-
Heliyon Jun 2024Acrylonitrile butadiene styrene (ABS) composites were prepared in filament form compatible with the material extrusion (MEX) 3D printing method, using biochar as a...
Acrylonitrile butadiene styrene (ABS) composites were prepared in filament form compatible with the material extrusion (MEX) 3D printing method, using biochar as a filler at various loadings of up to 10.0 wt %. Samples were fabricated to experimentally investigate their mechanical performance. The ABS/biochar composites were characterized using thermogravimetric analysis, differential scanning calorimetry, Raman spectroscopy, and rheological tests. The electrical properties of the composites were investigated using broadband dielectric spectroscopy. Scanning electron microscopy was utilized to analyze the morphological features of the fabricated specimens by examining their side and fracture surfaces. The results indicate that the composite with 4.0 wt % biochar content compared to pure ABS showed the highest mechanical response between the prepared composites (24.9 % and 21 % higher than the pure ABS tensile and flexural strength respectively). The composites retained their insulating behavior. These findings contribute to expanding the utilization of the material extrusion (MEX) 3D printing method while also unlocking prospects for potential applications in microelectronics, apart from mechanical reinforcement.
PubMed: 38882316
DOI: 10.1016/j.heliyon.2024.e32094 -
ACS Omega Jun 2024In this study, the functionality of an elastomer composite material containing polypyrrole (PPy) as a stress sensor was evaluated. The material was prepared using the...
In this study, the functionality of an elastomer composite material containing polypyrrole (PPy) as a stress sensor was evaluated. The material was prepared using the swelling method by diffusing the pyrrole monomer into the elastomer before polymerization. To achieve adequate diffusion, organic solvents with affinity for the elastomer were used. The resulting materials were characterized by scanning electron microscopy (SEM), surface electrical resistance, and thermal and mechanical properties for application as a stress sensor. The simultaneous change in electrical resistance and tension stress was measured using a digital multimeter with electrodes connected to the jaws of a universal mechanical testing machine. The influence of stress cycles on the piezoresistivity of the composite materials was investigated. The obtained PPy/NBR composite presented a good combination of electrical conductivity and mechanical properties. The strain at break remained with mild variation after coating with PPy.
PubMed: 38882075
DOI: 10.1021/acsomega.4c02166 -
Anais Da Academia Brasileira de Ciencias 2024The blend of butadiene and acrylonitrile copolymer (NBR) with natural poly-cis-isoprene (NR) shows increased resistance to swelling in solvents in comparison to the... (Comparative Study)
Comparative Study
The blend of butadiene and acrylonitrile copolymer (NBR) with natural poly-cis-isoprene (NR) shows increased resistance to swelling in solvents in comparison to the individual components. In aerospace, NBR rubber is used as thermal protection for rockets and shall not contain other polymers, even in low contents, otherwise, it can affect the protection performance and rocket safety by causing detachment of the elastomer/propellant interface; therefore, this investigation presents methodologies to determine the NR/NBR contents. This study explores different analytical techniques, such as Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy, in the mid-infrared (MIR) by reflection and in the near-infrared by reflectance (NIRA) modes, Furthermore, quantification strategies by univariate, bivariate and multivariate (chemometric) models are evaluated and compared. A proposed methodology, based on multivariate Raman microscopy with partial least squares regression (PLS), showed high linearity (R2 > 0.99) and low error (< 0.82 %). The validation of FT-MIR data for the CH3, which presented lower error (1.3%) than vinylidene band (6%), showed that both methodologies (reflection and NIRA reflectance) can be used for the quantification of NR in NR/NBR. These results constitute a contribution to the state of the art in researching industrial and aerospace elastomeric applications.
Topics: Spectrum Analysis, Raman; Rubber; Spectroscopy, Fourier Transform Infrared; Butadienes
PubMed: 38865508
DOI: 10.1590/0001-3765202420230387 -
ACS Omega Jun 2024An unprecedented and efficient three-component 1,3-dipolar cycloaddition reaction using (2-(benzo[d]thiazol-2-yl)-3-(aryl)acrylonitriles - and an in situ generated...
