Types Of Foams Research Articles

Effects of longitudinal bending stiffness and midsole foam on running energetics

Advanced footwear technology has become commonplace in the competitive running world. However, a systematic exploration of the effects of each of the primary components has not yet been presented. Our goal was to quantify running economy and step parameters in four different shoe conditions: PEBA shoes with plate, PEBA shoes without plate, EVA shoes with plate and EVA shoes without plate. Participants ran at 14 km/h (n = 8 males) or 12 km/h (n = 6 females) on a treadmill. The shoe order was randomly assigned for the four shoe conditions, where the participants wore each shoe twice in a mirrored order. There was a significant reduction in metabolic power (1.0%) associated with the presence of a plate, as well as a similar reduction based on foam type (1.0%). However, there was no significant interaction between presence of plate and foam type. Adding a plate significantly reduced metabolic power for EVA by 1.3% but not for PEBA. PEBA foam significantly reduced metabolic power by 1.3% in shoes without a plate, but not for the shoes with a plate. Step frequency and contact time were similar between shoes and not correlated to running economy improvements. Starting from a baseline condition with traditional foam without a plate, either adding a plate or using PEBA foam improved running economy with a similar amount (1.3%). Adding the alternate second feature non-significantly improved running economy with an additional 0.6%. The benefit of both technologies combined (1.9%) was smaller than the sum of its parts (1.3% each).

Development of shampoo formulations using plant/microbial biosurfactants as an alternative to shampoos formulated with harsh synthetic surfactants

AbstractThe presence of harmful chemical surfactants such as sodium lauryl sulfate (SLS) in healthcare products is a challenge that world is facing today. The present study aimed to formulate novel green shampoos using rhamnolipid and saponin instead of chemical surfactants, and comparison with commercial shampoos. Biosurfactants were confirmed by thin layer and high‐performance liquid chromatography, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and their performance was evaluated by zone inhibition and critical micelle concentration (CMC). The saponin and rhamnolipid reduced the surface tension (ST) of water from 72 to 40 and 30 mN/m at their CMCs, respectively. Four novel shampoo formulations were made with SLS, rhamnolipid, saponin, and a mixture of rhamnolipid and saponin. The green shampoos were evaluated with tests of color, odor, transparency, pH, ST, detergency, solid content, foam type, foam volume, wetting time and microbial contamination standard to determine the physicochemical properties. The green formulations with rhamnolipid, saponin and mixture of rhamnolipid and saponin were clear and transparent with a good odor. Low ST (34.13, 38.83, and 31.73 mN/m), good detergency (63.87%, 57.74%, and 64.45%), comparable solid contents (25.11%, 26.95%, and 27.50%), good wetting time (160, 165, and 153 s), and good foam stability even after 60 min were observed for three green shampoos, respectively. Based on the results, it can be concluded that these green shampoos can compete with commercial shampoos and be a suitable alternative to chemical shampoos containing sulfate and sulfate‐free, especially for children, people with eye and skin sensitivities and with oily hair.

Energy distribution in 1D chains of foam disks subjected to low-velocity impact at different temperatures

A series of experiments is conducted to study energy transfer in a chain of foam disks as a function of temperature. These experiments use two different densities of closed-cell Polyvinyl Chloride foams as an array. A puncture testing machine impacts the chain at a velocity of 1 m/s at five different temperatures. Piezoelectric sensors capture the output and input forces of the chain during the impact, while high-speed cameras record the disk deformations. The chain’s energy retention is computed using disk deformations and loading forces. Results indicate that high-density foam chains exhibit significantly higher force and energy retention than low-density counterparts. Notably, the foam’s stiffness decreases with rising temperature, more prominently in higher-density foam. However, the proportion of energy retained by the chains remains relatively consistent across different temperatures. Additionally, both foam types show a pattern of exponential decay in energy retention along the chain. These insights offer implications for designing and optimizing energy-absorbing foam systems, paving the way for enhanced energy mitigation in low-velocity impact applications.

Highly Flexible and Compressible 3D Interconnected Graphene Foam for Sensitive Pressure Detection.

