Addition Of Plasticizer Research Articles

Investigation of kinetics, reaction mechanisms, thermodynamics, and synergetic effects in co-pyrolysis of wood sawdust and linear low-density polyethylene using the thermogravimetric approach.

This study focused on investigating thermal degradation behaviors, kinetics, reaction mechanisms, synergistic effects, and thermodynamic parameters of wood sawdust (WSD), linear low-density polyethylene (LLDPE), and their blends (LW1:3, LW1:1, and LW3:1) during co-pyrolysis in a thermogravimetric analyzer (TGA). Thermal behavior exhibited a LW1:3 blend (25 wt.% LLDPE) showing significant mass loss at lower temperatures (150 to 300°C) compared to the individual feedstocks, such as 150 to 400°C and 300 to 520°C for WSD and LLDPE, respectively. The iso-conversional methods (KAS, FWO, and FM) were used to determine the kinetic parameters (Ea and A), and the activation energy drop was highest for the LW1:3 blend. According to the master plots, the third-order reaction (O3), nucleation (P2/3), and diffusional model (D4) were the predominant reaction mechanisms for the co-pyrolysis of the LW1:3, LW1:1, and LW3:1 blend, respectively. The thermodynamic parameters demonstrate that a small amount of plastic addition into WSD can improve the reactivity of the blend, shorten the reaction time, and cause less energy-intensive reactions. The values of ΔH, ΔG, and ΔS also confirmed the co-pyrolysis process's spontaneity and endothermic nature. The Fourier transforms infrared spectrometer (FTIR) spectra of raw feedstock, blends, and their biochar revealed some of the peaks were shifted, the intensity was reduced, and disappearance can happen when the temperature was increased. Using the experimental and theoretical/predicted activation energies, the parity chart illustrates the synergistic effects of co-pyrolysis of different blends, and the LW1:3 blend has a favorable synergistic impact. These results could be helpful in process optimization and designing an effective reactor system for co-pyrolysis.

Leaching behavior of microplastics during sludge mechanical dewatering and its effect on activated sludge

Dewatering is an indispensable link in sludge treatment, but its effect on the microplastics (MPs) remains inadequately understood. This study investigated the physicochemical changes and leaching behavior of MPs during the mechanical dewatering of sludge, as well as the impact of MP leachates on activated sludge (AS). After sludge dewatering, MPs exhibit rougher surfaces, decreased sizes and altered functional groups due to the addition of dewatering agents and the application of mechanical force. Meanwhile, plastic additives, depolymerization products, and derivatives of their interactions are leached from MPs during sludge dewatering process. The concentration of MP-based leachates in sludge is 2–25 times higher than that in water. The enhancement of pH and ionic strength caused by dewatering agents induces the release of MP leachates enriched with protein-like, fulvic acid-like, and soluble microbial by-product-like substances. The reflux of MP leachates in sludge dewatering liquor to the wastewater treatment system negatively impacts AS, leading to a decrease in COD removal rate and inhibition of the extracellular polymeric substances secretion. More importantly, MP leachates cause oxidative stress to microbial cells and alter the microbial community structure of AS at the phylum and genus levels. These findings confirm that MPs undergo aging and leaching during sludge dewatering process, and MP leachates may negatively affect the wastewater treatment system.

Potential mechanisms and modifications of dietary antioxidants on the associations between co-exposure to plastic additives and diabetes

BackgroundThe association of plastic additive mixture exposure with diabetes and the modifying effects of dietary antioxidants are unclear.MethodsThe data from the NHANES 2011–2018 were retrieved, and phthalates and organophosphate esters (OPEs) were selected as exposures. The coexposure effect was analyzed by the environmental risk score (ERS) and quantile g-computation. To mitigate any potential bias caused by using the internal weights, another version of ERS was constructed using the cross-validation approach. The level of dietary antioxidant intake was measured by the composite dietary antioxidant index (CDAI). The biological mechanism underlying the association was studied by the adverse outcome pathway (AOP) framework.ResultsFifteen chemicals (ten phthalates and five OPEs) were measured in 2824 adult participants. A higher ERS was significantly associated with an increased risk of diabetes (OR per 1-SD increment of ERS: 1.25, 95% CI: 1.13–1.39). This association apparently interacted with the CDAI level (ORlow: 1.83, 95% CI: 1.37–2.55; ORhigh: 1.28, 95% CI: 1.15–1.45; Pinteraction = 0.038). Moreover, quantile g-computation also revealed higher level of combined exposure was positively associated with diabetes (OR: 1.27, 95% CI: 1.05–2.87), and the addition of dietary antioxidants showed a null association (OR: 1.09, 95% CI: 0.85–2.34). The AOP study identified TCPP and TCEP as key chemicals that cause aberrant glucose metabolism and insulin signaling pathways and result in diabetes.ConclusionsCoexposure to phthalates and OPEs is positively associated with diabetes, where an antioxidative diet plays a modifying role. Several potential mechanisms have been proposed by AOP framework.

