Search

The present work investigates factors which control the stress generated at the back face of end wall-mounted shock-loaded aluminum foam. When the applied shock pressure is higher than the plastic strength of the foam, the foam deforms plastically generating a compaction wave traveling below shock velocity. Wave reflection and momentum transfer at the end wall result in shock amplification. With increasing foam length, the stress at the end wall decreases, finally leading to shock mitigation. A relation between compaction wave characteristics, foam densification, and stress generated at the end wall is established. [ABSTRACT FROM AUTHOR]

An effective type of polymer heat-insulating material (foams) based on reactive oligomers is casting epoxy foams with high technological and operational parameters. However, polyepoxide foams are highly flammable, which significantly restrains their application in the construction industry. The aim of this work was to develop effective methods for reducing the flammability of filling epoxy foams. In order to achieve the objective, the following objectives were addressed: determining the influence of the chemical nature and content of additive and reactive bromine- and phosphorus-containing compounds on the thermal stability, flammability and operational properties of filling epoxy foams, and the development of polyepoxy foams of reduced flammability with high-quality physical and mechanical characteristics. When estimating the flammability of epoxy foams, we used both state-approved methods and the methods described in scientific and technical literature. The thermal properties of epoxy foams were studied with the help of multimodular thermoanalytical complex DuPont-9900. The data on the influence of the apparent density of foams and oxygen concentration in the oxidant flow on the flame propagation speed on the horizontal surface of polyepoxy foams are presented. It was revealed that the chemical nature of amine hardeners does not affect the thermal stability and flammability of epoxy foams. It was established that phosphate plasticizers are ineffective flame retardants of foamed epoxy resin, and the chemical structure of additive organobromic flame retardants insignificantly affects their efficiency. It was shown that microencapsulated flame retardants are inferior in flame retardant efficiency to additive flame retardants. It was found that effective flame retardants for casting polyepoxy foams are phosphorus-containing oligoether methacrylate and epoxidized waste from the production of tetrabromodiphenylpropane. The results of this research will form the basis for the production of an experimental industrial batch of samples of pouring epoxy foams of reduced flammability. [ABSTRACT FROM AUTHOR]

Polyethersulfone (PES) is distinguished by its exceptional comprehensive properties, making it a highly valued engineering plastic employed in various cutting‐edge fields. However, the high cost of PES limits its wider application in industrial fields. Considering the cost‐reduction advantages of polymer foaming, PES foams were successfully prepared in this work using microcellular injection molding (MIM) and micro‐opening microcellular injection molding (MOMIM) foaming methods. Compared with the MIM foaming method, the PES foam samples prepared by the MOMIM foaming method have better microcellular structure and surface quality. As the micro‐opening distance increased, the cell density of the PES foam samples showed a gradual rise before plateauing, with the cell size remaining relatively constant. As a result, the density of the PES foam sample dropped to 1.07 g/cm3, which is 80.5% of the solid PES sample. Meanwhile, the mechanical properties of the PES foam samples remained robust, with both the specific flexural modulus and the specific flexural strength showing increases as the micro‐opening distance increased. The knowledge obtained from this study provides a method for preparing high‐performance PES foam materials, which will facilitate the application of PES in more civilian fields. [ABSTRACT FROM AUTHOR]

As one of the mainstream biodegradable materials, poly(butylene adipate-co-terephthalate) (PBAT) foams offer a sustainable alternative to traditional plastic foams, effectively reducing environmental pollution. However, the high cost and poor mechanical performance of PBAT foams impede their practical application. Herein, the glycidyl methacrylate-grafted biomass lignin (GML) was used to produce a PBAT/GML composite foam with good foaming performance and mechanical properties at high lignin-filling amounts by twin-screw melting free radical polymerization and supercritical CO2 foaming process. The compatibility of GML in the PBAT matrix was improved due to the formation of ester bonds in modified lignin, endowing the PBAT/GML (PGML) composite foam with exceptional foaming performance. Additionally, the mechanical properties of PGML composite foam were remarkably enhanced due to the introduction of the abundant aromatic structures of GML and the construction of a stable covalent crosslinking network. The compressive strengths and compression modulus of the PGML foam were improved by 2.53 times and 2.47 times, while its bending strength and bending modulus were improved by 1.27 times and 3.92 times compared to the neat PBAT. This research affords a new strategy for developing low-cost biodegradable biomass PBAT/lignin composite foam materials with good foaming performance and mechanical properties. [ABSTRACT FROM AUTHOR]

Environment plastic accumulation has been attracting the attention of both political and scientific communities, who wish to reduce global pollution. Plastic items have been detected everywhere, from oceans to the air, raising concerns about the fate of plastics within organisms. Leaked plastics are ingested by animals, entering the food chain and eventually reaching humans. Although a lot of studies focused on the evaluation of plastic particles in the environment and living organisms have already been published, the behavior of plastic at the cellular level is still missing. Here, we analyzed the bioaccumulation and extrusion trend of two differently sized plastic particles (1 and 2 µm), testing them on three human epithelial cell lines (liver, lung, and gut) that represent epithelial sites mainly exposed to plastic. A different behavior was detected, and the major plastic uptake was shown by liver cells, where the 1 µm beads accumulated with a dose-dependent profile. Moreover, a 60% reduction in the content of 1 µm particles in cells was evaluated after plastic removal. Finally, the viability and proliferation of the three human cell lines were not significantly affected by both the 1 and 2 µm beads, suggesting that cells might have a defense mechanism against plastic exposure risk. [ABSTRACT FROM AUTHOR]

