Massive accumulation of postconsumer plastic waste in eco-system has raised growing environmental concerns. Sustainable end-of-life managements of the indispensable plastic are highly demanding and challenging in modern society. To relieve the plastic menace, herein we present a full life cycle sustainable supramolecular bioplastic made from biomass-derived polyelectrolyte (chitosan quaternary ammonium salt, QCS) and natural sodium fatty acid (sodium laurate, SL) through solid-phase molecular self-assembly (SPMSA), by which the QCS-SL complexes, precipitated from mixing the aqueous solutions, self-assemble to form bioplastic film by mildly pressing at room temperature. The QCS-SL bioplastic films display superior hydroplasticity owing to the water-activated molecular rearrangement and electrostatic bond reconstruction, which allows facile self-healing and reprocessing at room temperature to significantly extend the service lifetime of both products and raw materials. With higher water content, the dynamic electrostatic interactions and precipitation-dissolution equilibrium endow the QCS-SL bioplastic films with considerable solubility in water, which is promising to mitigate the plastic accumulation in aquatic environment. Because both QCS and SL are biocompatible and biodegradable, the dissolved QCS-SL films are nontoxic and environmentally friendly. Thus, this novel supramolecular bioplastic is highly sustainable throughout the whole life cycle, which is expected to open a new vista in sustainable plastic materials.
The high use of plastic wraps leads to significant environmental pollution. In this study, the surface structure and microbial community evolution of commercially available plastic wraps [polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and polylactic acid (PLA)] in constructed wetlands (CWs) were investigated. The results indicated that all plastic wraps gradually decreased in molecular weight, crystallinity, melting, and crystallization temperatures, whereas a gradual increase was observed in the surface roughness, polymer dispersity index (PDI), carbonyl index (CI) and Shannon index of microorganisms colonizing the CWs. The aging rate of the plastic wrap was in the order: PLA > PVC > PE > PVDC, at the same site in the CWs, and it was in the order: soil surface > plant roots > subsoil, for the same plastic wrap. The diversity of microorganisms colonizing the same plastic wrap was in the order: plant roots > subsoil > soil surface. The Shannon indices of microorganisms on plastic wraps were lower than those in the soil, indicating that the diversity of microorganisms colonizing plastic wraps is limited. Additionally, the microbial community structure on the plastic surface was co-differentiated by the plastic type, placement position in the CWs, and aging time. Significantly different microbial community structures were found on the PVC and PVDC wrap surfaces, revealing that the chlorine in plastics limits microbial diversity. Unclassified members of Rhizobiaceae and Pseudomonadaceae were the dominant genera on the surface of the plastic wraps, suggesting that they may be the microorganisms involved in plastic degradation processes. The study provides valuable perspectives to facilitate a comprehensive understanding of the migration, fate, and environmental risks associated with microplastics (MPs) in wetlands.
Microbiota , Plastics , Wetlands , Soil Microbiology , Water Pollutants, Chemical/analysis
Anti-counterfeiting in 3D printing has gained significant attention, however, current approaches often fall short of fully capitalizing on the inherent advantages of personalized manufacturing with this technology. Herein, we propose an embedded anti-counterfeiting scheme for additive manufacturing, accompanied by a novel fluorescent encrypted quick response (QR) method. This approach involves the development of a 3D printing filament utilizing poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) bio-composites as the primary filament matrix, with varying quantities of Chlorella powder incorporated. The resulting filament has a good thermal stability near 200 °C and exhibits a distinctive red fluorescence under ultraviolet light, with the emission peak at 677 nm when excited by 415 nm blue light. Fluorescence imaging analysis confirms that the red fluorescence in 3D printed devices containing Chlorella is a result of the chlorophyll and its derivatives fluorescence effect. The fluorescent encrypted QR codes are inconspicuous in daylight but become easily discernible under ultraviolet light. In the cases of recognizable QR codes, the ∆Eab* values all exceed 35, and the LC/LB values deviate significantly from 1. This research delves into the fluorescence characteristics of Chlorella and highlights its applicability in 3D printing, specifically within the realm of product anti-counterfeiting, presenting a groundbreaking approach.
