Hygroscopic Materials Research Articles

Slow spreading with a large contact angle on hygroscopic materials.

Water transfer in wood plays a major role during the life time of timber structures but the physics of the various processes involved, such as wetting and imbibition, is not fully understood. Here we show that the angle of contact of a water drop placed in contact with an air dry wood surface is initially larger than 90°, then the drop slowly spreads over the surface, while the apparent (macroscopic) contact angle decreases down to a few tens of degrees. We show that similar results are obtained with a model material, i.e. hydrogel, as soon as a perturbation is induced onto the line of contact. We demonstrate that for the gel the initial large apparent contact angle results from a strong deformation of the gel in a thin softened region below the line of contact resulting from the fast diffusion of water and swelling of this region. This phenomenon ensures a real (local) contact angle close to zero. The spreading then results from the progressive diffusion of water at farther distance and successive perturbations of the line of contact when the drop enters in contact with small liquid droplets dispersed along the surface (residues of the chemical reaction during gel preparation). It is suggested that a similar effect occurs for the water drop over a wood surface and explains the large initial contact angle and slow spreading: the line of contact is initially pinned thanks to a wood surface deformation resulting from the wood surface swelling due to water absorption, thus leading to a large contact angle; it will then unpin when the local conditions have changed as a result of water diffusion at further distance, allowing for a small displacement up to the next pinning point and so on.

Energy-absorbing chair with reversible adaptation

An energy-absorbing chair with reversible adaptation (EACRA) is developed. A chair is presented with a seat and backrest made of expanded polyvinylformal of a hygroscopic material that changes its configuration with adaptation to the user's biometric data. Stiffness of expanded polyvinylformal depends on its moisture content. Recommendations on the use of EACRA are given. Keywords: energy-absorbing chair, reversible adaptation, stiffness. S.Sayapin@rambler.ru

HYGROSCOPIC CHARACTERIZATION OF EARTH BRICKS MADE FROM LATERITE AND CLAY OF SENEGAL

Earth is the main raw material most used in building construction in Africa and particularly in Senegal. It is a particularly malleable material, easy to handle, from which hard bricks (unfired or fired) can be made. Thus for a good prediction of the mechanical and thermal behavior of a material, it is important to determine its hygroscopic properties. This is why our study focuses on the hygroscopic characterization of earth materials based on laterite and clay. We are mainly interested in the study of adsorption and desorption isotherms by water vapor. The adsorption and desorption isotherm curves of the samples were determined by a volumetric method using the Belsorp Aqua3 apparatus. The measurement results showed that the earth materials are hygroscopic materials. Furthermore, unfired earth materials adsorb more moisture than fired earth materials.

Research on the use of agricultural waste to manufacture highly hygroscopic materials for agricultural applications

Material based on hydrogel from rice-straw with high absorption capacity and slow water release was prepared by cryogenic method, using citric acid as cross-linker and without creating waste stream to the environment. The structure and properties of the material were characterized by SEM, XRD, FTIR and TGA method. The results showed that the largest water absorbency of the material reached 30.67g/g, 4.48 times higher than the original rice-straw. The material was able to slowly release water in 6 days at room temperature and return water absorption of 3.97 g/g when reusing the material. In addition, the material is biodegradable and biocompatible. With the obtained results and simple, inexpensive, environmentally friendly method, this is a material that can be industrially produced and widely used in green agriculture.

Correlation between relative humidity and the strength and deformation characteristics of unstabilised earth masonry

The mechanical properties of unstabilised earthen building materials are distinctively influenced by changes in material moisture content. However, this moisture-dependency often remains unconsidered in the calculation of the load-bearing capacity of earth constructions. This paper aims to derive a convenient way to sufficiently consider the impact of different material moisture contents on the mechanical properties of unstabilised earth masonry. Therefore, the influence of relative humidity and temperature on the strength and deformation characteristics of unstabilised earth blocks, earth mortar and earth masonry is evaluated by conducting compression tests under various climate conditions. The results show that the compressive strength and the modulus of elasticity are linearly correlated with the relative humidity, whereas changes in temperature at constant relative humidity have no significant influence. To account the distinct moisture-dependency, a general applicable modification factor for unstabilised earthen materials is provided, which enables the adjustment of the compressive strength and the modulus of elasticity in dependency of arbitrary hygroscopic material moisture contents.

