Polymer Polyethylene Research Articles

Magnetism-Assisted Density Gradient Separation of Microplastics.

A versatile method for the efficient separation of different types of microplastics from particle mixtures is presented. Magnetism-assisted density gradient separation (Mag-DG-Sep) relies on a bespoke separation cell connected to a gradient pump and located between two like-pole-facing neodymium magnets. In Mag-DG-Sep, particle mixtures initially sunk in water are subjected to a gradient of increasing concentration of MnCl2, enabling the sequential suspension and collection of particles with different densities. The suspension process is assisted by the paramagnetism of the MnCl2 solution placed between the two magnets, which contributes to focusing the ascending particles from the bottom of the separation cell to the outlet, thus enhancing the resolution of the separation process. To demonstrate the concept, a mixture of polyethylene (PE) polymer particles with a similar size range (180-212 μm) but different densities (ca. 0.98, 1.025, 1.08, and 1.35 g cm-3) was selectively separated in a single Mag-DG-Sep run. These particles were also efficiently separated when mixed with other types of particles, such as glass or soil. A generic linear MnCl2 gradient can be directly applied for sample screening covering a broad range of densities (0.98-2.20 g cm-3), while steps can be introduced in the gradient, increasing the separation resolution of particles with close densities (1.025-1.08 g cm-3). As a proof-of-concept application, Mag-DG-Sep facilitated sample preparation of microplastics present in a soil sample prior to their examination by attenuated total reflection Fourier-transform infrared spectroscopy.

Density Functional Theory Analysis of the Copolymerization of Cyclopropenone with Ethylene Using a Palladium Catalyst

Density functional theory has been used to elucidate the mechanism of Pd copolymerization of cyclopropenone with ethylene. The results reveal that introducing ethylene and cyclopropenone to Pd catalyst is thermodynamically feasible and generates the α,β-unsaturated ketone unit (UnitA). Cis-mode insertion and Path A1a are the most favorable reaction routes for ethylene and cyclopropenone, respectively. Moreover, cyclopropenone decomposition can generate CO in situ without a catalyst or with a Pd catalyst. The Pd-catalyzed decomposition of cyclopropenone exhibits a lower reaction barrier (22.7 kcal/mol) than its direct decomposition. Our study demonstrates that incorporating CO into the Pd catalyst can generate the isolated ketone unit (UnitB). CO is formed first; thereafter, UnitB is generated. Therefore, the total energy barrier of UnitB generation, accounting for the CO barrier, is 22.7 kcal/mol, which is slightly lower than that of UnitA generation (24.0 kcal/mol). Additionally, the possibility of copolymerizing ethylene, cyclopropenone, and allyl acetate (AAc) has been investigated. The free energy and global reactivity index analyses indicate that the cyclopropenone introduction reaction is more favorable than the AAc insertion, which is consistent with the experimental results. Investigating the copolymerization mechanism will help to develop of a functionalization strategy for polyethylene polymers.

The role of magnetic nano CoFe2O4 and conductive MWCNT/graphene in LDPE-based composites for electromagnetic interference shielding in X-band

The use of polymer composites containing ferrite based magnetic fillers and conducting fillers are highly appreciated as materials for microwave shielding. In this regard, herein we present systematic optimization of compositional parameters by varying CoFe 2 O 4 and MWCNT/Graphene nanoplatelets to achieve efficient electromagnetic shielding in Low density polyethylene polymer. The magnetic filler, CoFe 2 O 4 was prepared by facile solution combustion process and the chemically exfoliated Graphene and CVD-derived MWCNT are used as conducting filler. Various compositions containing different weight ratios of CoFe 2 O 4 and Graphene nanoplatelets on the EMI shielding efficiency of LDPE composite is studied using vector network analyzer in the frequency range of 8–12 GHz. The critical concentration of all the materials in bringing synergy was evaluated. The combination of LDPE:MWCNT:GNP:CoFe 2 O 4 : 50:5:40:5 was found to be optimum concentration to bring a synergetic effect for gaining excellent dielectric, ohmic and magnetic losses in the X-band. Maximum total shielding effectiveness of about 49 dB was achieved at 10.3 GHz within the frequency range studied. • The use of magnetic CoFe 2 O 4 and carbon based MWCNT/ Graphene as fillers in LDPE matrix for enhanced shielding behavior. • Systematic optimization of the ferrite, carbon nanotubes and graphene is carried out to achieve maximum shielding effectiveness. • The synergetic effect is proved at an optimum fillers concentration and are correlated to the impedance and conductivity variations of the composites.

