Plastic Samples Research Articles

Evaluation of the physical parameters of water obtained from some groundwater sources of Tabuk city, Kingdom Saudi Arabia

After air, water is the second most important element for life, based on that, water quality parameters (physical, chemical and biological) should be concerned to detect contamination. The aim of this study was to evaluate the physical parameter of water brought from some groundwater sources of Tabuk City. A cross-sectional design was followed to collect groundwater from 12 sites (randomly selected) within Tabuk City to measure water temperature, color, odor, taste and turbidity, in addition to record the groundwater depth. In aseptic and clean plastic sample containers, 250 ml of the groundwater were collected. Water temperature was measured using a manual thermometer, immediately when it was collected. The data concerned the depth of the groundwater was obtained directly from the owners during groundwater sampling. The water color, odor, taste, in addition to turbidity were measured using the general human sense. The obtained physical parameters were compared with the local standards of the drinking water suggested by MEWA (2022). The results of this study show that, the groundwater temperature for the 12 samples obtained from Tabuk City ranged between 26oC and 33oC, with a mean of 29.33oC, while the groundwater depth (in meter) ranged between 120 m and 700 m with a mean depth of 479.2 m. The physical parameters of drinking water compared to the Saudi standards of quality showed that, all tested samples were agreed with the quality standards on color, odor, taste and turbidity. This work recommends for the prudent use of groundwater resources to keep its quality for long term usage as a drinking water.

Synthesis of azelaic acid copolyester plasticizers and their application in PVC.

A series of 2-methyl-1,3-propanediol (MPO) modified azelaic acid and hexylene glycol copolyester (PHMAZ) plasticizers with varying contents were synthesized using a direct esterification melt polycondensation method, and their structures were characterized systematically. Analysis using infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed the synthesis of the designed copolyester structure. Gel permeation chromatography (GPC) tests indicated that the number average molecular weight of each copolyester sample ranged between 2000 and 3000. These copolyesters were used to plasticize polyvinyl chloride (PVC) resin, and the glass transition temperature of the plasticized PVC samples was tested using a differential scanning calorimeter (DSC). Further characterization of the plasticizing effects was conducted using an electronic universal testing machine. The research results showed that as the content of MPO increased, the plasticizing effect of the copolyester initially increased and then decreased. Specifically, the copolyester containing 45% MPO, PHMAZ-45, demonstrated the best plasticizing effect on PVC, with the glass transition temperature of the plasticized PVC system around -35 °C, elongation at break at 908.4%, and a plasticizing efficiency of 254.5%. Additionally, this new type of copolyester plasticizer uses bio-based raw materials, exhibits excellent plasticizing effects, and the preparation process is stable and controllable. It holds promising potential to replace traditional volatile and toxic phthalate esters, presenting significant industrial application value.

Hydrothermal liquefaction of plastic marine debris from the North Pacific Garbage Patch

Ocean plastic waste poses a growing environmental threat, efforts are now underway to help clean the ocean surface or to prevent plastic streams entering. Repurposing these highly mixed polymers presents a great challenge due to their inherent complexity, intertanglement, and the presence of contaminants. Herein, we process real samples of ocean-floating plastics from the North Pacific Garage Patch through supercritical hydrothermal liquefaction (HTL), targeting their chemical recycling into synthetic crude oil. Investigating key process parameters (temperature, pressure, time, and plastic load), we found that plastic load and temperature are crucial parameters influencing oil yield and that moderate conditions maximized hydrocarbon yield, reaching 90 wt%. Overall, longer residence times and higher temperatures favored aromatic-rich oils. We suggest a reaction pathway to account for hydrogen release from aromatization reactions, influencing paraffin, olefin, and aromatic contents. Supercritical HTL offers an effective, tailored approach for recycling complex plastic mixtures to produce synthetic crude oil.