Knowledge-based machine learning for predicting and understanding the androgen receptor (AR)-mediated reproductive toxicity in zebrafish

Traditional methods for identifying endocrine-disrupting chemicals (EDCs) that activate androgen receptors (AR) are costly, time-consuming, and low-throughput. This study developed a knowledge-based deep neural network model (AR-DNN) to predict AR-mediated adverse outcomes on female zebrafish fertility. This model started with chemical fingerprints as the input layer and was implemented through a five-layer virtual AR-induced adverse outcome pathway (AOP). Results indicated that the AR-DNN effectively and accurately screens new reproductive toxicants (AUC = 0.94, accuracy = 0.85), providing potential toxicity pathways. Furthermore, 1477 and 2448 chemicals that could lead to infertility were identified in the plastic additives list (PLASTICMAP, n = 7112) and the Inventory of Existing Chemical Substances in China (IECSC, n = 17741), respectively. Colourants containing steroid-like structures are the major active plastic additives that might lower female zebrafish fertility through AR binding, DNA binding, and transcriptional activation. While active IECSC chemicals primarily have the same fragments, such as benzonitrile, nitrobenzene, and quinolone. The predicted toxicity pathways were consistent with existing fish evidence, demonstrating the model’s applicability. This knowledge-based approach offers a promising computational toxicology strategy for predicting and characterising the endocrine-disrupting effects and toxic mechanisms of organic chemicals, potentially leading to more efficient and cost-effective screening of EDCs.

Advantages of online supercritical fluid extraction and chromatography hyphenated to mass spectrometry to analyse plastic additives in laboratory gloves

Plastic additives are introduced in plastic material formulations, along with organic polymers, to offer different properties such as stability, plasticity or color. However, plastic additives may migrate from the plastic material to the content (in case of plastic containers) or to the material in contact with the plastic, like human skin. In the case of plastic medical devices, this migration is of particular interest, as plastic additives may be deleterious to health. In the present paper, we examined the interest of combining supercritical fluid extraction (SFE) to supercritical fluid chromatography (SFC) hyphenated to mass spectrometry (MS) in an online system to characterize plastic additives in laboratory gloves, taken as samples of medical devices. A set of target compounds comprising 18 plasticizers, 4 antioxidants and 2 lubricants was defined and their detectability with MS was examined, where it appeared that electrospray ionization (ESI) provided better detectability than atmospheric pressure chemical ionization (APCI). After examining possible stationary phases with the help of Derringer desirability function, an isocratic chromatographic method (CO2:methanol 95:5) was developed on Shim-pack UC Phenyl column. The extraction method was examined with a 3-level full factorial design of experiments to optimize the extraction temperature (40 °C) and pressure (200 bar). The online SFE-SFC-MS method was compared to offline methods where the samples were extracted with liquid solvents at atmospheric pressure or high pressure then analysed with SFC-MS. In all cases, offline methods showed significant contaminants (like the oleamide lubricant) issuing from laboratory plastic materials as nitrogen drying station, syringes and filters, while the online method allowed a complete elimination of laboratory contaminations. Furthermore, the online method saved time, solvents and laboratory consumables. It will also show that transferring a compressible fluid from a loading loop is favourable to high efficiency, as the resulting chromatographic peaks are much thinner than when transferring a liquid. Compared to injecting liquid heptane, the efficiency increase was 3.4-fold, while compared to injecting liquid methanol (a common practice in SFC), the efficiency increase was 13-fold. Finally, the additive composition of different laboratory gloves was compared.

