.7% more cradle-to-gate PED and GWP, respectively, than in the US. A higher reduction of 43.4% and 41.2% in the cradle-to-grave PED and GWP compared to aluminium can be achieved by increasing fibre mass fraction.

Towards realising circular economy, there has been an emphasis on decoupling economic growth from natural resources consumption. However, increasing product consumption has led to product technology changes that require different types of resources. Despite the use of different product life cycle studies to assist in improving the material usage and decision-making throughout the product life cycle, it is unclear how product development can improve material circularity. This work highlights the implication of product technological changes on material circularity using a complex product, such as a vehicle, through the Australian car door case study and the US new vehicle technologies. The Material Circularity Indicator is used to assess the material circularity for both case studies. This work shows that the transition to newer product design and vehicle technology has led to the reduction of material circularity and the increasing amount of virgin materials required and unrecoverable waste. In contrast, vehicle lightweighting improves the material circularity scores through reduced virgin materials due to the decreased vehicle mass.

The increasing use of lightweight materials and multi-material vehicle designs has improved the environmental impacts during the use phase through reduced vehicle mass. However, the growing complexity of vehicle designs has led to challenges in the choice of joining techniques. Previous ecodesign guidelines encourage less use of joints to reduce potential weak spots. However, minimizing the number of joints contradict with the increasing variety of multi-material combinations and their associated joining techniques. Consequently, the use of multi-material designs and their associated joining choices further reduces the effectiveness of current shredding and sorting recycling processes. This paper proposes a vehicle design framework for material and joining preferences to assist in material recyclability. Observations from previous case studies in Australia and Europe supplemented by literature data are used to assess the correlation between different material types, material separability through commonly used recycling practices, and material compatibility during the metallurgical processing. The method used to evaluate the design preferences for material separation during recycling are discussed. This work provides critical insights into the linkage between vehicle design and recycling phases to promote environmentally conscious design of products.

Mobility servitization modes are increasingly popular and some literature has suggested that their environmental impacts are less than those of privately owned cars. This research assesses the greenhouse gas (GHG) emissions of mobility servitization based on different scenarios: carsharing, carpooling and car ownership (representing the range of occupancy rates), and the changes in vehicle technology (lightweighting and electrification). Life Cycle Assessment is selected as the method and results are interpreted in passenger kilometre. The highest GHG reduction is recorded in pooled adoption scenario, representing the highest occupancy rate in servitization modes. The increasing trends of vehicle lightweighting and electrification can potentially reduce the GHG impacts (during production and use phases) by 35–37%.

The use of mobility services is increasing. There is a suggestion that this will present a range of different sustainable outcomes. Life Cycle Assessment is commonly used to assess the impact of mobility products, such as cars, as a function of distance. However, it is unclear how this approach applies to different servitization models with varying occupancy levels. This paper assesses the effect of different occupancy rates on life cycle impact of current mobility services: taxi and carpooling compared to the vehicle ownership model using two functional units: vehicle kilometre and passenger kilometre. Case studies were carried out in Europe and the US to assess the global warming potential This study showed that the use impact normalized to v.km is similar for different servitization modes but vary significantly when normalized to pion. The environmental impact of personal transportation can be reduced significantly with the increase in occupancy levels for mobility services. (C) 2020 The Authors. Published by Elsevier B.V.

The use of carbon fibre reinforced polymers (CFRP) faces high energy consumption of carbon fibre production and a lack of recycling. Increasing the use of recycled carbon fibres (rCF) to substitute virgin carbon fibres (vCF) can improve the sustainability of the carbon fibre industry. Nonetheless, the most impactful area of CF recycling on the quality of recycled CFRP (rCFRP) is unclear. In this study, a life cycle energy analysis compares the Primary Energy Demand (PED) of an rCFRP automotive roof panel with different CF recycling methods in the pre-processing, processing and post-processing stage. Results indicate that retaining CF architecture during the pre-processing stage reduces the cradle-to-gate energy demand of an rCFRP roof panel by 26.3%. Fibre realignment in the post-processing stage leads to 11.4% higher cradle-to-gate energy consumption of an rCFRP roof panel, despite improvements in the stiffness of rCFRP. This study demonstrates the significant impact of the preprocessing and post-processing stages of CF recycling on the quality and production energy demand of rCFRP. Moreover, improvement in the architecture of rCF leads to a more significant conservation of energy during rCFRP component production than preserving the tensile properties of rCF.

•Pyrolysis recycling of carbon fibre (CF) with/without sizing and surface oxidation.•Twice the reduction in tensile strength of surface-treated CF versus untreated CF.•More significant surface defects in surface-treated CF after recycling.•Interaction between sizing agent and functional groups causing fibre degradation.•Insights for CF producers and recyclers to reduce the down-cycling of CF.