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Microplastics (MPs) are one of the major substantial pollutants in the environment and are stored in sediments worldwide, especially in marine environments. This study shed light on the abundance, distribution, sources and chemical composition of MPs present in the surface sediments collected from the shelf part of the southeast coast of India, Bay of Bengal. A total of twenty-seven surface sediment samples were collected to study MPs pollution. The abundance and morphological characteristics of MPs were determined by counting using an Olympus SXZ7 stereo microscope. Raman spectroscopy analysis was used to identify the polymer type of the MPs. The average abundance of MPs in the study area is 460±275 MPs/kg in dry sediment. Regarding colour, transparent particles were predominant (46.42%), followed by blue, green, brown, etc. With respect to particle shape and size, fibres and 500-µm sized MPs are abundant. Polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polystyrene (PS) are the polymer types characterised in the study area. The higher abundance of MPs in the study area can be attenuated to human interruptions, viz., tourism, fishing and inappropriate sewage disposal in the marine environment. In addition to this, population density also plays an important role in providing MPs to the marine environment. This study provides the most valuable data to extrapolate the research for mitigating MP pollution in oceans. It also informs mankind about their disastrous activities on the marine environment, which is expected to recuperate quickly and negatively impact human health and the functionality of the marine system. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are prevalent environmental pollutants due to their durable composition, extensive use, and improper disposal. Despite their widespread presence, rivers have received less attention in microplastic research than other water bodies. This study focused on investigating the origins, prevalence, spatial distribution, and physicochemical characteristics of microplastics in the surface waters of the Balu River, located in Dhaka, Bangladesh. Surface water samples were collected at six sampling sites of Balu River (each about 1–5 km apart) adjacent to the footwear industry, jute factory, textile mill, paper mill, agro and beverage factory, and cement plant. The study found that the average concentration of microplastics in the sampled water bodies was 102.5 ± 12.83 (items/l). Samples near the textile mill had the highest microplastic abundance (122 ± 18 items/l), while the cement plant had the lowest (58.5 ± 8 items/l). Analysis using a stereomicroscope revealed that fibers (29%), microplastics smaller than 100 µm (45%), and transparent microplastics (19%) were the most prevalent types observed in terms of shape, size, and color, respectively. Furthermore, scanning electron microscopy (SEM) observation suggested the potential for additional degradation of these microplastics into smaller particles, potentially reaching the nanoplastic scale. Additionally, Fourier transform infrared (FTIR) analysis identified 07 distinct polymer types among the microplastics: nylon (24%), polyvinyl chloride (19%), high-density polyethylene (17%), low-density polyethylene (14%), polystyrene (12%), polypropylene (7%), and nitrile (7%). The findings of this study serve as a crucial indicator of microplastic contamination, providing valuable insights into the sources and magnitude of microplastic pollution within the significant freshwater ecosystem of Balu River, Bangladesh, particularly focusing on its river systems. [ABSTRACT FROM AUTHOR]

This research investigates the microbial degradation of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) plastics by Bacillus sp., Proteus sp., Pseudomonas sp., and Salmonella sp. The study employs a systematic approach, isolating microorganisms from plastic-contaminated soil and subjecting them to a series of biochemical tests for identification. The research evaluates the weight loss of LDPE and HDPE over two months, revealing varying degrees of degradation among the bacterial strains. Results suggest a potential greater susceptibility of HDPE to microbial degradation. Scanning Electron Microscopy (SEM) analysis provides high-resolution images of the plastic surface, indicating structural changes and biofilm formation during degradation. The findings highlight the unique enzymatic capabilities of each strain and underscore the significance of SEM in elucidating microbial interactions with plastics. The study prompts discussions on optimization, synergistic effects, and the identification of key enzymes in plastic degradation, emphasizing the importance of microbial strategies for waste management. Overall, this research contributes valuable insights into the potential of bacterial strains for addressing plastic pollution challenges. [ABSTRACT FROM AUTHOR]

Microplastic pollution in soil poses a growing environmental threat with far-reaching implications for ecosystems and human health. This study systematically investigated the distribution of microplastics (MPs) across various soil depths in diverse mulched agricultural fields. Soil samples were meticulously collected at three depths (0–5, 5–10, and 10–15 cm) from five distinct agricultural regions in Bangladesh. The analysis of MPs was conducted using Fourier Transform Infrared Spectroscopy (FTIR) and a fluorescent microscope. Notably, the results unveiled no discernible depth-related trends in MP concentration, displaying ranges of 0.13 ± 0.35 to 3.53 ± 1.77; 0 to 5.53 ± 2.36; and 0 to 4.07 ± 2.28 MPs/g of soil in 0–5 cm, 5–10 cm, and 10–15 cm, respectively. The soil exhibited a spectrum of microplastic types, including High-Density Polyethylene (HDPE), Polyethylene terephthalate (PET), Polypropylene (PP), Low-Density Polyethylene (LDPE), Poly Vinyl chloride (PVC), Poly Vinyl Alcohol (PVA), Poly vinyl fluoride (PVF), and Polytetrafluoroethylene (PTFE), ranging from 0.04 ± 0.21–3.71 ± 2.36 MPs/g of soil. Particularly, the industrial agricultural area displayed the highest microplastic concentration (12.89/g of soil). Further, Principal Component Analysis identified plastic mulch and organic manure as potential sources. Despite the presence of microplastic, the estimated concentrations indicated low risks to the farming community in Bangladesh. This research provides valuable insights into microplastic distribution in agricultural soils, enhancing our understanding of this form of pollution. [ABSTRACT FROM AUTHOR]

The co-pyrolysis of polyethylene terephthalate (PET) with low-density polyethylene (LDPE) and high-density polyethylene (HDPE) was carried out in a batch steel pyrolyzer in order to convert the PET into pyrolysis oil as its pyrolysis alone resulted in wax and gases. The study also aimed to increase the aromatic content of pyrolysis oil by the interaction of degradation fragments of linear chains of LDPE and HDPE with the benzene ring of PET during the pyrolysis. The reaction conditions were optimized for a higher yield of pyrolysis oil which were found to be 500 °C pyrolysis temperature with a heating rate of 0.5 °Cs−1, 1 h reaction time and 20 g of the initial mass of polymer mixture having 20% PET, 40% LDPE and 40% HDPE. Waste aluminium particles were applied as an economical catalyst in the process. The thermal co-pyrolysis yielded 8% pyrolysis oil, 32.3 wax, 39.7 wt% gases and 20% coke while the catalytic co-pyrolysis produced 30.2% pyrolysis oil, 4.2% wax, 53.6 wt% gases and 12% coke. The fractional distillation of catalytic oil resulted in 46% gasoline range oil, 31% kerosene range oil and 23% diesel range oil. These fractions resembled the standard fuels in terms of their fuel properties as well as FT-IR spectra. The GC-MS analysis revealed that the catalytic co-pyrolysis favoured the formation of relatively short-chain hydrocarbons with olefins and isoparaffins as major components while the thermal co-pyrolysis formed long-chain paraffins. The naphthenes and aromatics were also found in higher amounts in the catalytic oil compared with the thermal oil. [ABSTRACT FROM AUTHOR]