Nowadays, if one wants to renovate or build a building, the question of thermal insulation is an essential construction process. Polyurethane is a key thermal insulation material that belongs to plastic foams. It can be applied as a spread or board heat-insulating material. Its thermal insulation properties are superior compared to polystyrene, but still a bit neglected. In this article, we would like to perform thermal investigations executed on a new type of polymeric foam such as polyisocyanurate. We will present acceptably low thermal conductivity (~ 0.022 W m-1 k-1), raised specific heat capacity (~ 1400 J kg-1 K-1) and calorimetric (bomb and differential) measurement results completed with optical microscopic images. Moreover, scanning electron microscopic analysis and X-ray diffractometry will be also presented. The results will be used for cost calculations applied by buildings and will show justified reasons for its application based on structural measurements too. The results are extremely encouraging. [ABSTRACT FROM AUTHOR]

Highlights Interpenetrating phase composites (IPCs) can combine the advantages of each component and have a good application prospect. IPCs were prepared by combining open‐cell aluminum foam (AF) and epoxy resin (EP) in three‐dimensional space in this study. Different contents of silica powder (SP, 80, 100, 120, and 140 wt%) were added to EP to improve the compressive and three‐point bending properties of IPCs. In the bending test, acoustic emission (AE) was applied to track the bending deformation of the samples, and k‐means clustering algorithm was applied to identify the damage modes. The compressive and bending properties of IPCs increased first and then decreased with the increase of SP content, and reached the maximum when the SP content was 100 wt%, with a compressive yield strength of 74.6 MPa and a bending peak load of 1.96 kN. The performance degradation was mainly attributed to the AF/EP debonding due to SP distribution at the interface. The X‐type shear band and EP/AF debonding appeared in compression failures of AF and IPCs, respectively. The AE clustering results showed that under bending load, plastic deformation of matrix (60–200 kHz) and fracture failure (230–340 kHz) modes appeared in AF, while EP/AF debonding (60–120 kHz), EP failure (120–230 kHz) and plastic deformation of foam matrix (230–250 kHz) modes appeared in IPCs. Silica powder was added to improve compressive and bending properties of IPCs. Acoustic emission was used to monitor bending of foam and IPCs firstly. k‐means clustering was used to identify and classify bending damage patterns. [ABSTRACT FROM AUTHOR]

Research on nanocellular foams is motivated in part by the promise of physical properties, in particular mechanical properties, that can go beyond the classical mechanical framework. However, due to the difficulty in obtaining foams of a given density but different cell sizes, determining the effect of cell size on the mechanical properties of polymer foams remains a challenge. To overcome this difficulty, studies on the mechanical behaviour of mesocellular, microcellular and nanocellular polymer foams have been compiled in this review article. After describing the different cellular structures between meso-, micro- and nanocellular foams, the mechanical properties are examined as a function of relative density and cell size. It is shown that for small strains and at low strain rates, nanocellular foams exhibit mechanical behaviour predicted by the Gibson and Ashby model. Relative density remains the first important factor to be taken into account when studying the Young's modulus and buckling stress of nanocellular foams. The focus then shifts to fracture properties, as microcellular foams have already been shown to be far superior to more conventional foams. As studies are still scarce and different methodologies have been used, no general conclusions can be drawn. However, the fracture and impact properties could be greatly improved by this change in scale. The local confinement of molecular chains in polymeric nanocellular foams or the relaxation of the triaxial stress state in front of the crack tip could explain these observations. [ABSTRACT FROM AUTHOR]

Abstract Plastic foams, near-ubiquitous in everyday life and industry, show properties that depend primarily on density. Density measurement, although straightforward in principle, is not always easy. As such, while several methods are available, plastic foam industry is not yet supported with a standard technique that effectively enables to control density maps. To overcome this issue, this paper proposes Terahertz (THz) time-of-flight imaging using normal reflection measurements as a fast, relatively cheap, contactless, non-destructive and non-dangerous way to map plastic foam density, based on the expected relationship between density and refractive index. The approach is demonstrated in the case of polypropylene foams. First, the relationship between the estimated effective refractive index and the polypropylene foam density is derived by characterizing a set of carefully crafted samples having uniform density in the range 70–900 kg/m3. The obtained calibration curve subtends a linear relationship between the density and the refractive index in the range of interest. This relationship is validated against a set of test samples, whose estimated average densities are consistent with the nominal ones, with an absolute error lower than 10 kg/m3 and a percentage error on the estimate of 5%. Exploiting the calibration curve, it is possible to build quantitative images depicting the spatial distribution of the sample density. THz images are able to reveal the non-uniform density distribution of some samples, which cannot be appreciated from visual inspection. Finally, the complex spatial density pattern of a graded foam sample is characterized and quantitatively compared with the density map obtained via X-ray microscopy. The comparison confirms that the proposed THz approach successfully determines the density pattern with an accuracy and a spatial scale variability compliant with those commonly required for plastic foam density estimate.

A type of foamed plastic insulation that improves thermal performance while maintaining the original durability by adding fillers with low radiation rates in foamed plastic insulation is investigated. The thermal conductivity of extruded polystyrene foam (XPS) adding graphite is reduced by 14% compared to without graphite additives. The study investigates that mechanism by comparing the properties of XPS and XPS containing graphite (graph XPS) through the gas isotherm method and 3D imaging analysis by X‐ray CT. First, the specific surface area of the insulation's resin is examined through the gas isotherm method using N2, H2O, and CO2. The results confirmed that graph XPS has a more increased specific surface area than XPS. Second, the internal structure of the insulation and its strut/pore distribution is confirmed through X‐ray CT, which showed an increase in surface area with a thinning of the strut. The improved thermal performance due to the addition of graphite may contribute to an increase in the surface area of the insulation. [ABSTRACT FROM AUTHOR]