Microplastic pollution and its implicated risks in the estuarine environment of Tamil Nadu, India

Estuaries are transition zones between freshwater and seawater. There are only few studies on microplastic (MPs) pollution in estuaries. In this study, investigating the spatiotemporal variations of MPs in water, sediment and biota samples of 19 estuaries in Tamil Nadu, India, we assessed the chemical and human exposure risks of MPs. MPs extracted by digestion and density separation and characterized them using microscope, Fourier transform infrared spectroscopy and scanning electron microscopy with energy dispersive analysis of X-rays. MP abundancesin summer and monsoon range from 31.7 ± 3.8 to 154.7 ± 4.2 items/L in water and 51.7 ± 3.6 to 171.4 ± 9.1 items/kg in sediment. Highest MPs abundance is found in water and sediment of the urbanized Adayar estuary. MP levels are higher in monsoon than in summer (P < 0.05) due to the discharge of wastewater via storm water outlets. More small-size MPs are found in summer (<0.5–1 mm) while monsoon has a greater diversity of MP polymers (MPDII: 0.81). MP abundance in fish varies from 0.01 ± 0.003 to 0.15 ± 0.03 items/g, and in shellfish from 0.75 ± 0.12 to 9.7 ± 0.28 items/g. In fish, more MPs are found in intestine than in gill or muscle. Shell fishes contain more MPs than fishes. In all the matrices, fibers of different sizes, and polymers of polyethylene and polypropylene are commonly found. An average local person is likely to ingest 781 items of MPs via fish and 2809 items via shellfish annually. Polymer hazard index shows hazard levels of IV to V indicating the serious MP pollution trend, which poses a risk to the biota. In conclusion, MPs observed in this study show that estuaries are a major pathway for land-derived plastics to reach the ocean. The results will help implement remedial/clean-up measures for the estuary for better ecosystem conservation.

Effect of Polymer Substrate on Adhesion of Electroless Plating in Irradiation-Based Direct Immobilization of Pd Nanoparticles Catalyst.

Pd nanoparticles were directly immobilized on acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), polystyrene (PS), polyphenylene sulfide (PPS), poly(vinyl chloride) (PVC), polypropylene (PP), and polyethylene (PE) polymer substrates via chemical reactions induced by ionizing irradiation. X-ray photoelectron spectroscopy analysis revealed that the chemical state of the immobilized Pd nanoparticles depended on the polymer substrate type. Electroless plating was performed using the immobilized Pd nanoparticles as the catalyst, and Cu-plating films were deposited on all polymer substrates. The results of the tape-peeling test suggested that the chemical state of the immobilized Pd nanoparticles on the polymer substrates affected the plating adhesion strength. Notably, ABS with immobilized Pd particles exhibited a high adhesion strength beyond the practical level, even without prior chemical etching. It was presumed that the high adhesion strength was owing to the anchoring effect of the holes generated on the ABS surface by ionizing irradiation.