Granulated rubber in playgrounds and sports fields: A potential source of atmospheric plastic-related contaminants and plastic additives after runoff events

The use of “crumb rubber” coming from recycling materials in outdoor floors like playgrounds has been a frequent practice during the last years. However, these surfaces are object of abrasion and weathering being a potential source of micro and nanoplastics (MNPLs) to the atmosphere and a potential source of human exposure to them. Our main goal has been to expose different crumb rubber materials to summer weathering effects. The released inhalable fractions were sampled for two months with passive samplers and the composition of MNPLs and plastic additives (organic and inorganic) were evaluated. The ecotoxicological effects of leached materials emulating runoff events was evaluated in freshwater micro crustacean Daphnia magna and the green algae Chlorella vulgaris. The analysis of MNPLs showed the presence of polyethylene, polypropylene, polybutadiene, polysiloxanes and polybutylene at concentrations up to 30,426 ng/m3. In the same fraction, we also identified up to 56 plastic additives, including antioxidants, pigments, copolymers, flame retardants, fungicides, lubricants, plasticizers, UV filters and metal ions. Finally, runoff ecotoxicological effects on D. magna and C. vulgaris showed that leached compounds, either from virgin or aged material, would be toxicants for exposed organisms although at concentrations much higher than those expected to be released to the media.

Chitosan films tailored with deep eutectic solvent extracts from Hibiscus sabdariffa: Fabrication and characterization

Natural polymers are the most promising alternatives to petroleum-based plastics for developing biodegradable food packaging films. However, the brittleness and lack of active protection of films from most natural polymers pose a challenge to their practical application. The addition of plasticizers and natural extracts to these films is considered an effective solution to address these issues. In this study, the potential for the use of deep eutectic solvents (DESs) and DES extracts derived from Hibiscus sabdariffa in the production of chitosan films and their effects on their mechanical and antioxidant properties were examined. Initially, the extraction efficacy of DESs composed of choline chloride (ChCl) and various carboxylic acids (citric, lactic, tartaric, and oxalic acids) was evaluated in terms of phenolic and anthocyanin contents along with antioxidant activities. Optimal results were achieved with the utilization of ChCl-oxalic acid as the extraction medium. Subsequently, chitosan films were fabricated by introducing DESs and DES extracts as plasticizers and compared with glycerol-plasticized chitosan films. The incorporation of DESs and DES extracts into the film matrix led to a notable reduction (11.78–14.82%) in moisture content compared with glycerol (25.34%). Notably, using ChCl-tartaric acid improved the tensile strength, while ChCl-citric acid enhanced the film flexibility. Films containing ChCl-tartaric acid demonstrated exceptional light barrier properties. SEM analysis revealed an interaction between chitosan and DESs, which was further corroborated by FTIR and XRD. Additionally, DES extracts provided superior antioxidant activity to the films than their pure DESs. These findings suggest a significant potential for DES extracts from Hibiscus sabdariffa as bioactive agents and plasticizers in chitosan films.

Study of the thermal stability of spent bleaching clay-based geopolymer with waste polypropylene plastic aggregates

This study incorporated polypropylene (PP) plastic waste into the spent bleaching clay (SBC)-based geopolymer as aggregates, aiming to address pollution from plastic and edible oil industry waste while promoting a transition into circular economy of repurposing waste. The geopolymer mixture paste, containing PP plastic aggregates in different mass ratios (SBC:PP = 1:0.4, 1:0.6, 1:0.8, and 1:1) is oven cured at 60 °C and 80 °C for 8 h followed by 7 days of room temperature curing. Thermal properties of PP-SBC-based geopolymer mortars with varying compositions of PP plastic were assessed using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The TGA results revealed that the geopolymer's thermal stability within the temperature range of 620 °C–700 °C improved with an increase in PP plastic aggregate content, up to an optimal amount of 1:08 PPSBCG sample ratio of SBC to PP cured at oven temperature of 80 °C has been chosen as the representative sample for further discussion based on analysis result of ATR-FTIR spectroscopy and BET analysis. Beyond this amount, a reverse trend was observed. The DSC analysis revealed that incorporating PP plastic aggregates reduced its thermal stability towards the melting reaction but improved its thermal insulation properties. However, this effect was observed only up to a composition of PP plastic relative to SBC of 0.6, beyond this threshold, a reverse trend was observed. In addition to TGA and DSC, the geopolymer samples were characterized using Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectroscopy and N2 Brunauer-Emmett-Teller (BET) analysis. This study proved that the addition of high heat-resistant PP plastic into the geopolymer system increased the thermal stability of geopolymers, but only up to a certain optimal quantity. Excessive PP plastic resulted in a reverse trend due to significant effect of weakened interfacial bonding between the geopolymer matrix.

