Foam Production Research Articles

Mass production of biodegradable porous foam for simultaneous solar evaporation and thermoelectricity generation

We propose a cost-effective approach to construct 3D biodegradable foams by combining melt blending and surface coating, which show high performance in simultaneous solar-vapor conversion and thermoelectricity generation.

Industrial Vision: Rectifying Millimeter-Level Edge Deviation in Industrial Internet of Things With Camera-Based Edge Device

Nowadays, to realize the intelligent manufacturing in Industrial Internet of Things (IIoT) scenarios, novel approaches in computer vision are in great demand to tackle the new challenges in IIoT environment. These approaches, which we call <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Industrial Vision</i> , are expected to offer customized solutions for intelligent manufacturing in an accurate, time efficient and robust manner. In this paper, we propose a novel approach to industrial vision, called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Edge-Eye</i> , to rectify the edge deviation automatically for Irradiated Cross-linked Polyethylene Foam (IXPE) production with millimeter-level accuracy. IXPE has been one of the most commonly used materials in industry. During the production process of IXPE sheets, their edges need keep aligned strictly, otherwise, they could quickly get out of the border of the rolling plate and cause the huge economic loss. We deploy a commercial camera with mobile edge node in front of the IXPE sheet to continuously detect and rectify the edge deviation. Particularly, to handle the complex production environment when extracting the edge of IXPE sheet, we deploy a pair of reference bars with high-contrast colors to efficiently differentiate the sheet edge from the background. Then, we propose a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bi-direction Edge Tracking method</i> to perform the edge detection from both vertical and horizontal aspects. To realize the rectification using mobile edge nodes with limited computing resources, we reduce the cost of computation by extracting the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Minimized Region of Interest</i> , i.e., the edge area overlapped with the higher contrast reference bar on both sides. We further design a negative feedback control system with multi-stage feedback regulation mechanism, keeping the edge deviation within <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">millimeter-level</i> . We implemented <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Edge-Eye</i> on the ARM64 platform and performed evaluation in the practical IXPE production process. The experimental results show that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Edge-Eye</i> achieves the average accuracy of 5 mm for the edge deviation rectification, with the average latency of 200 ms for edge deviation detection. During the process of 20-month real deployment for 36 production lines, 66 manpower per day (90% of the overall manpower) has been saved, and the utilization rate of IXPE material increases from 87% to 94%.

HCFC-141b (CH3CCl2F) Emission Estimates for 2000–2050 in Eastern China

HCFC-141b (CH3CCl2F) has dual environmental impacts on ozone depletion and climate change, with the ozone depletion potential of 0.11 and the global warming potential of 782, and its emissions has attracted international attention. Under the control of the Montreal Protocol, China should phase out the production and consumption of HCFC-141b by 2030. This study firstly estimated the HCFC-141b emissions in eastern China based on the bottom-up method during 2000-2019. The results show that the HCFC-141b emissions in eastern China increased from 0.4 Gg yr-1 in 2000 to 7.1 Gg yr-1 in 2019, and there was a bank of 253.6 Gg in PU foam products in 2019, which may have an impact on future the HCFC-141b emissions. In addition, the HCFC-141b emissions were predicted in eastern China from 2020-2050 under the baseline scenario (BAU), the Montreal Protocol scenario (MP), and the accelerated phase-out scenario (AP), and the emission potential was analyzed. The results show that the HCFC-141b emissions increased rapidly under the BAU scenario, with cumulative emissions of 1162.6 Gg in 2020-2050. Under the MP and AP scenarios, the cumulative HCFC-141b emission reduction potential from 2020 to 2050 are 1002.1 Gg (equivalent to 110.2 Gg CFC-11-eq and 783.6 Tg CO2-eq) and 1034.8 Gg (equivalent to 113.8 Gg CFC-11-eq and 809.2 Tg CO2-eq), respectively. Compared with the MP scenario, under the AP scenario, eastern China will get an additional emission reduction potential of 32.7 Gg (equivalent to 3.6 Gg CFC-11-eq and 25.5 Tg CO2-eq) during 2020-2050, which will make greater contributions to protecting the ozone layer and mitigating climate change.

