Plastics Industry Research Articles

Combined valorization of industrial and post-consumer plastic waste. An industrial symbiosis approach

Combined valorization of industrial and post-consumer plastic waste. An industrial symbiosis approach

Plastic paradise: Ibiza’s 1971 ICSID congress

This article discusses the use of plastic at the annual meeting of the International Council of Societies of Industrial Design (ICSID), held in Ibiza in 1971. It focuses on the pneumatic sculptures of Josep Ponsatí and the inflated architecture of José Miguel Prada Poole, whose maquettes are today catalogued in museums as sculptures. The congress took place in the Sant Miquel cove during Franco’s dictatorship and exemplifies how plastic was understood under those specific social and political conditions, and how it was used on an island that embodied traditional Mediterranean culture, albeit dramatically transformed by tourism. The article also reveals the links established between this ICSID gathering and the plastics industry: Aiscondel, the factory that provided the materials for some of the sculptures, used documentary images taken at the festival in aggressive publicity campaigns in subsequent years. In adopting this focus, the article aims to show how the imagery of plastic has evolved in recent decades from the utopian vision prevalent at the time to its current association with a dystopian Anthropocene.

Camelina sativa (L.) Crantz straw and pomace as a green filler for integral skin polyurethane foam

The development of efficient methods for obtaining cellular materials with improved functional properties is a constant challenge for the plastics industry, including the polyurethane industry. In recent years, efforts have been made to obtain cheap and easily available raw materials that can be used as foam fillers. In addition to commercially used synthetic fillers, more and more attention is paid to materials of natural origin, in particular to agricultural and industrial waste. This solution not only meets the assumptions of the "Green Chemistry" concept but also creates the opportunity to improve the properties of plastics while reducing their production costs. This study focuses on the use of naturally derived materials as fillers in flexible integral polyurethane foams (Integral Skin Foams, ISFs) to produce economically advantageous and ecologically sustainable composite materials. Waste materials such as Camelina sativa (L.) Crantz straw and pomace were used as biofillers. The obtained samples were used to determine the processing parameters and functional properties of the foams: hardness, tensile strength, elongation at break and permanent deformation after compression. In the case of both straw and pomace, an increase in growth time and an increase in the free density of the foams were observed with an increase in the amount of added plant material. The analysis of morphology and chemical structure of the obtained composites led to the conclusion that the cellular structure, skin thickness, and functional groups present in biofillers had a direct impact on the functional properties of ISF. For most composites, a significant improvement in mechanical parameters was observed compared to the reference foam. The obtained results confirmed the utility potential of Camelina sativa (L.) Crantz straw and pomace. The main research assumption has been fully implemented that focused on obtaining innovative polyurethane composites with improved functional properties.

Eva Hesse and plastics: a study of collaborative fabrication

In the 1960s artists contributed to an optimistic moment for plastics in the United States, and were actively seeking out the material for its novel properties and abilities. Eva Hesse is seldom discussed in the context of the plastics industry, and yet her most ambitious sculptures in Fiberglas were created with fabricator Aegis Reinforced Plastics in New York. Hesse had begun exploring synthetic substances in 1967, attending classes offered by Experiments in Art and Technology (E.A.T.), an organization that bridged artistic and scientific communities. Then, in 1968, Hesse hired Aegis, and together they constructed the Fiberglas sculptures at the centre of her solo exhibition at the Fischbach Gallery in New York, entitled Chain Polymers. While Hesse – the woman, the artist – often looms large in the literature on her work, this text brings a more complex understanding to her approach to constructing objects, shifting the focus from the mythological presence of the artist’s hand in her sculptures. Hesse was driven by the possibilities of Fiberglas as an active participant rather than an inert substance. This article explores Hesse’s turn to Fiberglas, her collaboration with Aegis, and the steps she took to find, harness and then construct with the plastic substance.