Microplastic Leachate Negatively Affects Fertilization in the Coral Montipora capitata.

Microplastic pollution is an emerging stressor of concern to coral reef ecosystems which are already threatened by additional global and local level anthropogenic stressors. The effects of ingesting microplastics alone on corals have been well studied, but the effects of the chemical composition of these particles have been understudied. Many microplastic-associated chemicals are endocrine disrupters potentially posing a threat to organismal reproduction. Therefore, the goal of this study was to determine if differences exist between the effects of microplastics themselves and plastic leachate on Montipora capitata fertilization due to changes in fatty acid quantity and composition. Assays were conducted two years in a row which exposed M. capitata gamete bundles to either one of four types of recently manufactured, virgin microspheres (nylon, polypropylene, high-density polyethylene, or low-density polyethylene) at three concentrations (50, 100, or 200 particles/L) or microplastic leachates, presumably including plastic additives from these microspheres. Gamete fertilization was not impacted by plastic particles themselves, but some of the microplastic leachate treatments with the same polymer type significantly reduced fertilization rates for M. capitata. Additionally, a total of 17 fatty acids were seen in both years, but neither fatty acid quantity nor composition correlated with observed declines in fertilization. Instead, fertilization and fatty acid data independently varied by concentration and polymer type, likely due to the presence of different chemicals. This study is the first to directly test the toxicity of plastic leachate to coral reproduction. These findings show that microplastic-associated chemicals are an important stressor affecting successful coral fertilization and fatty acid quantity and composition and provide evidence for the negative effects of microplastic leachate to coral reproduction. Thus, plastic additives could pose an additional threat to coral replenishment and persistence in coral reef ecosystems.

The effect of polyvinyl chloride and polyethylene terephthalate on the mechanical properties of butyl rubber (IIR)-based thermoplastic elastomer using semi-efficient vulcanisation system and a nano zinc oxide as activator

Thermoplastic elastomers (TPEs), a class of materials bridging the gap between rubber and thermoplastics, have revolutionised diverse fields with their unique properties and applications. This study highlights the critical importance of compatibility between plastics, polyvinyl chloride (PVC), polyethylene terephthalate (PET), and butyl rubber (isobutylene-isoprene rubber, IIR) components in TPEs for optimal performance. Several TPEs were prepared with different amounts of plastics. Subsequently, the TPEs were cured, and curing and mechanical properties, and correspondent thermal stability and solvent resistance were measured. It revealed that the thermal stability of TPEs, containing PVC, PET and IIR, was influenced by the type and quantity of each plastic, affecting degradation temperatures. PVC and PET exhibited distinct effects on the curing behaviour of IIR-based TPEs, impacting scorch time and optimum cure time differently. The incorporation of PVC and PET enhanced the organic solvent resistance of the TPEs, attributed to physical barrier effects, enhanced crosslinking, increased crystallinity, and specific interfacial interactions. Tensile strength and elongation at break generally decreased with the addition of plastics, reflecting incompatible interactions and increased crystallinity. Meanwhile, hardness increased due to the rigid structure and filler effects of plastics. Achieving an optimal TPE formulation involves balancing these competing effects.

Toxicokinetics of microplastics in Macrobrachium nipponense and their impact on the bioavailability of loaded pollutants

Microplastics (MPs) have unique toxicokinetic (TK) processes that differ from those of soluble pollutants. This study investigated the ingestion, migration, accumulation, and clearance of environmental aging MPs in the Japanese swamp shrimp (Macrobrachium nipponense). The concentrations of plastic additives and personal care products adsorbed onto MPs in natural river water were determined, and TK models for MPs and MPs-loaded pollutants were developed. Results showed that the formation of surface biofilms and alterations in the distribution of MPs in waters caused by environmental aging affect MPs bioavailability, which is mainly related to the feeding habits of shrimp. The decrease in MPs particle size caused by biological digestion and the increase in the number of oxygen-containing functional groups caused by environmental aging affect the TK process of MPs. The TK model of MPs-loaded pollutants revealed the cleaning effect of shrimp on pollutants adsorbed onto MPs during swallowing and spitting MPs. This cleaning effect significantly increases the bioavailability of MPs-associated pollutants in aquatic environments. This study provides a new perspective for understanding the interactions between environmental MPs and their associated pollutants in aquatic ecosystems.