Photocatalysis is widely acknowledged as an efficient and environmentally friendly method for treating dye-contaminated wastewater. However, the utilization of powdered photocatalysts presents significant challenges, including issues related to recyclability and the potential for secondary pollution. Herein, a novel technique based on 3D printing for the synthesizing of iron oxide (Fe2O3) involving chlorella was presented. Initially, chlorella powders were immobilized within acrylonitrile butadiene styrene (ABS) and thermoplastic polyurethane (TPU) substrate plastics using melt extrusion technology. Subsequently, these composite materials were transformed into ABS/TPU/chlorella skeletons (ATCh40), through fused deposition molding (FDM) technology. The integration of Fe2O3 onto the ATCh40 (ATCh40-Fe2O3) skeletons was accomplished by subjecting them to controlled heating in an oil bath. A comprehensive characterization of the synthesized materials confirms the successful growth of Fe2O3 on the surface of 3D skeletons. This strategy effectively addresses the immobilization challenges associated with powdered photocatalysts. In photocatalytic degradation experiments targeting methyl orange (MO), the ATCh40-Fe2O3 skeletons exhibited a remarkable MO removal rate of 91% within 240 min. Under conditions where the pH of MO solution was maintained at 3, and the ATCh40-Fe2O3 skeletons were subjected to a heat treatment in a 150 °C blast drying oven for 2 hours, the degradation rate of MO remained substantial, achieving 90% removal after 6 cycles. In contrast, when the same synthetic procedure was applied to ABS/TPU (AT) skeletons, the resulting product was identified as α-FeOOH. The MO removal rate by the AT-α-FeOOH skeletons was considerably lower, reaching only 49% after 240 min. This research provided a practical approach for the construction of photocatalytic devices through the use of 3D printing technology.
Microplastics (MPs) are emerging contaminants with growing concerns due to their potential adverse effects on the environment. However, understanding the aging properties and adsorption behavior of MPs is still limited. In this study, we investigated the correlation between the adsorption capacity, aging stages, and aging properties of polyethylene MPs using a correlation equation. Our results revealed that the trends of O/C ratio and contact angle of polyethylene MPs with aging time were fitted to be linear under xenon lamp accelerated aging conditions. Conversely, the trends of other properties such as particle size, crystallinity, and molecular weight with time were fitted to conform to the Boltzmann equation. Moreover, the aging curve data for carbonyl index and molecular weight (Mw) perfectly matched, confirming Mw play a crucial role in verifying the aging process. Additionally, the adsorption amount of polyethylene MPs increased sharply with the increase of aging ages, reaching up to 1.850 mg/g. The adsorption data fit well to the pseudo-second-order kinetics and Langmuir model, suggesting that the adsorption process is dominated by chemisorption. The low pH and low salt concentration is beneficial to the adsorption capacity of MPs onto Cr(VI). Further, a relationship equation was established to predict adsorption risk at different aging stages. These findings provide new insights into the impact of aging on pollutants transport and the fate of MPs, enabling the prediction of adsorption risk of MPs at different aging stages in water environments.
Immobilization is considered as a promising strategy toward the practical applications of powdered adsorbent. Herein, three dimensional (3D) printing cylindrical capsules with cross-linked PVA hydrogels membrane in encapsulate Chlorella pyrenoidosa (Cp) were utilized for removal of lead ions. The chemical compositions, hydrogels performance and morphologies of the membranes were determined by Fourier transformed infrared spectroscopy (FTIR), cross-linking degree, swelling degree, membrane flux and scanning electron microscopy (SEM). It is found that PVA cross-linking structure is successfully synthesized on the surface of capsule body and cap due to the presence of PVA in the filament. The lead ions adsorption capacity related to initial concentration of 50 mg/L in 48 h is reached 75.61%, revealing a good removal ability. The self-floating 3D printed capsules device also shows an excellent recovering property. After 7 runs of adsorption experiment, the lead ions adsorption ratio remains 78.56%, which will bring a broad prospect in wastewater treatment, chemical slow release along with sample preparation and separation.
