Environmental damage promoted trough post‐consumer waste from the wood industry has worried the society, while its inadequate disposal has raised concerns of the scientific community. Environmentally ...and economically effective alternative is reusing this residue to produce smart composites. Therefore, this work aimed to investigate the performance of polypropylene (PP)/Jatobá Wood Powder (WP) composites compatibilized with ethylene propylene diene monomer rubber‐maleic anhydride (EPDM‐MA). The effect of distinct melt flow index (MFI) (PP H103 and PP H503) was also investigated. The composites were characterized using differential scanning calorimetry, thermogravimetry, mechanical properties (tensile, flexural, impact, and Shore D hardness), heat deflection temperature, Vicat softening temperature, water absorption and scanning electron microscopy (SEM). Addition of EPDM‐MA, increased impact strength. The best performance was observed for the composition with 10% EPDM‐MA and PP with lower MFI (PP H503). EPDM‐MA also decreased the water absorption for both PP, most due to the chemical interactions among composite phases. SEM images suggest encapsulation of wood particles by EPDM‐MA, promoting better composites performance. Reported results are valuable for the recycling industry, as well as are economically and environmentally promising.
Low‐density biopolyethylene (BioLDPE) ecocomposites added with particles of eggshell (ES) residue were produced using linear low‐density polyethylene grafted with maleic anhydride (LDPE‐g‐MA) as a ...compatibilizing agent. BioLDPE/ES and BioLDPE/ES/LDPE‐g‐MA compounds were processed in a twin‐screw extruder, and the specimens were injection molded. Torque rheometry increased and melt flow index reduced more prominently for the BioLDPE/LDPE‐g‐MA biocomposite with 20 phr ES, suggesting higher viscosity. Consequently, there was a higher level of ES particles breakdown, generating greater distribution and dispersion, as verified in optical microscopy and scanning electron microscopy images. This finding was supported by Fourier transform infrared spectroscopy, considering the intense absorption band at 871 cm−1 for BioLDPE/ES (20 phr)/LDPE‐g‐MA biocomposite, indicating a higher level of ES particles dispersion in BioLDPE matrix. Therefore, BioLDPE/ES (20 phr)/LDPE‐g‐MA biocomposite increased the elastic modulus, tensile strength, Shore D hardness, and heat deflection temperature by 51.4%, 16.9%, 16.4%, and 14, 6%, respectively, related to BioLDPE. Additionally, the flexibility was kept as seen in the elongation at break and impact strength, including not fractured during the impact test. Reported results for the biocomposites are valuable mainly for the polymer additive sector, since the ES has the potential to improve BioLDPE properties, expanding the range of applications.
Eggshell processing produced an ecologically based additive, with great potential for manufacturing biopolyethylene matrix composites.
Bioengineering, which studies the principles and design of biological systems, is a field that has inspired the development of several technologies that are currently in use. In this work, we use ...concepts from the fish lateral line sensing mechanism and apply them to seismic imaging processing. The lateral line is a sensory system composed of an integrated array of mechanical sensors spanning along the fish body. We compare the array of sensors along body fish with the seismic acquisition, which employs an array of equally spaced identical mechanical sensors to image the Earth's subsurface. In both situations, the mechanical sensors capture and process mechanical vibrations from the environment to produce useful information. We explore the strategy of using the low-pass and high-pass sensors schema of fish lateral line to improve the seismic technique. We use the full-wave inversion method to compare the conventional acquisition procedure of identical sensors with alternative sets of different sensors, which mimics the fish lateral line. Our results show that the alternate sensors arrangement surpasses the performance of the conventional acquisition method, using just half of the input information. The results point at an image processing technique that is computationally more efficient and economical than the usual seismic processing method.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The study of cooling materials is essential to analyse the thermal properties of substances, electronic devices, among many others. The physical law for describing the temporal temperature decrease ...has been dominated by Newton’s law of cooling (NLC), which assumes that the natural cooling occurs by following an exact exponential trend. However, several studies have questioned the broad validity of this law by arguing that cooling occurs following an approximate rather than an exact exponential trend. In this way, to mitigate the difficulties of a reliable-description of the natural cooling processes, we introduce in this work a new formulation of NLC in the context of the q- and κ-calculus, which are obtained from the Tsallis q- and Kaniadakis κ-generalised statistical mechanics. The NLC in the Tsallis and Kaniadakis frameworks, in which we call q-NLC and κ-NLC, respectively, are derived from the related deformed derivative operators. The q- and κ-NLC describes the cooling process through the deformation of the ordinary exponential function. To empirically validate our proposal, we consider two real data sets: in the first one, a water-cooling case-study; and then, in the second one, the cooling of a power battery pack. The results show that the NLC based on generalised statistics outperform the classical NLC, which demonstrates a new path to cooling-analyses.
•We propose generalisations of the Newton’s law of cooling consistent with q- and κ-calculus.•Our proposal appropriately describes the natural cooling process with a power-law behaviour.•We consider real data to show the effectiveness of our proposal.