Bacterial bioremediation as a sustainable strategy for the mitigation of Bisphenol-A.

In the era dominated by plastic, the widespread use of plastic in our daily lives has led to a growing accumulation of its degraded byproducts, such as microplastics and plastic additives like Bisphenol A (BPA). BPA is recognized as one of the earliest man-made substances that exhibit endocrine-disrupting properties. It is frequently employed in the manufacturing of epoxy resins, polycarbonates, dental fillings, food storage containers, infant bottles, and water containers. BPA is linked to a range of health issues including obesity, diabetes, chronic respiratory illnesses, cardiovascular diseases, and reproductive abnormalities. This study examines the bacterial bioremediation of the BPA, which is found in many sources and is known for its hazardous effects on the environment. The metabolic pathways for the breakdown of BPA in important bacterial strains were hypothesized based on the observed altered intermediate metabolites during the degradation of BPA. This review discusses the enzymes and genes involved in the bacterial degradation of BPA. The utilization of naturally occurring microorganisms is the most efficient and cost-effective method due to their selectivity of strains, ensuring sustainability.

Relaxation and entropy generation in dewetting thin glassy polymer films trapped far from equilibrium

AbstractPolymers when confined to a dimension comparable to the length scale of polymer chain coils such as thin films, often lead to molecular relaxation processes distinct from their bulk counterpart. Often observed as thermal and mechanical responses such relaxation has been frequently associated with the squeezing of polymer chains having conformations trapped far from thermodynamic equilibrium and subsequently generating processing‐induced molecular recoiling stress. Relaxation in polymer films can be modified by tuning the molecular recoiling stress, which is directly influenced by the preparation conditions of the polymer thin films. Hence a comprehensive understanding of the genesis and relaxation of molecular recoiling stress becomes necessary. Here, we provide insights into the nonequilibrium nature observed in polymer thin films, focusing majorly on the investigations into the molecular recoiling stress using the dewetting technique. The impact of various factors like temperature of dewetting, thickness of films, molecular weight of polymers, and physical aging affecting the relaxation of molecular recoiling stress is discussed. In addition, discussions on the possible mechanisms of relaxation and modification of molecular recoiling stress by varying the spin‐coating speed and addition of plasticizers are also provided. An alternate approach which gives a new perspective into the relaxation of molecular recoiling stress considering the entropy generated during the dewetting of polymer films is also included. The present work is expected to give the reader a comprehensive understanding of the characteristics of molecular recoiling stress relaxation occurring in polymer thin films.

Human Oral Exposure to Nano- and Microplastics and Plastic Additives in Barcelona, Spain: a series of single-case studies

Human Oral Exposure to Nano- and Microplastics and Plastic Additives in Barcelona, Spain: a series of single-case studies

Additive inclusion in plastic life cycle assessments, part II: Review of additive inventory data trends and availability

AbstractPlastic additives are as essential as polymers to the production and performance of plastic materials. Additive content can vary in composition and functionality depending on the product, producer, application, and production method. Such variation may be a barrier to achieving high‐quality recycling and planning for plastic circular economy futures. Yet, as found in Part I, although there is increasing awareness of the importance of additives in plastics, they are often poorly disclosed or only briefly discussed in life cycle assessments (LCAs). In part II, we focus on the inclusion of additives in plastic processes in the database most used in plastic LCAs to date (Ecoinvent) and find that additives have historically been omitted from plastic granulate data and in production processes in the evaluated database. Thus, many practitioners will need to separately include additives in their models of plastic life cycles. To support practitioners in this endeavor, we then assess the availability of the 13,587 additives identified in the recent UN Chemicals in Plastics Report across the three major LCI databases (CarbonMinds, Ecoinvent, and LCA for Experts [GaBi]). We find that databases currently cover only 1,209 of these additives. Moreover, we assert that transparency regarding additive inclusion in plastics datasets, availability of additive datasets, and additive data completeness are major barriers to additive inclusion in plastic LCAs. Thus, we recommend focusing on the development of additive datasets, and we provide a tool for the identification of additive dataset availability and data gaps to improve the quality of plastic LCAs.