Aqueous Supercapacitors with Low Cost and High Voltage Enabled by Co‐Solute Crowding Effect of Electrolyte

AbstractDeveloping high‐voltage and environmentally friendly aqueous electrolytes have become a significant trend in supercapacitors (SCs). However, achieving this goal usually requires the use of “water‐in‐salt” (WIS) electrolytes, inevitably increasing manufacturing costs and sometimes posing problems such as environmental pollution. Here, we developed a water/organic solvent hybrid electrolyte (8 m NaClO4‐20 % H2O‐30 % ACN‐50 % PEG‐200) with low cost and high‐voltage capacity using the water‐miscible polymer polyethylene glycol (PEG) as a crowding agent to suppress water activity, and acetonitrile (ACN) as a co‐solvent to improve the ion transport properties. The synergistic advantages of the two co‐solvents allow SCs using this electrolyte to have a high operative voltage window of up to 2.6 V, currently the highest operating voltage for aqueous carbon‐based SCs, excellent capacity retention (over 11000 cycles) and high energy densities (31.2 Wh kg−1). This work provides a promising method for developing green and inexpensive high‐voltage window aqueous electrolytes.

Development of a Workflow to Engineer Tailored Microparticles Via Inkjet Printing.

New drug development and delivery approaches result in an ever-increasing demand for tailored microparticles with defined sizes and structures. Inkjet printing technologies could be promising new processes to engineer particles with defined characteristics, as they are created to precisely deliver liquid droplets with high uniformity. D-mannitol was used as a model compound alone or co-processed with the pore former agent ammonium bicarbonate, and the polymer polyethylene glycol 200. Firstly, a drop shape analyzer was used to characterize and understand ink/substrate interactions, evaporation, and solidification kinetics. Consequently, the process was transferred to a laboratory-scale inkjet printer and the resulting particles collected, characterized and compared to others obtained via an industrial standard technique. The droplet shape analysis allowed to understand how 3D structures are formed and helped define the formulation and process parameters for inkjet printing. By adjusting the drop number and process waveform, spherical particles with a mean size of approximately 100µm were obtained. The addition of pore former and polymer allowed to tailor the crystallization kinetics, resulting in particles with a different surface (i.e., spike-like surface) and bulk (e.g. porous and non-porous) structure. The workflow described enabled the production of 3D structures via inkjet printing, demonstrating that this technique can be a promising approach to engineer microparticles.

ВЛИЯНИЕ КОМПАТИБИЛИЗАТОРА И СКОРОСТИ ПЕРЕМЕШИВАНИЯ НА ФИЗИКО-МЕХАНИЧЕСКИЕ СВОЙСТВА СМЕСИ ПОЛИМЕРОВ НА ОСНОВЕ ПОЛИВИНИЛХЛОРИДА И ПОЛИЭТИЛЕНА

This piece of work has investigated features of deformation of polyvinyl chloride (PVC) and polyethylene (PE) polymer blends, resulted in the presence of two types of compatibilizers, and made a comparative assessment of the elastic strength characteristics of the blends versus their variations produced in the intensity of mixing components in the melt. The effect of plasticization of PVC with dioctyl phthalate was found at increased speed of stirring, expressed by a decrease in the modulus of elasticity and stress at the yield point. For mixtures with a PVC matrix in the absence of a compatibilizer, an increase in the PE content leads to a drop in stress at the yield point and elongation at break; for equal mixture compositions with intense mixing, the deformation curves show a combination of the yield zone and orientational ordering.

Fabrication and Radiation Attenuation of Linear Low Density Polyethylene with Iron Slag in the Range of Peak Potentials 50 kVp to 150 kVp

