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Polymers Apr 2024The increased use of plastics in industrial and agricultural applications has led to high levels of pollution worldwide and is a significant challenge. To address this... (Review)
Review
The increased use of plastics in industrial and agricultural applications has led to high levels of pollution worldwide and is a significant challenge. To address this plastic pollution, conventional methods such as landfills and incineration are used, leading to further challenges such as the generation of greenhouse gas emissions. Therefore, increasing interest has been directed to identifying alternative methods to dispose of plastic waste from agriculture. The novelty of the current research arose from the lack of critical reviews on how 3-Dimensional (3D) printing was adopted for recycling plastics, its application in the production of agricultural plastics, and its specific benefits, disadvantages, and limitations in recycling plastics. The review paper offers novel insights regarding the application of 3D printing methods including Fused Particle Fabrication (FPF), Hot Melt Extrusion (HME), and Fused Deposition Modelling (FDM) to make filaments from plastics. However, the methods were adopted in local recycling setups where only small quantities of the raw materials were considered. Data was collected using a systematic review involving 39 studies. Findings showed that the application of the 3D printing methods led to the generation of agricultural plastics such as Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS), Polyethylene Terephthalate (PET), and High-Density Polyethylene (HDPE), which were found to have properties comparable to those of virgin plastic, suggesting the viability of 3D printing in managing plastic pollution. However, limitations were also associated with the 3D printing methods; 3D-printed plastics deteriorated rapidly under Ultraviolet (UV) light and are non-biodegradable, posing further risks of plastic pollution. However, UV stabilization helps reduce plastic deterioration, thus increasing longevity and reducing disposal. Future directions emphasize identifying methods to reduce the deterioration of 3D-printed agricultural plastics and increasing their longevity in addition to UV stability.
PubMed: 38675022
DOI: 10.3390/polym16081104 -
International Journal of Molecular... Apr 2024A method has been proposed for creating an operationally durable copper coating with antimicrobial properties for the buttons of electrical switches based on the gas...
A method has been proposed for creating an operationally durable copper coating with antimicrobial properties for the buttons of electrical switches based on the gas dynamic spray deposition of copper on acrylonitrile butadiene styrene (ABS) plastic. It is shown that during the coating process, a polymer film is formed on top of the copper layer. Comparative in situ studies of microbial contamination have shown that the copper-coated buttons have a significant antimicrobial effect compared to standard buttons. Analysis of swabs over a 22-week study in a hospital environment showed that the frequency of contamination for a copper-coated button with various microorganisms was 2.7 times lower than that of a control button. The presented results allow us to consider the developed copper coating for plastic switches an effective alternative method in the fight against healthcare-associated infections.
Topics: Copper; Hospitals; Anti-Infective Agents; Plastics; Cross Infection; Humans
PubMed: 38674057
DOI: 10.3390/ijms25084471 -
Materials (Basel, Switzerland) Apr 2024Polymers are essential in several sectors, yet some applications necessitate surface modification. One practical and eco-friendly option is non-thermal plasma exposure....
Polymers are essential in several sectors, yet some applications necessitate surface modification. One practical and eco-friendly option is non-thermal plasma exposure. The present research endeavors to examine the impacts of dielectric barrier discharge atmospheric pressure plasma on the chemical composition and wettability properties of acrylonitrile butadiene styrene surfaces subject to the action of additive manufacturing. The plasma source was produced by igniting either helium or argon and then adjusted to maximize the operational conditions for exposing polymers. The drop in contact angle and the improvement in wettability after plasma exposure can be due to the increased oxygen-containing groups onto the surface, together with a reduction in carbon content. The research findings indicated that plasma treatment significantly improved the wettability of the polymer surface, with an increase of up to 60% for both working gases, while the polar index increased from 0.01 up to 0.99 after plasma treatment. XPS measurements showed an increase of up to 10% in oxygen groups at the surface of He-plasma-treated samples and up to 13% after Ar-plasma treatment. Significant modifications were observed in the structure that led to a reduction of its roughness by 50% and also caused a leveling effect after plasma treatment. A slight decrease in the glass and melting temperature after plasma treatment was pointed out by differential scanning calorimetry and broadband dielectric spectroscopy. Up to a 15% crystallinity index was determined after plasma treatment, and the 3D printing process was measured through X-ray diffraction. The empirical findings encourage the implementation of atmospheric pressure plasma-based techniques for the environmentally sustainable manipulation of polymers for applications necessitating higher levels of adhesion and specific prerequisites.