A novel reaction mechanism for the synthesis of coconut oil-derived biopolyol for rigid poly(urethane-urea) hybrid foam application.

Coconut oil (CO) has become one of the most important renewable raw materials for polyol synthesis due to its abundance and low price. However, the saturated chemical structure of CO limits its capability for functionalization. In this study, a novel reaction mechanism via the sequential glycerolysis and amidation of CO triglycerides produced an amine-based polyol (p-CDEA). The synthesized biopolyol has a relatively higher hydroxyl value of 361 mg KOH per g relative to previously reported CO-based polyols with values ranging from 270-333 mg KOH per g. This primary hydroxyl-rich p-CDEA was used directly as a sole B-side polyol component in a polyurethane-forming reaction, without further purification. Results showed that a high-performance poly(urethane-urea) (PUA) hybrid foam was successfully produced. It has a compressive strength of 226 kPa and thermal conductivity of 23.2 mW (m-1 K-1), classified as type 1 for a rigid structural sandwich panel core and type 2 for rigid thermal insulation foam applications according to ASTM standards. Fourier-transform infrared (FTIR) spectroscopy was performed to characterize the chemical features of the polyols and foams. Scanning electron microscopy (SEM) analysis was also performed to evaluate the morphological structures of the synthesized foams. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were conducted to investigate the foam's thermal characteristics. Thus far, this work is the first to report a novel and effective reaction mechanism for the synthesis of a highly functional CO-derived polyol and the first CO-based polyol with no petroleum-based replacement that may serve as raw material for rigid PUA foam production. PUA hybrid foams are potential insulation and structural materials. This study further provided a compelling case for enhanced sustainability of p-CDEA PUA hybrid foam against petroleum-based polyurethane.

Autoclave foaming and steam-chest molding of polypropylene/polybutene-1 blend bead foams and their crystallization and mechanical properties

Expanded polypropylene (EPP) foams have showed wide applications in our daily life, such as automotive and packaging. Usually, autoclave foaming combined with steam-chest molding is the main artwork to prepare the high-precision EPP foam products. However, the foaming behavior of EPP and the excessive pressure required for molding still need to be further improved, which is great significance for energy saving and cost saving, etc. Herein, this study finds that adding a certain amount of polybutene-1 (PB-1) into the PP can help to reduce the temperature and pressure required for foaming/molding, and to broaden the foaming temperature. For example, in order to make the foam beads bonding well and with the expansion ratio of 20, the molding pressure should be higher than 2.7 bar for Neat PP foams, but just 1.5 bar for PP/PB-1 mixtures. Moreover, the effects of PB-1 content on the crystallization properties and foaming/molding behaviors of the PP/PB-1 bead foams are illustrated, and then the mechanical properties are also studied. Furthermore, the low-pressure foaming strategy presented here is beneficial for reducing the barriers of energy consumption and promoting the development of new bead foam materials.

Business growth through a sustained strategic management approach in manufacturing organisations

Organizations regularly encounter unforeseen occurrences like government policy change, market failure natural catastrophes, terrorist attacks, or technology failures in extremely unpredictable and uncertain times. Thus, the study of strategic management and organization growth was embarked upon. Two research questions were asked leading to two research hypothesis famulated to guide the study. The population of 63 of the study were taken from the staff of the Mouka and Frendy foam production industry which also formed the sample size. Fifteen (15) items Questionnaire instrument validated and tested for reliability at 0.75 Cronbach Alpha were then distributed to the sampled staff of Mouka and Frendy foam production industry in Warri and Abraka. There after the extracted data were subjected to statistical analysis. the result shows that there is significant effect between defensive strategy and organization growth; also, that there is no significant effect between prospective strategy and organizational growth. From the finding recommendation were made among others that defensive strategy boosts organizational growth, and it should be adopted by managers at all level and stages of business development as it help to fight competitors amidst harsh competitive business environment

Studies on the effect of additives concentrations on synthesis and characterization of furan-lignin foams