Developing high-performance and sustainable polylactic acid/recycled polyolefin blends: Tuning the degree of functional group reaction and performance optimization.

In the current development of the plastics industry, the use of biodegradable and recycled plastics not only effectively reduces the volume of landfills and incineration but also significantly decreases environmental damage. However, the extensive application of biodegradable polylactic acid (PLA) is limited by its poor toughness and thermal properties. The study introduced recycled linear low-density polyethylene (R-LLDPE) and ethylene-octene copolymer (POE) to modify PLA, primarily based on their excellent toughness and thermal resistance. Furthermore, being a recycled material, R-LLDPE is economically advantageous and conforms to the ecological requirements of resource recycling. Therefore study introduced glycidyl methacrylate (GMA) and styrene (St) to synthesize the graft copolymer (R-LLDPE/POE)-g-(GMA-co-St) (RPGS). The RPGS serves as a modifier for PLA resin. The effects of different GMA amounts in RPGS on the properties and microstructure of PLA/RPGS blends were examined. The results illustrate that GMA was successfully grafted onto the molecular chains of R-LLDPE/POE (RP), with St acting as a "bridge" to enhance further the grafting efficiency of GMA on RP macromolecular chains. After introducing RPGS into the PLA matrix, the epoxy groups of GMA reacted with the terminal hydroxyl groups of PLA, significantly decreasing the particle size of the dispersed phase and closely integrating with the PLA matrix, hence greatly improving the compatibility between PLA and RP. With the increase of GMA amount, the optical, thermal, and hydrophobic properties of the blends were increased, while the flexibility first increased and then decreased. When the GMA amounts were 5 wt% in RPGS, the Gd and Ge of GMA reached optimal values of 2.55 % and 51 %, the blend exhibited the optimum overall properties: haze decreased to 28.3 %, light transmittance increased to 92.5 %, thermal decomposition temperature increased to 368.12 °C, and the Vicat softening temperature increased to 78.2 °C. While maintaining the tensile strength at 54.3 MPa, the notched impact strength and elongation at break increased to 10,182.4 J/m2 and 231.7 %, respectively, with the matrix exhibiting significant shear yielding. The research presents an eco-friendly and efficient method for producing high-performance PLA-based materials, effectively addressing the shortcomings of PLA in toughness and thermal resistance. The modified materials had excellent mechanical and thermal capabilities while offering financial and environmental benefits. The development of this material is anticipated to enhance the industrial utilization of biodegradable and recycled plastics, offering essential support for attaining sustainable manufacturing and a circular economy.

Pyrolysis and beyond: Sustainable valorization of plastic waste

The recycling of plastics through pyrolysis has garnered significant attention as a waste management approach, particularly given upcoming regulations and the urgent need for absolute sustainability. This review paper evaluates pyrolysis's technological, environmental, and regulatory aspects, emphasizing the need to prioritize environmental impact over purely economic considerations. While it is recognized that financial challenges have constrained many past attempts at scaling pyrolysis systems, this paper argues that a shift in focus toward sustainability criteria is essential for the technology's long-term viability. Prioritizing environmental outcomes is critical given the pressing issues like plastic pollution, which presents significant threats to ecosystems and human health. A comprehensive assessment of environmental impacts is vital for technologies intended for large-scale deployment, ensuring that they align with global sustainability goals. This perspective is especially pertinent in light of the current United Nations Environment Programme (UNEP) global plastic pollution treaty negotiations, where there is a contentious debate over the true circularity of chemical recycling. Environmentalists and several nations advocate for significant reductions in plastic production and bans on single-use plastics. At the same time, oil-producing countries and petrochemical companies push for circularity in the plastic economy. The paper explores the promise and limitations of pyrolysis technology for valorizing plastic wastes, comparing its efficacy with other waste management methods. Biomass pyrolysis is discussed due to its significant synergies with plastic pyrolysis and its potential for carbon sequestration through biochar. However, the discussion on biomass pyrolysis is limited in scope, with the paper's primary focus on waste plastic pyrolysis. The paper discusses the challenges and opportunities in utilizing pyrolysis for waste plastics, which are considered along with regulatory and geopolitical aspects. Environmental impacts, including life cycle analysis and planetary boundary considerations, are examined to understand why pyrolysis has yet to achieve widespread adoption. A case study on Plastic Energy, SABIC, and Unilever highlights current industry status, technological advancements, and information gaps. Finally, a comprehensive framework is proposed to achieve net-zero emissions, improve air quality, and ensure absolute environmental sustainability in plastic recycling. Recommendations are provided for the plastic industry and research institutions to support the transition towards sustainable waste management practices.