PubMed: 38673204
DOI: 10.3390/ma17081848 -
Toxics Apr 2024(1) Background: Volatile organic compounds (VOCs) are indoor pollutants absorbed by inhalation. The association of several VOCs with lung function in children and...
(1) Background: Volatile organic compounds (VOCs) are indoor pollutants absorbed by inhalation. The association of several VOCs with lung function in children and adolescents is unknown. (2) Methods: We analyzed 505 participants, 6-17-year-olds from the 2011-2012 National Health and Nutrition Examination Survey. Multiple linear regression models were fitted to estimate the associations of VOC metabolites with spirometry outcomes adjusting for covariates. (3) Results: Urinary metabolites of xylene, acrylamide, acrolein, 1,3-butadiene, cyanide, toluene, 1-bromopropane, acrylonitrile, propylene oxide, styrene, ethylbenzene, and crotonaldehyde were all detected in ≥64.5% of participants. Forced expiratory volume in 1 s (FEV) % predicted was lower in participants with higher levels of metabolites of acrylamide (β: -7.95, 95% CI: -13.69, -2.21) and styrene (β: -6.33, 95% CI: -11.60, -1.07), whereas the FEV to forced vital capacity (FVC) ratio % was lower in children with higher propylene oxide metabolite levels (β: -2.05, 95% CI: -3.49, -0.61). FEV % predicted was lower with higher crotonaldehyde metabolite levels only in overweight/obese participants (β: -15.42, 95% CI: -26.76, -4.08) (P < 0.001) and with higher 1-bromopropane metabolite levels only in those with serum cotinine > 1 ng/mL (β: -6.26, 95% CI: -9.69, -2.82) (P < 0.001). (4) Conclusions: We found novel associations of metabolites for acrylamide, propylene oxide, styrene, 1-bromopropane and crotonaldehyde with lower lung function in children and adolescents.
PubMed: 38668512
DOI: 10.3390/toxics12040289 -
Molecules (Basel, Switzerland) Mar 2024Easy-to-handle -hydroxyacridinecarbimidoyl chloride hydrochlorides were synthesized as convenient nitrile oxide precursors in the preparation of...
Easy-to-handle -hydroxyacridinecarbimidoyl chloride hydrochlorides were synthesized as convenient nitrile oxide precursors in the preparation of 3-(acridin-9/2-yl)isoxazole derivatives via 1,3-dipolar cycloaddition with terminal alkynes, 1,1-dichloroethene, and acrylonitrile. Azirines with an acridin-9/2-yl substituent attached directly or via the 1,2,3-triazole linker to the azirine C2 were also synthesized. The three-membered rings of the acridine-azirine hybrids were found to be resistant to irradiation in the UV/visible boundary region, despite their long-wave absorption at 320-420 nm, indicating that the acridine moiety cannot be used as an antenna to transfer light energy to generate nitrile ylides from azirines for photoclick cycloaddition. The acridine-isoxazole hybrids linked at the C9-C3 or C2-C3 atoms under blue light irradiation underwent the addition of such hydrogen donor solvents, such as, toluene, -xylene, mesitylene, 4-chlorotoluene, THF, 1,4-dioxane, or methyl -butyl ether (MTBE), to the acridine system to give the corresponding 9-substituted acridanes in good yields. The synthesized acridine-azirine, acridine-isoxazole, and acridane-isoxazole hybrids exhibited cytotoxicity toward both all tested cancer cell lines (HCT 116, MCF7, and A704) and normal cells (WI-26 VA4).
PubMed: 38611817
DOI: 10.3390/molecules29071538 -
Polymers Mar 2024The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with...