The emergence of polymer composite materials has potential advantages for shielding application form low energy radiation. Four different samples of different ratio of iron slag (0%, 1%, 5%, and 10%) based on a linear low-density polyethylene (LLDPE) polymer mixed were prepared and examined in this study. The measured densities of fabricated LLDPE samples were in the range of 0.925 to 1.004 g cm−3. The distribution of ironpreserving particles in an LLDPE polymer sample was also demonstrated in this study by scanning electron microscopy (SEM). The linear and mass attenuation coefficients of the four samples were determined by using eight standard radiation qualities of different applied voltages (kVp) of 50, 60, 70, 84, 90, 105, 119, and 150 kVp. Moreover, the exposure radiation quality used with different energies was calculated through the half value layer (HVL). It was found that the dose value for different combinations of beam quality including the HVL and kVp did not exceed the recommended values given by the IEC 61267 standard with the effective energies of 28.7, 30.0, 33.0, 36.2, 37.7, 39.6, 44.3, and 50.0 keV. The results of the linear attenuation coefficients of four LLDPE samples were between 0.1886 cm−1 and 0.8412 cm−1. The composite that includes 10% iron slag has the highest attenuation across all incident beam energies. In addition, it exhibited the greatest mass attenuation coefficient among the selected samples. Furthermore, when the mean free path (MFP) was measured, the LLDPE + 10% iron slag composite has a lower MFP value which indicates it is best material for shielding photons in the selected energy range in our investigation.

How small is the big problem? Small microplastics

Particle size plays an important role in determining the behaviour, fate and effects of microplastics (MPs), yet little is known about MPs <300μm in aquatic environments. Therefore, we performed the first assessment of MPs in marine surface waters around the Whitsunday Islands region of the Great Barrier Reef Marine Park, Australia, to test for the presence of small MPs (50-300μm) in-situ. Using a modified manta net, we demonstrate that MPs were present in all marine surface water samples, with a mean sea surface concentration of 0.23±0.03 particles m-3. Microplastics were mainly blue, clear and black fibres and fragments, consisting of polyethylene terephthalate, high-density polyethylene and polypropylene plastic polymers. Tourism and marine recreation were considered the major contributing sources of MPs to surface waters around the Whitsunday Islands. Between 10 and 124 times the number of MPs exist in the 50μm-300μm size class, compared with the 1mm-5mm size range. This finding indicates that the global abundance of small MPs in marine surface waters is grossly underestimated and warrants further investigation. Research into the occurrence, characteristics and environmental fate of MPs <300μm is needed to improve our understanding of the cumulative threats facing valuable ecosystems due to this smaller, potentially more hazardous size class.

Fate of microplastics during composting and their leachability

The occurrence of chemical compounds specific to individual plastic polymers allowed the determination of components in compost feedstock (urban greenery and bio bins of households). The total concentration of plastic polymers is 431 mg/kg. The main identified polymers are polystyrene, polyethylene terephthalate, polyethylene, polycarbonate, and polypropylene. Additives used to modify the properties of plastics are present in the concentration of 195 mg/kg. Twelve compounds used as additives in the production of plastics in both the feedstock and the compost were identified. A statistically significant relationship was found between the decrease of concentration of organic matter and concentrations of compounds that identify plastic polymers (polyethylene terephthalate and polystyrene). The decrease of concentrations of compounds specific to polymers after three months was observed in the range between 33 and 84%, while the decrease for additives was 68%. After 18 months, the loss was higher than 82% except for polypropylene (only 70%). Compound leachability after three months of composting decreased to one-quarter for most polymers (except polypropylene and polyethylene), and to one-third for additives.

Spatial and seasonal distribution of microplastic in surface water of Bueng Boraphet Wetland-a Ramsar wetland in Thailand.

This study sought to assess microplastic contamination in the surface water of the inland freshwater wetland, Bueng Boraphet Wetland, Thailand, which is a lentic system with various land-use patterns, including community areas, agricultural areas, and natural resource conservation areas. In 2019, water samples were collected during the wet and dry periods from the three land-use zones at depths of 0-30cm using a plankton net with 333µm in mesh size. The water samples were digested via a wet peroxide oxidation process prior to the identification of microplastic morphology using a stereomicroscope. The polymer types of microplastic were analyzed using Fourier transform infrared spectrophotometry. Microplastic was found to range from 0.00 to 4.61 particles/m2 (0.34 ± 0.81 particles/m2) or 0.0 to 19.57 particles/m3 (1.44 ± 3.4 particles/m3). Furthermore, significantly high amounts of microplastics were found in samples from the community area. No microplastic was detected in the sample from the natural resource conservation area. The quantity of microplastic did not significantly differ between the sampling periods. Polymer types, including polyester, polypropylene, and polyethylene terephthalate, were identified in this study. The microplastics were predominantly small and were colored black or red. Microplastic with a fiber shape (93.8%) was observed. Besides the specific gravity of the microplastic and hydrological characteristics, the high concentration of microplastics found in samples from the community area (0.62 ± 0.79 particles/m2 or 2.63 ± 3.36 particles/m3) is likely related to the high human pressure. As microplastic contamination can impact aquatic animals and wetland ecosystems, appropriate control measures for human activities and plastic waste management are required.