Phototrophs as the central components of the plastisphere microbiome in coastal environments

Upon entering the marine environment, plastics are colonized by a plethora of microorganisms to form a plastisphere, influencing the fate and transport of the plastic debris and the health of marine ecosystems. The assembly of marine plastisphere is generally believed to be dominated by stochastic processes. However, it remains elusive whether microbial interaction in the assembly of plastisphere microbial communities is conserved or not. We analyzed the plastisphere microbiomes of 137 plastic debris samples from intertidal zones at different geographical locations and habitats (seagrass, coral, mangrove, beach, and open ocean) and compared them with the surrounding sediment and seawater microbiomes. Microbial community structures of the plastisphere from different locations were more similar to each other but differed substantially from the surrounding sediment and water microbiomes, implying a common mechanism of plastisphere assembly. We used different machine learning algorithms (Multinomial Logistic Regression, Support Vector Machine, Decision Trees, Random Forest, and Artificial Neural Networks) to classify plastic debris samples with high sensitivity based on the microbiome composition. Eukaryotic and prokaryotic phototrophic organisms such as green algae, diatoms, and cyanobacteria, were found to be enriched on the plastic surfaces. Network analysis revealed the central role of the phototrophic organisms in the formation and sustenance of the plastispheres. We found that phototrophs served as core members interacting strongly with heterotrophic organisms in marine plastisphere, irrespective of the sampling location, habitats, and polymer types. This would explain the stochastic assembly of the plastisphere along with conserved properties driven by the phototrophs in the surrounding environment. Our results highlight the importance of phototrophic organisms in shaping the marine plastisphere microbial communities.

Product classes characterization at micro-scale level applied to granular wastes fractions < 20 mm: a case-study

A product class characterization was requested on some plastic granular waste samples, already reduced in fine form with particles < 20 mm, derived from waste electrical wires and PC cables. The product class discrimination was worked out by visual characterization with the aid of optical stereomicroscopy and confirmation by electron scanning microscopy (SEM) and microanalysis. Characterization at a micro-scale level evidenced predominance of plastic materials with presence of metal wires, paper, textile and glass fibres at residual levels in the main fraction (0.5–4 mm). The fractions < 0.5 mm, when present, cannot easily be distinguished at sight and only approximate qualitative information can be extracted by SEM analysis. The described approach has been carried out effectively due to major shape and material differences between plastic particles and metal wires and other materials. However, this approach may not work in every case, or it may not lead to usable results with every type of waste.

Direct Mass Spectrometric Analysis of Brominated Flame Retardants in Synthetic Polymers.

Brominated flame retardants (BFRs) are persistent organic pollutants that pose a major threat to the environment. In this study, a direct insertion probe (DIP) coupled with atmospheric pressure chemical ionization (APCI) quadrupole time-of-flight mass spectrometry (QTOF-MS) was used to characterize additives, especially BFRs, from solid polymer samples with minimal sample preparation. A temperature-programmed DIP analysis, from 150 to 450 °C within 10 min, was utilized to achieve temporal separation of analytes based on their boiling or degradation temperatures, thereby facilitating their easier identification within a single run. Studied BFRs showed different behaviors during the analysis: decabromodiphenyl ether and tetrabromobisphenol A were found to be stable within the studied temperature range, while hexabromocyclododecane already started to debrominate. Our study showed that the DIP-APCI-MS method suited well for the direct qualitative identification of BFRs from polymer matrices. Furthermore, by optimizing the sampling procedure with cryogenic grinding, even quantitative analysis could be performed. The DIP measurements also provided important information about the composition of polymer matrices, including the identification of the comonomers present. Overall, DIP-APCI QTOF-MS was found to be an excellent tool for the compositional analysis of plastic samples. Developing rapid and reliable analysis methods can pave the way for more efficient plastic recycling and the safer use of plastic recyclates.

Experimenting the effectiveness of waste materials in improving the compressive strength of plastic-based mortar