With the aim of developing green coatings, styrene-acrylic emulsion has been widely used in architectural coatings due to its excellent environmental protection and energy conservation. Nevertheless, the lack of water and oxygen resistance of water-based styrofoam coatings has promoted various nanomaterials being studied for modification. To improve the performance of waterborne styrofoam coating, we introduced the graphene nanopowder and expected to enable it with the function of electromagnetic interference (EMI) shielding to reduce the damage of electromagnetic radiation. In this paper, the problem of poor interface compatibility between graphene and polymer resin was successfully addressed by in situ polymerization. In the process of pre-polymerization of styrene-acrylic emulsion monomer, graphene-modified styrene-acrylic emulsion was obtained by introducing graphene aqueous dispersion. The results showed that the styrene-acrylic emulsion with 4 wt% aqueous graphene dispersions exhibited the best dispersion stability, improved water and oxygen resistance, and the conductivity reached 1.89 × 10-2 S/cm. Then, the graphene-modified coating for building was prepared by using graphene-modified styrofoam emulsion. All the performance indexes of the coating are in line with the industry standards, and it still showed benign EMI shielding effect even when the graphene content was low. It is demonstrated that in situ polymerization technology and the application of graphene in resin coatings modification will promote the development of green coatings.
Metal 1T phase molybdenum disulfide (1T-MoS2) is being actively considered as a promising anode due to its high conductivity, which can improve electron transfer. Herein, we elaborately designed stable Sb-doped metallic 1T phase molybdenum sulfide (1T-MoS2-Sb) with a few-layered nanosheet structure via a simple calcination technique. The N-doping of the carbon and Sb-doping induce the formation of T-phase MoS2, which not only effectively enhances the entire stability of the structure, but also improves its cycling performance and stability. When employed as an anode of sodium-ion batteries (SIBs), 1T-MoS2-Sb exhibits a reversible capacity of 493 mA h g-1 at 0.1 A g-1 after 100 cycles and delivers prominent long-term performance (253 mA h g-1 at 1 A g-1 after 2200 cycles) along with decent rate capability. Paired with a Na3V2(PO4)3 cathode, it displays a superior capacity of 242 mA h g-1 at 0.5 A g-1 over 100 cycles, which is one of the best performances of a MoS2-based full cell for SIBs. Employed as the anode for potassium-ion batteries (PIBs), it exhibits a satisfactory specific capacity of 343 mA h g-1 at 0.1 A g-1 after 100 cycles. This facile strategy will provide new insights for designing T-phase advanced anode materials for SIBs/PIBs.
A major challenge in waste rubber (WR) industry is achieving a high sol fraction and high molecular weight of recycled rubber at the same time. Herein, the WR from the shoe industry was thermo-mechanically ground via the torque rheometer. The effect of grinding temperature and filling rate were systematically investigated. The particle size distribution, structure evolution, and morphology of the recycled rubber were explored by laser particle size analyzer, Fourier transform infrared spectroscopy (FTIR), sol fraction analysis, gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and scanning electron microscope (SEM). The results indicate that the thermo-mechanical method could reduce the particle size of WR. Moreover, the particle size distribution of WR after being ground can be described by Rosin's equation. The oxidation reaction occurs during thermal-mechanical grinding. With the increase of the grinding temperature and filling rate, the sol fraction of the recycled WR increases. It is also found that a high sol fraction (43.7%) and high molecular weight (35,284 g/mol) of reclaimed rubber could be achieved at 80 °C with a filling rate of 85%. Moreover, the obtained recycled rubber compound with SBR show a similar vulcanization characteristics to pure SBR. Our selective decomposition of waste rubber strategy opens up a new way for upgrading WR in shoe industry.