Metrological characteristics of solar evaporative coolers

The metrological characteristics such as the temperature and relative humidity of the cooled air in solar evaporative coolers in the form of an umbrella or awning are experimentally investigated in the work. Hygroscopic material was used for evaporative cooling. The results are compared with the data obtained from the waterproof material. They allow us to conclude that solar evaporative cooling is promising as an ecologically pure method for cooling air in open areas under canopies.

Using the screening layer of granulated foam glass to reduce the evaporation of hydrocarbon liquids

Introduction. The open surface of evaporation of hydrocarbon liquids during their storage in tanks (reservoirs) and in case of emergency spills are the fire hazards characterized by the mass rate of evaporation. The main way to reduce the fire hazard of hydrocarbon liquids is to isolate the evaporation surface of hydrocarbon liquids using various coatings, such as pontoons or floating roofs in tanks (reservoirs), and in case of emergency spills air-filled foam can be used, etc. An effective way to reduce the evaporation of hydrocarbon liquids is to isolate the evaporation surface using light slightly hygroscopic granular materials capable of being retained on the liquid surface by the Archimedean force. The authors address the analytical-experimental evaluation of a decrease in the mass rate of evaporation of hydrocarbon liquids when a layer of granulated foam glass shields the spill surface.Calculation methodology and results. A mathematical model has been developed to describe a reduction in the evaporation rate of hydrocarbon liquids through a “dry” layer of granulated foam glass, similar to the Bouguer – Lambert – Beer law. A method of experimental evaluation of the mass evaporation rate of hydrocarbon liquids through a shielding layer of granulated foam glass of different height has been developed. Screening coefficients for a number of hydrocarbon liquids and the averaged screening coefficient were identified using the results of an experimental research into parameters of evaporation of flammable liquids (acetone, gasoline AI-92, hexane, ethanol, kerosene, diesel fuel) through a “dry” layer of granulated foam glass of the Termoisol brand (fraction 5–7 mm) obtained using the methodology developed by the authors. Dependences between the rates of liquid evaporation through different thicknesses of a “dry” layer of granulated foam glass on the pressure of saturated vapours have been established. The area height, limited by the bottom concentration limit of the vapour flame, spreading during the evaporation of tested liquids from the free surface that may also have a shielding layer of Termoizol granulated foam glass is estimated analytically and experimentally.Conclusions. The developed mathematical model and the method of experimental estimation of the mass evaporation rate of hydrocarbon liquids allows to identify the evaporation rate of hydrocarbon liquids of different classes, and it can be used to study the parameters of evaporation shielded by materials having different granulo metric compositions.

A novel method for measuring viscoelastic parameters of epoxy resins under water bath environments using embedded strain gauges

Epoxy resins are a class of viscoelastic hygroscopic polymers widely used in plastic packaged devices. Stress relaxation and yielding may occur in plastic packaged devices under thermal-hygro environments, which seriously affect the reliability of the devices. It is important to obtain accurate viscoelastic parameters of the hygroscopic materials for analyzing the stresses and strains of plastic packaged devices. In this paper, a novel method for measuring the viscoelastic parameters of epoxy resins under water bath environments by using embedded strain gauges is proposed. A kind of epoxy resin-copper bi-layer plate is fabricated, and the biaxial strain gauges are embedded between the epoxy resin layer and the copper layer to monitor the deformations. The interfacial strains of the two test pieces at 85 °C/100% relative humidity are continuously measured up to 144 h. Combine the experimental strain curves and the analytical representation, the viscoelastic parameters of the epoxy resins are obtained by curve fitting with MATLAB and genetic algorithm. It is found that the viscoelasticity of epoxy resins could be described by an exponential function of order five shear modulus and relaxation times, and the interfacial strain curves obtained by genetic algorithm fit well with the experimental ones. The proposed testing and solving methods provide a valuable reference for getting the time-dependent viscoelasticities of epoxy resins under thermal-hygro environments.