Bio-based foams are growing and promising materials to replace petroleum-based foams because of their beneficial qualities including their affordability, outstanding fire resistance, high thermal insulation performance, eco-friendliness and the bio-sourced origin of the feedstock components. This study produced rigid bio-based foams using chemicals derived from plants, primarily from furfuryl alcohol and polyol derived from lignin. Lignin-based polyol and furfuryl alcohol were used to produce furan-lignin foams, which are free of formaldehyde and ozone damaging substances. Seven different furan-lignin foams were produced by substituting the toxic formaldehyde with a more eco-friendly glyoxal as a hardener while using diethyl ether and bentonite as blowing agent and filler respectively. Effects of these reagents on the quality of foams produced were assessed by varying their contents in the formulations. The properties of the produced bio-based foams such as compressive resistance, water absorption capacity, density and moisture content were evaluated. Further product characterizations: elemental composition, thermo-gravimetric analysis, Fourier transforms infrared spectroscopy and Scanning electron microscopy were carried out on the foams. The reaction leading to foam production was spontaneous at room temperature with an acid catalyst. Results showed that the concentrations of the blowing agent, hardener and filler, all had effects on the quality of the bio-based foams produced. Scanning electron microscopy results showed that the foams possessed closed cell morphologies, a rigid foam characteristic for good thermal and acoustic performance but modest water absorption, with cell widths of 10–200 μm, having high densities and strong compressive strengths as inherent characteristics. The results of the characterization indicated that the foams may be used as a thermal barrier or a support in construction and packaging applications because they had strong thermal stability, high compressive strengths, and a modest capacity to absorb water.

Mechanical and Physical Properties of Biodegradable Foams Made from Sorghum Fiber and Rice Straw for Food Packaging Applications

This study investigates the potential of agricultural by-products, rich in lignocellulosic materials, as sustainable food packaging materials to mitigate the environmental issues associated with nonbiodegradable plastics and styrofoam. Starch-based biodegradable food trays were developed using agricultural by-products, including sorghum stalk, rice straw, and kraft pulp through thermopressing method. By combining varying proportions of polyvinyl alcohol (PVA) and a sorghum-rice straw fiber mixture, biodegradable foam products with notable strength, water resistance, and cost-effectiveness for large-scale production were produced, exhibiting densities between 0.7 and 0.8 gr/m³. Notably, a 5% PVA composition in the sorghum fiber biodegradable foam displayed favourable mechanical properties and water resistance, with a tensile strength of 5 MPa and a contact angle of 73.79°, coupled with an appealing physical appearance. However, increasing PVA concentration beyond this level had negligible effects, indicates the optimal limit of PVA. Additionally, the distinct roles of rice straw powder as a matrix and sorghum fiber as reinforcement within the biodegradable foam were identified. Biodegradation tests revealed natural decomposition starting from the seventh day, with over 95% growth of Aspergillus Niger fungus, suggesting that these biodegradable foam products hold promise for mass production in the packaging industry, presenting a sustainable alternative to conventional plastic packaging.

Onsite coalescence behavior of whey protein-stabilized bubbles generated at parallel microscale pores: Role of pore geometry and liquid phase properties

In the formulation of (food) foams, an excess of protein is needed to prevent instant coalescence of bubbles from happening at (sub)millisecond time scales. However, protein adsorption and its influences on coalescence stability rarely have been investigated under such conditions of short time scales and high protein concentrations. In the current study, the coalescence stability of whey protein isolate-stabilized bubbles was studied using a microfluidic device, for a wide range of process conditions, including bubble-forming pore geometries and liquid phase properties. The bubble formation time was varied via the applied pressure, and the corresponding extent of bubble coalescence was quantified via the analysis of bubble sizes obtained through high-speed recordings. The experimental results of bubble coalescence as function of bubble formation time, in the presence of various protein concentrations, were also captured in a semi-empirical model. The amount of proteins accumulating at the surface of coalescing bubbles can be derived from a mass balance, with protein adsorption towards the surface of coalescing bubbles assumed to follow a Langmuir isotherm. The model showed a good fit with the experimental results, and we found that as the protein concentration increases from 2.5 to 7.5% wt., in our device the minimum time required to stabilize bubbles decreases from 0.5 to 0.1 ms. From a practical perspective, our microfluidic device can be used as an efficient tool to capture the instant, (sub)milliseconds, behavior of bubble coalescence, providing closer insights for industrial-scale production of (food) foams that also takes place at these time scales.