PE100 features excellent creep and slow crack resistance (SCG). It is common to add color masterbatch to the natural PE100 material to produce compound ready for pipe extrusion. The polyethylene base of the masterbatch is not usually PE100 and therefore can harm the creep and SCG resistance of the PE100. In this paper the effects of small contents of a linear low-density polyethylene (LLDPE) and a unimodal high-density polyethylene (uni-HDPE) on the physical and mechanical properties, specifically strain hardening modulus (SHM) and SCG resistance of a pipe grade bimodal high-density polyethylene (bi-HDPE, PE100) were investigated. Varying contents of 0, 2.5, 5, and 10 wt% of the LLDPE or uni-HDPE were blended with the bi-HDPE in either a lab single screw extruder or internal mixer to compare the effects of the mixing method. Strain hardening test, notched constant tensile load (NCTL) test, Pennsylvania notched test (PENT) were employed to study the SCG resistance. Tensile test, melt flow index (MFI), rheological measurements, scanning electron microscopy (SEM) were also used for characterizing the samples. The results showed that the addition of 2.5 and 5 wt% of LLDPE or uni-HDPE had no significant influence on the strain hardening modulus of bi-HDPE while adding 10 wt% of LLDPE or uni-HDPE resulted in 4.3 to 12.2% reduction in SHM. The blends prepared with the single screw extruder showed more deterioration in the SHM values of the final blends compared to those prepared in the internal mixer. NCTL and PENT confirmed the trend of SHM results. [ABSTRACT FROM AUTHOR]

Advanced recycling offers a unique opportunity for the circular economy, especially for mixed and contaminated plastics that are difficult to recycle mechanically. However, advanced recycling has barriers such as poor selectivity, contaminant sensitivity, and the need for expensive catalysts. Reported herein is a simple yet scalable methodology for converting mixed polyethylene (high-density and low-density polyethylene recycled polyethylene) into upcycled waxes with up to 94% yield. This high yield was possible by performing the reaction at a mild temperature and was enabled by using inexpensive and reusable table salt. Without table salt, in otherwise identical conditions, the plastic remained essentially undegraded. These upcycled waxes were used as prototypes for applications such as water- and oil-resistant paper, as well as rheology modifiers for plastics. Their performance is similar to that of commercial wax as well as rheology modifiers. A preliminary economic analysis shows that the upcycled waxes obtained by this table salt-catalyzed approach offer three times more revenue than those reported in the literature. This pioneering discovery opens the door for a circular economy of plastics in general and polyolefins in particular. [ABSTRACT FROM AUTHOR]

Microplastic contamination in agricultural soil is an emerging problem worldwide as it contaminates the food chain. Therefore, this research investigated the distribution of microplastics (MPs) in agricultural soils without mulch at various depths (0–5, 5–10, and 10–15 cm) across different zones: rural, local market, industrial, coastal, and research areas. The detection of MP types and morphology was conducted using FTIR and fluorescence microscopy, respectively. Eight types of MPs were identified, including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl fluoride (PVF), polyvinyl alcohol (PVA), and polytetrafluoroethylene (PTFE), with concentrations ranging from 0.6 ± 0.21 to 3.71 ± 2.36 MPs/g of soil. The study found no significant trends in MP concentration, with ranges of 0–2.1 ± 0.38, 0–2.87 ± 0.55, and 0–2.0 ± 0.34 MPs/g of soil at depths of 0–5 cm, 5–10 cm, and 10–15 cm, respectively. The highest MP quantity was recorded at 8.67 in coastal area, while the lowest was 6.44 in the local market area. Various MP shapes, e.g., fiber, film, pellet, fragment, and irregular, were observed across all layers. PCA suggested irrigation and organic manure as potential sources of MPs. The estimated concentrations of MPs possessed low non-carcinogenic and carcinogenic risks to the farming community of Bangladesh. [ABSTRACT FROM AUTHOR]

Several researchers are investigating the polymer nanocomposite usage as electrical insulating materials since it has attracted their attention. The aims are to determine an appropriate nanocomposite blending for the optimization of the dielectric insulation performance. Extruding is one of the main process in blending the composite material. The ideal blends with mixed nanofillers are determined using a conventional technique like the one-factor-at-a-time (OFAT) method. This traditional method required a large number of samples to achieve the blended optimization that could increase the time and cost. In this work, Design of Experiment (DOE) method was used to find the optimization of compounding process using The Two-Level Factorial. The new insulation material contains linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) blends with aluminium oxide (Al2O3) nanofillers being tested in this study. The research on employing compounding polymer-based nanocomposite as a high voltage direct current (HVDC) cable insulating material is presented. In this research, the sample is compounded with twin screw extruder that need 3 factors to be set which are: the concentration of the material, rotation per minute of screw speed and the temperature of the machine. The conductivity of the blended samples is measured and analyzed. The crystallinity of the samples also being tested to see the effect of the compounding process. Trough the DOE approach, eight samples are required to be produced to find the optimization in compounding process. The results found that there is enhancement in the conductivity and performance of the samples by optimizing the concentrations of nanofillers to the LLDPE/HDPE-Nanocomposite. This saves a great deal of time and money in contrast to the command approach, which is a one-of-the-time (OFAT) method. Weightage has the most noticeable impact on the sample's conductivity, as shown by the DOE results, which show a percentage contribution of 73.67%. The response surface plot indicates that the optimal weightage concentration and temperature for the LLDPE/HDPE-Alumina that yields the lowest conductivity level are 5wt% and 180OC, respectively. It can be concluded that DOE is a feasible alternative to determine the optimum processing condition using twin screw extruder in sampling the compounding of LLDPE/HDPE-Alumina, which in turn, helps improve the conductivity of these polymer nanocomposite with the low conductivity value. [ABSTRACT FROM AUTHOR]

Microplastic has emerged as a global threat owing to its chronic ubiquity and persistence. Microplastics' small size expedites their ingestion at each trophic level causing biomagnification and bioaccumulation, which has raised public concerns. The present study isolated, quantified and characterized the abundance, shape, size, color, and chemical composition of the microplastics from water and sediments of the Hirakud Reservoir through a scanning electron microscope and FTIR. The ecological risk associated with the microplastics was assessed using the species sensitivity distribution (SSD) method to derive the Predicted No-Effect Concentration (PNEC) value and risk quotient (RQ). The abundance of microplastics in the surface water and sediments of the Hirakud Reservoir was estimated at 82-89 particles/L and 159-163 particles/kg, respectively. Fiber-shaped microplastics dominated both surface water (46.21%) and sediment samples (44.86%). Small-sized microplastics (53-300 μm) prevailed in all samples. Color delineation exhibited an abundance of transparent microplastics. Chemical characterization indicated the dominance of polypropylene (38%), followed by high-density polyethylene, low-density polyethylene, and polystyrene. The calculated PNEC value was 3,954 particles/m³, and the RQ was estimated to be 0.02073-0.04122 indicating negligible ecological risk to freshwater species in all the sampling sites. [ABSTRACT FROM AUTHOR]

Background: Plastics pollution and antimicrobial resistance (AMR) are two major environmental threats, but potential connections between plastic associated biofilms, the 'plastisphere', and dissemination of AMR genes are not well explored. Results: We conducted mesocosm experiments tracking microbial community changes on plastic surfaces transitioning from wastewater effluent to marine environments over 16 weeks. Commonly used plastics, polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE) and polyethylene terephthalate (PET) incubated in wastewater effluent, river water, estuarine water, and in the seawater for 16 weeks, were analysed via 16S rRNA gene amplicon and shotgun metagenome sequencing. Within one week, plastic-colonizing communities shifted from wastewater effluent-associated microorganisms to marine taxa, some members of which (e.g. Oleibacter-Thalassolituus and Sphingomonas spp., on PET, Alcanivoracaceae on PET and PP, or Oleiphilaceae, on all polymers), were selectively enriched from levels undetectable in the starting communities. Remarkably, microbial biofilms were also susceptible to parasitism, with Saprospiraceae feeding on biofilms at late colonisation stages (from week 6 onwards), while Bdellovibrionaceae were prominently present on HDPE from week 2 and LDPE from day 1. Relative AMR gene abundance declined over time, and plastics did not become enriched for key AMR genes after wastewater exposure. Conclusion: Although some resistance genes occurred during the mesocosm transition on plastic substrata, those originated from the seawater organisms. Overall, plastic surfaces incubated in wastewater did not act as hotspots for AMR proliferation in simulated marine environments. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of storage conditions “relative humidity”, “temperature” and “light”, each one at two levels (high and low), on the weight and color of dried seedless barberry after 120 days' storage . The effect of conditions was statistically analyzed in a completely randomized design experiment based on factorial . After adjusting the moisture content barberry color were measured for both samples. The samples in weights of 100g in the bags made of low density polyethylene (LDPE), high density polyethylene (HDPE) and polypropylene cast (CPP) were packaged and coded. Then samples were placed in a given storage conditions. Based on the results, all the hue angle and a/b ratio have not changed in all the packaging samples of films in the condition of “high relative humidity, low temperature and darkness” and “high relative humidity, low temperature and brightness” after 120 days of storage . The lowest difference in weight was observed in both samples packaged in bags of LDPE and HDPE films, at the same conditions . Also, in all the packaging samples at the “high relative humidity × low temperature” state, the lowest hue angle, lowest chroma and highest a/b ratio were observed, whilst at the similar state, the lowest difference in weight in samples packaged in polypropylene cast film bags was observed. [ABSTRACT FROM AUTHOR]

