Are functional fillers improving environmental behavior of plastics? A review on LCA studies

Circularity of new composites from recycled high density polyethylene and leather waste for automotive bumpers. Testing performance and environmental impact

New composite materials (suitable for automotive bumpers), composed of recycled high-density polyethylene (rHDPE) and leather buffing dust waste (BF) ranging from 20 to 50 wt%, were produced and investigated for mechanical properties. Optimal mechanical performance was achieved with composites containing 30 % wt BF. The environmental performance of automotive bumper production from both virgin and recycled HDPE reinforced with 30 % wt BF (HDPE-BF, rHDPE-BF) composites was compared to that of conventional polypropylene (PP) by performing a cradle to gate life cycle assessment. A component-based approach, instead of a comprehensive LCA assessment for the entire car was adopted using various functional units (FU) such as mass (FU1), volume (FU2), and volume of raw material fulfilling a specific impact strength requirement (FU3), thus enriching the paper with methodological discussions. The rHDPE-BF system provided better environmental performance compared to the virgin PP system, when considering both mass and volume-related functional units, mainly due to the avoidance of virgin polymer production. Even with the inclusion of the use phase in FU2 and a slightly higher density (+1.7 %) of composites than PP-based bumpers, the rHDPE system still provides better environmental performance (10 % less impact). The sensitivity analysis highlighted the significance of car type and final density of the bumper on the impact results. Finally, when using FU3, due to its higher impact strength, HDPE-BF system is clearly the best environmental alternative (50 % less impact) followed by rHDPE-BF system. In all cases, rising the content of recycled materials in the bumpers increases its circularity. The paper illustrates the importance of selecting a suitable functional unit, based on a specific application (i.e., automotive bumpers), to evaluate the environmental impact of new composite materials in comparison to traditional options. Expanding the assessment to encompass multiple functions provides a more accurate portrayal of reality but also introduces greater result uncertainty.

Synergies and gaps between circularity assessment and Life Cycle Assessment (LCA)

This article evaluates the synergies between circularity assessment and Life Cycle Assessment (LCA) by investigating their alignments, misalignments, and challenges in addressing sustainability. The analysis emphasizes the significance of a multi-level approach, positioning these methods at various levels, including philosophy, strategy, assessment, and communication. The findings demonstrate that both LCA and circularity assessment can serve as sustainability assessment methods for circularity strategies, despite existing gaps. However, neither approach can provide a complete picture of a system's environmental performance on its own. Data availability, diverse assumptions, spotlights and shadows (highlighted and neglected elements), multiple life cycles, products, functions, strategies, and as well as temporal aspects are identified as the main challenges in addressing sustainability. This article provides recommendations based on the lessons learned from each approach, suggesting the integration of their strengths and addressing challenges to achieve a comprehensive understanding of environmental sustainability and make informed decisions for a circular and sustainable future. These recommendations include using function-based models and the principles of prospective and dynamic LCAs for the development of future circularity assessments. Additionally, circularity assessment can be used to establish LCA models, aiding in identifying hotspots during the goal and scope definition, and determining allocation and weighting factors in both Life Cycle Inventory (LCI) and Life Cycle Impact Assessment (LCIA).

Holes on surfaces of the weathered plastic fragments from coastal beaches

The surface morphology of weathered plastics undergoes a variety of changes. In this study, 3950 plastic fragments from 26 beaches around the world, were assessed to identify holes. Holes were identified on 123 fragments on 20 beaches, with the highest frequency (10.3 %) being identified at Qesm AL Gomrok Beach in Egypt. The distribution of holes could be divided into even, single-sided, and random types. The external and internal holes were similar in size (37 ± 15 μm) of even type fragments. The external holes were larger than the internal holes in single-sided (516 ± 259 μm and 383 ± 161 μm) and random (588 ± 262 μm and 454 ± 210 μm) fragment types. The external hole sizes were positively correlated with the internal hole sizes for each type. This study reports a novel deformation phenomenon on the surface of weathered plastics and highlights their potential effects on plastics.