Unravelling the influence of microplastics with/without additives on radish (Raphanus sativus) and microbiota in two agricultural soils differing in pH

Here we investigated the effects of three types of microplastics (MPs), i.e., PS (P), ABS (B), PVC (V), and each with additive (MPAs) (PA, BA, and VA), on soil health, microbial community, and plant growth in two acidic and slightly alkaline soils. Incubation experiment revealed that although MPs and MPAs consistently stimulated soil nutrients and heavy metals (e.g., Mn, Cu) in weakly alkaline soils, only BA and VA led to increase in soil nutrients and heavy metals in acidic soils. This suggests distinct response patterns in the two soils depending on their initial pH. Concerning microorganisms, MPs and MPAs reduced the assembly degree of bacteria in acidic soils, with a reduction of Chloroflexi and Acidobacteriota but an increase of WPS-2 in VA. Culture experiment showed consistent positive or negative responses in radish seed germination, roots, and antioxidant activity across MPs and MPAs types in both soils, while the responses of seed heavy metals (e.g., Cr, Cd) were consistent in acidic soils but dependent on MPs and MPAs types in alkaline soils. Therefore, our study strongly suggests that the effects of MPs on soil-microbial-plant systems were highly dependent on initial soil characteristics and the types of MPs with plastic additives.

Effect of interaction between different plastics and polyvinyl chloride on the chlorine transformation behavior in volatiles during low-temperature pyrolysis

To reduce the pollution during the pyrolysis recovery of chlorine-containing plastic waste from different sources, effects of the interaction between different plastics and polyvinyl chloride (PVC) on the transformation of chlorine at low temperature were investigated by thermogravimetry-Fourier transform infrared (TG-FTIR) and fixed-bed pyrolysis experiments. Results showed that the proportions of chlorine in chars were all <0.04 %, indicating that almost all chlorine was released after pyrolysis. However, the chlorine forms in volatiles were significantly changed with mixing different plastics. HCl production was significantly inhibited due to the addition of other plastics, while the organic chlorinated compounds (OCCs) formation was promoted, which increased the distribution of chlorine in liquid products. During PVC pyrolysis, chlorine was mainly distributed in gas (93.09 %) in the form of HCl, only a small amount of aliphatic chlorides were generated and distributed in liquid (6.89 %). After the addition of polystyrene (PS), polyethylene (PE) and polyethylene terephthalate (PET), the chlorine distribution in liquid increased to 8.86 %, 11.98 % and 25.99 %, respectively. The formation of OCCs was significantly affected by the difference in thermochemical reaction characteristics of plastics. Specifically, the production of aromatic chlorides was promoted by PS, while the generation of aliphatic chlorides and aromatic chloroesters was significantly promoted by PE and PET, respectively. Therefore, the release form of chlorine could be significantly altered by the interaction between PVC and other waste plastics, which provides a reference for the regulation of chlorine-containing pollutants in the recovery and utilization of plastic waste.

Utilization of spent bleaching earth as green filler and plasticizer in the manufacture of rubber compounds for solid tire production

This study utilized spent bleaching earth (SBE) as a single form of filler and plasticizer in the manufacture of rubber components for solid tire vulcanizate. SBE, an underutilized byproduct of vegetable oil purification, is abundantly available globally and can be used as a filler and plasticizer in rubber compounds. This aligns with environmental sustainability principles, reduces disposal costs, and lowers raw material expenses in rubber manufacturing. In this research, the SBE was applied for each formula from SBE-02 to SBE-05 at ratios of 15–30 per hundred rubber (phr). As a comparison, carbon black (CB) filler (65 phr), CaCO3 (35 phr), and plasticizer derived from petroleum in the form of paraffinic oil (PO) (6 phr) were used. Rubber components were produced by masticating natural and synthetic rubber in an open mill, followed by the addition of filler, plasticizer, accelerator, co-activator, anti-degradant, and vulcanization agent. The resulting compounds were vulcanized at 150 °C and 10 MPa for 17 minutes. The test results demonstrated that incorporating SBE at a ratio of 15 phr (SBE-02) significantly reduced the cure time (t90) to 8 minutes and 20 seconds, the shortest among all tested formulations. The mechanical properties of the SBE-02 vulcanizate rubber met the requirements for solid wheelchair tire applications, with a hardness of 70 Shore A. However, its abrasion resistance test result of 189.1 g/cm³ was the lowest among the formulations tested. Furthermore, the scorch time (ts2) of the SBE-02 was determined to be 2 minutes and 35 seconds. Results from a 1000x magnification scanning electron microscope (SEM) reveal air gaps on all sample surfaces of different sizes. The elements C, O, Zn, Si, Ca, and Pb dominate the SEM-EDX results for all rubber vulcanizate samples from all three spectra, in varying weight percentages. The identification of functional groups with FTIR on all rubber vulcanizate samples shows Si–O–Si bending at 2, 4, and 5 and Si–O–Al stretching at 3, 5 on the wave number spectrum of 680–413 cm−1 Si–O–Si on the wave number spectrum 1100–1050 cm−1 from the infrared spectrum.