Copyright of Jurnal Ilmu dan Teknologi Kelautan Tropis is the property of IPB University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plastic foams, near-ubiquitous in everyday life and industry, show properties that depend primarily on density. Density measurement, although straightforward in principle, is not always easy. As such, while several methods are available, plastic foam industry is not yet supported with a standard technique that effectively enables to control density maps. To overcome this issue, this paper proposes Terahertz (THz) time-of-flight imaging using normal reflection measurements as a fast, relatively cheap, contactless, non-destructive and non-dangerous way to map plastic foam density, based on the expected relationship between density and refractive index. The approach is demonstrated in the case of polypropylene foams. First, the relationship between the estimated effective refractive index and the polypropylene foam density is derived by characterizing a set of carefully crafted samples having uniform density in the range 70–900 kg/m3. The obtained calibration curve subtends a linear relationship between the density and the refractive index in the range of interest. This relationship is validated against a set of test samples, whose estimated average densities are consistent with the nominal ones, with an absolute error lower than 10 kg/m3 and a percentage error on the estimate of 5%. Exploiting the calibration curve, it is possible to build quantitative images depicting the spatial distribution of the sample density. THz images are able to reveal the non-uniform density distribution of some samples, which cannot be appreciated from visual inspection. Finally, the complex spatial density pattern of a graded foam sample is characterized and quantitatively compared with the density map obtained via X-ray microscopy. The comparison confirms that the proposed THz approach successfully determines the density pattern with an accuracy and a spatial scale variability compliant with those commonly required for plastic foam density estimate. [ABSTRACT FROM AUTHOR]

Poly(propylene carbonate-co-phthalate) (PPC-P) is an amorphous copolymer of aliphatic polycarbonate and aromatic polyester; it possesses good biodegradability, superior mechanical performances, high thermal properties, and excellent affinity with CO2. Hence, we fabricate PPC-P foams in an autoclave by using subcritical CO2 as a physical blowing agent. Both saturation pressure and foaming temperature affect the foaming behaviors of PPC-P, including CO2 adsorption and desorption performance, foaming ratio, cell size, porosity, cell density, and nucleation density, which are investigated in this research. Moreover, the low-cost PPC-P/nano-CaCO3 and PPC-P/starch composites are prepared and foamed using the same procedure. The obtained PPC-P-based foams show ultra-high expansion ratio and refined microcellular structures simultaneously. Besides, nano-CaCO3 can effectively improve PPC-P's rheological properties and foamability. In addition, the introduction of starch into PPC-P can lead to a large number of open cells. Beyond all doubt, this work can certainly provide both a kind of new biodegradable PPC-P-based foam materials and an economic methodology to make biodegradable plastic foams. These foams are potentially applicable in the packaging, transportation, and food industry. [ABSTRACT FROM AUTHOR]

In this paper, a new foam concrete-extruded polystyrene composite wall panel (FCPW) is proposed. In order to investigate the response of these wall panels to the loading conditions that may occur during an earthquake event, a total of three specimens were designed in this study to study the seismic performance of the wall panels with different sizes of cyclic loads applied to them. By analyzing the seismic parameters such as hysteresis curve, skeleton curve, ductility and stiffness degradation factor of the wall panels, it is concluded that the wall panels have good seismic performance. Both the test phenomenon and damage mechanism indicate that shear damage is the damage form of the specimen. Comparing the specimens, it can be seen that the height-to-width ratio and the strength of the specimen itself have obvious effects on the seismic performance. The larger the height-to-width ratio is, the larger the ductility is and the better the seismic performance is. The smaller the thickness of the concrete is, the smaller the ductility is and the worse the seismic performance is. This study helps to update the iteration of composite wall panels composed of extruded plastic board and concrete and provide a reference for future research. [ABSTRACT FROM AUTHOR]

The paper is a contribution of authors to the knowledge enrichment on the recent development of the new manufacturing technique of wood foam for packaging excluding plastics in its preparation mixture. Given that there is only one industrial manufacturer in the world of this type of wood foam with excellent heat-insulating properties, the current work presents an original method of its production using raw materials different from those applied in the industrial manufacturing recipe. Oak and beech wood waste, bentonite clay as a nanomaterial, calcium lignosulfonate as a surfactant, and distilled water were materials chosen by authors. The features of the new optimal product were density of 0.06 g·cm-3, heat conductivity of 0.027 W·m-1·K-1, porosity of 94.1 %, and compression strength of 985 kPa, being approximately similar by comparison with industrial products. [ABSTRACT FROM AUTHOR]

Poly(lactide acid) (PLA) foams have shown considerable promise as eco-friendly alternatives to nondegradable plastic foams, such as polystyrene (PS) foams. Nevertheless, PLA foam typically suffers from low heat-resistance and poor cellular structure stemming from its inherent slow crystallization rate and low melt strength. In this study, a high-performance PLA foam with well-defined cell morphology, exceptional strength and enhanced heat-resistance was successfully fabricated via a core-back microcellular injection molding (MIM) process. Differential scanning calorimetry (DSC) results revealed that the added hydrazine-based nucleating agent (HNA) significantly increased the crystallization temperature and accelerated the crystallization process of PLA. Remarkably, the addition of a 1.5 wt% of HNA led to a significant reduction in PLA's cell size, from 43.5 µm to 2.87 µm, and a remarkable increase in cell density, from 1.08×107 cells/cm3 to 2.15×1010 cells/cm3. This enhancement resulted in a final crystallinity of approximately 55.7% for the PLA blend foam, a marked improvement compared to the pure PLA foam. Furthermore, at 1.5 wt% HNA concentration, the tensile strength and tensile toughness of PLA blend foams demonstrated remarkable improvements of 136% and 463%, respectively. Additionally, the Vicat softening temperature of PLA blend foam increased significantly to 134.8 °C, whereas the pure PLA foam exhibited only about 59.7 °C. These findings underscore the potential for the preparation of lightweight injection-molded PLA foam with enhanced toughness and heat-resistance, which offers a viable approach for the production of high-performance PLA foams suitable for large-scale applications. [ABSTRACT FROM AUTHOR]