Sustainability of cellulose micro-/nanofibers: A comparative life cycle assessment of pathway technologies

Cellulose micro- and nanofibers (CNFs) are commonly regarded as "greener" than petro-based materials. The high energy input that their production still demands, along with the use of chemicals or heat in some pretreatments, asks for a critical view. This paper attempts a life cycle assessment of CNFs produced from bleached hardwood kraft pulp via three different pre-treatments before mechanical homogenization. First, a fully mechanical route, based on a Valley beating pre-treatment. Second, an enzymatic route, based on endoglucanases and requiring certain temperature (~50 °C). Third, a TEMPO-mediated oxidation route, considering not only the impact of the chemical treatment itself but also the production of TEMPO from ammonia and acetone. The main output of the study is that both, mechanical and TEMPO-mediated oxidation routes, present lower impacts than the enzymatic pre-treatment. Although the mechanical route presents slightly milder contributions to climate change, acidification, eutrophication, and other indicators, saying that TEMPO-mediated oxidation is environmentally unfeasible should be put under question. After all, and despite being disregarded in most assessment publications up to date, it is the only well-known way to selectively oxidize primary hydroxyl groups and thus producing kinds of CNFs that are unthinkable by other ways.

Life cycle assessment on calcium zincate production methods for rechargeable batteries

The world's energy transition from fossil to renewable energy is unthinkable without further research in energy storage. Decreasing the environmental impacts from the production of energy storage technologies is essential for achieving a green energy transition. Calcium Zincate (CAZN) is used as active material in rechargeable zinc-based batteries (and other products, such as heterogeneous catalysts for biodiesel or antifungal products). They present a low-cost, safer, alternative to Lithium based batteries and are targeted as replacement solutions for lead-acid batteries. We propose a novelty in the synthesis of CAZN, the hydro-micro-mechanical process (HMMS). The residence time of this new route is about 20 times lower than the traditional processes, so its production needs less infrastructure and can deliver quicker at an industrial scale. In addition, laboratory tests indicate that HMMS CAZN has more reaction surface area and the activation of the battery is 1.77 times faster. Using the life cycle assessment (LCA) method, we compare this new process with the current best option, hydro-thermal synthesis (HTS). The cradle-to-gate results per kg of CAZN already indicates that HMMS is an environmentally better alternative for all indicators; especially when considering the normalization of the results with the residence time and the surface area, HMMS delivers better results, with improvements of 97 % in global warming, for instance. With this, we demonstrate that, outside of the cradle-to-gate, variables that make the final products better service units or give more function should be considered as valuable additional information when deciding among alternatives. This also highlights the importance of life cycle thinking when working with chemical processes and substances. In the sensitivity analysis, we developed 7 scenarios related to the energy demand of the processes, and we incorporated the projection in the European electricity mix for 2030 and 2050.

Continuous long-term monitoring of leaching from microplastics into ambient water - A multi-endpoint approach

Widespread pollution of aquatic environments by microplastics (MPs) is a serious environmental threat. Despite the knowledge of their occurrence and properties rapidly evolving, the potential leaching from MPs remains largely unexplored. In this study, 16 different types of MPs prepared from consumer products were kept in long-term contact with water, while the leachates were continuously analysed. Most of the MPs released significant amounts of dissolved organic carbon, up to approximately 65 mg per g MPs after 12 weeks of leaching, and some MPs also released dissolved inorganic carbon. Other elements identified in the leachates were Al, Ba, Ca, Fe, K, Mg, Mn, Na, Si, and Zn. Of those, Ca, K, and Na were detected most frequently, while Ca reached the highest amounts (up to almost 2.5 mg per g MPs). Additionally, 80 organic individuals were tentatively identified in the leachates, mostly esters, alcohols, and carboxylic acids. Some compounds considered harmful to human health and/or the environment were detected, e.g., bisphenol A or phthalate esters. The current results provide insight into the transfer of various compounds from MPs to ambient water, which might have consequences on the fluxes of carbon and metals, as well as of specific organic contaminants.

Starch consolidation of calcium carbonate as a tool to develop lightweight fillers for LDPE-based plastics

Calcium carbonate (CaCO3) is used as a filler to improve the stiffness and processability of plastics at low cost. However, its high density limits the quantity to be used. In this work, the feasibility of using starch consolidation of eggshells-derived CaCO3 (ES) to develop lightweight fillers for low density polyethylene (LDPE)-based materials was studied. Starch, recovered from potato by-products, was combined with ES, gelatinized, dried, and milled as a fine powder. The obtained ES/starch-based particles were then compounded with LDPE and their influence on chromatic, mechanical, morphological, and density properties of mold injected LDPE-based materials was studied. Commercially available CaCO3 (COM) was used as control. ES/starch particles were 18 times less dense than the commercially available CaCO3 (2.62 g cm-3). When incorporated into LDPE-based formulations, ES/starch originated brownish materials with lower density (1.18 g cm-3) and higher stiffness (542 MPa of Young's modulus) than those produced with the COM sample (1.33 g cm-3 of density; 221 MPa of Young's modulus). Therefore, starch consolidation of ES revealed to be a promising approach to develop lightweight fillers able to provide stiffness and color to LDPE-based plastics, while valorizing biomolecules-rich by-products.