A flexible pressure sensor, capable of effectively detecting forces exerted on soft or deformable surfaces, has demonstrated broad application in diverse fields, including human motion tracking, health monitoring, electronic skin, and artificial intelligence systems. However, the design of convenient sensors with high sensitivity and excellent stability is still a great challenge. Herein, we present a multi-scale 3D graphene pressure sensor composed of two types of 3D graphene foam. The sensor exhibits a high sensitivity of 0.42 kPa-1 within the low-pressure range of 0-390 Pa and 0.012 kPa-1 within the higher-pressure range of 0.4 to 42 kPa, a rapid response time of 62 ms, and exceptional repeatability and stability exceeding 10,000 cycles. These characteristics empower the sensor to realize the sensation of a drop of water, the speed of airflow, and human movements.

Active control for higher order micro sandwich beam with various cores integrated by piezoelectric layers based on MSGT on the Pasternak foundation

In the present article, the vibration suppression of higher order micro sandwich beams based on modified strain gradient beam theory (MSGT) and Reddy/Timoshenko beam theories is developed. Three types of core, including honeycomb, foam, and porous for a micro sandwich beam, are considered. The core’s top and bottom are integrated by piezoelectric layers as actuator and sensor, respectively. Displacement fields are defined via third-order shear deformation beam theory (TSDBT) (or Reddy beam theory (RBT)) and first-order shear deformation beam theory (FSDBT) (or Timoshenko beam theory (TBT)). The governing equations of motion are derived using MSGT to consider the small-scale effect. To optimal approaches for the controller, state feedback is designed based on a linear quadratic regulator (LQR) in the state-space form. Moreover, the effect of various parameters, including small-scale parameters, three types of core, temperature changes, Pasternak foundation, density of core, dimensionless cell thickness ([Formula: see text]), and internal aspect ratio ([Formula: see text]), angles ([Formula: see text]) of honeycomb, and the porosity parameter is performed on the active control of the smart micro sandwich beam. The numerical results indicate that the parameters mentioned significantly affect the optimal vibration control of the smart micro sandwich beam. It is found that the lightweight cores have more attenuation of the transient response and faster settling time. By analyzing the effect of temperature changes on active vibration control of lighter core, it was found that the frequency decreases as the temperature increases. Also, by considering the Pasternak foundation, it is found that the time period without considering the elastic foundation is longer than when considering the elastic foundation, and the natural frequency is vice versa. Also, the settling time by considering the elastic foundation occurs earlier. In the active control field of smart micro beams, this theoretical investigation developed widely as a benchmark for experimental research and the manufacturing process.

Observation of micropolar modes in the transmission of acoustic waves at oblique incidence by polystyrene plates.

This study investigates micropolar plates through the analysis of transmitted acoustic waves at various incident angles. Using a combined theoretical and experimental approach, we explore the non-classical elasto-dynamic behavior of these materials. Theoretical transmission coefficients are tailored to highlight generalized Lamb modes and a new type of vibration mode called micropolar modes, considering the constant thickness of the plate and the effects of material micropolarity on linear elasticity. Overlaying diverse transmission coefficients for different angles provides insight into micropolar behavior, aiding in the understanding of mode evolution in the frequency domain and the estimation of the critical angle. We employ two types of low-density closed-cell foams made from polystyrene (expanded in one case, extruded in the other), covering a frequency range from 4 to 60 kHz using a tweeter loudspeaker and a microphone integrated with a National Instruments acquisition system. Identification of the first vibration mode of the plates is facilitated by the frequency range rich in low frequencies. Additionally, all responses exhibit supersonic velocities with substantial attenuations. The originality of this paper is twofold: it provides theoretical predictions of micropolar modes, along with their experimental observations above a critical angle of incidence. Consequently, this research enriches our understanding of micropolar materials and their potential contribution to effective noise reduction strategies in acoustic engineering.

Influence of Foam Content and Concentration on the Physical and Mechanical Properties of Foam Concrete

Foam concrete has been used in various real-life applications for decades. Simple manufacturing methods, lightweight, high flowability, easy transportability, and low cost make it a useful construction material. This study aims to develop foam concrete mixtures for various civil and geotechnical engineering applications, such as in-fill, wall backfill and soil replacement work. A blended binder mix containing cement, fly ash and silica fume was produced for this study. Its compressive strength performance was compared against conventional general purpose (GP) cement-based foam concrete. Polypropylene (PP) fibre was used for both mixtures and the effect of various percentages of foam content on the compressive strength was thoroughly investigated. Additionally, two types of foaming agents were used to examine their impact on density, strength and setting time. One foaming agent was conventional, whereas the second foaming agent type can be used to manufacture permeable foam concrete. Results indicate that an increase in foam content significantly decreases the strength; however, this reduction is higher in GP mixes than in blended mixes. Nevertheless, the GP mixes attained two times higher compressive strength than the blended mix’s compressive strengths at any foam content. It was also found that the foaming agent associated with creating permeable foam concrete lost its strength (reduced by more than half), even though the density is comparable. The compressive stress–deformation behaviour showed that densification occurs in foam concrete due to its low density, and fibres contributed significantly to crack bridging. These two effects resulted in a long plateau in the compressive stress–strain behaviour of the fibre-reinforced foam concrete.