Hygroscopy of Single‐Stranded DNA Nano‐Brushes: Atomic Workings of its Hydration‐Induced Deformation

AbstractHydration control of structure and mechanical properties is a process widely exploited in living organisms for key biological functions and, most recently, also in man‐made smart materials. Here, the challenge of unveiling the underlying atomistic mechanisms of this phenomenon using all‐atom Molecular Dynamics (MD) simulations to model the hygroscopic properties of polymer‐brushes composed by single‐stranded DNA (ssDNA) molecules is faced. The simulations identify three swelling regimes with a markedly different mechanical response. This evolution is produced by the competition between the formation of additional water–ssDNA and water–water hydrogen bonds, in a subtle interplay with the co‐evolving structure of the ssDNA SAM. This cooperative interaction between conformational and hydration degrees of freedom should be applicable to other polymer brushes and related hydrogen‐bonded systems. The results have direct implications for the use of ssDNA SAMs as sequencing devices, explaining the crucial role of the polymer‐brush density in the SAM collective response to hydration, and for the alternative design of hygroscopic materials, that exploit the extreme hygroscopic power of biological polymers like ssDNA brushes.

Hygroscopicity of Gel-Forming Composite Materials: Thermodynamic Assessment and Technological Significance

Hygroscopicity is an important technological property of composite materials for the conservation and treatment of water in modern technologies for sustainable green environment and agriculture. Using a thermodynamic approach, this study analyzes the hygroscopicity of composite gel-forming soil conditioners as a function of water activity and temperature. A simple and generally available method of water thermo-desorption is proposed for the quantitative assessment of hygroscopicity, dispersity and potential resistance of composite materials to osmotic collapse. It is based on the fundamental thermodynamic dependence of water potential and temperature of the dried material in a thermodynamic reservoir (laboratory) with constant relative humidity. The hygroscopicity of the studied composite materials in humid air (relative humidity over 90%) reaches a water content of 80–130% (wt); however, this water has too high retention energy and cannot be consumed by green plants, which calls into question the technology of obtaining water from the air using hygroscopic materials. The high hygroscopicity of hydrogels and its dynamics, depending on the controlling factors of temperature and air humidity, must necessarily be taken into account in the materials trade and in the technological calculation of doses for the use of these materials in sustainable agriculture and landscaping.

Hygro-mechanical short-term behaviour of selected coatings: experiments and material modelling on vapour permeability and mechanical properties

Many pieces of fine art are made of wood that has been treated with coatings. Since wood is a very hygroscopic material, the moisture content strongly influences the deformation of wooden parts. Coatings often act as moisture barriers. Therefore, the moisture permeability of coatings must be considered for the evaluation of the structural behaviour. The mechanical properties are also relevant to evaluate the deformation of thin artwork like panel paintings as well as the damage of paintings and varnishes. Therefore, the mechanical properties and the permeability of selected coatings used for cultural wooden artwork are investigated and presented in the article at hand. In this study, coatings of three artworks are investigated: a Lusatian cupboard from the eighteenth century, an altarpiece by L. Cranach the Elder and a Russian icon from 1912. The coatings considered are white ground, colours, varnishes, glue and textile reinforced sizing. Mechanical tests are conducted to evaluate the stiffness and tensile strength of the Russian icon’s coating. Cup tests are made to identify the moisture permeability of the coatings. This test was conducted for single coatings as well as for coating systems consisting of different coatings to investigate both the moisture barrier of single coatings and the interaction of coatings. Exponential functions for the relative humidity-dependent permeability are fitted based on the experimental data. The results allow the quantification of permeability for all investigated coatings—from white ground with a high permeability to beeswax with a low permeability—and the magnitude of moisture dependency of the coating’s permeability. Furthermore, it is shown that the simple addition of the water vapour resistance of single coatings underrates the resistance of a total coating system. By the mechanical tests, the strength, ultimate strain and Young’s modulus are obtained. The permeability and the mechanical parameters are required as input for numerical simulations of the structural behaviour of coated wooden artwork. These results are a good step forward to assess the risk of damage of coated wooden artwork.