Exploration of the plastic packaging product industry towards green manufacturing, efforts to consolidate environmental impact versus productivity issues

Plastic products, including plastic packaging, were products whose increasing demand continued because the community still needed plastic as packaging. On the other hand, plastic waste, which was increasingly high and difficult to decompose, was a problem that needed to be solved together. This study aims to understand how plastic company packaging implements TQM, its environmental impact, and how plastic packaging companies are taking steps towards green manufacturing. This research used a qualitative phenomenological method to understand the problem based on the actor’s perspective. The data collection method was in-depth interviews with informants from 3 plastic companies in East Java, Indonesia, followed by observation and FGD. We carried out Triangulation, member checking, and professional involvement to determine the data’s validity, reliability, and trustworthiness. The results of this study indicated a management system that promotes quality as a business strategy and is oriented towards customer satisfaction by involving all members of the organization. TQM emphasized continuous improvement, customer satisfaction, and employee involvement. By implementing aspects of TQM, plastic packaging companies could improve their production processes and reduce waste, increasing efficiency and profitability. In addition, TQM could also contribute to the company’s green performance by promoting environmentally friendly practices, including using electric machines to replace hydraulic machines, thereby reducing the use of electrical energy and CO2 emissions. The use of solar panels was a step towards green manufacturing. Companies that adopt TQM principles are more likely to implement environmentally friendly initiatives such as reducing energy consumption and using recyclable materials and can demonstrate a commitment to corporate social responsibility. The company’s membership in EcoVadis and SMETA further strengthens the company’s direction towards Green Manufacturing and competitive advantage.

Competitive Strategies and Performance of Plastic Packaging Industries in Kenya: A Case Study of Coca-Cola Beverages Kenya-Preform Manufacturing Plant

Manufacturing, especially the plastics manufacturing sector, faces significant challenges from the constantly shifting competitive business environment, and companies have been working hard to maintain their competitiveness. Porter provided evidence that implementing a generic competitive strategy can result in a more robust competitive advantage. The purpose of this research is to determine the effects of Porter's generic strategies on competitive advantage in the plastic packaging industries especially Coca-Cola Beverages Kenya. The sample size for this study was 50 respondents, whereas the population was roughly 45 respondents. Questionnaires were the primary means of gathering data. The findings underscore the required need to adapt specific porter strategy to have advantage over their competitors, such as Cost Leadership, Differentiation, cost focus and differentiation focus strategy. The study demonstrated that the cost focus, cost leadership, differentiation and differentiation focus strategy had impacted the Coca-Cola beverage Kenya's success among the competitors. Hence the study concludes that to maximize competitive advantage, the firm should focus on theses strategy to edge out competition.