Investigating the effect of hot and cold polyurethane foam on reducing whole body vibration of forklift operators.

Vibration is one of the harmful factors for forklift drivers. The use of non- standard seats and not paying attention to how the seats are maintained can be affected by the amount of vibration transmitted to the person. This study investigates the amount of vibration transmitted from the forklift and the effect of different types of polyurethane foam in reducing the vibration transmitted from the forklift seat. This descriptive-analytical study was performed on 38 forklifts in 4 diesel models with the same weight class. The amount of vibration transmitted from forklift seats according to ISO2631 standard, taking into account the effect of various factors such as foam type (hot and cold), thickness (6-12 cm), load and year Function was measured. The amount of vibration caused by the forklift on the seat and under the seat was evaluated using ISO7096 standard. The average total vibration of the whole body in all foams in no-load mode is more than with load. The transmission vibration of cold polyurethane foam is less than that of hot polyurethane foam. With increasing thickness, the efficiency of cold polyurethane foam increases by 12 cm and in the loaded state 40.63% and in the unloaded state 49.58% in reducing the vibration transmitted to drivers. The results of this study show that cold foam has better effectiveness and efficiency than hot polyurethane foam. Also, the thicker the foam, the less vibration is transmitted to the driver.

Cell topology during coarsening of simulated three-dimensional dry liquid foams.

Cell topology provides a deep insight into the structure of dry liquid foams. This paper analyses the cell topology of simulated 3-dimensional monodisperse dry liquid foams through the process of coarsening, where gas slowly diffuses through the cell interfaces. The coarsened foams are polydisperse, yet show a difference in cell types to annealed, low energy foams of comparable polydispersity. These two types of foams are analysed using average face degree of the cells and a measure of combinatorial roundedness, a new concept from combinatorial topology. We see that the spectrum of cell types changes drastically through the evolution of the foam via coarsening, from cells with a face degree between 12 and 14, with many 4-, 5-, and 6-side faces, to a combination of very large cells with many faces alongside a high frequency of tetrahedra and other cells with low face degree. These results demonstrate the insight that topological methods can give into foams and other complex structures.

Energy and materials analysis of wet channels structures for evaporative cooling systems manufactured by FFF technique with foam materials

The development of new evaporative cooling technologies can significantly reduce energy consumption and help mitigate the effects of climate change. This study aimed to evaluate the evaporative cooling capacity of air passage channel structures. Six different channels were manufacturing using two types of foam, Wfoam and Bfoam, three of each type, made from polylactic acid added with a chemical blowing agent, employing the Additive Manufacturing (AM) technique of fused filament fabrication and modifying manufacturing parameters. The experimental analysis consisted of two phases: initially, all six channels were tested under constant inlet air conditions; subsequently, the channel exhibiting the highest evaporative cooling capacity was further analysed under different air velocities. The results obtained allowed for an analysis of the relationship between material properties, energy performance, and cooling capacity, with the goal of optimizing and designing more efficient cooling systems. The energy performance of the channels was assessed in terms of heat flux, and sensible and latent powers. The results indicated that the channel made from the type of foam with the highest porosity achieved the lowest supply air temperature and the highest sensible and latent powers. Additionally, this channel demonstrated the highest wet bulb effectiveness, reaching up to 0.86 at the maximum tested air velocity. These findings confirm the feasibility of using AM to generate porosity in evaporative cooling systems manufactured with polymeric materials.