The aim of the study is to understand and achieve storage stable, compatible plastic-modified asphalt binders. In view of global plastic accumulation, the potentiality of polymeric waste plastics is evaluated as an asphalt binder modifier; providing an alternate recycling option. However, due to phase separation issues between asphalt and plastic, the usage of waste plastic is preferred through dry mixing in asphalt mixture. In this study, the compatibility of polyethylene-modified asphalt binder was assessed along with appropriate parameters that can explain the actual phase separation occurring during storage stability testing. Two types of plastics including low-density polyethylene (LDPE) and high-density polyethylene (HDPE) were blended with a PG 58-28 neat binder after assessing their melting behavior along with polystyrene (PS) and polyethylene terephthalate (PET). The impacts of polyethylene size (2.36–1.18 mm, 0.6–0.3 mm, less than 0.3 mm), blending time (30, 60, 120, 180 min), hot storage duration (0, 24, 48 h), and compatibilizers (styrene-butadiene-styrene, nanosilica, corn oil, polyphosphoric acid) on the storage stability were assessed. G*/Sinδ was used as an initial measure to assess the separation index (SI) value. The results concluded that polyethylene is observed to be inert to asphalt and phase separation persists irrespective of size and compatibilizer. Nanosilica at a dosage of 0.5% was able to partially compatibilize (SI value improved from 5.4 to 1.87) PE with asphalt. Also, in the need for better parameters to better understand the phase separation, percentage recovery, fluorescence microscopy, and black space analysis were identified as proper tests to detect phase separation. [ABSTRACT FROM AUTHOR]

The article considers the possibility of involving in the technological production of commercial greases, secondary polymeric raw materials represented by such polyolefins as high and low density polyethylene (LDPE and HDPE) and polypropylene (PP). The results of laboratory studies of the obtained greases samples are presented. On the basis of the obtained results, a scheme for the production of greases is proposed, in which the stage of dispersion of components is realised by boiling the polymer in the base oil. The proposed scheme makes it possible to reduce the degree of grinding of polymer raw materials, which reduces energy consumption and the duration of preliminary preparation of the polymer thickener. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are globally observed in marine as well as freshwater habitats, and laboratory studies have shown that marine organisms can accidentally ingest them. Monitoring the MP ingestion by fish in the environment is very crucial for understanding the risk of consuming MP-contaminated fish for human health. In this study, we investigated MP ingestion in 400 fish individuals from the Veraval Coast, in the state of Gujarat, India. There was 100% MP occurrence in the inedible tissues of fish, and 68% of the analyzed fishes presented MPs in edible tissues. The most dominant MPs based on their size in fishes were 0.05–0.1 mm. One hundred percent presence of only fibres in edible tissue was observed, while in inedible tissue, it was 77%, 20.42% and 2.58% of fibre, fragment and film respectively. The most common MP colour was blue. The predominant polymers were low-density polyethylene (LDPE) followed by polypropylene, high-density polyethylene (HDPE) and polystyrene. This is the first study performed on MPs in marine fishes from this region. Our findings suggest that the abundance of MPs observed in this area is higher than in other states of the country. [ABSTRACT FROM AUTHOR]

The research examined the ability of each treatment to recover a known quantity of particles and the impact on identifying polymer type using a microscope. By conducting extensive research on the changes induced in the chemical structures and morphologies of microplastics (MPs) there is potential for enhancing the detection and analysis of MPs by incorporating pre-treatment methods in the future. When treating environmental matrices with high organic content, chemical digestion treatment is required to get rid of microplastics and release particles. This type of treatment involves using a range of chemical agents, including acids, bases, and oxidizing agents. Unfortunately, there has been limited research into the chemical resistance of various types of microplastics to these substances. To address this issue, a study was conducted to examine the chemical resistance of four species of microplastics high-density polyethylene (HD-PE), low-density polyethylene (LD-PE), polypropylene (PP) and polyethylene terephthalate (PET) to hydrogen peroxide (H2O2), potassium hydroxide (KOH), nitric acid (HNO3) and acetic acid (CH3COOH). The results showed that acidic and alkaline substances were the most destructive to microplastics, while oxidative reagents resulted in fewer changes to plastic properties. These findings provide valuable insights into the properties of MPs and their response to strong acids, bases and oxidizing agents, which can serve as a reference for future studies on MP pre-treatment. In addition, used as a guideline to update current protocols and ensure that microplastics can be treated without causing damage. Highlights: The purpose of this study was to investigate the effects of different chemical digestion protocols, including acidic, oxidative, and alkaline reagents, on the physical and chemical properties of microplastics. Before processing and analyzing samples, it is critical to assess chemical digestion protocols to ensure that microplastics are recovered optimally. Based on the observations of different types of microplastics and methods tested, oxidative digestion at room temperature (20–23 °C) appears to be the most appropriate for digestion, but it can be destructive over an extended period. Selective processing conditions that eliminate certain materials may result in incomplete assessments of the occurrence, types, sources, and impacts of microplastics. The properties related to digestion can vary depending on the polymer type, so further research is needed on the specific polymer types relevant to each study. [ABSTRACT FROM AUTHOR]

The insulation layer of deep-sea optoelectronic composite cables in direct contact with high-pressure and highly corrosive seawater is required for excellent water resistance, environmental stress cracking resistance (ESCR), and the ability to withstand high DC voltage. Although high-density polyethylene (HDPE) displays remarkable water resistance, it lacks sufficient resistance to environmental stress cracking (ESCR). This article is based on a blend modification approach to mixing HDPE with different vinyl copolymer materials (cPE-A and cPE-B). The processing performance and mechanical properties of the materials are evaluated through rheological and mechanical testing. The materials' durability in working environments is assessed through ESCR tests and water resistance experiments. Ultimately, the direct current electrical performance of the materials is evaluated through tests measuring space charge distribution, direct current resistivity, and direct current breakdown strength. The results indicate that, in the polyethylene blend system, the rheological properties and ESCR characteristics of HDPE/cPE-A composite materials did not show significant improvement. Further incorporation of high melt index linear low-density polyethylene (LLDPE) material not only meets the requirements of extrusion processing but also exhibits a notable enhancement in ESCR performance. Meanwhile, copolymerized polyethylene cPE-B, with a more complex structure, proves effective in toughening HDPE materials. The material's hardness significantly decreases, and when incorporating cPE-B at a level exceeding 20 phr, the composite materials achieve excellent ESCR performance. In a simulated seawater environment at 50 MPa, the water permeability of all co-modified composite materials remained below 0.16% after 120 h. The spatial charge distribution and direct current resistivity characteristics of the HDPE, cPE-A, and LLDPE composite systems surpassed those of the HDPE/cPE-B materials. However, the HDPE/cPE-B composite system exhibited superior dielectric strength. The application of composite materials in deep-sea electro–optical composite cables is highly promising. [ABSTRACT FROM AUTHOR]