Life Cycle Assessment Model of a Catering Product: Comparing Environmental Impacts for Different End-of-Life Scenarios

This paper assesses the primary energy and environmental impacts of a restaurant main course product’s lifecycle, especially focusing on end-of-life (EoL) stage. In the first step, a cradle-to-grave complex life cycle assessment (LCA) model of the product has been set up from the extraction of the required raw materials through the preparation, cooking and use phase to the end-of-life. In the second step, three scenarios (landfilling, incineration, and composting) were compared for the generated food waste in the end-of-life stage given that one of the biggest challenges in waste management is the optimal management of food waste. We calculated eleven environmental impact categories for the examined food product with the help of GaBi 9.0 software. During our research work, the primary energy was examined in each phase. In the third step, a comparison between the traditional and “sous vide” cooking technologies has been created to optimise of the cooking/frying life cycle phase. This paper basically answers three main questions: (1) How can the main environmental impacts and primary energy throughout the whole life cycle of the examined product be characterised? (2) What methods can optimise the different life cycle stages while reducing and recycling energy and material streams? and (3) what is the most optimal waste management scenario at the end-of-life stage? Based on the analysis, the highest environmental impact comes from the preparation phase and the end-of-life scenario for the traditional incineration caused almost twice the environmental load as the landfilling of the food waste. Composting has the lowest environmental impact, and the value of the primary energy for composting is very low. The sous vide cooking technique is advantageous, and the continuously controlled conditions result in a more reliable process. These research results can be used to design sustainable cooking and catering with lower environmental impacts and energy resources in catering units.

Investigation into the Current State of Nuclear Energy and Nuclear Waste Management—A State-of-the-Art Review

Nuclear power can replace fossil fuels and will have a decisive impact on the change in the approach to conventional energy. However, nuclear (or radioactive) wastes are produced by the operation of the nuclear reactors should be safely and properly disposed of. This paper assesses the uranium resources and the global state of nuclear power plants and determines the energy mixes in different countries using the most nuclear energy. Furthermore, this paper analysed the nuclear waste management and disposal and the depletion of abiotic resources, and the primary energy sources of a basic production process using electricity mix and nuclear electricity for a basic production (PET bottle manufacturing) process. The life cycle assessment was completed by applying the GaBi 8.0 (version 10.6) software and the CML method. In this study, we limit our discussion to high-level nuclear waste (HLW) and spent nuclear fuel (SNF) waste. We do not consider waste generated from uranium mining and milling, which is usually disposed of in near-surface impoundments close to the mine or the mill. The investigation of waste management methods is limited to European countries. This research work is relevant because determining abiotic resources is important in a life cycle assessment and current literature available on LCA analysis for nuclear powers remains under-developed. These results can guide and compare manufacturing processes involving a nuclear electricity and electricity grid mix input. The results of this research can be used to develop production processes using nuclear energy with lower abiotic depletion impacts. This research work facilitates the industry in making predictions for a production-scale plant using an LCA of production processes with nuclear energy consumption.

Valorization Strategy for Leather Waste as Filler for High-Density Polyethylene Composites: Analysis of the Thermal Stability, Insulation Properties and Chromium Leaching

Leather waste (BF) and high-density polyethylene (HDPE) were compounded in a lab scale internal mixer and processed by means of injection molding. In this study, leather waste and HDPE composites were characterized by instrumental techniques such as differential scanning calorimetry (DSC), thermo-gravimetric Analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Physical integrity of composites against chemical exposure and chromium-leaching properties of the composites were also investigated. This study shows that the incorporation of 30% leather waste fiber into HDPE composites decreases the thermal conductivity of the composite samples by 17% in comparison to that of neat HDPE samples. Composites showed no thermal degradation during processing cycle. Strong interfacial bonding between leather waste and polymer results in comparable low-leachate levels to maximum allowed concentration for nonhazardous waste, and good chemical resistance properties. The BF/HDPE composites could be a promising low-cost alternative in industrial application areas of HDPE, where high-mechanical strength and low-thermal conductivity is required.