The processability and properties of agar/gelatin film in a melt-mixing process

The rising concern in the use of non-biodegradable plastics has triggered the search for potential substitutes from renewable sources. Agar and gelatin are two potential sources of biobased plastic; however, their preparation process mostly uses solution casting, which uses toxic substances and limiting its processability in industrial machinery. In this study, agar/gelatin film was produced through a twin-roll mixer without any involvement of any toxic chemicals, creating a greener process of bioplastic. The resulting films were investigated in terms of processability, chemical structure, thermal properties, tensile properties, contact angle and biodegradation. The loading of gelatin improved the processability of the agar film blends, which is comparable with synthetic plastic such as high density polyethylene (HDPE) and polypropylene (PP). With the gelatin loading of 3 wt.%, the tensile strength increased from 20.80 MPa to 25.89 MPa. The presence of gelatin enhanced the Tdonset and Tdpeak of glycerol while lowering both values in agar. Contact angle increased from 38.17 ° to 67.77 ° with the presence of 4 wt.% gelatin. These results show that agar/gelatin has a promising future to be an environmentally friendly substitution for synthetic, non-degradable plastic and produce in a common plastic industry equipment.

A Combined Capacity Planning and Simulation Approach for the Optimization of AGV Systems in Complex Production Logistics Environments

Background: The capacity planning of production systems is one of the most fundamental strategic problems in the creation of a production plant. However, the implementation of increasingly complex production systems combined with sophisticated automated material handling justifies the development of novel approaches to solve the combined capacity planning and material handling problem, which is also the objective of the current study. Methods: The presented approach combines the use of capacity planning formulas and discrete event simulation for optimizing extensive automated guided vehicle (AGV) systems from the aspect of the number of required vehicles. Extensive series of simulation experiments are applied in the case of each model variant for optimal results and to account for machine failures in the system. Results: The application of the proposed method is demonstrated through a realistic sample problem in a plastic industry setting with the use of the Siemens Tecnomatix Plant Simulation software (version 2302.0003, Educational license). Conclusions: The results from the sample problem demonstrate the usefulness of the approach, as a non-intuitive solution proved to be the most efficient. Additionally, the main advantage of the method is that it provides a standardized framework for the simulation-based optimization of AGV systems starting out from the comprehensive production capacity parameters.

Enhanced degradation of methylene blue dye using hydrothermally synthesized Nickel-doped Strontium oxide catalysts

Methylene blue is an organic contaminant that is produced by the plastic, textile, and dye industries. Many studies have been undertaken to investigate the cleanup of methylene blue from industrial effluents. SrO nanoparticles are now being utilized to remove methylene blue colours from water. We used a hydrothermal technique to create strontium oxide nanoparticles for photocatalytic MB breakdown under light conditions. To enhance the solar light activity and avoid charge recombination, we employed a hydrothermal technique to add Ni as a dopant in strontium oxide nanoparticles. Strong base NaOH, nickel nitrate, and strontium nitrate were used as precursors. The nanoparticles were crushed into powder and calcined at 450 °C in a muffle furnace to produce SrO and Ni-doped SrO nanoparticles. The nanoparticles were analyzed using several analytical methods to determine their morphological and structural properties. At 309, 312, and 317 nm, UV-Vis spectroscopy showed absorbance values of SrO doped with varied nickel concentrations. The Ni–O stretching peak was identified in the FTIR analysis of strontium oxide nanoparticles at 402 cm-1 and 581 cm-1, whereas the Sr–O bond gave a signal at 854.84 cm-1. SEM images of Ni-doped SrO nanoparticles were created at various magnifications. The nanostrips are hexagonal and cylindrical. Sherrer's equation was used to compute the average crystalline structure, which showed that the diameters of pure and Ni-doped SrO (2 percent, 3 percent, and 4 percent) nanoparticles were 45.54 nm, 36.14 nm, 42.93 nm, and 41.21 nm, respectively. According to the EDX examination, the relative concentration of Ni-doped SrO is about 72 percent Sr and oxygen, with around 1.34 percent Ni. The resulting sample was tested for photocatalytic degradation of organic pollutants in aqueous solution, such as methylene blue, and the completion of the reaction was monitored using UV-visible spectroscopy to measure the % photocatalytic degradation during light illumination. According to the UV-visible spectra, 90% of the dye was effectively destroyed.