Shrinking resources of fossil oil prompt search for other biosphere‐present substrates to obtain polyols, which in turn are basic components to synthesize polyurethane foams (PUF). Widely available examples are biopolymers like starch, cellulose, and chitosan. It has been shown that oligomeric chitosan as well as water soluble chitosan can be applied to obtain polyols and rigid PUF of good performance properties. In this paper, the higher molecular mass chitosans, insoluble in organic solvents and water, were converted to polyols and ultimately into foamed polyurethane plastics. The polyols were characterized by the infrared spectra (IR), 1H‐NMR, and MALDI‐ToF methods. Their properties, such as density, viscosity, surface tension and hydroxyl numbers, were determined. The PUF were obtained from these polyols of various molecular mass. The biodegradable, rigid PUF of enhanced thermal resistance were obtained. Their physical parameters like apparent density, water volume absorption, dimension stability, heat conductance, compressive strength, and heat resistance at 150 and 175°C were studied and compared with those synthesized previously from oligomeric chitosan and water soluble chitosan. [ABSTRACT FROM AUTHOR]

A metallic foam specimen was plastically joined with a resin (polymethyl methacrylate, PMMA) sheet by applying friction stir incremental forming (FSIF) process. In FSIF process, a rotating flat-ended (no probe) rod tool was pushed vertically and fed horizontally against the resin sheet which was placed on the foam. The tool operation heated frictionally the resin and deformed incrementally to the resin, while the tool operation did not deform plastically to the cellular matrix of the foam. Due to the plastic flow of the heated resin, the bottom of the resin was interlocked mechanically to the pores near the top surface of the foam. In this study, the relationship between the pore morphology (form and size) and the joining characteristics (joinability, flow thickness of the resin, and joining strength) was investigated using commercial open-cell nickel and closed-cell aluminum foams. According to the experimental investigations, the foam with small size and low depression angle of the surface pore showed better results in relation with the joining strength and the (flow thickness of the resin)/(depth of the surface pore). [ABSTRACT FROM AUTHOR]

The disposal of plastic foam, mostly composed of polystyrene, poses significant environmental challenges due to its high popularity, slow degradation, and low cost. To address this problem, recycling polystyrene foam waste (PF) has emerged as a promising solution to reduce plastic pollution. This paper presents a novel approach to mass‐produce highly ordered, porous honeycomb‐patterned film (hc‐film) using wasted PF as the raw material. The hc‐film is produced using an improved phase separation (IPS) method that utilizes methanol as a suitable pore inducer and template droplet stabilizer. Methanol provides the hc‐film with customizable features such as pore ordering, size, and separation. The freestanding hc‐film, achieved by adopting a water‐soluble polystyrene sulfonate as a scarified layer, can be transferred and utilized as a flexible mold to pattern various solid substrates with complicated surface morphologies using the pre‐impregnated technique. This study demonstrates the potential of this cost‐effective and efficient approach for various applications, such as super/anti‐wetting surfaces, microelectronics, optical devices, sensors, and nanogenerators. [ABSTRACT FROM AUTHOR]

In this study, the double-layered thermo-expandable microcapsules with n-hexane as the core and styrene maleic anhydride copolymer (SMA) / polyurea (PUA) as the shell materials are prepared by combination of interfacial polymerization and co-precipitation method. The successful encapsulation of n-hexane in the PUA microcapsules is confirmed by simultaneous thermal analyzer (TG-IR). The properties of the thermo-expandable microcapsules (TEMs) are investigated by thermo-gravimetric analyzer (TGA), laser particle size analyzer, optical microscope and thermo-mechanical analyzer (TMA), respectively. The results show that polyurea shows a good encapsulation effect on n-hexane. When the dosage of n-hexane is 60 wt%, the microcapsules with polyurea as the shell have the encapsulation efficiency as high as 96.7%. However, the thermo-expandable performance of PUA-TEMs is poor. Double-layered thermo-expandable microcapsules with SMA/PUA as the shell (SMA/PUA-TEMs) are then obtained by introducing SMA copolymer as a second layer to enhance the thermo-expandable performance of the microcapsules. The introduction of styrene-maleic anhydride copolymer onto the PUA-TEMs reduces the encapsulation amount of n-hexane in the microcapsules, but the thermo-expandable performance is significantly improved. When the mass ratio of SMA to PUA-TEMs is 2:1, the SMA/PUA-TEMs with the encapsulation efficiency of n-hexane of 41.1% and the particle size of about 2.5 μm are obtained. SMA/PUA-TEMs show onset and peak expansion temperatures of 195 and 216 °C, respectively, and the expansion ratio of 2.4 time. The tentative investigation of the foaming performance of the SMA/PUA thermo-expandable microcapsules in polyvinyl butyral matrix shows that the thermo-expandable microcapsules can be well dispersed in the polymer matrix and have good expandable performance. This study provides a novel kind of thermo-expandable microcapsules with high onset and peak expansion temperatures which are beneficial to produce plastic foam with high Tg or Tm. [ABSTRACT FROM AUTHOR]