Tuning the high properties of segregated conductive polymer materials (CPCs) by incorporating nanoscale carbon fillers has drawn increasing attention in the industry and academy fields, although weak interfacial interaction of matrix-filler is a daunting challenge for high-loading CPCs. Herein, we present a facile and efficient strategy for preparing the segregated conducting ultra-high molecular weight polyethylene (UHMWPE)-based composites with acceptable mechanical properties. The interfacial interactions, mechanical properties, electrical properties and electromagnetic interference (EMI) shielding effectiveness (SE) of the UHMWPE/conducting carbon black (CCB) composites were investigated. The morphological and Raman mapping results showed that UHMWPE/high specific surface area CCB (h-CCB) composites demonstrate an obviously interfacial transition layer and strongly interfacial adhesion, as compared to UHMWPE/low specific surface area CCB (l-CCB) composites. Consequently, the high-loading UHMWPE/h-CCB composite (beyond 10 wt% CCB dosage) exhibits higher strength and elongation at break than the UHMWPE/l-CCB composite. Moreover, due to the formation of a densely stacked h-CCB network under the enhanced filler-matrix interfacial interactions, UHMWPE/h-CCB composite possesses a higher EMI SE than those of UHMWPE/l-CCB composites. The electrical conductivity and EMI SE value of the UHMWPE/h-CCB composite increase sharply with the increasing content of h-CCB. The EMI SE of UHMWPE/h-CCB composite with 10 wt% h-CCB is 22.3 dB at X-band, as four times that of the UHMWPE/l-CCB composite with same l-CCB dosage (5.6 dB). This work will help to manufacture a low-cost and high-performance EMI shielding material for modern electronic systems.
Improving the processability of ultrahigh molecular weight polyethylene (UHMWPE) and understanding the effect of the polymeric chain mobility has long been a challenging task. Herein, we show that UHMWPE without any processing aids can be processed at a lower temperature of 180 °C compared to conventional processing temperatures (~250 °C) under a continuous elongational flow (CEF) by using an eccentric rotor extruder (ERE). By probing the effect of the residence time of UHMWPE samples under a CEF on the morphology, rheological behavior and molecular orientation, we find that the long polymer chains of UHMWPE are apt to orientate under a consecutive volume elongational deformation, thereby leading to a higher residual stress for the extruded sample. Meanwhile, the residence time of samples can regulate the polymeric chain mobility, giving rise to the simultaneous decrease of the melting defects and residual stress as well as Hermans orientation function with increasing residence time from 0 to 60 s. This also engenders the enhanced diffusion of UHMWPE segments, resulting in a defect-free morphology and higher entanglement with lower crystallinity but without causing obvious thermal oxidative degradation of UHMWPE. This interesting result could originate from the fast chain entanglement and particle welding enabled by a desirably short residence time, which could be explained by the empirical, entropy-driven melting explosion mechanism.
Herein, we produced a series of ultrahigh molecular weight polyethylene/polypropylene (UHMWPE/PP) blends by elongational-flow-field dominated eccentric rotor extruder (ERE) and shear-flow-field dominated twin screw extruder (TSE) respectively and presented a detailed comparative study on microstructures and tribological properties of UHMWPE/PP by different processing modes. Compared with the shear flow field in TSE, the elongational flow field in ERE facilitates the dispersion of PP in the UHMWPE matrix and promotes the interdiffusion of UHMWPE and PP molecular chains. For the first time, we discovered the presence of the interlayer phase in blends with different processing modes by using Raman mapping inspection. The elongational flow field introduces strong interaction to enable excellent compatibility of UHMWPE and PP and induces more pronounced interlayer phase with respect to the shear flow field, eventually endowing UHMWPE/PP with improved wear resistance. The optimized UHMWPE/PP (85/15) blend processed by ERE displayed higher tensile strength (25.3 MPa), higher elongation at break (341.77%) and lower wear loss of ERE-85/15 (1.5 mg) compared to the blend created by TSE. By systematically investigating the microstructures and mechanical properties of blends, we found that with increased content of PP, the wear mechanism of blends varies from abrasive wear, fatigue wear, to adhesion wear as the dominant mechanism for two processing modes.