Experimental study of a LiCl-modified fibrous core material for energy wheels

In this study, an experimental investigation is presented of a core material with irregular-shaped air flow channels for energy wheel applications. An experimental setup is established to test the performance of the material and study and analyze its characteristics. The core material has polyester wadding as the matrix and is sprayed with activated carbon as a hygroscopic material. Pores are found in the hygroscopic material attached to the fiber which contribute to the improvement of the heat exchange area between air and the material. To improve the performance of the material, it is modified by a lithium chloride solution. The test results showed that by implementing the lithium chloride modification, the hygroscopic capacity of the material can be significantly enhanced. The material latent and enthalpy efficiencies can be improved by about 10 % and 20 % at 0.5 rpm rotational speed with the action of lithium chloride at 2 % and 6 % mass concentration respectively. In addition, the efficiencies of the test material can be improved by more than 10 % by increasing its length from 38 mm to 50 mm. It is shown that the increase in the air flow rate leads to a decrease in the latent and enthalpy efficiencies. Mathematical models are used to analyze the latent efficiency of the material. Results showed that the efficiency of the modified material improved substantially at both high rotational speeds (>10 rpm) and low rotational speeds (0–10 rpm). Overall, the proposed core material offers an alternative low-cost and compact choice for energy wheel applications in air conditioning systems. The current study provides a preliminary assessment of such material and is aimed at establishing a better understanding of the promising potential in energy wheel applications.

Water vapor diffusion properties of Obernkirchener sandstone: Analysis of DVS data

In this paper, experimental characterization by dynamic vapor sorption (DVS) experiments on Obernkirchener sandstone samples is presented, giving access to the sorption isotherm of the porous building material. The latter may be classified as sigmoidal type II with a hysteresis in the high-humidity range. As the specimens were prepared with a defined geometry (circular plate, thickness of 7 mm), the recorded mass history in response to a step-wise increase or decrease of the sample-enclosing humidity was employed to backcalculate diffusivity of the porous material. Hereby, modeling focuses on vapor diffusion in the unsaturated pore space with water vapor concentration gradients as the driving force. We disregard capillary transport in the model, which, hence, is only valid in the low-humidity range, i.e. modeling in the scopes of a porous, hygroscopic material. The vapor diffusion coefficient of the porous material is estimated as 2600 mm 2 /h (at a temperature of 25 ° C ), what relates well to the bulk diffusion coefficient of water vapor in air taking into account tortuosity and porosity of the considered sandstone. As regards the influence of surface resistance to mass transfer, the samples may be characterized as borderline thick with a Biot number of approximately 50. • Transport model taking into account instantaneous adsorption at pore walls. • Relation of macroscopic vapor diffusion coefficient to molecular diffusion coefficient. • Discussion of influence of surface resistance to mass transfer (Biot number). • Comparison with results for other sandstone lithotypes in the open literature.

Substantiation of application technology of hygroscopic materials for dust prevention of roads with the lowest type of surfaces

The article presents the results of experimental study for types of loose soils are easily subject to dusting. In connection with this problem, the task is the study and study of the causes and structure of the formation of dustiness in the roadside zone of roads with common types of coatings or without coatings. The experimental study aims to determine the drying time of chemical dust prevention solutions under the influence of solar radiation and the norm of their distribution. The object of the research is dust generated on roads with low transport and operational performance (temporary roads in places of road repair work, roads to quarries, etc.), and materials used for dedusting road surfaces. The problem to be solved is to reduce the emission of a large amount of dust on roads without pavements or with inferior types of pavements, which adversely affects the human body. The results obtained are the identification of a way to combat dust on road surfaces, ensuring a decrease in wear when vehicles move on roads without pavements. At the same time, the classification of dust according to their sources of formation is expected at the output result. Due to their features and characteristics, these results allowed the author to solve this problem - effective ways to combat dust on road surfaces are: treating them with dust-removing materials that reduce wear; maintaining the original evenness; reduction of air pollution; improvement of traffic conditions for cars and the sanitary and hygienic condition of roads near settlements. For experimental tests, traditional salt solutions of various concentrations (NaCl, MgCl2, CaCl2, MgCl2×6H2O, etc.) and solutions of foreign–made stabilizing additives Durasoil and Soiltac from SOILWORKS were taken.