The reduction in compressive strength (CS) of cementitious composites incorporating waste plastic is the main concern limiting its applicability in the building sector. Using industrial wastes as cement substitutes to enhance the CS of plastic mortar is a sustainable approach. This study used fine powdered waste materials such as silica fume (SF), marble powder (MP), and glass powder (GP) in plastic-based mortar for their effectiveness in enhancing CS. Plastic mortar specimens were cast using plastic waste in 5–25 % contents as sand replacement by mass, and their 28-day CS was recorded as a reference. SF, GP, and MP were utilized in plastic mortar mixtures separately in proportions of 5–25 %, with a 5 % increment, substituting cement by mass. These waste powders were also used in combinations of two (SF+GP, SF+MP, and GP+MP) and three (SF+GP+MP) in plastic mortar mixtures. Moreover, prediction models were built using the experimental database for the CS of plastic mortar. Gradient boosting and bagging ensemble machine learning (ML) techniques were chosen for model development. The decrease in CS was limited by substituting SF, GP, and MP for cement in plastic mortar. It was determined that the most effective substitution levels for SF, GP, and MP in plastic mortar, according to the strength enhancement, were 15, 10, and 15 wt.% of cement, respectively. The ML models closely matched experimental results, and in terms of R2 and error evaluations, bagging model outputs were more accurate than gradient boosting. The gradient boosting and bagging models had R2 of 0.89 and 0.94, respectively, with average absolute errors of 0.87 and 0.65 MPa.

Adsorption of trace metals onto different plastics during long-term exposure in an estuarine environment: Influence of time, stratified water column, and specific surface area

The pervasive increase of plastics in marine systems and subsequent trace metals (TM) adsorption represents a critical environmental challenge. This long-term study is first to investigate how duration of exposure and stratified water column impact TM adsorption on various plastics in an estuary. We exposed polypropylene (PP), polyethylene (PE), poly(ethylene terephthalate) (PET), and fluorinated ethylene propylene (FEP) to estuarine conditions, categorizing them into three distinct groups to capture diverse human activities: pre-production pellets (Pellets), single-use plastics (SUP) and laboratory plastics (Lab). Plastic and water samples were analyzed before deployment and 1, 4, 7 and 16 months after deployment at three depths in the stratified Krka River estuary (Croatia). We measured TM concentrations, pH and salinity in the water column, and adsorbed TM amounts on plastics. Additionally, we examined plastic sample surfaces by Raman spectroscopy and scanning electron microscopy. TM speciation was modeled from water column data to better explain adsorption processes. Statistical analysis indicates that Zn, Cd, Pb, Ni, and Co adsorption depends on both duration of exposure and stratified water column, while Cu is influenced solely by duration of exposure to estuarine environment. Adsorbed TM amounts varied significantly among the plastic groups (Pellets, SUP and Lab), but not among different polymer types (PP, PE, PET and FEP). A noteworthy observation was the difference in the results of statistical analysis when investigating TM amounts expressed by plastic sample mass and by plastic sample surface area. Results expressed by plastic sample mass showed a difference between SUP group versus Pellets and Lab groups, while results expressed by plastic sample surface area distinguished Pellets group compared to other two groups. Therefore, we suggest presenting TM adsorption results in similar studies both by plastic sample mass and by plastic sample surface area. This approach will improve the understanding of TM adsorption on plastics, and enable more effective comparisons among the scientific literature dealing with plastics of different specific surface areas.

One-step electrochemical preparation of platinum nanoparticle decorated self-healing reduced graphene oxide three-dimensional nanoarray for portable detection of bisphenol A

Highly selective and sensitive analysis of bisphenol A (BPA) in many plastic products remains its significance. We explored a simple, highly sensitive, and inexpensive electrochemical sensor based on a self-healing three-dimensional nanoarray (3DN) via a single-step electrochemical preparation of both platinum nanoparticles (PtNPs) and reduced graphene oxide (rGO) on a glassy carbon electrode for the portable detection of bisphenol (BPA) in plastic bottled waters. The structure of PtNPs/3DNrGO was confirmed by electron microscope and spectroscopic characterization. Electrochemical characteristics indicated that PtNPs/3DNrGO could decrease the oxidation overpotential due to the self-healing effect of the physical interaction between PtNPs and hydroxyl groups of rGO with an increase in the active surface area. The PtNPs/3DNrGO exhibited remarkably efficient electrocatalytic performance for the oxidation of BPA. The PtNPs/3DNrGO sensor for BPA demonstrated a wide linear range from 0.7 to 20 µM with a low limit of detection of 6 nM (S/N = 3) and effective performance including high sensitivity, high repeatability, and excellent selectivity. The developed sensor had been effectively implemented to assess BPA in plastic samples with desirable impacts. The interaction mechanism of both PtNPs and rGO was inferred by density functional theory. The proposed electrochemical sensor enabled the development of a portable, low-cost, and user-friendly monitoring of water quality, which will offer theoretical support for environmental monitoring.