The low-percolation-threshold conductive networking structure is indispensable for the high performance and functionalization of conductive polymer composites (CPCs). In this work, conductive carbon black (CCB)-reinforced ultrahigh-molecular-weight polyethylene (UHMWPE)/polypropylene (PP) blend with tunable electrical conductivity and good mechanical properties was prepared using a high-speed mechanical mixing method and a compression-molded process. An interconnecting segregated hybrid CCB-polymer network is formed in electrically conductive UHMWPE/PP/CCB (UPC) composites. The UPC composites possess a dense conductive pathway at a low percolation threshold of 0.48 phr. The composite with 3 phr CCB gives an electrical conductivity value of 1.67 × 10-3 S/cm, 12 orders of magnitude higher than that of the polymeric matrix, suggesting that CCB improves both the electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) of the composite at the loading fraction over its percolation threshold. The composite with 15 phr CCB presents an absorption-dominated electromagnetic interference shielding effectiveness (EMI SE) as high as 27.29 dB at the X-band. The composite also presents higher tribological properties, mechanical properties, and thermal stability compared to the UP blend. This effort provides a simple and effective way for the mass fabrication of CPC materials with excellent performance.
In this study, polyethylene microplastics were artificially photoaged by xenon light. Experiments were then performed with methylene blue (MB) dye to compare the changes in the structure, properties, and adsorption-desorption behaviors of the aged and virgin polyethylene microplastics. The results showed that the aged polyethylene microplastics were hydrophilic with oxygen-containing functional groups, which enhanced the adsorption capacity of polyethylene for MB from 0.63 mg·g-1 to 8.12 mg·g-1. The adsorption isotherms changed from the Henry model (virgin polyethylene microplastics) to the Langmuir model (aged polyethylene microplastics), indicating that the partitioning function was gradually replaced by a single-layer covering during the adsorption process. In addition, 7% and 17.8% of the MB loaded onto the aged polyethylene microplastics was desorbed into water and a simulated intestinal fluid, respectively. These findings reveal that aged polyethylene microplastics can accumulate MB, thus posing potential risks to aqueous environments and biological tissues.
Microplastics , Water Pollutants, Chemical , Adsorption , Kinetics , Methylene Blue , Plastics , Polyethylene , Water , Water Pollutants, Chemical/analysis
Unsatisfactory oxygen mobility is a considerable barrier to the development of perovskites for low-temperature volatile organic compounds (VOCs) oxidation. This work introduced small amounts of dispersed non-metal boron into the LaCoO3 crystal through an easy sol-gel method to create more oxygen defects, which are conducive to the catalytic performance of propane (C3 H8 ) oxidation. It reveals that moderate addition of boron successfully induces a high distortion of the LaCoO3 crystal, decreases the perovskite particle size, and produces a large proportion of bulk Co2+ species corresponding to abundant oxygen vacancies. Additionally, surface Co3+ species, as the acid sites, which are active for cleaving the C-H bonds of C3 H8 molecules, are enriched. As a result, the LCB-7 (molar ratio of Co/B=0.93:0.07) displays the best C3 H8 oxidation activity. Simultaneously, the above catalyst exhibits superior thermal stability against CO2 and H2 O, lasting 200â h. This work provides a new strategy for modifying the catalytic VOCs oxidation performance of perovskites by the regulation of amorphous boron dispersion.
Adsorption is considered to be one of the most effective and economically viable technologies for removing contaminants from the environment. However, the disadvantages of its high-cost complicated process and difficulty in efficient recycling limit its practical application. Herein, a thermoplastic elastomer-polyvinyl alcohol composite (LAY-FOMM 60) sponge three-dimensional structure (3D printing sponge) was fabricated by the fused filament fabrication combined with water erosion technique. The size and shape of the resultant sponge were tailored, and the batch of adsorption/desorption experiments of Rhodamine B (RhB) onto the sponge was performed. The results show that the adsorption of RhB on the 3D printing sponge was mainly via physical adsorption, and pseudo-second-order and Langmuir models exhibited good correlation with the adsorption kinetic and isotherm data, respectively. Thermodynamic parameters suggest that the adsorption is an endothermic and spontaneous process. It is worth to note that the adsorption/desorption efficiency can be raised by compression. This results in high efficiency and low cost for adsorption/desorption process and benefit for regeneration of the adsorbent. The adsorption capacity was maintained over 85% of the initial capacity after being used for five cycles. The approach provides a simple strategy for manufacturing customizable porous adsorbent materials that meet various water treatment requirements.