Sustainable treatment of sewage sludge via plasma-electrolytic liquefaction for bio-friendly production of polyurethane foam

Safe and green disposal or utilization of sewage sludge (SS) has attracted significant attention as SS is increasingly produced worldwide and emerges as an environmental burden if without proper treatment. In this study, efficient and sustainable treatment of SS was achieved using plasma-electrolytic liquefaction (PEL) with alkaline catalysts including sodium hydroxide (NaOH), sodium carbonate (Na2CO3), and sodium acetate (NaAc) and renewable solvents including polyethylene glycol (PEG) 200 and glycerol. Furthermore, the obtained bio-oil with abundant hydroxyl groups could partially replace polyols derived from fossil energy to synthesize bio-based polyurethane foams (BPUFs) for oil adsorption. The results showed that the Na2CO3 catalyst exhibited better performance and yielded bio-oil with a higher heating value (HHV) of 26.26 MJ/kg, very low nitrogen content (0.14%) and metal ions, and a nearly neutral pH of 7.41, under the optimized conditions. Compared with conventional oil bath liquefaction, PEL can significantly improve the liquefaction efficiency, promote the transfer of metal ions in SS to the solid residue (SR), and facilitate the transfer of nitrogen to the gas phase and SR, thereby upgrading the bio-oil to a certain extent. The BPUFs showed excellent oil adsorption capacity, reusability, and desorption and can play an important role in combating oil spills. The PEL method may provide a green avenue for SS valorization and the comprehensive utilization of the obtained products.

Production and Application of Polymer Foams Employing Supercritical Carbon Dioxide

Polymeric foams have characteristics that make them attractive for different applications. However, some foaming methods rely on chemicals that are not environmentally friendly. One of the possibilities to tackle the environmental issue is to utilize supercritical carbon dioxide ScCO2 since it is a “green” solvent, thus facilitating a sustainable method of producing foams. ScCO2 is nontoxic, chemically inert, and soluble in molten plastic. It can act as a plasticizer, decreasing the viscosity of polymers according to temperature and pressure. Most foam processes can benefit from ScCO2 since the methods rely on nucleation, growth, and expansion mechanisms. Process considerations such as pretreatment, temperature, pressure, pressure drop, and diffusion time are relevant parameters for foaming. Other variables such as additives, fillers, and chain extenders also play a role in the foaming process. This review highlights the morphology, performance, and features of the foam produced with ScCO2, considering relevant aspects of replacing or introducing a novel foam. Recent findings related to foaming assisted by ScCO2 and how processing parameters influence the foam product are addressed. In addition, we discuss possible applications where foams have significant benefits. This review shows the recent progress and possibilities of ScCO2 in processing polymer foams.

Production and characterisation of self-blowing lignin-based foams

Self-blowing lignin-furanic foams were produced using formulations comprising Kraft lignin and furfuryl alcohol as the major components. Diethyl ether, Tween 85 and sulphuric acid were used as blowing agent, surfactant and catalyst. The influence of the components and the ratio of furfuryl alcohol to lignin was investigated with regard to the foam density, mechanical properties, water absorption, thermal properties, and fire behaviour. Depending on the formulation, the density of lignin-furanic foams ranged between 60 and 320 kg m−3. Increasing the furfuryl alcohol content increased the density of the foams. Low-density foams were obtained with a higher proportion of diethyl ether. The compression strength and modulus of elasticity (MoE) of lignin-furanic foams also increased with foam density. All lignin-furanic foams showed good thermal stability and residual masses by thermogravimetric analysis. Cone calorimetric analysis showed that lignin-furanic foams have poor flammability and self-extinguish within few seconds.