Development of biobased aliphatic polyesters with better mechanical (tensile) properties in film has attracted considerable attention. This report presents the synthesis of soluble network biobased aliphatic polyesters by acyclic diene metathesis (ADMET) polymerization of bis(undec-10-enyl)isosorbide diester [M1, dianhydro-D-glucityl bis(undec-10-enoate)] in the presence of a tri-arm crosslinker [CL, glycerol tris(undec-10-enoate)] using a ruthenium–carbene catalyst, and subsequent olefin hydrogenation using RhCl(PPh3)3. The resultant polymers, after hydrogenation (expressed as HCP1) and prepared in the presence of 1.0 mol% CL, showed better tensile properties than the linear polymer (HP1) with similar molecular weight [tensile strength (elongation at break): 20.8 MPa (282%) in HP1 vs. 35.4 MPa (572%) in HCP1]. It turned out that the polymer films prepared by the addition of CL during the polymerization (expressed as a 2-step approach) showed better tensile properties. The resultant polymer film also shows better tensile properties than the conventional polyolefins such as linear high density polyethylene, polypropylene, and low density polyethylene. [ABSTRACT FROM AUTHOR]

The aging of microplastics (MPs) due to environmental abiotic effects in diverse habitats, which might negatively affect the environment and human health, is a rising issue. The major concern is the release of additives and plasticizers and their fragmentation into nanoplastics which are more harmful due to their larger surface area. The virgin MPs (low-density polyethylene, polyethylene, polystyrene, polyethylene terephthalate, high-density polyethylene, and polypropylene) were kept for natural aging in indoor and outdoor environments for one year. They showed morphological changes like racks, broken edges, ridges, grooves, and rough and uneven surfaces. It was also discovered that MPs had lost weight. The highest weight reduction in outdoor MPs was recorded in polypropylene (18.52%), with the least weight loss in polyethylene (0.69%). The highest weight loss in indoor MPs was seen in low-density polyethylene (6.54%), while the lowest was for polyethylene terephthalate (0.04%). Change in the chemical composition in these virgin MPs also showed the formation of additional peaks or the disappearance of some main peaks, like in high-density polyethylene additional peak was found at 2345.44 cm−1. In polystyrene, CH bending peak, CH2 bending peak, aromatic ring stretching peak, C–H stretching at 2847 cm−1, and aromatic C–H stretching were not seen. In polypropylene, the CH2 twisting and rocking peaks were not found. In polyethylene, the additional peak was found at 871.82 cm−1. The morphological and chemical alterations in the MPs can enhance the possibility of bioaccumulation, alter their capacity to adsorb chemicals and make them more harmful. [ABSTRACT FROM AUTHOR]

Riparian areas are highly dynamic bio-geophysical settings with a surge of waste deposition predominantly including land-based plastic discards. These polymer discards are destined to be the prime constitution of marine "plastisphere." The polymer fate is determined by waterbodies, where the chances of plastic retention are higher, eventually mediating the formation of microplastics (MPs) in years or decades. Such formed MPs are a potential threat to the aqua bio-regime. A systematic investigation of three waterbody basin soils (Karamana River, Killiyar, and Akkulam-Veli Lake) showed the presence of MPs in all the samples analyzed with varying sizes, shapes, colors, and compositions. MPs of the shapes flakes, fragments, filaments, sheets, foams, and fibers were observed with dimensions 0.3–4.7 mm. Most of the particles were white in hue (WT), followed by colorless (CL), light yellow (L.Y), light brown (L.B), orange (OR), red (RD), and blue (BL), respectively. The polymer communities were identified as high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), and nylon. The highest average MP density was identified in the basin of Killiyar (799 ± 0.09 pieces/kg) followed by Karamana River (671 ± 3.45 pieces/kg), indicating the closeness of the sampling station to the city center compared to Akkulam-Veli Lake (486 ± 58.55 pieces/kg). The majority of the sampling sites belonged to the slopy areas and came under the highly urbanized land category. A close association was observed between particle abundance and urban activity. The study foresees possible threats inflicted by MP abundance upon the area-wide hydro-biological system. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the physical characteristics and chemical composition of microplastics in sediments of the Vaal River, South Africa. Microplastics were detected in all samples, with abundance ranging from 29.12 to 1095.89 particles/kg dw. The physical identification of microplastics revealed dominance of small-sized particles of less than 0.5 mm, which accounted for 31.75% of the total microplastics detected in all samples. Fragments and fibres were significantly abundant compared to pellets, representing 63% and 35%, respectively. Microplastics were observed in different colours, among which blue, white and green were the most dominant. Raman analyses of microplastics showed the presence of high density polyethylene, low density polyethylene, polyurethane foam, polypropylene, polyethylene co-vinyl acetate, and poly(ethylene-co-1-hexene). Additionally, two pigments (vine black and smalt), one dye (saffron), three minerals (orthoclase, carbon, and microcline), and one additive (cis-13-docosanol) were also identified. The dominance of fragments and fibres, with the clear signs of fragmentation implied that microplastics in the Vaal River are mostly from secondary sources. The study reported the first data on microplastic pollution and characteristics in sediments of the Vaal River, thus, providing a benchmark and reference platform for relevant formulation and decision-making regarding this essential water source. [ABSTRACT FROM AUTHOR]

Many polymers are processed and compounded in co‐rotating, fully intermeshing twin screw extruders. A typical compounding process consists of multiple unit operations including feed introduction, solids transport, transitioning from the conveying zone to the kneading block melting zone, melting, a downstream feed zone, a mixing zone, a devolatilization region, and a pressure generating discharge section. This paper will focus on the kneading block melting zone which typically includes a reverse pitch element so the kneaders remain full. Mechanisms for flow and energy input to pellets in kneading elements, including friction heating, pellet compression, energy diffusion, and viscous dissipation to form a melt phase: followed by viscous dissipation in a solid pellet/melt slurry, and heat transfer; are developed and implemented in a novel melting model. The model is validated with extrusion measurements and visualizations using low density polyethylene (LDPE). The predictions of the model are also compared with a classical set of experiments using high density polyethylene (HDPE). This paper describes the physics and engineering concepts that the authors feel are inherent in the melting section of the twin screw extruder where a large pressure peak is calculated using the friction and compression of the polymer pellets. The modeled increase in pellet bulk/surface temperature is due to the inclusion of four energy sources, pellet compression, thermal diffusion, friction energy dissipation, and viscous energy dissipation. This combined thermal dynamics based melting model results in a novel melting protocol. The melting mechanisms are coupled to flow regimes in the kneading blocks as melting progresses. The effects of throughput, Q, and screw rotation speed, N, are also examined. Highlights: Novel 2.5D melting model for corotating, intermeshing twin‐screw extruders.Energy for melting; friction, deformation, diffusion, and viscous dissipation.The model helps elucidate mechanisms during melting in a twin‐screw extruder. [ABSTRACT FROM AUTHOR]