New tartrate and α-tocopherol based environmentally friendly plasticizers for improvement of the ductility of polylactic acid

This study focuses on developing environmentally friendly plasticized poly(lactide) (PLA) formulations using tartaric acid and α-tocopherol at 20 wt%. The extrusion and injection molding processes demonstrated the industrial applicability of these plasticizers. Mechanical tests revealed positive results for tartrate-based plasticizers, with elongation at break surpassing 220 %, while α-tocopherol succinate achieved 170 %. However, α-tocopherol acetate showed limited PLA plasticization. Field emission scanning electron microscopy confirmed plasticization in fractured surfaces. Thermal analysis indicated a reduction in PLA's glass transition temperature (Tg) from 60 °C to around 30 °C with these plasticizers, underscoring tartrates' exceptional efficiency. The cold crystallization temperature (Tcc) decreased for all plasticized samples due to enhanced chain mobility. Thermomechanical analysis revealed dimensional shrinkage, with dimethyl tartrate (DMT) causing less pronounced effects. Generally, tartrates yielded formulations with superior properties, attributed to their lower molecular weight compared to α-tocopherol-derived plasticizers. Notably, all plasticizers employed are an eco-friendly approach to improve PLA's processability and enhancing ductile properties.

FLAW DEFECTION ANALYSE OF THE SURFACE OF ACRYLIC BASE PLASTICS

This study examines the possibility of assessing the quality of removable orthopedic devices by measuring the smoothness of their surfaces and detecting microscopic defects. The methodology involves comparing standard samples of the base material with samples that have been intentionally defective, using defectoscopy techniques for analysis. Initially, twenty samples of basic acrylic plastic were selected: half of them were perfectly machined to dental standards and the other half were intentionally scratched with sandpaper. These samples were then examined by macrophotography and analyzed using Image J software for quantitative image measurement. This analysis provided numerical data on the polished surface's quality, focusing on metrics such as the total number of defects, and the average size and perimeter of these defects. Statistical evaluation through the JUSP program compared the two sets of samples, highlighting significant differences between them. From the most prominent data points provided by Image J, conclusions were made regarding the surface quality of the acrylic plastic and how it is affected by specific mechanical imperfections. This method of using optical flaw detection offers a new way to clinically evaluate the quality of detachable orthopedic devices (like base plastic) in terms of their susceptibility to bacterial buildup, which could lead to inflammation in the prosthetic bed's mucosal lining. The use of flaw detection analysis allows for a general assessment of the quality of the material surface polishing, detection of surface defects in its structure that may occur during the production stage or during operation, thereby preventing areas of biofilm accumulation. Light-optical flaw detection in the experiment proved its effectiveness and makes us pay attention to the prospects of its improvement and wider implementation in clinical practice.

The assembly and ecological roles of biofilms attached to plastic debris of Ashmore reef

Plastic pollution in the ocean is a global environmental hazard aggravated by poor management of plastic waste and growth of annual plastic consumption. Microbial communities colonizing the plastic's surface, the plastisphere, has gained global interest resulting in numerous efforts to characterize the plastisphere. However, there are insufficient studies deciphering the underlying metabolic processes governing the function of the plastisphere and the plastic they reside upon. Here, we collected plastic and seawater samples from Ashmore Reef in Australia to examine the planktonic microbes and plastic associated biofilm (PAB) to investigate the ecological impact, pathogenic potential, and plastic degradation capabilities of PAB in Ashmore Reef, as well as the role and impact of bacteriophages on PAB. Using high-throughput metagenomic sequencing, we demonstrated distinct microbial communities between seawater and PAB. Similar numbers of pathogenic bacteria were found in both sample types, yet plastic and seawater select for different pathogen populations. Virulence Factor analysis further illustrated stronger pathogenic potential in PAB, highlighting the pathogenicity of environmental PAB. Furthermore, functional analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathways revealed xenobiotic degradation and fatty acid degradation to be enriched in PABs. In addition, construction of metagenome-assembled genomes (MAG) and functional analysis further demonstrated the presence of a complete Polyethylene (PE) degradation pathway in multiple Proteobacteria MAGs, especially in Rhodobacteriaceae sp. Additionally, we identified viral population presence in PAB, revealing the key role of bacteriophages in shaping these communities within the PAB. Our result provides a comprehensive overview of the various ecological processes shaping microbial community on marine plastic debris.