Foam detection in a stirred tank using deep learning neural networks

A deep learning method based on the Convolutional Neural Network (CNN) U-Net architecture has been explored as an image analysis tool for the detection and automated quantification of foam generated in a stirred tank. Multiple datasets of different sizes and with different types of foam were obtained experimentally and processed with data augmentation techniques in order to train the deep learning networks. The impact of adding attention and residual gates to the U-Net model to improve its performance, as well as the size of the dataset used to train the model have been assessed. The main factor influencing the accuracy of the models to detect the foam in the stirred tank is the size and quality of the dataset use to train the U-Net models; it must be sufficiently large and varied in terms of foam type/structure. The addition of attention gates and residual blocks to the U-Net model slightly improves the accuracy of foam detection, particularly for images that contain additional objects or obstructions, however the training time is 30 % longer than the standard U-Net model. In all cases, this image analysis method based on the U-Net model largely out performs conventional image analysis, which was not able to automatically differentiate between foam, additional objects in the tank and bubbles in the liquid. Two methods for the measurement of foam quantity (maximum foam height and foam volume) have also been developed based on the foam regions detected by the models. This is important for the application of the tool, which is to be used to understand the impact of operating conditions on foam formation in lab-/pilot-scale stirred tanks and then develop scale-up guidelines for foam control in industrial tanks.

Production of aluminum foam using an alternative porophore

Subject of research: blowing agent in the form of natural CaCO3 powder to obtain high-quality aluminum foam material. Purpose of research: selection of the optimal type of foam as a pore-forming element and production of aluminum foam with special functional properties. Methods and objects of research: when studying the gas-forming properties, the residual substances and thermal stability of the powder were determined using a thermogravimetric analyzer TG-DTG, DSC. The processes of obtaining aluminum foam samples sintered in a protective environment on an experimental installation are considered. The object of research is the resulting CaCO3 powders, as well as the determination of the physical and mechanical properties of aluminum foam samples. Main results of research: production of foamed aluminum with special functional properties with the introduction of powder blowing agent CaCO3. Selection of the optimal component of the amount of powder injected into the metal matrix of the substance, based on the physical properties of the resulting material.

Catalytic decomposition of sulphuric acid in Iodine-Sulphur and Hybrid-Sulphur processes for Hydrogen production: Estimation of effectiveness factor of catalyst

High endothermic heat of SO3 decomposition reaction (ΔHR∼+98 kJ mol−1) can lead to significant thermal gradients (lower temperatures) inside the catalyst particle, depending up on mass diffusion, heat conduction and intrinsic reaction kinetics in the particle. The lower catalyst effectiveness (due to thermal gradients) leads to lower decomposition conversions in Packed Bed Reactors (PBR), which has to be maximized. In this study, a multi-scale model (Double Porosity Model, DPM) is used for the estimation of non-isothermal effectiveness factor (η) of Cr-Fe2O3 catalyst types; less porous pellet and porous foam types. η obtained using DPM (foam∼0.249 and pellet∼0.147) are found to be in good agreement with experimental data and also with the results of derived model (Weisz model). Further, effect of porosity and size/diameter on η are studied and obtained the optimum porosity required for maximum η. The present study is useful for estimation and optimization of non-isothermal η of catalysts.

Nanoarchitectonics of lignin-sepiolite bionanocomposite foams for application in environmental remediation

Innovative bionanocomposite foams based on precipitated Kraft lignin (Lig) and Kraft black liquor (BL) loaded with sepiolite (Sep) were prepared. BL/Sep bionanocomposites were synthesized by emulsion templating and Lig/Sep bionanocomposites were prepared by freeze-drying, resulting in stable and rigid foams. BL/Sep bionanocomposites displayed a closed cell structure, a specific area between 19 and 35 m2/g and macropores of varying sizes. The porosity in this technique is achieved by the mechanical agitation of the emulsion. On the other hand, freeze-dried Lig/Sep bionanocomposites showed open cell morphology with surface areas ranging from 1 to 4 m2/g and uniform macropores due to the ice-templating process. The presence of sepiolite in both types of bionanocomposite foams improved their stiffness, with Young's moduli ranging from 0.21 to 9.6 MPa. The capacity of the foams to adsorb metals, drugs and dyes was evaluated and it was found that the synthesized bionanocomposite foams exhibiting similar adsorption capacities as that reported for lignin. Sepiolite significantly improved the adsorption of Cu(II), Cd(II), acetaminophen (ACT), and methylene blue (MB) in BL/Sep bionanocomposites. Meanwhile, the Lig/Sep bionanocomposites demonstrated superior adsorption capacities for the Cr(VI) anion and aromatic ring compounds, including ACT and MB. In this respect, these lignin-sepiolite foams can be considered as promising materials for the removal of pollutants in aqueous solution.