The in-series connections of multi-pipes involving steel and polymeric materials were identified as being an effective design tool to extenuate water-hammer surges induced into an existing steel-main pipe-based hydraulic system. Although this design measure significantly reduced the magnitude of pressure-wave surges, it was limited by the expansion of the period of pressure-wave oscillations. This study addressed a holistical exploration and comparison of the effectiveness of the in-series connections of multi-pipes design measure used to control water-hammer surges into an existing steel water distribution piping systems. The extended one-dimensional water-hammer model, including the Vitkovsky and Kelvin-Voigt formulations, was developed to describe the transient flow, together with the Method of Characteristics implemented for numerical computations. The comparison of the numerical solution with observed data, quoted in the literature, and the alternative numerical solution demonstrated the accuracy of the developed solver. The test case appraised the capability of a variety of in-series setups of steel and plastic main-pipes for a reservoir-pipe-valve – based hydraulic system. The high- and low-density polyethylene (HDPE and LDPE) plastic material types were considered in this investigation. Results showed that the hydraulic system setup built upon an (LDPE-steel-LDPE) provided a satisfactory tradeoff between the dampening of pressure-wave magnitude and the expansion of the period of pressure-wave oscillations [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis of waste HDPE and LDPE polyethylene was successfully carried out using a silica-alumina catalyst at 450 °C under N2 atmosphere. The synthesized silica-alumina is mesoporous and shows type IV isotherm. Thermal pyrolysis (without any catalyst) provided 47% waxlike hydrocarbons at 485 °C. On the other hand, more than 80% liquid yield was achieved using silica-alumina catalysts from waste HDPE and LDPE. The highest liquid yield was obtained from LDPE (87.69%) than HDPE (83.25%) at a catalyst-to-plastic ratio of 1:25. The 1H NMR shows that the liquid product does not contain any aromatic compound. The GCMS, 1H NMR, and FTIR confirmed that the liquid contains linear and branched alkanes and alkenes. [ABSTRACT FROM AUTHOR]

Marine plastic pollution is a major concern worldwide, but the understanding of plastisphere dynamics remains limited in the southern hemisphere. To address this knowledge gap, we conducted a study in South Australia to investigate the prokaryotic community of the plastisphere and its temporal changes over 4 weeks. We submerged six plastic types (i.e., High‐Density Polyethylene [HDPE], Polyvinyl chloride [PVC], Low‐Density Polyethylene [LDPE], Polypropylene [PP], Polystyrene [PS] and the understudied textile, polyester [PET]) and wood in seawater and sampled them weekly to characterize the prokaryotic community using 16S rRNA gene metabarcoding. Our results showed that the plastisphere composition shifted significantly over short time scales (i.e., 4 weeks), and each plastic type had distinct groups of unique genera. In particular, the PVC plastisphere was dominated by Cellvibrionaceae taxa, distinguishing it from other plastics. Additionally, the textile polyester, which is rarely studied in plastisphere research, supported the growth of a unique group of 25 prokaryotic genera (which included the potential pathogenic Legionella genus). Overall, this study provides valuable insights into the colonization dynamics of the plastisphere over short time scales and contributes to narrowing the research gap on the southern hemisphere plastisphere. [ABSTRACT FROM AUTHOR]

Safety concerns pertaining to PAHs occurrence in agri-food commodities have been a source of great concern. Concerns have been expressed about offering additional insights on screening agri-food commodities to benefit consumers, as evidence-based study knowledge on the health risks posed by ingestion of PAHs-contaminated food by people has increased. According to research, the majority of edible oil-yielding seeds are contaminated with PAHs. These toxins of PAHs can enter the human food chain through the consumption of edible oils. At present, the control of PAHs is mainly through the optimization of the production process, and the specificity is not strong. PAHs' contamination levels varied in different edible oils depending on the type of oil, production process and oilseeds' storage conditions. In this overview, we have decisively assessed the existing data on PAH incidence, main sources, and decontamination in assorted edible oils. This review seeks to provide a comprehensive overview of existing and emerging methods/technologies for PAH determination and elimination, in order to bridge information gaps toward ensuring a green and sustainable remedial approach for PAH-contaminated in edible plant-based oils. This work summarizes the very recently published works of the last years. Abbreviations: PAHs, Polycyclic aromatic hydrocarbons; HPAHs, high Polycyclic aromatic hydrocarbons; LPAHs, low Polycyclic aromatic hydrocarbons; Nap, naphthalene; Acy, acenaphthylene; Ace, acenaphthene; Flu, fluorine; Phe, phenanthrene; Ant, anthracene; Flt, fluoranthene; Pyr, pyrene; BaA, benz[a]anthracene; Chr, chrysene; BbF, benzo[b]fluoranthene; BkF, benzo[k]flouranthene; BaP, benzo[a]pyrene; DahA, dibenz[a,h]anthracene; BghiP, benzo[g,h,i] perylene; IcdP, indeno[1,2,3-cd]pyrene; 5MC, 5-methylchrysene; BjF, benzo[j]fluoranthene; DBaiP, dibenzo[a,i]pyrene; DalP, dibenzo[a,l]pyrene; DaeP, dibenzo[a,e]pyrene; DahP, dibenzo[a,h]pyrene; GC, gas chromatography; FLD, fluorescence detector; MS, mass spectrometry; SPE, solid-phase extraction; HACA, hydrogen abstraction acetylene addition; SPMD, short path molecular distillation; TP, tocopherol; TBHQ, tert-butyl hydroquinone; PET, polyethylene, HDPE, high-density polyethylene; LDPE, low-density polyethylene. [ABSTRACT FROM AUTHOR]

Microplastic pollution has become a global concern, with potential negative impacts on various ecosystems and wildlife species. Among these species, ducks (Anas platyrhynchos) are particularly vulnerable due to their feeding habits and proximity to aquatic environments contaminated with microplastics. The current study was designed to monitor microplastic (MP) pollutants in the freshwater ecosystem of the Panjkora River, Lower Dir, Pakistan. A total of twenty (20) duck samples were brought up for four months and 13 days on the banks of the river, with no food intake outside the river. When they reached an average weight of 2.41 ± 0.53 kg, all samples were sacrificed, dissected, and transported in an ice box to the laboratory for further analysis. After sample preparation, such as digestion with 10% potassium hydroxide (KOH), density separation, filtration, and identification, the MP content was counted. A total of 2033 MP particles were recovered from 20 ducks with a mean value of 44.6 ± 15.8 MPs/crop and 57.05 ± 18.7 MPs/gizzard. MPs detected in surface water were 31.2 ± 15.5 MPs/L. The major shape types of MPs recovered were fragments in crop (67%) and gizzard (58%) samples and fibers in surface water (56%). Other types of particles recovered were fibers, sheets, and foams. The majority of these detected MP particles were in the size range of 300–500 µm (63%) in crops, and 50–150 µm (55%) in gizzards, while in water samples the most detected particles were in the range of 150–300 µm (61%). Chemical characterization by FTIR found six types of polymers. Low-density polyethylene (LDPE) had the greatest polymer detection rate (39.2%), followed by polyvinyl chloride (PVC) (28.3%), high-density polyethylene (HDPE) (22.7%), polystyrene (6.6%), co-polymerized polypropylene (2.5%), and polypropylene homopolymer (0.7%). This study investigated the presence of microplastics in the crops and gizzards of ducks, as well as in river surface water. The results revealed the significant and pervasive occurrence of microplastics in both the avian digestive systems and the surrounding water environment. These findings highlight the potential threat of microplastic pollution to wildlife and ecosystems, emphasizing the need for further research and effective mitigation strategies to address this pressing environmental concern. [ABSTRACT FROM AUTHOR]

This paper aims to examine physical and mechanical performances of a Reclaimed asphalt pavement (RAP) material reinforced with 5 to 15 mm size sheets of plastic waste. The three types of plastic used in the study are: low density polyethylene (LDPE), high density polyethylene (HDPE) and polyethylene terephthalate (PET) with 1%, 1.5%, and 2% dosage by weight of aggregates. Obtained Duriez test results testify to a 9% to 30% improvement in moisture resistance for all types of plastic compared to virgin mixture while for LDPE waste plastic type workability test attests an acceptable compaction condition for RAP material with less than 1.5% of waste plastic. Nevertheless, it has been noticed an increase in void index and compaction difficulties starting from 1.5% dosage, resistance to rutting has also improved with the addition of waste plastic, an improvement in fatigue strength was also observed particularly at 2% dosage. [ABSTRACT FROM AUTHOR]