Environmental impacts of functional fillers in polylactide (PLA)-based bottles using life cycle assessment methodology

The use of functional fillers added to PLA-based products can be beneficial in terms of cost reduction and properties improvement. The existing life cycle assessment of PLA containers mainly focuses on the greenhouse gas (GHG) emission of PLA material model without fillers, and overlooked environmental impacts of functional fillers and the significant environmental problem-shifting on other indicators. This paper presents a life cycle assessment (LCA) of cooking oil bottles made from PLA, PLA/Fibers and PLA/CaCO₃ considering a wide spectrum impacts, and compares the environmental profile of them based on normalization and weighting analysis. The functional unit was set at 1000 bottles of 900 mL. The system boundary is from cradle to gate, including PLA-based particles production, bottle processing and transportation. The results showed that the contribution of the primary energy demand (PED) index of PLA-based bottles accounted for 159% to 192% of the global warming potential (GWP) index, which may be overlooked in previous studies. Compared to PLA and PLA/Fibers bottles, PLA/CaCO₃ bottles have lower environmental impacts in most categories and the lowest integrated impact index. In terms of PLA/CaCO₃ bottles, PLA particles and electricity contributed the most to energy conservation and emission reduction (ECER) results, accounting for 63.09% and 28.26% to the integrated impacts index, respectively. The results imply that the use of fillers in PLA bottles tends to reduce the environmental impacts, especially calcium carbonate can efficiently minimize environmental impacts of PLA-based bottles. And PED, SO₂ and NO_X indicators ranking above CO₂ should be taken into consideration to avoid the environmental problem-shifting, which can provide valuable reference for the creation of the method of making biodegradable plastic and carbon neutral policies.

Life Cycle Assessment Model of Plastic Products: Comparing Environmental Impacts for Different Scenarios in the Production Stage

This paper assesses the environmental loads of polypropylene and PP-PE-PET mixed-plastic products throughout the products’ life cycle in the production stage, with particular focus on the looping method. A life cycle model of homogeneous and mixed-plastic products has been developed from the raw material extraction and production phase through its transport with the help of the life cycle assessment method. To find the answers to the questions posed, different impacts were analyzed by the GaBi 9.5 software. The analysis lasted from the beginning of the production process to the end. The aim of this research was to determine the energy and material resources used, the emissions produced, and the environmental impact indicators involved. This article examines three scenarios in the production stage, based on the usage of plastic scrap and process water: (1) plastic scrap and wastewater are recirculated with looping method; (2) plastic scrap goes through an incineration process and wastewater is treated in a municipal wastewater treatment plant; (3) plastic scrap is sent to a municipal landfill and wastewater is treated. This article tries to answer three questions: (1) how can we optimize the production stage? (2) Which materials and streams are recyclable in the design of the life cycle assessment? (3) What is the relationship between the environmental impacts of homogeneous and mixed-plastic products? The results of this research can be used to develop injection-molding processes with lower environmental impacts and lower releases of emissions.

Pozzolan Based 3D Printing Composites: From the Formulation Till the Final Application in the Precision Irrigation Field

A new eco-composite polymer for material extrusion fabrication based on fine fraction pozzolan waste was developed. In addition, the composite materials obtained were used to produce a self-watering pot with complex geometry and a permeable porous part to regulate the passage of water from the storage area to the roots of the plant. Moreover, the system was devised with a cover characterized by a UV-B barrier film. The results have shown the possibility of the 3D printing of complex geometric parts as microporous structures or thin films using a composite based on poly lactic acid (PLA) and pozzolan. The pozzolan has an effect of reinforcement for the composite and at the same time improves the cohesion between the layers of the part during printing.

Leather Waste to Enhance Mechanical Performance of High-Density Polyethylene

Leather buffing dust (BF) is a waste from tannery which is usually disposed on landfills. The interest in using wastes as fillers or reinforcements for composites has raised recently due to environmental concerns. This study investigates the potential use of BF waste as filler for a high density polyethylene matrix (HDPE). A series of HDPE-BF composites, containing filler concentrations ranging from 20 to 50wt%, were formulated, injection molded and tested. The effect of filler contents on the mechanical properties of the composites were evaluated and discussed. Composites with BF contents up to 30wt% improved the tensile strength and Young’s modulus of the matrix, achieving similar mechanical properties to polypropylene (PP). In the case of flexural strength, it was found to be proportionally enhanced by increasing reinforcement content, maintaining high impact strength. These composites present great opportunities for PP application areas that require higher impact resistance. The materials were submitted to a series of closed-loop recycling cycles in order to assess their recyclability, being able to maintain better tensile strength than virgin HDPE after 5 cycles. The study develops new low-cost and sustainable composites by using a waste as composite filler.