욕창예방 방석의 충격 흡수 시험 장치 개발과 적용

Bedsores mainly occur in bedridden patients who have to lie in the same position for a long period of time, or in people with spinal cord disabilities who use wheelchairs and cannot change positions on their own. In order to prevent excessive pressure on the skin over bone protrusions, which causes circulation problems in peripheral blood vessels and causes bedsores, the Ministry of Food and Drug Safety has designated and operates bedsore prevention cushions as medical devices. ISO, an international standardization organization, established and operates ISO 16840-2 to evaluate the performance of cushions to prevent bedsores for wheelchair users. The purpose of this study is to design and develop a test device to apply this international standard to the test and evaluation of domestic bedsore prevention cushions. In particular, the main purpose was to develop a shock absorption test device to determine how effectively bedsore prevention cushions cushion the shock that occurs when a wheelchair collides with the road surface on a bump or pothole.
 The impact absorption test device was manufactured by modifying part of the guidelines of ISO 16840-2. In the above international standard, the crash plate is to be supported with a piece of wood block. However, in this study, the time delay that may occur during removal of the block was shortened and convenience was improved by using a roller system instead of wooden block to drop the object. Using the manufactured test device, a shock absorption test was conducted on an air-grid type bedsore prevention cushion and a hybrid bedsore prevention cushion that is a mixture of foam type and air grid type. When the human hip model falls, the falling acceleration was reduced to 63% with the air-grid type cusion compared to the value with no cushion, and it decreased to 42% with the hybrid cushion. However, the occurrence of bedsores is affected not only by the impact force applied to the skin when the wheelchair collides with the ground, but also by the breathability and humidity of the impact area, so it is necessary to comprehensively evaluate various risk factors, including shock absorption tests. The roller-type shock absorption test device will be proposed as an amendment to ISO 16840-2 to the International Standards Committee.

Continuous turbulent liquid-liquid emulsification using open-cell solid foams: Experimental investigation and modelling

The study investigates the efficiency of liquid-liquid emulsification using three types of open-cell solid foams. Initially, the pressure drop profiles revealed the non-negligible impact of the inertial term at a low viscosity of the continuous phase, with profiles becoming more linear at higher viscosities. The Darcy-Forchheimer model effectively predicted pressure drops with a maximum mean relative error of 14%. Emulsification performance (seen as a decrease in the droplet size) was then evaluated by varying dispersed phase viscosity, superficial fluid flow velocity and foam insert packing length, comparing results with structured static mixers (SMX+). The droplet size of the dispersed phase rapidly decreased within the first foam inserts before stabilizing at a length of 175 mm. Under the same superficial velocity, the mean droplet diameter is correlated to the foam's mean pore size. SMX+ mixers exhibited emulsification capability comparable to solid foam with the largest pores, while medium and small pore foams produced smaller droplets. Finally, the Middleman's correlation with viscosity correction accurately predicted mean droplet size at equilibrium and across various scenarios.

Airborne microplastic contamination across diverse university indoor environments: A comprehensive ambient analysis

Microplastics (MPs) have become a growing concern in the context of environmental pollution, with an increasing focus on their presence in indoor environments, including university facilities. This study investigates the presence and characteristics of MPs in different university indoor environments. Initial examination of indoor ambient MPs involved physical characterization through optical microscopy, focusing on classifying MPs by shape and color. Various types of MPs, including fibers, fragments, pellets, foams, films, and lines, were identified, with the most common colors being black, red, blue, and brown. Fragments were the predominant type of MPs found, although accurately quantifying their numbers proved challenging due to the dense sample content. These MPs displayed rough and irregular margins suggestive of abrasion. Subsequent chemical and elemental characterization was conducted using micro-Raman and SEM-EDX, revealing the presence of 25 different types of MPs, including PA 66, PTFE, PP, HDPE, and PE. The study indicates that university inhabitants are exposed to airborne MPs (≥ 2.5–336.89 μm) at inhalation rates of 13.88–18.51 MPs/m3 and 180–240 MPs daily. These MPs exhibited significant variations in size, and their distribution varied among the different indoor environments studied. SEM-EDX analysis revealed common elements in the identified MPs, with C, O, F, Na, Cl, Al, Si, and others consistently detected. This research is the first to comprehensively analyze MPs in nine different indoor university environments using active sampling. Identifying and reducing MP contamination in these facilities might stimulate more awareness, promote extensive scientific investigation, and facilitate the development of informed policies.