The chemical composition of surface geological materials may cause metabolic changes and promote endemic diseases (e.g., oncological, gastrointestinal, neurological or cardiovascular diseases). The ...results of a geochemical survey is presented following the guidelines proposed by the International Project IGCP 259 performed on the alluvium of Santiago Island (Cape Verde) and focused on public health issues. Geochemical mapping is the base knowledge needed to determine critical contents of potential toxic elements and the potentially harmful regions in the planet. This work presents maps of baseline values of potentially toxic elements (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn) in Santiago alluvium and the assessment of their human health risks. According to the results the Cd, Co, Cr, Ni and V baseline values are above the Canadian guidelines for stream sediments (for any proposal use) and for soils (for agricultural and residential proposal uses) and also above the target values of Dutch guidelines. Hazard indexes (HI) were calculated for children and adults. For children (HI) are higher than 1 for Co, Cr and Mn, indicating potential non-carcinogenic risk. For the other elements and for adults there is no potential non-carcinogenic risk. Cancer risk was calculated for Cd, Cr and Ni exposures, for adults and children, and the results are only slightly higher than the carcinogenic target risk of 1 × 10
for adults exposed to Cr by inhalation. However, these results may be underestimated because alluvial contaminants may be indirectly ingested by groundwater and by crop and vegetables consumption.
Acrylonitrile‐EPDM‐styrene (AES) was applied as an impact modifier for poly(lactic acid) (PLA), and the combined effect of dicumyl peroxide (DCP) crosslinking and annealing heat treatment was ...investigated. Torque rheometry, melt flow index (MFI), mechanical properties (impact, tensile, and Shore D hardness), X‐ray diffraction (XRD), infrared spectroscopy (FTIR), heat deflection temperature (HDT), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were investigated. There was a considerable torque increment and fluidity drop in the PLA/AES/DCP blends caused by the crosslinking process and the formation of PLA‐g‐AES. Consequently, the impact strength and elongation at break properties improved. As an engineering terpolymer, AES was decisive in maintaining high elastic modulus, Shore D hardness, and HDT values. The PLA/AES/DCP (0.8 phr) composition leaned towards a synergism of mechanical properties, gaining 505.6% and 264.8% in impact strength and elongation at break, respectively, compared to neat PLA. FTIR and XRD analysis revealed high crystallinity, with samples presenting large crystals. The higher crystallinity had a deleterious effect on the mechanical properties of the PLA/AES/DCP blends. However, there was a marked improvement in HDT and higher toughness compared to PLA. The results before and after annealing the PLA/AES/DCP (0.8 phr) blend are promising for constructing new semi‐biodegradable materials for additive manufacturing.
The crosslinking of the PLA/AES blend with dicumyl peroxide in the molten state formed a tough material, suggesting the formation of PLA‐g‐AES.
Bacteriostatic and bactericidal clays: an overview Gomes, Celso Figueiredo; Gomes, Jorge Hamilton; da Silva, Eduardo Ferreira
Environmental geochemistry and health,
11/2020, Letnik:
42, Številka:
11
Journal Article
Recenzirano
This article aims to draw an overview on the actual knowledge on bacteriostatic and bactericidal natural clays. Particular emphasis is given to the role of clay itself, the action of reduced metals ...located either in the structure of clay minerals or external to them as constituents of associate minerals, and the definition of the mechanisms of action based on the achievements found in all available studies being carried out so far. The term bactericidal is herein used when a clay or a clay mineral kill the bacteria, whereas the term bacteriostatic is used when those minerals stop bacteria growth and replication. The second part of this article deals with experimental studies on bactericidal natural clay, experience and perspective for the preparation of bactericidal natural clays, interesting on the authors perspective and experience for the preparation of pathogens safe both therapeutic and cosmetic
natural mud/natural peloid
, and better yet of both therapeutic 87oooand cosmetic
peloid itself
and
designed and engineered peloid
. The authors also show how to convert non-antimicrobial clay into antimicrobial one, opening the way in the field of
pelotherapy
to the preparation of sanitary safe peloids addressed, for instance, to the treatment of rheumatic disabilities, as well as to the preparation of
antimicrobial peloids
and, in particular, of dermatological ointments, all able to fight infectious skin disorders.
Herein, we prepared toughened and electrical nanocomposites of polyamide 6 (PA6)/acrylonitrile‐butadiene‐styrene (ABS) compatibilized with maleic anhydride‐grafted acrylonitrile‐butadiene‐styrene ...(ABS‐MA). Functionalized multi‐walled carbon nanotubes (MWCNTf) were used as conductive nanofillers. Nanocomposites were processed in an internal mixer and injection molded. Torque rheometry, impact strength, elastic modulus, heat deflection temperature (HDT), differential exploratory calorimetry (DSC), melting and crystallization kinetic curves, electrical conductivity, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were evaluated. Torque increased with the MWCNTf content in the PA6/ABS/ABS‐MA/MWCNTf nanocomposites, suggesting an increase in viscosity. The MWCNTf were well dispersed in the nanocomposites, generating an electrical percolation path. The impact strength of the PA6/ABS/ABS‐MA/MWCNTf nanocomposites was superior to that of pure PA6, indicating improved flexibility and toughness. The addition of 1 pcr of MWCNTf in the PA6/ABS/ABS‐MA system was sufficient for antistatic application, with a 221% higher impact strength, compared to pure PA6. The DSC studies showed that the crystallization temperature of the nanocomposites shifted to higher temperatures. This was due to the MWCNTf that accelerated crystallization. Additionally, the nanocomposites HDT increased by 20°C compared to the PA6 matrix, suggesting a superior thermomechanical strength. The developed nanocomposites show improved mechanical, electrical, and thermomechanical properties. Therefore, they exhibit great technological potential for application in antistatic packaging.
Schematic representation of the preparation of electrical and toughed nanocomposites.
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