Single-use plastic foams are used extensively as interior packaging to insulate and protect items during shipment but have come under increasing scrutiny due to the volume sent to landfills and their negative impact on the environment. Insulative compression molded cellulose fiber foams could be a viable alternative, but they do not have the mechanical strength of plastic foams. To address this issue, a novel approach was used that combined the insulative properties of cellulose fiber foams, a binder (starch), and three different reinforcing paperboard elements (angular, cylindrical, and grid) to make low-density foam composites with excellent mechanical strength. Compression molded foams and composites had a consistent thickness and a smooth, flat finish. Respirometry tests showed the fiber foams mineralized in the range of 37 to 49% over a 46 d testing period. All of the samples had relatively low density (Dd) and thermal conductivity (TC). The Dd of samples ranged from 33.1 to 64.9 kg/m3, and TC ranged from 0.039 to 0.049 W/mk. The addition of starch to the fiber foam (FF+S) and composites not only increased Dd, drying time (Td), and TC by an average of 18%, 55%, and 5.5%, respectively, but also dramatically increased the mechanical strength. The FF+S foam and paperboard composites had 240% and 350% higher average flexural strength (σfM) and modulus (Ef), respectively, than the FF-S composites. The FF-S grid composite and all the FF+S foam and composite samples had equal or higher σfM than EPS foam. Additionally, FF+S foam and paperboard composites had 187% and 354% higher average compression strength (CS) and modulus (Ec), respectively, than the FF-S foam and composites. All the paperboard composites for both FF+S and FF-S samples had comparable or higher CS, but only the FF+S cylinder and grid samples had greater toughness (Ωc) than EPS foam. Fiber foams and foam composites are compatible with existing paper recycling streams and show promise as a biodegradable, insulative alternative to EPS foam internal packaging. [ABSTRACT FROM AUTHOR]

With concern growing regarding the impact of microplastics (MPs) on terrestrial ecosystems, it is important to assess the role invertebrates may play in the fate of MPs within these ecosystems. Commonly, MPs enter these environments through improperly discarded waste or the application of treated biosolids and/or wastewater on agricultural soils. The present study investigated whether three species of terrestrial isopod (Porcellio scaber, Porcellio laevis, and Porcellionides pruinosus) ingest plastic debris and generate MPs during exposures varying from 24 h to 14 days and whether this may have an adverse effect on their health. Test vessels were designed to expose isopods to plastic fragments in the form of polyethylene plastic foam. Isopods were exposed to plastic that was either (1) pristine, or (2) weathered in a soil and water solution prior to incorporation in test vessels. When exposed to weathered polyethylene, all three species generated MPs (minimum–maximum size values for all durations inclusive: P. laevis = 114–1673 µm, P. scaber = 99–1635 µm, P. pruinosus = 85–1113 µm) through the consumption of macroplastic fragments with no observed impact on their health. In the shorter‐duration exposures, the number of MPs generated by the isopod species in the present study was highly variable between experimental vessels (minimum–maximum generated MPs for 14‐day exposure: P. laevis = 25–420, P. scaber = 50–583, P. pruinosus = 48–311). However, as the exposure durations increased, there was a clear trend of increasing MP generation, indicating that the isopods continued to consume the plastic fragments as long as the surface was weathered. A significant difference in the size of generated MPs was observed as well, with smaller isopod species generating smaller MP fragments on average. The results of the present study confirm that certain species of isopod can contribute to the generation of MPs, which constitutes an additional pathway of MP exposure to soil ecosystems. Environ Toxicol Chem 2024;43:784–792. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

This article presents an improved and extended modeling approach for acoustic wave propagation in rigid porous materials, focusing on examples, such as plastic foams used for noise reduction in automotive applications. We demonstrate that the classical model (Johnson-Champoux-Allard) in the asymptotic high-frequency limit, widely employed in the literature, fails to accurately reconstruct the transmitted acoustic signal through high absorbent porous materials characterized by significant wave attenuation. The study focuses on the airborne ultrasonic frequency range (30–200 kHz). To address this limitation, we introduce new non-acoustic parameters Σ and V for viscous effects, and Σ ′ and V ′ for thermal effects, with surface and volumetric dimensions, respectively, allowing for the reconstruction of the transmitted signal and accurate modeling of the pronounced acoustic attenuation within the material. These parameters are incorporated into the expansion on skin depths of the dynamic tortuosity α(ω) and thermal tortuosity α ′ (ω) response functions, which describe the inertial-viscous and thermal interactions between the fluid and the solid, respectively. This novel modeling approach enables a more comprehensive study of high attenuating porous media, which are crucial for effective noise reduction. Additionally, it opens up new possibilities for characterization beyond the capabilities of current models. [ABSTRACT FROM AUTHOR]

Upgrading cyclohexanone to ϵ‐caprolactone (ϵ‐CL) is of great importance to the synthesis of high value‐added downstream chemicals and the reduction of foam plastic. The catalytic synthesis of ϵ‐CL from cyclohexanone through O2/aldehyde method is an environmentally benign one‐pot tandem reaction without using peroxy acid, balancing the requirements of safety and efficiency. However, due to lack of elaborate design and collaboration of multiple active sites for catalysts, the catalytic efficiency of O2/aldehyde method still remains to be improved. Herein, a pitaya‐like catalyst (CeFe@RDC‐3) with Ce and Fe highly dispersed on resin‐derived‐carbon is synthesized through high temperature self‐assembly. On this bimetallic catalyst, high yield (97 %) of ϵ‐CL is achieved through aerobic oxidation of cyclohexanone with only 1.5 equivalent benzaldehyde. Moreover, considerable yields of ϵ‐CL, 88.3 % and 74.7 %, respectively, are also obtained over CeFe@RDC‐3 with green solvent (EtOAc) or even without solvent. No loss of activity is observed after five successive cycles, demonstrating high stability of CeFe@RDC‐3. The mechanism study reveals that the high performance of CeFe@RDC‐3 is ascribed to the Ce−Fe bimetallic synergy, uniform metal dispersion, abundant active oxygen and stabilizing effect of resin‐derived‐carbon to free radicals. This work provides prospect for a green, safe and low‐cost strategy for Baeyer‐Villiger process. [ABSTRACT FROM AUTHOR]