Study on Regio- and Diastereoselectivity of the 1,3-Dipolar Cycloaddition Reaction of Azomethine Ylide with 2-(Benzo[]thiazol-2-yl)-3-(aryl)acrylonitrile: Synthesis, Spectroscopic, and Computational Approach.
An unprecedented and efficient three-component 1,3-dipolar cycloaddition reaction using (2-(benzo[d]thiazol-2-yl)-3-(aryl)acrylonitriles - and an in situ generated azomethine ylide from isatin and -methylglycine is described. The reaction exhibits exclusive regioselectivity, resulting in the formation of 3'-(benzo[]thiazol-2-yl)-1'-methyl-2-oxo-4'-(aryl)spiro[indoline-3,2'-pyrrolidine]-3'-carbonitriles regioisomers through / approaches. The diastereoselectivity of the reaction is highly dependent on the substitution pattern of the phenyl ring in dipolarophiles -, leading to the formation of /-cycloadducts in varying ratios. To understand the stereoselectivity, the transition state structures were optimized using the TS guess geometry with the QST3-based method. The reaction mechanism and regioselectivity were elucidated by evaluating global and local electrophilicity and nucleophilicity descriptors at the B3LYP/cc-pVTZ level of theory, along with considerations based on the HSAB principle. The analysis of global electron density transfer (GEDT) showed that the reactions are polar and electron density fluxes from azomethine ylide toward dipolarophile -. It was found from the molecular electrostatic potential map (MESP) that at the more favorable transition state, approach of reactants locates the oppositely charged regions over each other resulting in attractive forces between the two fragments. The computational results are consistent with the experimental observations, confirming that the reactions proceed through an asynchronous one-step mechanism.
PubMed: 38854577
DOI: 10.1021/acsomega.4c01552 -
Scientific Reports Jun 2024This study explores the mechanical properties and fracture characteristics of additively manufactured acrylonitrile butadiene styrene specimens, focusing on the impact...
This study explores the mechanical properties and fracture characteristics of additively manufactured acrylonitrile butadiene styrene specimens, focusing on the impact of raster angle and post-process heat treatment. To this end, a large number of tensile and semi-circular bending samples with three distinct raster angles of 0/90°, 22/ - 68°, and 45/ - 45° were prepared and exposed to four types of heat treatments with different temperature and pressure conditions. Simultaneously, theoretical models of maximum tangential stress (MTS) and generalized MTS (GMTS) were developed to estimate the onset of specimen fracture under mixed-mode in-plane loading conditions. Recognizing the non-linear behavior within the stress-strain curve of tensile test samples, particularly in the annealed samples, an effort was undertaken to transform the original ductile material into a virtual brittle material through the application of the equivalent material concept (EMC). This approach serves the dual purpose of bypassing intricate and tedious elastoplastic analysis, while concurrently enhancing the precision of the GMTS criterion. The experimental findings have revealed that while the annealing process has a minimal effect on the yield strength, it considerably enhances energy absorption capacity, increases fracture toughness, and reduces the anisotropy. Additionally, the combined EMC-GMTS criterion has demonstrated its capability to predict the failure of the additively manufactured parts with an acceptable level of accuracy.
PubMed: 38851832
DOI: 10.1038/s41598-024-64136-y -
Frontiers in Public Health 2024An increasing body of research has demonstrated a correlation between pollutants from the environment and the development of cardiovascular diseases (CVD). However, the...
INTRODUCTION
An increasing body of research has demonstrated a correlation between pollutants from the environment and the development of cardiovascular diseases (CVD). However, the impact of volatile organic chemicals (VOC) on CVD remains unknown and needs further investigation.
OBJECTIVES
This study assessed whether exposure to VOC was associated with CVD in the general population.
METHODS
A cross-sectional analysis was conducted utilizing data from five survey cycles (2005-2006, 2011-2012, 2013-2014, 2015-2016, and 2017-2018) of the National Health and Nutrition Examination Survey (NHANES) program. We analyzed the association between urinary VOC metabolites (VOCs) and participants by multiple logistic regression models, further Bayesian Kernel Machine Regression (BKMR) models and Weighted Quantile Sum (WQS) regression were performed for mixture exposure analysis.