Development of ultralight, tough and hydrophobic polymethylmethacrylate/polyvinylidene fluoride shape memory foams for heat insulation applications

Thermal insulation is vital for achieving efficient thermal management, energy conservation, and emission reduction. However, the existing polymer foams still have some performance limitations and cannot meet the application demands in a wider range of situations. Accordingly, herein, an innovative strategy based on polyvinylidene fluoride (PVDF) melt blending and CO2 microcellular foaming was proposed for the fabrication of lightweight high-performance polymethylmethacrylate (PMMA) foams for heat insulation, and ultralight, tough, and hydrophobic foams with outstanding heat insulation and shape memory performances were successfully prepared. Because of the plasticization of PVDF and nucleation of PVDF microcrystals, the foaming temperature window of PMMA substantially descended, and the cellular structure of PMMA became refined. Blend foams with expansion ratios of 36.2, cell sizes of 15.8 μm, and foam densities of 0.0357 g∙cm−3 were obtained at 130 °C. Due to higher porosity and strong infrared absorption ability of PMMA, the resulting foams exhibited thermal conductivities of less than 32 mW∙m−1∙K−1. Owing to the hydrophobicity and incombustibility of PVDF and its microcrystals, the blend foams demonstrated better hydrophobicities, shape memory properties, and flame retardancies. This study provides an effective way for the green and mass production of high-performance polymer foams with appropriate thermal insulation performances.

Surfactant in a Polyol-CO2 Mixture: Insights from a Classical Density Functional Theory Study.

Silicone-polyether (SPE) surfactants, made of a polydimethyl-siloxane (PDMS) backbone and polyether branches, are commonly used as additives in the production of polymeric foams with improved properties. A key step in the production of polymeric foams is the nucleation of gas bubbles in the polymer matrix upon supersaturation of dissolved gas. However, the role of SPE surfactants in the nucleation of gas bubbles is not well understood. In this study, we use classical density functional theory to investigate the effect of an SPE surfactant on the nucleation of CO2 bubbles in a polyol foam formulation. We find that the addition of an SPE surfactant leads to a ∼3-fold decrease in the polyol-CO2 interfacial tension at the surfactant's critical micelle concentration. Additionally, the surfactant is found to reduce the free energy barrier and affect the minimum free energy pathway (MFEP) associated with CO2 bubble nucleation. In the absence of a surfactant, a CO2-rich bubble nucleates from a homogeneous CO2-supersaturated polyol solution by following an MFEP characterized by a single nucleation barrier. Adding a surfactant results in a two-step nucleation process with reduced free energy barriers. The first barrier corresponds to the formation of a spherical aggregate with a liquid-like CO2 core. This spherical aggregate then grows into a CO2-rich bubble (spherical aggregate with a vapor-like CO2 core) of a critical size representing the second barrier. We hypothesize that the stronger affinity of CO2 for PDMS (than polyether) stabilizes the spherical aggregate with the liquid-like CO2 core, leading to a lower free energy barrier for CO2 bubble nucleation. Stabilization of such an aggregate during the early stages of the nucleation may lead to foams with more, smaller bubbles, which can improve their microstrustural features and insulating abilities.

Insight into the mechanism of gasification fine slag enhanced flotation with selective dispersion flocculation

Coal gasification fine slag (CGFS) produced in the coal chemical industry has caused severe environmental pollution and resource waste. To realize the utilization of CGFS, we have to efficiently separate unburned carbon (UC) in CGFS. In this work, based on the discovery of the covering between CGFS particles, the selective dispersion flocculation flotation method is proposed to improve the efficient separation of UC from CGFS. The mechanism of selective dispersion flocculation is revealed through adsorption mode, interaction force between particles, and the particle size distribution of floc under different reagent conditions. Results show that a hydrophilic layer is formed on the surface of ash particles, which hinders the adsorption of PAM and ash particles due to the chemical adsorption of SHMP with ash particles. However, carbon particles are not affected by SHMP and can be directly adsorbed with PAM. This selective adsorption dominates the interaction force of adsorbed particles, and then controls the agglomeration of particles. After selective dispersion flocculation, the original carbon-ash selective agglomeration state is changed to the carbon–carbon selective agglomeration state. D90 of fine carbon particles changed from 110.21 μm to 356.84 μm. Compared with the traditional flotation process, the combustible recovery rate of foam products is increased by 10.4 % and loss on ignition (LOI) is increased by approximately 5 %. This work is conducive to fundamentally understanding the mechanism of selective dispersion flocculation. It is helpful to guide the separation of carbon and ash from gasification slag in industry.