Preparation of hemp‐based biocomposites and their potential industrial application

AbstractBiocomposites are an emerging field in plastic industry. The incorporation of agri‐food waste in conventional or biobased polymer matrices allows the industry to lessen its carbon footprint, while producing recyclable plastic products. In this work, hemp hurd, a byproduct of hemp fiber production process, was used as a filler to prepare novel compostable composites in two different loadings (22% and 32% w/w respectively). Waste hemp hurds were selected due to their abundance and the lack of derived high‐value products. Three different polymers were used, namely poly[(tetramethyleneadipate)‐co‐(tetramethyleneterephthalate)] (PBAT) and poly(tetramethylene succinate) (PBS) as compostable polymers and a polyethylene elastomer for comparison. The bare polymers and prepared blends were then characterized for their structure and morphology by XRD and FESEM, as well as for their wettability, thermal and mechanical properties (namely energy absorbed on impact and flexural modulus). Structural and morphological characterization unveiled the different interactions occurring between hemp and the polymer matrices, suggesting the major impact of the type of used polymer when compared with biomass loading percentages. Mechanical tests showed that both PBAT and PBS blends properties are comparable to those of the pure polymers (i.e., in the case of PBAT the flexural modulus of the pure polymer was 82.2 MPa while the hemp‐loaded blends stood at around 50 MPa, whereas all PBS polymers and blends were 220 MPa, with no statistical difference between samples). These biomaterials have also similar thermal properties with respect to the bare polymers, underlining the promising potential as sustainable alternative to pure polymers.Highlights Waste hemp hurds were used to load biodegradable polymers at different percentages. Hemp hurd‐based biomaterials with excellent properties were prepared. Polymer flexural behavior was maintained even after hemp addition. Polymer‐hemp interactions for each polymeric matrix were elucidated. Hemp substitutes up to 32% w/w of polymer without affecting its properties.

Evaluation of Performance Improvement Rate of Plastic Production System Using ARENA: A Case Study of Phoenix Plastic Services

Production improvement has become essential to all industrial activity because of the fierce competition among today's production systems and organizations and the unquenchable customer demand. The shorter product life cycle has significantly increased the demand for prompt reactions to increase the productivity and efficiency of these industrial systems. This study examined the evaluation of performance improvement rate of plastic production system using ARENA. The report provided by the plastics industry was used in the study to analyze and assess the rate of performance improvement of the plastic manufacturing system. The location of the bottleneck was determined by the research following a thorough analysis of the plastic company's data, which included information on all manufacturing lines and procedures. The research employed Arena to assess and compute the rate of improvement in system performance while accounting for the material transporting process throughout the production line. The conveyor velocity maintains a lock at 75m/min, despite the company's report stating that the transports run at 30m/min. The optimized and unoptimized processes when obtained from a finished recycling process running for 1000 working hours, indicate that the conveyor process had 1045 and 1027 entity input and output, respectively, and the transporter process had 953 and 929 entities input and output respectively. The remaining number left when considering the number that enters the system with the number that leaves the system went to waste, resulting from the sorting and demagnetization process. The introduction of the conveyor brings 10.549% in the production rate and 50% decrease on expenses spent in labor. Through the conveyor system's speed control factor, which is an automated procedure, the system's percentage increment may be further raised. By raising the conveyor system's speed, more items will be produced. Conveyor system installation free up more space for additional production-related equipment, increasing products formed and the company's profit. The cost of purchasing and installing the conveyor will be covered by the excess profit.