Due to its chemical structure and the resulting dielectric properties, the processing of the commonly used particle foam material, expanded polypropylene (ePP), is limited. Processing within the radio-frequency welding process is therefore only possible with the use of processing aids. In this paper, a new approach for the use of a solid and dielectric heatable coating for the production of three-dimensional welded components out of ePP is presented. For this purpose, three different types of water-soluble polymer polyvinyl alcohol (PVA) were analyzed as potential coating materials. The thermal and dielectric properties of the coating were further adjusted by a modification with glycerol. The maximum amount of glycerol tested was 25% by volume. It influences both the temperature development in the radio-frequency (RF) welding process as well as the adhesive bond between the ePP foam particles. It is shown that the 120 °C approach in the RF welding process resulted in a cohesive bond between the coating layers. In this way, bonded plates can be produced. In mechanical tests with compression of 20%, the manufactured plates show sufficient load capacity. Furthermore, it can be shown that a separation of PVA and ePP by type, and thereby a separation of the foam particles, is possible with the use of hot water. This might open a new way for recycling of particle foams. [ABSTRACT FROM AUTHOR]

The object of research is the «boiler plant – heat consumers – environment» system, which is caused, in particular, by high fuel consumption by city boilers serving high-rise residential buildings, including a significant number of buildings of an outdated housing stock, which are characterized by a low level of energy saving. One of the most problematic areas is the increase in emissions of pollutants and greenhouse gases into the atmosphere by boiler units and other power plants, especially during the heating season. In the course of the research, an assessment and analysis of the level of pollution of the city’s atmosphere by emissions from boiler plants, taking into account background pollution, and an analysis of the normative calculation method for determining emissions of pollutants into the atmosphere from power plants were used. The theoretical justification of the method of operational determination of current emissions of urban boiler houses and indicators of their energy-ecological efficiency based on current daily fuel consumption recorded during the entire heating season is also given, with a simultaneous assessment of the energy efficiency of fuel use and the degree of ecological hazard of emissions. The essence of the method is to use the indicator (energy-ecological index) introduced by the authors – K. This indicator simultaneously characterizes the multiplicity of exceeding both the current fuel consumption and the corresponding current emissions of pollutants by the boiler room, relative to their reference (reference) values determined once at the beginning of the heating season at an ambient air temperature of about 8 °C. The proposed temperature method for determining the K index before and after the implementation of both resource-saving technologies and technologies for protecting the atmosphere from emissions in the «boiler plant – heat consumers – environment» system allows to evaluate their effectiveness by the level of reduction in the value of the index, compared to its previous value, that is, to implementation obtained under similar conditions. It has been proven that in order to obtain a tangible energy-ecological effect at the level of a large city from its technology of warming the walls of buildings, its mass centralized implementation is necessary, both for individual high-rise buildings and on the scale of existing residential neighborhoods. For the reconstruction of existing facades, it is proposed to use current industrial technologies for warming the walls of buildings, which are used in new buildings, which are based on the use of mineral wool, in particular ISOVER-plaster. Insulation of walls with ISOVER-plaster will have the following advantages compared to foam plastic: thermal conductivity coefficient – 0.034 W/m·K, against 0.048 W/m·K for foam plastic. When using plates with a thickness of 100 mm ISOVER-plaster is expected to reduce heat loss to approximately 2.8 %, against 2.17 % obtained for foam plastic, which will provide a correspondingly greater energy and ecological effect. [ABSTRACT FROM AUTHOR]

Polyformaldehyde (POM) and Polyamide 66 (PA66) are engineering plastics with excellent mechanical properties and thermal stability. Producing microcellular injection molded POM and PA66 parts with high dimensional accuracy would be beneficial to reduce material cost and product quality. In this research, foamed POM and PA66 gear parts were fabricated by using microcellular injection molding with supercritical nitrogen as the blowing agent. Compared to conventional injection molded parts (parts that foaming is not involved), the foamed POM and PA66 gear parts achieved 5% and 10% average weight reduction, respectively. The foamed parts displayed a lower shrinkage ratio when compared to the solid counterparts, which was attributed to the cell expansion that offset part of the inward shrinkage stress. Moreover, POM gear parts with a higher crystallinity degree presented more serious shrinkage ratio compared to the PA66 gear parts, which contributed to the denser polymer molecular chains arrangement. The shrinkage ratio in both directions of PA66 foamed gear parts depended on the injection volume, and the lowest shrinkage ratio of 0.043‰ was obtained at the injection volume of 74 mm, when the polymer reached the maximum foaming ratio. The findings from this study could provide practical guidance for preparing microcellular injection molded products with high dimensional accuracy. [ABSTRACT FROM AUTHOR]

Light-duty vehicles are increasingly incorporating plastic materials to reduce production costs and achieve lightweight designs. On average, a conventional car utilizes over 200 kg of plastic, comprising more than 23 different types, which often present challenges for recycling due to their incompatibility. Consequently, the focus on plastic recycling in end-of-life vehicles has intensified. This study aims to analyze critical car parts based on the plastics used, employing a novel thermodynamic approach that examines the embodied exergy (EE) of different plastics. Six vehicles from various segments, years, and equipment levels were assessed to understand their plastic compositions. The findings reveal that, on average, a vehicle contains 222 kg of plastic, accounting for 17.7% of its total weight. Among these plastics, 47.5% (105 kg) are utilized in car parts weighing over 1 kg, with plastics comprising over 80% of the part's weight. The identified critical car parts include the front door trim panel, front and rear covers, fuel tank, floor covering, front lighting, dashboard, rear door trim panel, plastic front end, backrest pad, door trim panel pocket, plastic foam rear seat, rear lighting, window guide, molded headliner, bulkhead sound insulation, foam seat part, and wheel trim. Regarding their contribution to EE, the plastics with the highest shares are polypropylene—PP (24.5%), polypropylene and ethylene blends—E/P (20.3%), and polyurethane- PU (15.3%). Understanding the criticality of these car parts and their associated plastics enables targeted efforts in design, material selection, and end-of-life management to enhance recycling and promote circularity within the automotive industry. [ABSTRACT FROM AUTHOR]