Both adsorption and photocatalysis are considered to be effective methods for removing organic contaminants from dye wastewater. In this study, the construction of 3D skeletons based on the nanoparticles ZnO and ABS/TPU/calcium silicate (CaSiO3) (shortened as ATC) were fabricated via fused deposition molding (FDM) technology. Characterization by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) depicted that ZnO nanospheres had been successfully grown on the 3D skeleton surface with an enlarged specific surface area. As the results of the RhB adsorption and photocatalytic degradation experiments showed, the removal ratio of RhB onto the ZnO-ATC skeleton was as high as 97.94% and the synergistic effect of adsorption and photocatalysis greatly shortened the RhB degradation time under ultraviolet light irradiation. The nanocomposites synthesized in this study showed a significant removal ability for organic pollutants, and could effectively overcome the limitation of the secondary removal of photocatalysts.
This paper presents our study on the use of dissipative particle dynamics (DPD) simulations to discover the flow behavior in ultra high molecular weight polyethylene/polyamide 6 (UHMWPE/PA6) blends associated with extensional-shear coupled flow, based on the Souza-Martins method, for the first time. By way of simulations, we aimed at investigating the mesoscopic morphology and alignment behavior in response to extensional-shear coupled flow, in comparison with simple shear flow and simple extensional flow. Our results reveal that the aggregation of polymers is noticeable under zero flow, as expected. Within the considered range of extensional-shear coupled rates, the morphology transforms from micelle-like clusters to a chain-like network structure by increasing coupled rates from 0.01 to 2.0. Furthermore, it shows a linear distribution along the flow direction at a high coupled rate. It can be concluded that the flow behaviors in UHMWPE/PA6 blends are significantly impacted by extensional-shear coupled rates. The orientation behavior induced by extensional-shear coupled flow is more obvious than shear flow, even though flow variations and mass fractions yield less effects on the distribution behaviors of UHMWPE/PA6 blends. The DPD results are verified by mean square displacement (MSD) as a function of simulation time and relative concentration distribution along Z direction.
The property of carbon nanotubes (CNTs)-based composites are significantly dependent on the orientation and dispersion evolution of CNTs in the polymer matrix. In this work, the dissipative particle dynamics (DPD) simulations are employed to discover the orientation and dispersion evolution of CNTs in ultraâ»high molecular weight polyethylene (UHMWPE) under extensionalâ»shear coupled flow conditions for the first time. In this paper, we investigate the roles of the increasing extensional-shear coupled rate in morphology of CNTs/UHMWPE composites by varying CNTs concentration and observe that the system under consideration lies in the same evolution morphologies. When comparing our results for various morphologies, we notice that the orientation is affected more significantly by changing the extensional-shear coupled rates. A good alignment appears with an increase of extensional-shear coupled rates, which transform it into ordered morphology. In addition, a higher extensional-shear coupled rate does not necessarily contribute to better dispersion even though CNTs concentration varies, as shown by the mean square displacement (MSD) and the relative concentration distribution functions of CNTs in CNTs/UHMWPE composites.
The potential prospect of expandable graphite (EG) in the development of polymer composites is severely limited by required large additions and poor interface compatibility with the polymer. Inspired by mussels, polydopamine (PDA) can be used as an effective interface modifier for EG to prepare ultra high molecular weight polyethylene (UHMWPE) composites with superior mechanical properties and high flame retardancy. The surface of expandable graphite (EG) was coated with a thin adhesive PDA film through self-polymerization of dopamine. The modified expandable graphite (EG@PDA) was combined with APP to prepare UHMWPE flame retardant composites. Compared with UHMWPE/APP/EG (with 20 wt% APP/EG), UHMWPE/APP/EG@PDA (with 20 wt% APP/EG@PDA) gives a decrement by 16.7% in limiting oxygen index, 29.7% in the peak of the heat release rate, 20.4% in total heat release and 49.3% in total smoke release, with an increment by 37% in tensile strength and 67.9% in elongation at break, respectively. It is suggested that the presence of PDA as an interface modifier can greatly improve the interfacial compatibility between EG and UHMWPE. Moreover, it can lead to forming more char residue and reducing the release of smoke particulates during combustion of the composites.