Effect of the Compounding Method on the Development of High-Performance Binary and Ternary Blends Based on PPE

The polymer blends are an effective strategy for materials design with new properties in the plastic industry; such features may depend on the blend components and the processing method. This study aimed to understand the effect of styrene-butadiene-styrene (SBS) content and its architecture on blends based on polyphenylene ether (PPE), high-impact polystyrene (HIPS), and SBS. In addition, this research compared and analyzed the blends formulated by different processing methods: twin-screw extrusion (TSE) and internal mixing (IM). Furthermore, three SBS copolymers, two radial and one linear (with different molecular weights), were used to produce PPE/HIPS/SBS blends, analyzing which SBS copolymer feature provides excellent viscoelasticity, thermomechanical properties, and impact resistance. The findings revealed that the melt processing method played a crucial role in Izod impact resistance of the PPE/HIPS/SBS blends, as well as the molecular architecture, molecular weight, and SBS content. The findings also demonstrated that the TSE process is more effective than the IM. Since the PPE/HIPS/SBS blends displayed higher Izod impact resistance than the PPE/HIPS or PPE/SBS binary blends, a synergistic effect of SBS and HIPS is suggested.

Can the Manufacturing Process Be Improved by FMEA? A Study on X Company in Plastic Packaging Industry in Vietnam

This study based on the FMEA method, provides a systematic approach, which include identifying potential errors in the production process, tracking priority issues, proposing improvement solutions, and putting those solutions into practice in order to improve the flexible plastic packaging manufacturing process at a typical X company in the plastic packaging industry in Vietnam. It is found that four large errors – GP8, SM4, LM4, and BF4 – stand out as having an RPN index higher than 250. The aforementioned issues are also analyzed, and their root causes are tracked down using techniques like brainstorming, cause-effect diagram, and 5 Whys. Then, appropriate actions are taken to deal with these causes. Overall, the findings can serve as an insightful reference for Vietnamese manufacturing companies using the FMEA method to identify any potential errors in their production processes. After that, the company is able to organize proper inquiries and make recommendations for potential failure prevention strategies as well.

Preliminary Research to Assess the Possibility of Grinding Selected Plastics Using Crushers.

This study aims to investigate the effect of the shredding machine used on the recyclability of plastic fractions after primary crushing. This work presents a method for producing aggregates that has yet to be used in the plastics industry. This study included crushing of polymethylmethacrylate (PMMA), polyamide (PA-6), acrylonitrile butadiene-styrene (ABS), polycarbonate (PC), polystyrene (PS), and polypropylene (PP) waste in a jaw, a hammer, and a cone crusher. An analysis of the grain composition was carried out to characterize the obtained crushing products. The influence of feed size on the grain composition of the product and, only on the jaw crusher, the influence of the material used on the parameters of the crushing process was studied. This paper proposes a method to evaluate the grain composition and a way to assess plastic shredding capabilities based on machine kinematics and mechanical properties of a given material.

A novel data-driven rolling horizon production planning approach for the plastic industry under the uncertainty of demand and recycling rate

Efficient production planning in the plastic industry requires integrating sustainability practices, particularly the use of recycled plastics. Recycling helps reduce environmental impacts and conserve resources by decreasing the reliance on virgin materials. To develop a responsive plan, dynamic approaches are beneficial to confront fluctuations in uncertain parameters such as recycling rate and market demand. The present study proposes a novel Data-driven Rolling Horizon Planning (DRHP) approach for a sustainable and dynamic production plan in the plastic industry. A dynamic Rolling Horizon (RH) planning framework is formulated as a multi-product, multi-period Mixed Integer Linear Programming (MILP) model for the problem. This model aims to minimize total production cost while taking into account the system’s constraints and sustainability considerations. To deal with uncertainty, the RH-based MILP model is coupled with a rolling Long Short-Term Memory (LSTM) model. The rolling LSTM model leverages historical data of market demand and recycling rate to predict their future values and consequently improve the responsiveness of the production plan. The outperformance of the proposed DRHP approach is demonstrated through an extensive comparison with a robust static counterpart in terms of total production cost and sustainability performance. Results indicate significant reductions, up to 80%, in production costs using the proposed DRHP approach. Furthermore, the effect of rolling duration is investigated concerning production cost, backlog, late-order, and inventory level. Findings highlight the potential of the proposed DRHP approach to mitigate inventory- and late-order-related challenges.