Analysis of Factors Influencing the Efficiency of Catalysts Used in Waste PU Degradation.

Polyurethane (PU) is an indispensable part of people's lives. With the development of polyurethane, the disposal of polyurethane waste has become a significant issue around the world. Conventional degradation catalysts have poor dispersion and low degradation efficiency when used in the process of solid degradation into liquid. Therefore, this paper innovatively adopts self-made core-shell nanoscale titanium catalysis, traditional alkali metal catalyst (KOH), and polyol to carry out the glycolysis of waste polyurethane (PU) pipeline foam. The homogenized nanoscale titanium catalyst coated with alcohol gel has an obvious core-shell structure. The alcohol gel not only protects the catalyst but also dissolves with the alcoholysis agent in the process of glycolysis and disperses more evenly into the alcoholysis agent to avoid the phenomenon of nanocatalyst agglomeration, so as to facilitate catalytic cracking without reducing catalyst activity. In this study, investigated and compared the production of renewable polyurethane foam via a one-step method based on use of a homogeneous core-shell nanostructured titanium catalyst vs. a traditional alkaline catalyst in terms of the properties of regenerated polyether polyols as well as of the foams produced from these polyols. The physicochemical properties of regenerated polyether polyols that were analyzed included viscosity, hydroxyl value, and average molecular weight. The regenerated polyurethane foams were characterized based on water absorption, TG, SEM, and thermal conductivity analyses. The results show that, when the addition of homogeneous titanium catalyst was T2 0.050 wt.%, the viscosity of regenerated polyether polyols was the lowest, at 5356.7 mPa·s, which was reduced by 9.97% compared with those obtained using the alkali metal catalyst (KOH). When the amount of titanium catalyst was T3 0.075 wt.%, the hard foam made of regenerated polyurethane prepared by the catalyst showed the best properties, with a compressive strength of 0.168 MPa, which is 4.76% higher than that of the foam prepared using KOH catalyst.

Hybrid Organic–Inorganic Composites Based on Glycolyzed Polyurethane

We present a simple approach to upcycle glycolyzed polyurethane foam products by fabricating robust, highly filled organic/inorganic composites (46–60 wt % solid loading). These composites, consisting of recycled polyols, naturally occurring or synthetic aluminosilicate minerals, and isocyanate linkers, are shown to possess superior mechanical (flexural) properties compared to ordinary Portland cement (OPC). Optimization of chemical composition (isocyanate and inorganic content) and curing temperatures (25–50 °C) results in low-density composites (up to 3× less dense than OPC) with flexural strengths comparable to OPC while exhibiting strain capacities up to 5× as compared to OPC-based systems. In contrast, parallel fabrication approaches using low OH-value virgin polyols resulted in flexible composites and much lower flexural strengths, highlighting the advantage of employing high −OH density recycled polyols. Variations in the flexural strength of the composites were correlated with differences in their morphology─uniformity in the distribution of inorganic particles contributed to improved flexural properties. The generality of this fabrication approach is demonstrated using quartz sand as the inorganic particle and recycled polyols with different hydroxyl values.