To meet objectives such as the sound insulation characteristics of timber structures and the comfort of residents, this study assessed an ordinary floor and three kinds of floating floors (Portuguese cork, graphite polystyrene sound insulation boards and expanded polypropylene plastic foam boards) in the same bedroom of a two-storey light wooden building. Adopting standard white noise and music noise excitation, structural design, theoretical checks and sound insulation tests of the floors were conducted. For the four floor structures, the sound insulation volume, sound pressure distribution characteristic spectrum of the building floor under different noise source environments, the frequency characteristics of the noise source, the multiple relationship of the sound insulation sound pressure level and the sound insulation mechanism were analysed. It was found that the sound pressure multiple of the space separating the upper and lower floors of the building was 8–18 times greater than that of the light wooden floor structure. The airborne sound insulation volume–frequency curves of the four floors, calculated by the transfer matrix method, were consistent with the actual measured values. The sound insulation effect was better in the low and middle frequencies. [ABSTRACT FROM AUTHOR]

The high level of air pollution in the cities of central and southern Chile, largely due to the burning of firewood, causes serious damage to people's health, felling of native forests, house fires, and people's deaths. An alternative that has been working for more than 100 years in the northern hemisphere is district heating. In Chile, there are two district heating systems operating for several decades and in recent years small projects have been slowly increasing. It is proposed to promote district heating for a greater number of population, either using industrial energy sources that are wasted or from non-polluting renewable energy sources. Then, the analysis is focused on the buried distribution pipe network in relation to its interaction with the ground related to mechanical and thermal response. These pipes are made of steel, insulated with foam and protected with a plastic jacket. Results of measurements in an instrumented pipe circuit connected to a district heating network in operation are presented. The axial displacements of the pipes in stationary conditions are possible to adequately estimate using the available calculation methodologies. However, steady-state conditions of sudden changes in temperature and pressure are difficult to estimate. [ABSTRACT FROM AUTHOR]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plastic foam molding methods include thermoforming, extrusion and injection molding. Injection foam molding is a one-time molding method with high production efficiency and good product quality. It is suitable for foamed plastic products with complex shapes and strict size requirements. It is also the main method for producing structural bubbles. In this investigation, we developed a structural foam injection molding technology using the gas supply equipment connected to the unique plasticizing mechanism of the injection machine and studied its influence on the specimens' melt rheology quality and foam structures. In the experiment, the forming material was polypropylene (PP), and the gas for mixing/forming foaming characteristics was nitrogen (N2). Additionally, in order to observe the rheological properties of N2/melt mixing, a melt flow specimen mold cavity was designed and the change in the melt viscosity index was observed using a melt pressure sensing element installed at the nozzle position. With the nitrogen supply equipment connected to a unique plasticizing mechanism, the mixing of gas and molten plastic can be achieved at the screw plasticizing stage, where the foaming effect is realized during the melt-filling process due to the thermodynamic instability of the gas. It was also found that an increase in N2 fill content increased melt fluidity, and the trend of melt pressure and melt viscosity index showed that the higher the gas content, the lower the trend. The foaming characteristic depends on the gas thermodynamic instability and the pressure release, so it can be seen from the melt fill path that, the greater the pressure near the gate, the lower the foaming amount and the internal structure (SEM) after molding; the farther from the gate, the greater the relative increase in the foaming growth/amount. This phenomenon will be more obvious when the N2 fill content is increased. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A more sustainable future calls for bio-based alternatives to replace plastic foams for various applications, such as packaging, insulation and cushioning. Some bio-based foams emerging in scientific publications are fabricated using liquid foam templating and methyl cellulose as well as fibers as main constituents. Scaling up of the production, however, requires a comprehensive understanding of the rheology of the foam during the shaping and drying processes. In this article, we report rheological studies of cellulose based systems in the context of thermal gelation. In more precise terms, we study how the presence of cellulose fibers and other additive materials influences the thermal gelation properties of methyl cellulose. We observe that the rheological properties, while heavily dependent on the material composition, are reasonably adjustable by appropriate material choices. The fibers are seen to decrease the temperature required for methyl cellulose to undergo a viscoelastic transition which is useful in the solid foam fabrication process. We anticipate that in the present application, the fibers increase the stability of the desired structure during the drying stage of the foam. [ABSTRACT FROM AUTHOR]

Due to the limitation of model coloring process, 3D solid sand table cannot satisfactorily restore the color information of electronic sand table, which has become a technical bottleneck for the development of solid sand table model to higher accuracy and color restoration. This paper mainly studies the coating treatment of three - dimensional spray painting surface; independently prepares the coating solution, coating the three-dimensional surface, analyzes the physical properties and printing properties of the coating; solves the problems of ink absorption, ink color rendering and dot expansion of three -dimensional spray painting coating; and improves the color reduction of three-dimensional spray painting. The specific research conclusions are as follows: with the decrease of pigment particle size, the whiteness of the coating first increases and then decreases, the contact angle of the coating gradually decreases, and the color density of the coating gradually increases. When VAE-707 and SBR are used as adhesives, the whiteness of the coating is improved, with the decrease of the ratio of VAE-705 to PVA-1788, the whiteness decreased first and then increased. When the ratio of VAE-705 to PVA-1788 was 2:8, the whiteness was higher. VAE-707 as adhesive has the highest color density, followed by PVA-1799; When the ratio of VAE -705 to PVA-1788 is 6:4, the color density of the printing coating is higher and the ability of tone reproduction is better. [ABSTRACT FROM AUTHOR]