RESULTS
Total VOCs were found to be positively linked with CVD in multivariable-adjusted models (p for trend = 0.025), independent of established CVD risk variables, such as hypertension, diabetes, drinking and smoking, and total cholesterol levels. Compared with the reference quartile of total VOCs levels, the multivariable-adjusted odds ratios in increasing quartiles were 1.01 [95% confidence interval (CI): 0.78-1.31], 1.26 (95% CI: 1.05-1.21) and 1.75 (95% CI: 1.36-1.64) for total CVD. Similar positive associations were found when considering individual VOCs, including AAMA, CEMA, CYMA, 2HPMA, 3HPMA, IPM3 and MHBMA3 (acrolein, acrylamide, acrylonitrile, propylene oxide, isoprene, and 1,3-butadiene). In BKMR analysis, the overall effect of a mixture is significantly related to VOCs when all chemicals reach or exceed the 75th percentile. Moreover, in the WQS models, the most influential VOCs were found to be CEMA (40.30%), DHBMA (21.00%), and AMCC (19.70%).
CONCLUSION
The results of our study indicated that VOC was all found to have a significant association with CVD when comparing results from different models. These findings hold significant potential for public health implications and offer valuable insights for future research directions.
Topics: Humans; Volatile Organic Compounds; Nutrition Surveys; Cardiovascular Diseases; Cross-Sectional Studies; Male; Female; Middle Aged; Adult; Environmental Exposure; Risk Factors; Air Pollutants; United States; Aged
PubMed: 38846604
DOI: 10.3389/fpubh.2024.1378444 -
Journal of Chemical Health & Safety May 2024The current technique to assess glove resistance to chemicals for worker protection relies on challenging a flat, 2.54 cm diameter glove piece at or near room...
The current technique to assess glove resistance to chemicals for worker protection relies on challenging a flat, 2.54 cm diameter glove piece at or near room temperature. This does not simulate a donned whole glove near the skin temperature subjected to work activity forces. Four different types of disposable nonpowdered unlined/unsupported nitrile gloves in triplicate were measured for thickness, porosity, and for the acrylonitrile content () of the challenge and collection sides. Limonene permeation at 35 °C through a whole glove on a clenching and nonclenching dextrous robot hand and with the standard ASTM F739 technique were facilitated by taking samples from the collection sides for GC-MS analysis. The standardized breakthrough time (SBT) when permeation reached 100 ng/cm/min and the steady state permeation rate (SSPR) depended on , thickness, and porosity. Only the thinnest glove (Lavender) showed statistically significant ( ≤ 0.05) increased average SSPR for the clenching hand relative to the nonclenching hand and for the ASTM technique. The ASTM test data for the three thickest gloves were not statistically different from those of the robot hand, but differed from the manufacturer's. More research with different chemicals and higher clenching forces is needed. Clenching forces can enhance the permeation. Workers wearing ultrathin disposable nitrile gloves have a higher potential for chemical penetration/permeation. Company glove permeation data obtained near room temperature may have a longer SBT and lower SSPR than in practice. Double gloving may be advisible in emergencies and for unknown chemicals when no appropriate thicker Chemical Protective glove is available.
PubMed: 38818310
DOI: 10.1021/acs.chas.3c00117 -
Polymers May 2024A new technique of additive prototyping filament volumetric nanostructuring based on the high-speed mechanical mixing of acrylonitrile-butadiene-styrene (ABS) copolymer...