Multiscale modeling of lignocellulosic foams under compression

Biodegradable lignocellulosic foams have the potential to replace foams produced from petroleum sources that have environmental issues. These lignocellulosic foams contain randomly oriented fibers or particles bonded by cellulose nanofibrils (CNFs). In this work, effort was focused on the production of lignocellulosic foams using wood flour or thermomechanical pulp (TMP) fibers bound with CNFs. Multiscale modeling is proposed to predict the mechanical properties. Microwave drying was employed to produce the low-density porous foam structures. Compression tests conducted on the foams exhibited elastic–plastic responses. Finite element analysis (FEA), a numerical method to determine the elastic–plastic mechanical properties was utilized. The Young’s modulus of lignocellulosic foams calculated from fiber-scale modeling methods exhibits strong agreement with experimental results for strains up to 10%. Meso-scale modeling indicates an FEA approach to determine Young’s modulus considering cellulose as matrix and porosity inclusions to create different porous structures. Macro-scale FEA was performed using crushable foam material model to determine the elastic–plastic behavior of the foams for strains up to 20% reveals a solid agreement with the experimental results. Modeling results at different scales promise a robust numerical framework to predict mechanical behavior of these novel lignocellulosic foams.

Aluminium metal foam production methods, properties and applications- a review

Aluminium metal foam has a cellular structure. It's lightweight with these unique physical and mechanical properties and widely used in structural and functional applications. This paper's studies show the possible ways to produce Aluminium metal foam and its different properties and, based on that, the field it has applications. During the studies, it is observed that the Aluminium metal foam can develop in two ways: solid route and liquid route, after acquiring unique properties, such as light in weight to strength, suitable acoustic properties, and shock and energy absorption capabilities. The application will be selected based on properties and open or closed pore cells obtained in Aluminium metal foam. The significant finding from the review is that Aluminium metal foam has broad applications. However, the main lacunas that are still Aluminium metal foam are commercially not used because it is challenging to get good properties such as attaining uniform distribution and percentage of porosity in the prepared foam sample and uniform pore size. Another critical factor is that the cost will be high if the liquid or solid route develops the metal foam. So powder metallurgy process is the best method to produce metal foam to get better surface integrity and a proper network connection between each pore.

New Method to Biomonitor Workers Exposed to 1,6-Hexamethylene Diisocyanate.

Isocyanates such as 1,6-hexamethylene diisocyanate (HDI), 4,4'-methylenediphenyl diisocyanate, and toluene diisocyanate are highly reactive compounds that have a variety of commercial applications, including manufacturing polyurethane foam, elastomers, paints, adhesives, coatings, insecticides, and many other products. Their primary route of occupational exposure is through inhalation. Due to their high chemical reactivity, they are toxic and have adverse effects at the cellular and subcellular levels, leading to irritative and immunological reactions associated with lung disease. High concentrations of isocyanates are strong respiratory irritants. Bronchial sensitization and asthma are among the major adverse clinical reactions associated with low-level chronic exposure to isocyanates. Albumin adducts have been linked to the mechanism of occupational asthma caused by isocyanates. Isocyanates react in vivo with albumin, which is recognized by the immune system. Albumin adducts of isocyanates trigger immune responses and are probably the antigenic basis for isocyanate asthma. Sensitization to isocyanates is the main pathway for adverse health effects. Therefore, markers for the biologically effective dose such as albumin adducts of HDI are needed. A new isocyanate adduct of HDI with lysine─Nε-[(6-amino-hexyl-amino)carbonyl]-lysine (HDI-Lys)─was synthesized and characterized by 1H-NMR, 13C-NMR, and mass spectrometry (MS). Appropriate internal standards─HDI-Lys-4,4'-5,5'-d4 (HDI-d4-Lys) and Nε-[(7-amino-heptyl-amino)carbonyl]-lysine (Hep-Lys)─were synthesized to establish a LC-MS/MS method for the analysis of HDI adducts in in vitro modified albumin and in workers. The presence of HDI-Lys was found after pronase digestion of albumin and confirmed by two independent chromatographic approaches: with a C8 reversed-phase column and with a hydrophilic interaction liquid chromatography column. Quantification was performed with positive electrospray ionization (ESI)-MS. The adduct peak found in vivo was confirmed with the less sensitive negative ESI-MS. In summary, these are new compounds and methods to determine isocyanate-specific adducts with albumin in workers exposed to HDI.