The blue crab Callinectes sapidus Rathbun, 1896 is native to the western coasts of the Atlantic Ocean and is currently considered an invasive species in the Mediterranean Sea. In this study, we examined the stomach contents of C. sapidus to determine the frequency of occurrence of microplastics (MPs) and microfibers (MFs) in the Balearic Islands archipelago in the western Mediterranean Sea. A total of 120 individuals were collected from six locations between 2017 and 2020. Overall, 65.8% of the individuals had MPs and/or MFs particles with an average of 1.4 ± 1.6 particles ind.−1 of which an average of 1.0 ± 1.3 items ind.−1 were MFs and an average of 0.4 ± 0.8 items ind.−1 were MPs. In terms of type, fragments were the dominant type of MPs and the most common size of items ranged from between 0.5 and 1 mm (40%) followed by 1–5 mm (31%). The most prevalent polymers were low-density polyethylene (39%) and high-density polyethylene (26%). In terms of links to human activities, MP ingestion was positively correlated with an increase in drain pipes, whereas MF ingestion was positively correlated with an increase in sewage pipelines, providing evidence of potential sources and the bioavailability of these particles in various environments. This study confirms the widespread presence of MP and MF particles, even in areas that are currently managed under different protection statuses, in the stomach contents of invasive blue crab species throughout coastal communities. [ABSTRACT FROM AUTHOR]

This study investigates the antimicrobial effectiveness of 405 nm light emitting diodes (LEDs) against pathogenic Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, and Staphylococcus aureus, in thin liquid films (TLF) and on solid surfaces. Stainless steel (SS), high density polyethylene (HDPE), low density polyethylene (LDPE), and borosilicate glass were used as materials typically encountered in food processing, food service, and clinical environments. Anodic aluminum oxide (AAO) coupons with nanoscale topography were used, to evaluate the effect of topography on inactivation. The impact of surface roughness, hydrophobicity, and reflectivity on inactivation was assessed. A 48 h exposure to 405 nm led to reductions ranging from 1.3 (E. coli) to 5.7 (S. aureus) log CFU in TLF and 3.1 to 6.3 log CFU on different solid contact surfaces and packaging materials. All inactivation curves were nonlinear and followed Weibull kinetics, with better inactivation predictions on surfaces (0.89 ≤ R2 ≤ 1.0) compared to TLF (0.76 ≤ R2 ≤ 0.99). The fastest inactivation rate was observed on small nanopore AAO coupons inoculated with L. monocytogenes and S. aureus, indicating inactivation enhancing potential of these surfaces. These results demonstrate significant promise of 405 nm LEDs for antimicrobial applications in food processing and handling and the healthcare industry. [ABSTRACT FROM AUTHOR]

As a lifestyle habit, shoppers like to lick their fingers before opening the polyethylene (PE) shopping bag. In fact, this implies a scientific problem, that is, moisture has an impact on the friction behavior between the plastic bag and the surface of the finger skin. In this study, an experimental method was employed to measure skin friction at three different hydration levels. The high-density polyethylene (HDPE) and low-density polyethylene (LDPE) materials were performed, and photographs of fingertips touching PE films were recorded by a camera. The experimental results showed that the applied normal load is positively correlated with the friction force and negatively correlated with the friction coefficient. And moisture content will increase friction. Specifically, when the fingertip slides on the HDPE film, the friction coefficient of the water-soaked skin is 5.9 times that of the dry skin. It can be inferred that the decrease in modulus of elasticity, as well as volume expansion, leads to an increase in contact area when the skin is wetted with water. This is the main reason for the increase in finger friction. In addition, a negative power function model was established to describe the relationship between the coefficient and the friction conditions by considering the combined effects of hydration level, normal load and material. Abbreviations: CCD: Charge-coupled Device; COF: Coefficient of friction; HbA1C: Hemoglobin A1C; HDPE: High-density polyethylene; LDPE: Low-density polyethylene; PE: Polyethylene; SC: Stratum corneum; [ABSTRACT FROM AUTHOR]

Featured Application: This work is of particular interest in the design of products widely used in daily life, such as HDPE and LLDPE blend plastic bags. The aim of this study is to analyze how the main process parameters (BUR, TUR, and TR) affect the mechanical properties of this type of product, helping designers to adapt the production to customers' new requirements while maintaining the product properties. All the samples were manufactured on an industrial scale. The results are beneficial so that the highest tensile and impact properties can be obtained through minimal changes in the already mentioned process parameters, thus also reducing the amount of waste due to products manufactured outside the specification limits. Polyethylene plastic bags manufactured via blown film extrusion have different quality specifications depending on their intended use. It is known that the mechanical properties of a film depend on the process parameters established, but little is known concerning how they affect one another, even more so due to the variety of polyethylene materials and processing techniques. This study focuses on establishing a proper correspondence of important mechanical properties like the dart impact, tensile strength at break, and elongation at break with commonly used process parameters like the blow-up ratio, take-up ratio, thickness reduction, and neck height, for a high-density polyethylene hexene copolymer and a linear low-density polyethylene butene copolymer blend film. Because this polyethylene mixture is an anisotropic material, interesting R2 values equal to or higher than 0.90 were found: a BUR with elongation at break and tensile strength at break in the MD and TD, a TUR with elongation at break in the MD and tensile strength at break in the MD and TD, and a TR with elongation at break and tensile strength at break in the MD. Also, a relationship between the dart impact and both the neck height and thickness were found. [ABSTRACT FROM AUTHOR]

Polyethylenes endowed with low densities of in‐chain hydrolyzable and photocleavable groups can improve their circularity and potentially reduce their environmental persistency. We show with model polymers derived from acyclic diene metathesis polymerization that the simultaneous presence of both groups has no adverse effect on the polyethylene crystal structure and thermal properties. Post‐polymerization Baeyer–Villiger oxidation of keto‐polyethylenes from non‐alternating catalytic ethylene‐CO chain growth copolymerization yield high molecular weight in‐chain keto‐ester polyethylenes (Mn≈50.000 g mol−1). Oxidation can proceed without chain scission and consequently the desirable materials properties of HDPE are retained. At the same time we demonstrate the suitability of the in‐chain ester groups for chemical recycling by methanolysis, and show that photolytic degradation by extended exposure to simulated sunlight occurs via the keto groups. [ABSTRACT FROM AUTHOR]

In this research, a self-reinforced composite material was manufactured using a single polyethylene material, and this self-reinforced composite material has excellent recyclability and is environmentally friendly compared to composite materials composed of other types of material, such as glass fiber reinforced composites (GFRP) and carbon fiber reinforced composites (CFRP). In this research, the manufactured self-reinforced composite material consists of an outer layer and an inner layer. To manufacture the outer layer, low density polyethylene (LDPE) films were laminated on high density polyethylene (HDPE) fabrics and knitted fabrics, and composite materials were prepared at various temperatures using hot stamping. A 3D printing process was utilized to manufacture the inner layer. After designing a structure with a cross-sectional shape of a triangle, circle, or hexagon, the inner layer structure was manufactured by 3D printing high-density polyethylene material. As an adhesive film for bonding the outer layer and the inner layer, a polyethylene-based self-reinforced composite material was prepared using a low-density polyethylene material. Input data for simulation of self-reinforced composite materials were obtained through tensile property analysis using a universal testing machine (UTM, Shimadzu, Kyoto, Japan), and the physical property values derived as output data and actual experimental values were obtained. As a result of the comparison, the error rate between simulation data and experimental data was 5.4% when the shape of the inner layer of self-reinforced composite material was a hexagon, 3.6% when it was a circle, and 7.8% when a triangular shape showed the highest value. Simulation in a virtual space can reduce the time and cost required for actual research and can be important data for producing high-quality products. [ABSTRACT FROM AUTHOR]