A Study on Over-Molded Copper-Based Flexible Electronic Circuits.

Over-molding has been proposed in recent years as an integrated functional flexible circuit board in a plastic part. This method uses the conventional process for film insert technology. Over-molding has attracted significant attention across many industries due to its potential to deliver different electrical functions in a variety of different part geometries, especially in automotive interiors and home appliances. While it has great application potential, manufacturing challenges continue throughout foil fabrication and injection molding. This raises challenges for designers and researchers responsible for maintaining the reliability of such electronic flexible circuits. Therefore, the purpose of this research paper is to improve some of the over-molding process parameters. On 0805 and 1206 over-molded zero-ohm resistors, electrical, mechanical, and failure characterization was performed. Those components were mounted in parallel, perpendicular, and 45° angled arrangements on two different polymer substrates, polyimide (PI) and polyethylene terephthalate (PET) using lead-free solder, low-melt solder, and conductive adhesive paste. Moreover, as an over-molding material, polycarbonate (PC) with medium viscosity was used. The effect of using different mold shapes (corner mold, 2 mm flat mold, and 3 mm flat mold) and injection molding process parameters (injection speeds and melt temperature) was studied.

Evaluation of the properties of modified local asphalt binder by using styrene butadiene rubber (SBR) or low-density polyethylene (LDPE)

The influence of styrene butadiene rubber (SBR) or low-density polyethylene (LDPE) polymers on the characteristics of local asphalt binder was analyzed to characterize the rheological properties. The results indicated that the SBR or LDPE increased the softening point. The softening point was enhanced by around 35% when 9% of SBR was used in comparison to the unmodified asphalt, while there was a 15% increment when LDPE was used. The results also indicated that the SBR or LDPE decreased the penetration rate. The penetration decreases by around 36% when 9% of SBR is used compared to the neat asphalt, while a significant increment was 89% when 9% of LDPE is used. Additionally, when 9% SBR was employed, the ductility of the asphalt binder rose by roughly 73%, but 64% less ductility was seen when 9% LDPE was utilized. Finally, the addition of the additive has improved the penetration index, thus reducing the temperature sensitivity. Due to said above, SBR and LDPE are practical and promising modifiers that will be useful in enhancing the performance of the asphalt binder straightforwardly and efficiently.

Microplastics characteristics of lorjuk Solen sp. in east coastal waters of Surabaya

Microplastics (MPs) are plastic particles with sizes between <1 m to 5 mm. Microplastics are known to contaminate the environment and marine organisms. One type of marine organism that is often found on the east coast of the city of Surabaya is Lorjuk, namely bamboo shells or razor clams. Lorjuk is seafood and is known as a typical food of the city of Surabaya. This study aims to determine the potential for microplastic pollution in Lorjuk (Solen sp.) from 3 locations on the east coast of the city of Surabaya. Lorjuk observed were adult Lorjuk with a size of 5-6 cm. With the nature of Lorjuk as an infauna and filter feeder, microplastic observations were also carried out on sediment and water. The number, shape, color, size, and polymer type of microplastics were observed using an optical microscope and FTIR spectrophotometer. MPs were found in all samples of Lorjuk in the three locations, with an average number of 6-7 MPs/ind. The physical characteristics of microplastics indicate that fiber is the dominant form of microplastic (>90%) with the majority being blue. The MPs found in Lorjuk have an average size of 20-40 µm with low-density polyethylene (LDPE) polymer. The results of the Pearson correlation test showed that there was an effect of the relationship between the number of microplastics found in Lorjuk and microplastics in the environment around where Lorjuk lived (water column and sediment).