Multifunctional N-doped MXene/Ammonium polyphosphate reclaimed carbon fiber veil for enhanced electromagnetic shielding, flame retardance, and thermal efficiency

The application of carbon fiber reinforced plastics (CFRPs) in various industries significantly increased the need for sustainable recycling of carbon fiber (CF) to enhance economic efficiency. In this study, we prepared lightweight multifunctional flame-retardant Ti3CNTx/Ammonium Polyphosphate (APP)/Polyethyleneimine (PEI)/reclaimed carbon fiber (MArCF) nonwoven veils with superior Electro-Magnetic Interference (EMI) shielding effectiveness (SE) using a combination of multiple vacuum-assisted filtration, improved etching, and delamination strategies, followed by annealing treatments. The resulting MArCF nonwoven veils exhibited an impressive EMI SE of a maximum of 72.65 dB, with a SSE/t value reaching 10730 dB cm2 g−1. Moreover, the MArCF nonwoven veil demonstrated excellent flame retardance properties, with a substantial decrease of 63 % in Heat Release (HR) capacity, 60 % in Total Heat Release (THR), and 83.15 % in Heat Release Rate (HRR). The modified veils also exhibited excellent Joule heating and photothermal properties, indicating a promising potential for multifunctional reinforcement in composites.

Modification of polyolefins utilizing C–H insertion of azides: Azidoformate end-functionalized polystyrene for modifying polypropylene

Polyolefins dominate the global plastics industry, constituting roughly 60% of all commercial plastics. However, their limited chemical functionality restricts their applicability in adhesion, printability, and compatibility-dependent applications. To overcome these limitations, this study investigated metal-free, melt-process post-polymerization modification of polypropylene (PP) via C-H insertion of azidoformate (AF) groups. We investigated grafting of AF end-functionalized polystyrene (PS) onto PP and demonstrated the successful preparation of novel PP hybrids with interesting properties, including enhanced compatibility between PP and PS components due to grafting, smaller PP crystallite size, high Young's modulus, and elastic rheological behaviors likely attributable to the presence of PS branches. Importantly, the presented approach avoids chain scission of PP and undesirable coloration of the product, offering a promising avenue for industrial transformations of conventional polyolefins. This research paves the way for developing polyolefin-based hybrid materials with enhanced properties and environmental benefits.

Distinct exposure impact of non-degradable and biodegradable microplastics on freshwater microalgae (Chlorella pyrenoidosa): Implications for polylactic acid as a sustainable plastic alternative

Microplastics (MPs) are increasingly recognized as significant sources of harm to biota in various environments. However, the detrimental impacts of aged MPs with different structures and degradability remain poorly understood. In this study, aged MPs from polylactic acid (PLA), polyethylene (PE), and polystyrene (PS), representing biodegradable, aliphatic, and aromatic plastics, respectively, were prepared to examine their effects on microalgae (Chlorella pyrenoidosa). Structural and property analyses indicated the presence of aging and oxygen-containing functional groups on the surfaces of the MPs, which correlated with an increase in negative electrical charge (i.e., aged PLA > aged PE ≈ aged PS). Aged PLA MPs affected microalgae biomass, promoted protein synthesis, and elevated mild oxidative stress. In contrast, aged PE and PS MPs not only affected biomass, protein, and carbohydrate synthesis but also inhibited photosynthetic pigment production and activity, resulting in intracellular oxidative stress. Excitation-emission-matrix spectra analysis showed that PLA induced microalgae to secrete large amounts of humic acid-like extracellular polymers, whereas aged PE and aged PS groups contained only small amounts of them and proteins. This study addresses critical knowledge gaps in the toxicology of various aged MPs on microalgae and provides valuable insights into the potential of PLA as a sustainable alternative to conventional plastics in microalgae culture industry.