Linear low‐density polyethylene (LLDPE) and high‐density polyethylene (HDPE) are polyolefins widely used in the packaging sector. Seeking to improve the mechanical properties with good cost‐effectiveness, attapulgite (ATP) was chosen as a reinforcing filler for the polyolefins. ATP is a hydrated magnesium and aluminum clay mineral with a microfibrous morphology, and the purity of this filler depends on the deposit. ATP is associated with the presence of accessory minerals that need to be removed so as not to interfere with its final application. Thus, an ATP purification process was carried out through physical separation and chemical treatment with hydrogen peroxide (H2O2) and sulfuric acid (H2SO4). This purification process despite having a low yield and is very effective in reducing impurities and organic matter. This ATP was named ATPa. LLDPE/ATPa and HDPE/ATPa nanocomposites with the addition of 1, 3, and 5 wt% of ATPa were prepared by extrusion and hot pressing. The mechanical properties (Shore D hardness, tensile tests, and Izod impact strength), thermal properties (differential scanning calorimetry—DSC and thermogravimetric analysis—TGA), X‐ray diffraction, rheological, and transmission scanning microscopy (TEM) were determined for these nanocomposites. The mechanical properties of the nanocomposites increased with the addition of ATPa. HDPE/ATPa nanocomposites showed more promise than LLDPE/ATPa nanocomposites. The addition of 5 wt% ATPa increased the tensile strength by 14% for the HDPE matrix and 5% for the LLDPE matrix and increased the elastic modulus by 46% for HDPE and 26% for LLDPE. [ABSTRACT FROM AUTHOR]

Radiation cross-linked low-density polyethylene (LDPE)/high-density polyethylene (HDPE) foams containing 30 wt% high-density polyethylene (HDPE) were further modified with different weight ratios (0, 4, 8, 12, and 16 wt%) of modified calcium sulfate whiskers (mCSW). The effects of mCSW content were investigated regarding the chemical structure, rheological structure, crystallization behavior, thermal stability, heat conductivity, cellular structure, and mechanical properties of the resulting LDPE/ HDPE/mCSW foams. Consequently, the successfully synthesized mCSW could serve as the reinforcing filler and nucleating agent to improve the crystallization temperature, thermal stability, and mechanical properties of LDPE/HDPE/mCSW foams. The presence of mCSW influenced the LDPE/HDPE phase separation, which provided good interfacial compatibility and adhesion properties between the mCSW and the LDPE/HDPE matrix. In this case, the addition of 8 wt% mCSW increased the impact strength from 2.2 to 3.2 kJ m-2 by B45.5% relative to the LDPE/HDPE foam. Similarly, the 8 wt% mCSWreinforced LDPE/HDPE/mCSW foam produced homogeneous cellular structures and showed a considerable compressive strength of 239 KPa. Furthermore, the thermal stability of the LDPE/HDPE/ mCSW foams also increased with increasing mCSW loading. [ABSTRACT FROM AUTHOR]

The durability of five 1.5-mm thick geomembranes (GMBs) is investigated in pH 0.5 and 13.5 synthetic mining solutions using immersion tests. Two high density polyethylene (HDPE), two linear low density polyethylene (LLDPE), and one blended polyethylene (BPO) GMBs are investigated at 85 °C for incubation durations of 4.5–6.5 years. It is shown that the degradation of all five GMBs in the high pH solution is faster than in the low pH solution. In the pH 0.5 solution, one of the HDPEs and the BPO GMBs exhibited polymer degradation before or at the time of the depletion of their antioxidants. In pH 13.5, four out of the five GMBs exhibited degradation and followed the conceptual three-stage degradation model until nominal failure. However, there is no correlation between the long-term performance of these GMBs and their resin type or their initial properties since one of the examined LLDPEs outperformed all the higher density/crystallinity GMBs with higher initial properties while the other LLDPE did not perform well. Thus, when selecting a GMB for a desired application, the relative performance of different candidate GMBs can be only assessed using immersion tests using the solutions expected in the field. • First comparison of the degradation behaviour of HDPE, LLDPE, and BPO geomembranes incubated for up to 6.5 years at 85 °C. • Estimates the time to nominal failure in pH 0.5 and pH 13.5 synthetic mining solutions. • Examines the role of the stabilizers and the resin type on the longevity of five different geomembranes. • Compares the morphology of the failure surfaces after stress cracking from HDPE, LLDPE, and BPO geomembranes. [ABSTRACT FROM AUTHOR]

Electrodynamic Dust Shield (EDS) technology is a dust mitigation strategy that is commonly studied for rigid applications such as photovoltaics or thermal radiators where soiling of the surfaces can reduce performance. The goal of the current work was to test the performance of a flexible, patterned nanocomposite EDS system produced through spray-coating and melt infiltration of chemically modified reduced graphene oxide (CMrGO) traces with thermoplastic high-density polyethylene (HDPE). The EDS performance was tested for a dusting of lunar regolith simulant under high vacuum conditions (∼10−6 Torr) using both 2-phase and 3-phase device configurations. Uncapped (bare) devices showed efficient dust removal at moderate voltages (1000–3000 V) for both 2-phase and 3-phase designs. Further tests carried out while illuminating the dust surface with a UV excimer lamp showed that the EDS voltage needed to reach the maximum cleanliness was reduced by almost 50% for the 2-phase devices (500 V minimum for rough and 1000 V for smooth), while the 3-phase devices were unaffected by the application of UV. However, the performance of the uncapped devices degraded after several sequential tests due to erosion of the traces caused by electric discharges and dielectric breakdown. Capping the CMrGO traces with low-density polyethylene (LDPE) eliminated breakdown of the materials and device degradation, but larger voltages (3000 V) coupled with UV illumination were required to remove the grains from the capped devices. • Spray-coated EDS systems were produced using a conductive nanocomposite material. • 2-phase and 3-phase device configurations efficiently removed >80% of deposited dust. • The 2-phase devices were cleaned at ∼50% lower voltage when illuminated with UV light. • Using a dielectric cap eliminates electrical discharges on the surface. [ABSTRACT FROM AUTHOR]

Crystallinity and rheological behavior are significant for processing semi-crystalline polymers with fine mechanical properties. There is always an economical need to create a less expensive new material with better properties. Non-isothermal crystallization and oscillatory shear rheology of different branch-type polyethylene–polyethylene blends were investigated. Samples of high-density and low-density polyethylene (HDPE/LDPE) (20/80, 40/60, 60/40 and 80/20 weight ratios) and two types of high-density and linear low-density polyethylene (HDPE/LLDPE) (40/60 and 60/40 weight ratios) were prepared via extrusion. The materials were tested by differential scanning calorimetry (DSC) at several cooling rates (5, 10, 20, 30 and 40°/min) and by oscillation rheometry (ARES G2) at low angular frequency range to prove their miscibility or immiscibility. It was found that the one-peak melting endotherm of the 80–20% HDPE-LDPE blend could indicate miscibility in the solid phase, while the other HDPE-LDPE blends with two-peak curves are partially or not miscible. In contrast, all the HDPE-LLDPE blends indicate co-crystallization, but the 40–60% HDPE-LLDPE butylene blend is probably immiscible. It was revealed that complex viscosity decreases with angular frequency: linearly for HD-LD blends and not linearly for HD-LLDPE blends. The complex viscosity shows linear behavior with composition for HD-LLDPE blends, while there is a positive–negative deviation for HD-LD blends. In the liquid phase, according to rheological measurements, the HDPE-LDPE blends are not or partially miscible, while the HDPE-LLDPE blends are probably miscible. [ABSTRACT FROM AUTHOR]