Parameter study of waste shiitake substrate/waste polyethylene Co-gasification using Aspen Plus kinetic modeling

Waste Shiitake Substrate, a major agricultural waste in Taiwan, is typically packaged in plastic bags (Waste Polyethylene, PE) during mushroom cultivation process. Consequently, these plastic bags become additional waste that requires proper disposal. In recent years, Taiwan has produced over 150,000 tons of waste shiitake substrate annually, with approximately 1580 tons of plastic bags used for mushroom cultivation. Up to now, there has not been an effective method for handling this waste. This study aims to develop a co-gasification process using the complementary characteristics of WSS and PE. Unlike traditional direct combustion, the co-gasification approach can convert these wastes into cleaner bioenergy. This study aims to develop an Aspen Plus model for a laboratory-scale 1 kWth bubbling fluidized bed gasifier. This model incorporates kinetic reactions and tar formation during co-gasification. The model accurately predicted the experimental results. Different variables were investigated, including gasifier temperature, blending ratio (BR) of the two fuels, mixing ratio (MR) of the gasifying agent, and equivalence ratio (ER). The results showed that hydrogen production correlated positively with the steam-to-carbon ratio in the gasification medium, whereas carbon monoxide (CO) was more affected by the feedstock type and equivalence ratio, with CO reaching its peak at an equivalence ratio of 0.2. When gasifying using only waste shiitake substrate (BR = 0%), at an ER of 0.2, a gasification furnace temperature of 950 °C, and an MR of 100% (pure CO2), the maximum CO mass flow rate in the syngas is obtained. Waste plastics contain significant amounts of volatile matter and no oxygen, leading to increased production of CH4, CO, and H2 during co-gasification with the addition of waste plastic. For plastics, high temperature and low ER conditions promote the production of CO, H2, and CH4 because of the significant tar content, thereby enhancing the Cold gas efficiency (CGE). When the gasification temperature is 950 °C, with 80% polyethylene (BR = 80%) and an ER of 0.1, the highest HHV is achieved. These results can serve as a reference for determining the operational conditions for the scale-up of gasification systems.

Leveraging integrative toxicogenomic approach towards development of stressor-centric adverse outcome pathway networks for plastic additives

Plastics are widespread pollutants found in atmospheric, terrestrial and aquatic ecosystems due to their extensive usage and environmental persistence. Plastic additives, that are intentionally added to achieve specific functionality in plastics, leach into the environment upon plastic degradation and pose considerable risk to ecological and human health. Limited knowledge concerning the presence of plastic additives throughout plastic life cycle has hindered their effective regulation, thereby posing risks to product safety. In this study, we leveraged the adverse outcome pathway (AOP) framework to understand the mechanisms underlying plastic additives-induced toxicities. We first identified an exhaustive list of 6470 plastic additives from chemicals documented in plastics. Next, we leveraged heterogenous toxicogenomics and biological endpoints data from five exposome-relevant resources, and identified associations between 1287 plastic additives and 322 complete and high quality AOPs within AOP–Wiki. Based on these plastic additive–AOP associations, we constructed a stressor-centric AOP network, wherein the stressors are categorized into ten priority use sectors and AOPs are linked to 27 disease categories. We visualized the plastic additives–AOP network for each of the 1287 plastic additives and made them available in a dedicated website: https://cb.imsc.res.in/saopadditives/. Finally, we showed the utility of the constructed plastic additives–AOP network by identifying highly relevant AOPs associated with benzo[a]pyrene (B[a]P), bisphenol A (BPA), and bis(2-ethylhexyl) phthalate (DEHP) and thereafter, explored the associated toxicity pathways in humans and aquatic species. Overall, the constructed plastic additives–AOP network will assist regulatory risk assessment of plastic additives, thereby contributing towards a toxic-free circular economy for plastics.