A new technique of additive prototyping filament volumetric nanostructuring based on the high-speed mechanical mixing of acrylonitrile-butadiene-styrene (ABS) copolymer granules and single-walled carbon nanotube (CNT) powder (without prior dispersion in solvents) is considered. The morphological spectra of scanning electron microscopy (SEM) images of nanostructured filament slice surfaces were obtained and characterized with the original mathematical simulation. The relations of structural changes in the "ingredient-matrix" polymer system with dielectric and mechanical properties of the ABS-based filaments were established. The supplementation of 1.5 mass.% of CNT powder to the ABS filament composition leads to the tensile strength increasing from 36 ± 2 to 42 ± 2 MPa. It is shown that the greater the average biharmonic amplitude and the morphological spectrum localization radius of the slice surfaces' SEM images, the lower the electrical resistance of the corresponding nanostructured filaments. The possibility of carbon nanotube-modified filament functional layers forming using the extrusion additive prototyping technique (FFF) on the surface of plasma-chemically modified PET substrates (for the creation of load cell elements) is experimentally demonstrated.
PubMed: 38794615
DOI: 10.3390/polym16101423 -
Polymers May 2024It is generally recognized that the use of physical and digital information-based solutions for tracking plastic materials along a value chain can favour the transition... (Review)
Review
It is generally recognized that the use of physical and digital information-based solutions for tracking plastic materials along a value chain can favour the transition to a circular economy and help to overcome obstacles. In the near future, traceability and information exchange between all actors in the value chain of the plastics industry will be crucial to establishing more effective recycling systems. Recycling plastics is a complex process that is particularly complicated in the case of acrylonitrile butadiene styrene (ABS) plastic because of its versatility and use in many applications. This literature study is part of a larger EU-funded project with the acronym ABSolEU (Paving the way for an ABS recycling revolution in the EU). One of its goals is to propose a suitable traceability system for ABS products through physical marking with a digital connection to a suitable data-management system to facilitate the circular use of ABS. The aim of this paper is therefore to review and assess the current and future techniques for traceability with a particular focus on their use for ABS plastics as a basis for this proposal. The scientific literature and initiatives are discussed within three technological areas, viz., labelling and traceability systems currently in use, digital data sharing systems and physical marking. The first section includes some examples of systems used commonly today. For data sharing, three digital technologies are discussed, viz., Digital Product Passports, blockchain solutions and certification systems, which identify a product through information that is attached to it and store, share and analyse data throughout the product's life cycle. Finally, several different methods for physical marking are described and evaluated, including different labels on a product's surface and the addition of a specific material to a polymer matrix that can be identified at any point in time with the use of a special light source or device. The conclusion from this study is that the most promising data management technology for the near future is blockchain technology, which could be shared by all ABS products. Regarding physical marking, producers must evaluate different options for individual products, using the most appropriate and economical technology for each specific product. It is also important to evaluate what information should be attached to a specific product to meet the needs of all actors in the value chain.
PubMed: 38794535
DOI: 10.3390/polym16101343 -
Polymers May 2024Quantitative converse piezoelectric coefficient () mapping of polymer ultrafine fibers of poly(acrylonitrile) (PAN), as well as of poly(vinylidene fluoride) (PVDF) as a...
Quantitative converse piezoelectric coefficient () mapping of polymer ultrafine fibers of poly(acrylonitrile) (PAN), as well as of poly(vinylidene fluoride) (PVDF) as a reference material, obtained by rotating electrospinning, was carried out by piezoresponse force microscopy in the constant-excitation frequency-modulation mode (CE-FM-PFM). PFM mapping of single fibers reveals their piezoelectric activity and provides information on its distribution along the fiber length. Uniform behavior is typically observed on a length scale of a few micrometers. In some cases, variations with sinusoidal dependence along the fiber are reported, compatibly with a possible twisting around the fiber axis. The observed features of the piezoelectric yield have motivated numerical simulations of the surface displacement in a piezoelectric ultrafine fiber concerned by the electric field generated by biasing of the PFM probe. Uniform alignment of the piezoelectric axis along the fiber would comply with the uniform but strongly variable values observed, and sinusoidal variations were occasionally found on the fibers laying on the conductive substrate. Furthermore, in the latter case, numerical simulations show that the piezoelectric tensor's shear terms should be carefully considered in estimations since they may provide a remarkably different contribution to the overall deformation profile.
PubMed: 38794498
DOI: 10.3390/polym16101305