Phosphorus-Based Flame-Retardant Acrylonitrile Butadiene Styrene Copolymer with Enhanced Mechanical Properties by Combining Ultrahigh Molecular Weight Silicone Rubber and Ethylene Methyl Acrylate Copolymer.
The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with different methyl acrylate (MA) content on the mechanical and fire performance of a fireproof acrylonitrile butadiene styrene copolymer (ABS) composite, with an optimum amount of ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi). ABS formulations with a global flame retardant weight content of 20 wt.% (ABS P) were melt-compounded, with and without EMA and UHMW-SR, in a Brabender mixer. During this batch process, ABS P formulations with UHMW-SR and/or EMA registered lower torque values than those of ABS P. By means of scanning electron microscopy (SEM), it was possible to observe that all ABS composites exhibited a homogenous structure without phase separation or particle agglomeration. Slightly improved interfacial interaction between the well-dispersed flame-retardant particles in the presence of EMA and/or UHMW-SR was also noticed. Furthermore, synergies in mechanical properties by adding both EMA and UHMW-SR into ABS P were ascertained. An enhancement of molecular mobility that contributed to the softening of ABS P was observed under dynamic mechanical thermal analysis (DMTA). An improvement of its flexibility, ductility and toughness were also registered under three-point-bending trials, and even more remarkable synergies were noticed in Charpy notched impact strength. Particularly, a 212% increase was achieved when 5 wt.% of EMA with 29 wt.% of MA and 2 wt.% of UHMW-SR in ABS P (ABS E29 S P) were added. Thermogravimetric analysis (TGA) showed that the presence of EMA copolymers in ABS P formulations did not interfere with its thermal decomposition, whereas UHMW-SR presence decreased its thermal stability at the beginning of the decomposition. Although the addition of EMA or UHMW-SR, as well as the combination of both in ABS P increased the pHRR in cone calorimetry, UL 94 V-0 classification was maintained for all flame-retarded ABS composites. In addition, through SEM analysis of cone calorimetry sample residue, a more cohesive surface char layer, with Si-O-C network formation confirmed by Fourier transform infrared (FTIR), was shown in ABS P formulations with UHMW-SR.
PubMed: 38611181
DOI: 10.3390/polym16070923 -
Heliyon Apr 2024Mercury's neurotoxic effects have prompted the development of advanced control and remediation methods to meet stringent measures for industries with high-mercury... (Review)
Review
Mercury's neurotoxic effects have prompted the development of advanced control and remediation methods to meet stringent measures for industries with high-mercury feedstocks. Industries with significant Hg emissions, including artisanal and small-scale gold mining (ASGM)-789.2 Mg year, coal combustion-564.1 Mg year, waste combustion-316.1 Mg year, cement production-224.5 Mg year, and non-ferrous metals smelting-204.1 Mg year, use oxidants and adsorbents capture Hg from waste streams. Oxidizing agents such as O, Cl, HCl, CaBr, CaCl, and NHCl oxidize Hg to Hg for easier adsorption. To functionalize adsorbents, carbonaceous ones use S, SO, and NaS, metal-based adsorbents use dimercaprol, and polymer-based adsorbents are grafted with acrylonitrile and hydroxylamine hydrochloride. Adsorption capacities span 0.2-85.6 mg g for carbonaceous, 0.5-14.8 mg g for metal-based, and 168.1-1216 mg g for polymer-based adsorbents. Assessing Hg contamination in soils and sediments uses bioindicators and stable isotopes. Remediation approaches include heat treatment, chemical stabilization and immobilization, and phytoremediation techniques when contamination exceeds thresholds. Achieving a substantially Hg-free ecosystem remains a formidable challenge, chiefly due to the ASGM industry, policy gaps, and Hg persistence. Nevertheless, improvements in adsorbent technologies hold potential.
PubMed: 38571637
DOI: 10.1016/j.heliyon.2024.e28253 -
Polymers Mar 2024This research investigates the durability of large-format 3D-printed thermoplastic composite material systems under environmental exposure conditions of moisture and...