Filler dependent microstructural and optical properties of PVDF/PEG blends versus PVDF/GO nanocomposites

The micro-structural features and the optical properties of polymer blends (PB) of polyvinylidene fluoride (PVDF) base with polyethylene glycol (PEG) and polymer nanocomposites (PNC) of PVDF base with graphene oxide (GO) as fillers are compared. Different weight fractions of PVDF/PEG and PVDF/GO samples were prepared through the solution casting followed by spin coating method. The microstructure of PVDF/PEG blends and PVDF/GO nanocomposites shows formation of immiscible/compatible/homogenous microstructures over different extents of loading of the filler components. UV–visible spectrometry revealed an increase in absorbance with the amount of filler and the absorbance was found to be lesser and highly dispersive for the PB as compared to PNC, attributed to the heterogeneity/electrical conductivity of the respective fillers of the two different systems. Spectroscopic ellipsometry was used to study the various optical constants (e.g. refractive index, extinction co-efficient, etc.) and their dispersion behavior over the visible range of wavelengths. The parameters show large variation as a function of component fillers due to the different extent of interaction of matrix/filler. The optimized parameters were obtained for the 20% PB and the 5% PNC samples respectively, suggesting PNC with nano fillers are always to be a better choice for developing them as materials suitable for various optical and other related applications.

Enhancement of the Rutting Resistance of Asphalt Mixtures at Different High Temperatures Using Waste Polyethylene Polymer

The temperature and stress caused by the load can be cited as two main parameters leading to breakage in asphalt pavement, especially rutting (permanent deformation). So, to reduce the problems of rutting of roads, several actions have been taken, including improving pavement quality and the structure design methods. The increase in the attention of respective engineers in the last few years to modify and improve the asphalt performance through providing different types of additives and replacing the raw materials of asphalt mixture with recycled materials to improve the environment and reduce the cost of modified pavement mixture. This study discussed the use of low-density waste polyethylene as an asphalt modifier in percentages of (2, 4, and 6) % by the weight of asphalt and their impact on the performance of asphalt mixtures at high temperatures. This study showed that using plastic waste (low-density polyethylene) as a bitumen modifier improved the performance of asphalt mixtures at different high temperatures. This was achieved by reducing the rut depth by (80.5) % and (82.3) % at temperatures of 50 C and 60 C, respectively, using low-density polyethylene waste at an optimum value of about 4% by weight of asphalt in addition to enhancing the Marshall stability by using this percentage of polymer.

A 75-year history of microplastic fragment accumulation rates in a semi-enclosed hypoxic basin

Plastic budgets in the marine environment and their long-term trends are yet to be fully understood. Measuring the accumulation rates in bottom sediments is crucial to solving the riddle of missing ocean plastics. Previous studies based on coastal sediment cores have found that accumulation rates have increased with increases in plastic production and/or regional populations. However, the correlations between the rates and bioactivities or ocean dynamics, which are crucial for modeling the microplastic sinking process, have not been examined. We revealed a 75-year microplastic fragment (0.3–5.0 mm) accumulation rate history in a hypoxic basin, Beppu Bay, Japan, based on multi-core analysis and 210Pb dating of the sediment which was cross-checked by time control with 137Cs radioactivity peaks. We found that a long-term linear increasing trend with an approximately 20-year variation overlapped with significant peaks around 1990 and 2014 with the first polypropylene microplastic fragment detected from a 1958.8–1961.0 CE sediment layer. The maximum rate was 203 pieces m−2 y−1 with an abundance of 86 pieces kg−1-dry in 2014. Smaller fragments in the size range of 0.3–2.0 mm have been consistently dominant in terms of the accumulation rate throughout the 1955–2015 period, accounting for 85.3 % of the total accumulation rate. The three major polymers (polyethylene, polypropylene, and polystyrene) accounted for 96.6 % of the total rate. The rate was highly and positively correlated with the chlorophyll-a accumulation rate and concentration in the sediment. Based on the microplastic accumulation rates and concentration in the seawater, the mean sinking velocity of microplastics was estimated to be in the order of 101 m d−1. Our results will contribute to significant progress in modeling the microplastic sinking process by offering the first field measurement-based mean sinking velocity and significant correlations between the rate and bioactivity-related signals.