Uncovering the characteristics of plastic-associated biofilm from the inland river system of Mongolia

The occurrence and characteristics of plastic debris in aquatic and terrestrial environments have been extensively studied. However, limited information exists on the properties and dynamic behavior of plastic-associated biofilms in the environment. In this study, we collected plastic samples from an inland river system in Mongolia and extracted biofilms to uncover their characteristics using spectroscopic, isotopic, and thermogravimetric techniques. Mixtures of organic and mineral particles were detected in the extracted biofilms, revealing plastic as a carrier for exogenous substances, including contaminants, in the river ecosystem. Thermogravimetric analysis (TGA) indicated the predominant contribution of minerals primarily comprising aluminosilicate and calcite, representing approximately 80 wt% of the biofilms. Differential thermal analysis (DTA) coupled with Fourier transform infrared (FTIR) spectrometry operated at 25°C–600 °C enabled the detection of gaseous decomposition products, such as CO2, H2O, CO, and functional groups (O–H, C–H, C–O, CO, CC, and C–C), released from biopolymers in the extracted biofilms. Dehydration, dehydroxylation, and decarboxylation reactions explain the thermal properties of biofilms. The stable carbon (δ13C) and nitrogen (δ15N) isotope ratios of the biofilms demonstrated variable signatures ranging from −24.1‰ to −27.0‰ and 3.1‰–12.3‰, respectively. A significant difference in the δ13C value (p < 0.05) among the upstream, middle, and downstream research sites could be characterized by available organic carbon sources in the river environment, depending on the research sites. This study provides insights into the characteristics and environmental behavior of biofilms which are useful to elucidate the impact of plastic-associated biofilms on organic matter and material cycling in aquatic ecosystems.

Microplastic identification in marine environments: A low-cost and effective approach based on transmitted light measurements

Microplastics have become a significant concern for the well-being of marine ecosystems. Small fragments of plastic debris are released into the environment from both the direct disposal of plastic products and the deterioration of larger items. Ingestion of microplastics by marine life can result in detrimental effects, including physical harm and the accumulation of toxic chemicals in their tissues. The aim of this research is to design a compact and cost-effective measurement system for effectively detecting and quantifying microplastics in marine environments. The proposed system uses a 2.4-inch liquid-crystal display (LCD) panel and a digital USB microscope, both of which are connected to a single-board computer, with a dedicated python-based graphical user interface (GUI). Specifically, the light transmitted through plastic and organic samples was measured in order to identify and classify them. Various types of materials, such as polypropylene, polyvinyl chloride, polycarbonate, polyethylene, and organic algae samples, were tested and the metrological performance of the system has been estimated. The transmittance of the samples analyzed was primarily influenced by their opacity and thickness. In general, thicker materials exhibited significantly lower transmittance values. This trend was particularly evident in organic components and opaque plastic samples, where transmittance was significantly low. In addition, the experimental results suggest that the colour of the material also affects transmittance, although as a secondary factor. The employed technique could be used to identify and distinguish samples based on material properties, thereby allowing the proposed system to be a valuable tool for further research on microplastics in marine environments.

Advanced chemometric methodologies on single shot hyphenated LIBS data for rapid and reliable characterization of plastic classes