Polyethylene (PE) is widely used as a gas-sealing material in packing films and gas transport pipes. A technique for evaluating the permeability of water-insoluble gases has recently been developed. This technique is a volumetric analysis that is used to calculate the gas permeability by measuring the gas uptake and diffusivity. With this technique, we investigated the permeability of pure gases, such as H2, He, N2, O2 and Ar, enriched under high pressure up to 9 MPa in low-density polyethylene (LDPE), ultrahigh molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE). The gas uptake showed a linear pressure-dependent behavior that followed Henry's law, and the diffusivity was independent of the pressure. Furthermore, the logarithmic diffusivity values of the five gases linearly decreased as their molecular kinetic diameters increased. The logarithmic solubility values linearly increased as the critical temperatures of the gases increased. The calculated permeability results were correlated with the volume fraction of the amorphous phase and the fractional free volume. This result newly showed that the amorphous phase was directly correlated to the fractional free volume. [ABSTRACT FROM AUTHOR]

High-density polyethylene (HDPE) geomembranes (GMs) are frequently used as fluid barrier components of cover systems for mine site reclamation in regions that are prone to freeze–thaw cycles (FTCs). However, HDPE GMs are more susceptible to stress cracking than linear low-density polyethylene (LLDPE) GMs. Hence, LLDPE GMs are increasingly considered as alternatives to HDPE GMs in cover systems. Nevertheless, little information is available on LLDPE compared to HDPE GMs. Moreover, little is known about the changes in the fluid barrier properties (the equivalent hydraulic conductivity and the oxygen sorption and diffusion coefficients) for these two materials with FTCs. The purpose of this study is therefore to compare the effects of FTCs on the tensile, hydraulic, and oxygen sorption and diffusion properties of HDPE and LLDPE GMs. To do so, GM sheets were subjected up to 300 FTCs. Mechanically, both GMs got stiffer and their tensile break properties increased with increasing number of FTCs. However, although the GM fluid barrier properties changed with FTCs, the equivalent hydraulic conductivity and the oxygen permeation coefficient remained within an order of magnitude of 10−14 m/s and 10−13 m2/s, respectively. Up to 300 FTCs would therefore have no adverse effects on HDPE and LLDPE GMs. [ABSTRACT FROM AUTHOR]

Nanometer Zinc oxide (nano ZnO) composites are widely used in the packaging industry due to their excellent antibacterial properties. In this study, low-doped (0.2%) and high-antibacterial (99.9%, R = 6.9) nano ZnO composites with different matrices were prepared using a masterbatch blending method. To investigate the effect of different matrices on antibacterial properties, we decreased the solid content of nano ZnO to 0.05% and prepared antibacterial films by melt-blending with ethylene vinyl acetate copolymer (EVA), polyolefin elastomer (POE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and amorphous polymer polycarbonate (PC). The results showed that low melt strength and high crystallinity would decrease the antibacterial activity of the composite. At room temperature, the PC with a frozen molecular chain can hinder the migration of small molecules, thereby reducing antibacterial activity. Polar ZnO is more compatible with polar vinyl acetate (VA), leading to the hindered surface migration of ZnO and reduced antibacterial activity. Most importantly, low crystallinity does not necessarily lead to a reduction in barrier properties. The dense and rich layered arrangement of polyolefin elastomer (POE) increases its ability to impede the migration of nano ZnO, thereby significantly reducing its antibacterial effectiveness. A concentration of 0.05% ZnO/linear low-density polyethylene (LLDPE) exhibited an antibacterial rate of up to 99.3%. Additionally, adding a small amount of nano ZnO improves the tear resistance of antibacterial composite materials. This study provides a theoretical basis for the preparation of low doping, high antibacterial and excellent comprehensive performance. [ABSTRACT FROM AUTHOR]

Unrestrained utilization of plastic has reached an intemperate state, menacing environment and human lives. The preliminary focus of this research was to investigate and divulge the contemporary status of microplastics (MPs) in commercialized and open pan salts from Cox's Bazar and Maheshkhali channels. A total of 27 samples were obtained. The samples were analyzed for the prevalence of MPs by FTIR and Raman spectroscopy (RS); the prevailing amount, color, size, and shapes were analyzed by stereomicroscope and SEM. The abundance of high‐density polyethylene, polyethylene terephthalate (PET), and low‐density polyethylene (LDPE) were detected by FTIR, meanwhile exuberance of cellulose acetate, polypropylene, PET, LDPE, and Nylon 6 were identified by RS. The average quantifications of MPs in Cox's Bazar, Maheshkhali, and packaged salts were found to be 6851.11 ± 538.18, 5638.89 ± 1001.18, and 3405.56 ± 638.57 per kg, respectively. ANOVA resulted in highly significant association between MPs and sampling sites (p =.001*). Post hoc Tukey's test revealed prominent link between commercialized and open pan salts based on the amount of MPs (p =.001*). The most prevalent colors were purple (28%) and blue (27%). The most frequent shapes were fibrous (79%) and fragmented (19.9%) MPs. The smallest MP was detected in commercial salt (1.55 μm), nearly identical and closer to the size of nanoplastics. [ABSTRACT FROM AUTHOR]

Microplastics have now been identified as a class of emerging pollutants and is considered as a threat to aquatic organisms. This baseline paper investigated the distribution, composition, and potential ecological risks of microplastic (MP) pollution on St. Mary's Island, revealing an average abundance of 0.218 particles/L in water samples. Blue fibres and white foams were the primary MPs identified, and fishing activities and packaging were the main sources of pollution. Six types of polymers were identified: low-density polyethylene (LDPE), polystyrene (PS), polyamide (PA), polypropylene (PP), polyethylene (PE), and high-density polyethylene (HDPE). The Polymer Hazard Index (PHI) and Potential Ecological Risk Index (PERI) indicated a medium environmental risk for the island. Additionally, it was discovered that MPs' surfaces contained dangerous substances that could endanger aquatic life. The research emphasizes the significance of implementing measures such as responsible disposal, management, elimination, regulatory policies, and local administration techniques to mitigate the impact of MP pollution on the island's shores and marine biota. This research provides a baseline for monitoring MP contamination and underscores the need for continuous investigation to assess their impacts on marine life. [ABSTRACT FROM AUTHOR]

I n the present study, the thermal oxidation behaviour of high-density polyethylene (HDPE) containing each of two types of oxidized polyethylene (OPE), one prepared using 500 ppm of iron (III) stearate as pro-oxidant and the other without the pro-oxidant, was investigated. Fourier-transform infrared spectroscopy (FTIR) showed that the carbonyl index of the HDPE increased from 1.03 to 6.37 upon the addition of 5.0 wt.% of OPE containing the pro-oxidant after 100 h of thermo-oxidative aging at 90°C. Moreover, it was observed that the rate of changes in retained tensile strength and retained elongation-at-break of the HDPE during the thermal oxidation increased in the presence of 5.0 wt.% of each type of OPE, especially, the one containing iron (III) stearate, which was consistent with the obtained data from gel content measurements. Lastly, the evolution in crystallinity of the film samples was monitored by density measurements as well as differential scanning calorimetry (DSC). It was revealed that the crystallinity of the tested films during thermo-oxidative degradation grows faster in the presence of OPE. Overall, the findings indicated that the utilization of OPE containing trace amounts of iron (III) stearate can accelerate the thermal oxidation of HDPE films and facilitate entering the final biodegradation stage, while resolving the need to use high concentrations of harmful heavy metal salts. [ABSTRACT FROM AUTHOR]