Polylactic Acid/Polycaprolactone Blends: On the Path to Circular Economy, Substituting Single-Use Commodity Plastic Products

Circular economy comes to break the linear resource to waste economy, by introducing different strategies, two of them being: using material from renewable sources and producing biodegradable products. The present work aims at developing polylactic acid (PLA), typically made from fermented plant starch, and polycaprolactone (PCL) blends, a biodegradable polyester, to study their potential to be used as substitutes of oil-based commodity plastics. For this, PLA/PCL blends were compounded in a batch and lab scale internal mixer and processed by means of injection molding. Tensile and impact characteristics were determined and compared to different thermoplastic materials, such as polypropylene, high density polyethylene, polystyrene, and others. It has been found that the incorporation of PCL into a PLA matrix can lead to materials in the range of 18.25 to 63.13 megapascals of tensile strength, 0.56 to 3.82 gigapascals of Young’s modulus, 12.65 to 3.27 percent of strain at maximum strength, and 35 to 2 kJ/m² of notched impact strength. The evolution of the tensile strength fitted the Voigt and Reuss model, while Young’s modulus was successfully described by the rule of mixtures. Toughness of PLA was significantly improved with the incorporation of PCL, significantly increasing the energy required to fracture the specimens. Blends containing more than 20 wt% of PCL did not break when unnotched specimens were tested. Overall, it was found that the obtained PLA/PCL blends can constitute a strong and environmentally friendly alternative to oil-based commodity materials.

Insights on the structure-performance relationship of polyphthalamide (PPA) composites reinforced with high-temperature produced biocarbon

Biocarbon-filled polyphthalamide composites were made, achieving comparable mechanical and thermal characteristics to talc-filled ones, at a lower density.

Evaluation of the environmental impact of plastic cap production, packaging, and disposal

This study analysed the impact of the production of high-density polyethylene (HDPE) caps on the environment. To determine the environmental impact of injection moulding production, a life-cycle assessment was performed. The life-cycle assessment results showed that, in the injection moulding tool manufacturing process, the largest amount of environmental loading is attributable to electricity and steel consumption. Additionally, the HDPE cap production phase had the largest environmental impact associated with electricity consumption. However, scenario analysis showed that the environmental impact from electricity consumption can be reduced by up to ten times if cleaner sources of electricity are used. Large differences related to electricity sourcing should help developing countries to better understand the need to increase the use of cleaner sources of electricity.

Technical feasibility and life cycle assessment of an industrial waste as stabilizing product for unpaved roads, and influence of packaging

The use of industrial solid wastes with a high content of SiO₂ and Al₂O₃, called "precursors", is often studied in the construction industry when combined with NaOH as "activator". The precursor and activator system is generally proposed as a binder material with similar characteristics to Portland cement. In this work, we technically and environmentally evaluated such a system elaborated with an industrial waste: coal ash with caustic soda in solid state. This product, mixed with the soil, acts as a stabilizer to increase the capacity of load support, allowing the improvement of the conditions of performance in low volume traffic roads. An experimental design applied to the stabilizing product showed the incidence of different factors on the load carrying capacity response: packaging material, type of seal, baling moisture and storage humidity. The application of the stabilizer product was found to increase the resistance of the ground over a 500%. Finally, the environmental aspects were evaluated through a simplified Life Cycle Assessment methodology (LCA), the scope of the study was restricted to cradle to gate, collecting data up to the packaged stabilizing product. The results showed that the highest impacts were caused, for most impact categories, by NaOH production, and transport was relevant as well.

Influence of the Composition on the Environmental Impact of Soft Ferrites

The aim of this paper is to analyze the influence of the composition on the environmental impact of the two main types of soft ferrites, allowing scientists and engineers to compare them based not only on cost and properties, but also on an environmental point of view. Iron oxides are the basis of soft ferrites, but these ferrites have a wide range of compositions, using materials such as manganese or nickel, which affect their magnetic properties, but also modify the environmental impact. A Life Cycle Assessment has been carried out for manganese‒zinc (MnZn) and nickel‒zinc (NiZn) soft ferrites, with a Monte Carlo approach to assess multiple compositions. The LCA model was developed with SimaPro 8.4, using the EcoInvent v3.4 life cycle inventory database. Environmental impact values were calculated under the ReCiPe and Carbon Footprint methodologies, obtaining a broad variety of results depending on the composition. The results were also significantly different from the standard EcoInvent ferrite. For the analyzed soft ferrites, the presence of manganese or nickel is a key factor from an environmental perspective, as these materials involve high environmental impacts, and their supply risk has increased during recent years, making them a concern for European manufacturers.