BackgroundPlastic Solid Waste (PSW) sorting is a procedure of paramount importance in the mechanical recycling process of plastics waste. The major limitation of the techniques relying on physical properties of plastics is the time taken for analysis and poor accuracy. Spectroscopy has been shown to be a suitable method in plastic sorting due to its atomic and molecular characterization capabilities, and ability to give results in very short time scales. However, for practical applications it is essential to translate this technique into an automatic technology, by combining it with advanced chemometric tools which can give observer independent judgement. ResultsThe indigenously developed bi-model Laser Induced Breakdown Spectroscopy (LIBS)-Raman system with single source and single detector can record the LIBS-Raman spectral signals in single-shot mode in a total time frame of 20 ms. Out of the combinations of Principal Component Analysis (PCA) and Partial Least Squares (PLS) with Logistic Regression (LR), Linear Discriminant Analysis (LDA), Support Vector Machine (SVM), and Partial Least Squares-Discriminant Analysis (PLS-DA) based classifiers, the PLS-DA based model showed the maximum classification accuracy with 95 % based on LIBS data and 100 % based on Raman data. The reliability of the model was assessed using 4-fold cross-validation which showed a sensitivity of 90.28 % and specificity of 98.29 % for predictions based on LIBS data, and 99 % sensitivity and 99.82 % specificity for predictions relying on Raman data. SignificanceThe results show how the combination of multimodal spectroscopy with chemometric analysis enhances the applicability of spectroscopic techniques for plastic sorting. The classification model successfully classified seven types of post-consumer plastic samples based on combined LIBS and Raman data. With the home-built software for automated prediction, the system takes less than a second to predict the plastic type illustrating the potential of the method for translation to regular routine industrial applications.

Surface conductivity of clays

SUMMARY Clay minerals are extensively used in a wide range of applications. In particular, clay-bearing formations are considered as suitable radioactive waste repository. Electrical resistivity tomography is an appropriate tool to monitor the properties of clay-bearing locations. However, an inherent drawback of a conventional resistivity survey is its ambiguity in distinguishing between the effects of groundwater salinity, clay content and porosity. A discrimination can be achieved on the basis of the induced polarization method that provides a complex conductivity. The main purpose of this study is the investigation of the complex conductivity of clay samples with a special focus on the contribution of surface conductivity produced by an excess of ions in the electrical double-layer coating the solid particles. Six clay mixtures were selected that include an almost pure kaolinite sample, a sample consisting of a mixture of kaolinite, illite and smectite, a crushed saponite breccia, a Ca-bentonite sample and two illite clay samples. Besides the enriched kaolinite, the other samples are natural geomaterials that contain more than 40 weight per cent clay minerals. The mineralogical compositions of the samples were determined by quantitative X-ray diffraction analysis. The clay powder was mixed with a varying volume of sodium chloride solution to get plastic state clay samples with varying water content. The samples were investigated by the spectral induced polarization method in a frequency range between 1 mHz and 1 kHz. The resulting complex conductivity spectra indicate a decrease of the real part of the electrical conductivity with rising water content for the illite, bentonite and saponite breccia samples. The overall conductivity of these clay samples is dominated by their surface conductivity. In contrast, the electrical conductivity of kaolinite and kaolinite–illite mixture does not show any significant changes with the water content. For all samples, the imaginary part of electrical conductivity increases at low water content. The real part of the surface conductivity indicates a linear dependence on the volumetric clay content. The slope of this linear relationship can be used to distinguish the types of clay. The ratio between imaginary conductivity and surface conductivity, which decreases with increasing clay content, proves to be a suitable parameter that characterizes the connectivity of clay aggregates in the sample. The surface conductivity of the pure kaolinite sample has been determined in an additional multisalinity experiment. The resulting surface conductivity is in good agreement with the experiment of varying water content. The multisalinity experiment has shown that the resulting petrophysical parameters depend on the procedure of sample packing, which may lead to anisotropy. The effect of anisotropy is attributed to the alignment of the plate-like kaolinite particles in the course of the packing and consolidation procedure.

Processes influencing the toxicity of microplastics ingested through the diet

The present study assesses the effect of culinary treatment and gastrointestinal digestion upon the release of additives present in microplastics. Organic additives were determined by gas chromatography–mass spectrometry, and inorganic additives using inductively coupled plasma-mass spectrometry.The results revealed a large number of organic additives in the plastic samples, some being classified as possible carcinogens. Contents of Sb in PET (polyethylene terephthalate), Zn and Ba in LDPE (low-density polyethylene) and PVC (polyvinylchloride), and Ti and Pb in LDPE were also noteworthy. The culinary process promotes the release and solubilization of additives into the cooking liquid, with phthalates, benzophenone, N-butylbenzenesulfonamide (NBBS) and bisphenol A being of particular concern. The solubilization of phthalates and NBBS was also observed during gastrointestinal digestion.This study demonstrates that culinary treatment and gastrointestinal digestion promote release and solubilization of additives from plastics ingested with the diet. Such solubilization may facilitate their entry into the systemic circulation.