Scientists are exploring the use of fungi to grow furniture, building insulation, siding, and even entire structures. The construction industry, responsible for a significant amount of greenhouse gas pollution, is interested in using grown materials to reduce plastic waste and reliance on fossil fuels. Mycelium, the hidden part of the fungal organism, can be grown as sheets, blocks, or customized forms and has the potential to process low-value materials into high-value products. Mycelium-based materials offer advantages such as customization, energy efficiency, fireproofing, and biodegradability. Researchers are also investigating the use of mycelium for extraterrestrial structures due to its ability to support less weight in lower gravity environments. [Extracted from the article]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mesenchymal stem cells (MSCs) are harvested after birth; they are adult stem cells and, due to their unique potential, are considered very valuable tools for equine regenerative medicine. MSCs have self-renewal capacity and multilinear differentiation potential. Multiple protocols are used to induce the directed differentiation of these cells. The aim of our study was to evaluate the osteoinductive potential of a glycoprotein from the transferrin family, lactoferrin (Lf) on MSCs isolated from equine synovial fluid. The cell line (syMSCs) used for this study was obtained from synovial fluid samples from a healthy horse. The isolated cells were characterized morphologically, immunophenotypically and functionally respecting the standards of the International Society for Cell Therapy which were originally drawn up for human MSCs (cellular plastic adherence, expression of specific surface markers and trilinear differentiation capacity). The cells were cultivated in normal propagation medium for MSCs. For osteogenic differentiation, syMSCs were seeded at a concentration of 1 × 105 cells/3 mm well, and cultured in osteogenic induction medium with (3 different concentration: 20, 50, 100 μg/mL) and without Lf. The proliferation potential of the cells were assessed using CCK8 assay and the markers of osteogenic differentiation (alkaline phosphatase, ALP) were detected using fluorimetric assay. Our results demonstrate the osteogenic potentiation capacity of human lactoferrin correlated with concentration, thus our future studies will try to elucidate the osteoinductive mechanism of lactoferrin by applying genomics and proteomics techniques. [ABSTRACT FROM AUTHOR]

Copyright of Iteckne is the property of Universidad Santo Tomas, Division de Ingenierias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sucrose shows the potential of stabilizing foam system. This study systematically evaluated the mechanism by which sucrose improved foaming properties and mechanical characteristics of foams stabilized by soy protein isolate/gellan gum/guar gum ternary complex. Results showed that sucrose could bond to the surface of ternary complex or self-aggregate within the continuous phase, resulting in the neutralization of charges (nearly zero) and an increase in particle size (up to 62.54 μm). The addition of 30 % sucrose reinforced foam system with an increased foamability (305.99 %) but a longer foaming time (10 min) during foaming process. Moreover, the mechanical characteristics, including hardness, elastic strength (Power-law constant) and solid characteristic (frequency exponent), were also significantly enhanced to 1.26 N, 354.7956 and 2.5873, respectively, which were 1.65, 1.94 and 1.11 times than those of foams without sucrose. The microscopic mechanism lied in the reduced water freedom degree caused by sucrose, which generated a compact structural network around bubbles for providing a stable and stiff structure to foams. These findings will provide clear theoretical guidance for regulating mechanical characteristics of aerated foods by using sucrose as structural building blocks. [Display omitted] • Sucrose bonded to the surface of complex through hydrogen bonding. • The sucrose-reinfor c ed foam system showed an increased foamability and foam stability. • Sucrose effectively improved textural strength by reducing water freedom degree. • Sucrose connected bubbles to endow foams with a plastic and stiff structure. [ABSTRACT FROM AUTHOR]

Capturing and predicting the effective mechanical properties of highly porous cellular media still represents a significant challenge for the research community, due to their complex structural interdependencies and known size effects. Micromorphic theories are often applied in this context to model the inelastic deformation behavior of foam-like structures, in particular to incorporate such size effect into the investigation of structure–property correlations. This raises the problems of formulating appropriate constitutive relations for the numerous non-classical stress measures and determining the corresponding material parameters, which are usually difficult to assess experimentally. The present contribution therefore alternatively employs a hierarchical micromorphic multi-scale approach within the direct FE2 framework to simulate the complex irreversible behavior of foam-like porous solids. The predictions of Cosserat (micropolar) and a fully-micromorphic theory are compared with conventional FE2 results and direct numerical simulations (DNS) for complex loading scenarios with elastic, elastic–plastic, and creep deformations. Therein, non-classical deformation modes of the microstructure resulting from the introduced micromorphic kinematics are visualized, as are the macroscopic hyperstresses and deformations. [Display omitted] • Micromorphic Direct FE2 simulations. • Foam applications with non-linear material in finite strains. • Comparison of micromorphic and micropolar (Cosserat) results. • Interpretation of non-classical deformation modes. • Four benchmark problems for size effects. • Local fields at microscale and macroscale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bagasse was used as raw material for preparing aerogel. • Aerogels were prepared by refrigerator freezing combined ambient pressure drying technique. • The bagasse cellulose aerogels have excellent thermal insulation. • The bagasse cellulose aerogels exhibited an excellent fire resistance and flame-retardant ability. Cellulose aerogel is a most promising alternative to the plastic foam owing to its low thermal conductivity, eco-friendliness and renewability, which however suffers from the complex preparation process, poor mechanical property and flammability. Herein, we develop a flexible, thermal-insulating, and fire-resistant cellulose aerogel by a facile refrigerator freezing and ambient pressure drying process, using bagasse and inorganic minerals as the main raw materials. The as-obtained bagasse-derived cellulose (BC) aerogel exhibited a high porosity of 92 %, an acceptable thermal conductivity of 51.5 mW/(m·K) and an excellent compressible cyclability. Furthermore, an inorganic mineral-reinforced bagasse-derived cellulose aerogel (IM r -BC) with improved fire-resistant property was prepared via the same method. The inorganic minerals endowed the original BC aerogel with a superior flame retardancy, which was able to withstand a continuous burning of butane gun at 1300 °C for over 20 min, and its thermal insulation application could be extended to a temperature as high as 1100 °C. These aerogels prepared in this work are expected to be used for thermal management applications in harsh environments. [ABSTRACT FROM AUTHOR]