Microplastic pollution in sediments of tropical shallow lakes

Forty-eight tropical shallow lakes (depth ≤ 4 m) across a climatic gradient were assessed for microplastic (MPs; <5 mm) pollution based on MPs concentrations in archive samples from lake shore sediments. The MPs were classified by type (fragments or fibres), colour (yellow, black, red, green, blue, white, and transparent), size (0.55 to 4.93 mm), and polymer (polyester, polyethylene, chlorinated polyethylene, and polyamide). Sediments were predominantly medium sand, and all samples (144) contained MPs, consisting of 24 % fragments (6.3 ± 11.3 MPs·300 g−1) and 76 % fibres (21.25 ± 12.7 MPs·300 g−1). The lake climate (humid, transitional, or semi-arid), type of surrounding land use (urban, semi-arid, or rural), and distance from the shoreline (0, 5 or 10 m) did not explain the differences in MPs concentrations, partially refuting the initial hypothesis. The only significant difference was between the sample medians for the number of fragments based on the region (H = 7.586; p = 0.0481). The number of fragments in the lakes in the humid region was greater than that in the semi-arid region (p < 0.05). Poor sanitation, sewage effluents, and solid wastes reaching and accumulating in the lakes may be the primary and transversal conditioning factors for this small difference among diverse environments. Freshwater lakes are investigated in all continents, and the present study contributes to the first record of MPs in shallow lake sediments in eastern South America. The 48 shallow lakes assessed showed a relatively low concentration of MPs compared to other lake contaminants reported in the international literature. This information coincides with public policies issued, regarding the control and reduction of plastics and MPs in Brazil, and the study region.

High solid content preparation of size controllable BiOCl crystals as pearlescent pigment in solvent-free polyurethane coating

In the current research, we are committed to solving the irreconcilable contradiction between fragmentation, agglomeration, poor size controllability, and high solid content in the preparation of BiOCl crystals. Water soluble block polymer polyethylene glycol monomethyl ether-b-polydimethylaminoethyl methacrylate (mPEG-b-PDMAEMA) was synthesized as dispersant to achieve high solid content by reducing the frequency of crystal collisions to avoid crystal fragments and agglomerates. With the reaction temperature of 80 °C, urea dosage of 40 g, bismuth salt solution addition rate of 0.45 ml/min, and variable amount of pre-added HCl in the reaction vessel, fragment-free BiOCl crystals of wide size ranges were successfully obtained with record-high solid content of above 10 wt%. Furthermore, bio-based pearlescent coatings were prepared by using as-synthesized BiOCl crystals as pearlescent pigments and polyglyceryl tetrastearate and polyphenyl polymethylene polyisocyanate (PAPI) as the formulations of two-component solvent free polyurethane. The decorative polyurethane coatings demonstrated excellent physical properties and corrosion resistance, which exhibited eye-catching gloss effects from pearl luster, glitter pearl luster, to shimmering luster derived from the size variation of 20, 50, and 70 µm, respectively. The large-scaled production of size controllable BiOCl crystals with high solid content in wide size range promises the practical applications in decorative coatings, cosmetics, clothing accessories, and car interior accessories.