This research investigates the durability of large-format 3D-printed thermoplastic composite material systems under environmental exposure conditions of moisture and freeze-thaw. Durability was evaluated for two bio-based composite material systems, namely wood-fiber-reinforced semi-crystalline polylactic acid (WF/PLA) and wood-fiber-reinforced amorphous polylactic acid (WF/aPLA), and one conventionally used synthetic material system, namely short-carbon-fiber-reinforced acrylonitrile butadiene styrene (CF/ABS). The moisture absorption, coefficient of moisture expansion, and reduction of relevant mechanical properties-flexural strength and flexural modulus-after accelerated exposure were experimentally characterized. The results showed that the large-format 3D-printed parts made from bio-based thermoplastic polymer composites, compared to conventional polymer composites, were more susceptible to moisture and freeze-thaw exposure, with higher moisture absorption and greater reductions in mechanical properties.
PubMed: 38543392
DOI: 10.3390/polym16060787 -
Nanomaterials (Basel, Switzerland) Mar 2024The high elasticity and excellent gas barrier properties of rubber composites make them irreplaceable in the field of sealing. Constructing a complicated barrier network...
The high elasticity and excellent gas barrier properties of rubber composites make them irreplaceable in the field of sealing. Constructing a complicated barrier network to reduce free volume is crucial to improving gas barrier properties. In this research, liquid acrylonitrile-butadiene rubber/γ-Methacryloxypropyl trimethoxy silane (KH570) modified graphene oxide/butyl rubber composites (LNBR/KGO/IIR) were fabricated. A KGO lamellar network was constructed to resist gas diffusion in the IIR matrix. Meanwhile, LNBR macromolecules further occupied the free volume inside the IIR composites, thereby maximizing the retardation of the path of small molecule gas permeation. The modification of GO by KH570 was successfully demonstrated through FTIR and XRD. The grafting rate of KH570 was calculated to be approximately 71.4%. KGO was well dispersed in IIR due to emulsion compounding and the formation of lamellar networks. The 300% modulus, tensile strength and tear strength of KGO/IIR were improved by 43.5%, 39.1% and 14.8%, respectively, compared to those of the IIR composite. In addition, the introduction of LNBR resulted in a 44.2% improvement in the gas barrier performance of nitrogen permeability relative to the original IIR composite.
PubMed: 38535682
DOI: 10.3390/nano14060534 -
Medycyna Pracy May 2024This paper discusses the potential of additive printing, the risks it poses to users' health (including 3D printer operators) and the effects of chemical substances... (Review)
Review
This paper discusses the potential of additive printing, the risks it poses to users' health (including 3D printer operators) and the effects of chemical substances released during the printing based on the available and studies. It was shown that substances emitted during printing with the commonly used acrylonitrile butadiene styrene filament in additive manufacturing might have carcinogenic, hepatotoxic and teratogenic effects, as well as toxic effect on the respiratory system. The latest research on the mechanism of formation of particles and volatile organic compounds during 3D printing, the parameters affecting their potential emission, and trends in reducing these hazards are indicated. The need for the design of more environmentally friendly and less emissive printing materials, as well as strategies for prevention and individual and collective protection measures are emphasized. Users of 3D printers should be familiar with all possible aspects of the threats associated with the printing process. Insufficient data on direct exposure to chemicals and particles released during the use of filaments makes it difficult to build awareness of safe working practices. Of particular concern is the health impact of emitted chemicals and particles from thermally treated materials in one of the most popular technologies for 3D printing, i.e., fused deposition modelling. Exposure of the users to, e.g., plasticizers added to filaments occurs through a variety of routes, by absorption through the skin, by inhalation or ingestion. Available epidemiological data, as well as current experimental works, indicate that such exposure is a high risk of cardiovascular diseases, atherosclerosis in adults, and cardiac problems and metabolic disorders in children. This review, by identifying potential risk factors, may contribute to reducing the health loss of printer users and improving working conditions and safety, especially in enterprises where additive manufacturing technology is used. Med Pr Work Health Saf. 2024;75(2):159-171.
Topics: Humans; Occupational Exposure; Printing, Three-Dimensional; Risk Assessment; Child; Adult
PubMed: 38523548
DOI: 10.13075/mp.5893.01486