X-ray study of the density distribution of FFF-printed samples with different fill patterns

Three-dimensional printing has a wide range of applications in science and technology. Fused filament fabrication (FFF) is a commonly used 3D printing technology, which is now being increasingly employed in radiation physics. In FFF, the internal structure of an object is primarily determined by its fill pattern and selected print modes. Therefore, this study aims to examine the interaction between X-rays and 3D-printed plastic samples with various infill patterns. The 3D-printed objects were produced using FFF with plastic and different infill patterns, including Rectilinear, Grid, Triangles, Stars, Honeycomb, Concentric, Archimedean Chords, Gyroid, and Hilbert Curve. Infill densities of 80% and 90% were utilized. Tomographic methods were applied to analyze the resulting samples. The study provides tomograms of the internal structure for each infill pattern. It was observed that Rectilinear and Grid patterns produced the most homogeneous samples. The findings of this study contribute to understanding of the propagation of X-rays through 3D-printed plastic samples with complex internal structures.

Towards improved flexural behavior of plastic-based mortars: An experimental and modeling study on waste material incorporation

A considerable fraction of solid waste, which is harmful, chemically reactive, and infectious, is generated globally. The frequent deposition of these wastes in landfills has significant environmental and health consequences. This study aims to develop an environmentally conscious approach by incorporating finely ground waste materials, namely marble powder (MP), glass powder (GP), and silica fume (SF), into plastic waste (PW) based mortar to assess their efficacy in improving flexural strength (FS). Plastic waste mortar samples were cast using shredded PW, replacing sand in amounts ranging from 5 % to 25 %. The FS of these samples was measured after 28 days and used as a reference. MP, GP, and SF were individually incorporated into PW-based mortar formulations in varying quantities of 5–25 %, with increments of 5 %, by replacing cement. In PW-based mortar formulations, waste materials were also utilized in various combinations, including GP+SF, MP+SF, MP+GP, and MP+GP+SF. In addition, prediction models, including decision tree (DT) and artificial neural network (ANN), were constructed utilizing experimental data for the FS of PW-based mortar. The substitution of PW with sand reduces the FS of mortar samples. The research findings emphasize that optimal replacement levels for MP, GP, and SF in PW-based mortar mixtures, based on their ability to enhance FS, were 15 %, 10 %, and 15 % by cement mass, respectively. However, the cumulative incorporation of MP, GP, and SF in PW-based mortar suggests cement should not be replaced beyond 15 %, as it reduces the FS. Both prediction models exhibited a high degree of correlation with the coefficient of determination (R2) value of 0.925 for ANN and 0.959 for the DT model. The findings showed that MP, GP, and SF may be used in PW-based mortar to improve the FS while producing eco-friendly building material.

Using hyperspectral imaging to identify and classify large microplastic contamination in industrial composting processes

Compostable plastics are used as alternatives to conventional (non-compostable) plastics due to their ability to decompose through industrial composting comingled with food waste. However conventional (non-compostable) plastics sometimes contaminate this industrial composting process resulting in the formation of microplastics in the end compost. Therefore, it is crucial to effectively identify the types of plastics entering industrial composters to improve composting rates and enhance compost quality. In this study, we applied Hyperspectral Imaging (HSI) with various pre-processing techniques in the short-wave infrared (SWIR) region to develop an efficient model for identifying and classifying plastics and large microplastics during the industrial composting process. The materials used in the experimental analysis included compostable plastics such as PLA and PBAT, and conventional (non-compostable) plastics including PP, PET, and LDPE. Chemometric techniques, namely Partial Least Squares Discriminant Analysis (PLS-DA), was applied to develop a classification model. The Partial Least Squares Discriminant Analysis (PLS-DA) model effectively distinguished between virgin PP, PET, PBAT, PLA, and PHA plastics and soil-contaminated plastics measuring larger than 20 mm × 20 mm, achieving accuracy of 100%. Furthermore, it demonstrated a 90% accuracy rate in discriminating between pristine large microplastics and those contaminated with soil. When we tested our model on plastic samples during industrial composting we found that the accuracy of identification depended on parameters such as darkness, size, color, thickness and contamination level. Nevertheless, we achieved 85% for plastics and large microplastics detected within compost.