Supercooling suppression and thermal conductivity enhancement of erythritol using graphite foam with ultrahigh thermal conductivity for thermal energy storage

The application of erythritol to medium-temperature latent heat energy storage systems is limited by its low thermal conductivity and large supercooling. Three types of graphite foams (GFs) with different thermal conductivities were used as the porous skeleton for encapsulating erythritol via vacuum impregnation, and the erythritol/GF composites were investigated using different methods to solve the aforementioned problems. The GF pores were effectively filled with erythritol via vacuum impregnation, and the filling rate of erythritol reached more than 90%. The thermal conductivity of the erythritol/GF composites was 73.80, 35.05, and 13.30 W/m·K. The thermal conductivity of the erythritol/GFs was improved by 26–158 times over that of pure erythritol. The subcooling degree of the erythritol/GF composites was reduced from 64.1 °C to 59.4 °C, facilitating the release of latent heat. The erythritol/GF composites had remarkably boosted thermal stability compared with that of pure erythritol. The developed erythritol/GF phase-change composite material exhibits excellent heat transfer and storage properties, and it has broad prospects in the field of phase-change heat storage at intermediate temperatures.

Occurrence of microplastics in fish gastrointestinal tracts belongs to different feeding habits from the Bangladesh coast of the Bay of Bengal.

The Bay of Bengal (BoB) is home to a range of commercially important species with different food habits and feeding features. Microplastic (MP) contamination in the fish of BoB, like in many other marine environments, is a significant environmental concern. The study aimed to investigate the presence of microplastics (MPs) in the gastrointestinal tracts (GITs) of selected commercial marine fishes from the Bangladesh coast of the BoB. Six fish species (Escualosa thoracata, Tenualosa ilisha, Johnius belangerii, Trichiurus lepturus, Planiliza parsia, and Mystus gulio) were investigated (n = 120) following hydrogen peroxide digestion, and floatation (saline solution) protocols. After analyses, a total number of 696 MPs (dimension 0.3 to 5 mm) were identified. Moreover, the highest occurrence of MPs in fish GITs was found in planktivorous fish (average of 7.7 items/individual), followed by omnivorous (average of 5.2 items/individual), and carnivorous fish (average of 4.6 items/individual) (p < 0.001). However, planktivorous E. thoracata showed the highest number of MPs per g of GIT (average of 30.99 items/g GIT), whereas T. ilisha showed the lowest count (average of 0.77 items/g GIT). Different types of MPs (fibers (19 to 76%), fragments (6 to 61%), films (8 to 35%), microbeads (0 to 5%), and foams (0 to 2%)) were also observed. In terms of the color of MPs, the transparent, black, green, and blue types were the most common. Polymers were found as polyethylene (35 to 43%), polyethylene terephthalate (28 to 35%), polyamide (20 to 31%), and polystyrene (0 to 7%). The study provides a significant incidence of MPs in fish from the Bangladesh part of the BoB, which is very concerning. Therefore, long-term research is indispensable to ascertain the variables affecting the presence of MPs in fish, their origins, and their potential effects on the BoB fisheries. Stringent policies on plastic use and disposal should be strongly urged in this coastal region.

Challenges in the thermal modeling of highly porous carbon foams

The heat pulse (flash) experiment is a well-known, widely used method to determine thermal diffusivity. However, for heterogeneous, highly porous materials, neither the measurement nor the evaluation methodologies are straightforward. In the present paper, we focus on two open-cell carbon foam types, differing in their porosity but having the same sample size. Recent experiments showed that a non-Fourier behavior, called ’over-diffusive’ propagation, can be present for such a complex structure. The (continuum) Guyer–Krumhansl equation stands as a promising candidate to model such transient thermal behavior. In order to obtain a reliable evaluation and thus reliable thermal parameters, we utilize a novel, state-of-the-art evaluation procedure developed recently using an analytical solution of the Guyer–Krumhansl equation. Based on our observations, it turned out that the presence of high porosity alone is necessary but not satisfactory for non-Fourier behavior. Additionally, the mentioned non-Fourier effects are porosity-dependent; however, porous samples can also follow the Fourier law on a particular time scale. These data serve as a basis to properly identify the characteristic heat transfer mechanisms and their corresponding time scales, which altogether result in the present non-Fourier behavior. Based on these, we determined the validity region of Fourier’s law in respect of time scales.