On the rate of cooling of aerated food grains

Aeration is one of the most powerful tools available to the managers and handlers of stored grains. Irrespective of the initial temperature and moisture content of the grains, the biological and chemical phenomena that occur in the stored grains are significantly influenced by the wet bulb temperature of the air entering the grain. Several authors have developed mathematical expressions to estimate the rate at which aerated stored grains and other hygroscopic materials cool. They refer to ‘difficulties in comprehension’, remark that ‘results are difficult to interpret’ and ‘necessarily complicated’. The principal objective of this work is to clarify and quantify the factors that determine the rate of cooling aerated food grains. This is achieved by deriving an equation that arises as a direct consequence of the conservation of energy and moisture in aerated grains. It is found that the rate of cooling of aerated grains depends strongly on the sorption isotherm, a mathematical function that relates grain moisture content to the equilibrium relative humidity and temperature of their surrounding atmosphere. The integral heat of wetting, a function of the sorption isotherm, contributes to the effective specific heat of grains. However, its effects are typically neglected in analyses of the rate at which aerated grain cools because published sorption isotherms are insufficiently accurate for them to be included. It is proposed that a multidisciplinary approach be taken to measuring the psychrometric properties of food grains. • A new and simple equation is derived for the rate of cooling of aerated grains. • The equation highlights the factors that govern the rate of grain cooling. • Published sorption data lead to inconsistent values of the heat of sorption.

The European Standard EN 15757 Concerning Specifications for Relative Humidity: Suggested Improvements for Its Revision

The European Standard EN 15757: 2010 ‘Conservation of Cultural Property—Specifications for temperature and relative humidity to limit climate-induced mechanical damage in organic hygroscopic materials’ is a guide specifying the allowed limits of variability of the indoor climate, in particular relative humidity (RH) to preserve cultural heritage objects and collections composed of climate-vulnerable materials. This paper is finalized to provide useful elements to improve the Standard at its next revision, based on focused research. The methodologies and the mathematical tools used are performed on 18 case studies representing different buildings, climates, and use, including heated and unheated buildings, museums, churches, concert halls, archives, and storage rooms. The first aim is to compare the method based on the centred moving average suggested by Annex A of EN15757 with an alternative method based on percentile interpolation to calculate the reference RH values, and in particular the safe band of RH variability, as well as the upper and lower risky bands. It has been found that the two methods provided the same results, but the latter is easier to manage. The second aim is to verify if the duration of the record necessary for the determination of the safe band is really 13 months of measurements as required by the Standard to account for the specific request of the centred moving average with a 30-day time window. This paper demonstrates that the same goal may be reached with a 12-month record, but extracting from the record itself the two periods required by the time window, i.e., the last 15 days of the year will be copied before the start of the record, and the same with the first 15 days after the end. The third aim is to test if the particular choice of the width of the time window is influential on the width of the safe band, and to assess the relationship between the width of the safe band and the width of the time window. The results show that the safe band logarithmically depends on the length of the time window, so it is crucial to respect the 30-day window established by the Standard.

Numerical modelling of mechanical degradation of canvas paintings under desiccation

Mechanical damage in oil paintings on canvas show up as cracks and loss of original paint. Several parameters can contribute to this type of degradation. These paintings have a complex layered structure, typically composed of minimum four or more hygroscopic materials, each of which has different (non-linear) material properties and geometrical complexities. The mechanical degradation of canvas paintings occurs because each of these materials have diverse responses under fluctuating environmental conditions, especially temperature and relative humidity (RH). By examining the geometrical complexities and the non-linear material properties, this paper presents an investigation of three degradation phenomena under desiccation: (1) bulging formation around the corners, (2) crack formation in glue and ground layers, and (3) plastic deformation in the ground and oil paint layers.This on-going investigation provides further insights into the global and local stress distribution in typically constructed oil canvas paintings. This includes finite element method (FEM) and extended-FEM (XFEM) computer models at various scales, under desiccation from the initial RH of 90%, and 50–10%. The models consist of four to five different materials, namely lead white oil paint, red iron oxide oil paint, rabbit skin glue, linen canvas, and a spruce stretcher. The models were constructed using several combinations of materials to conduct parametric studies on the effects of glue shrinkage in paintings due to desiccation, and changing the mechanical properties of the ground layers. The relevant geometrical and mechanical properties with respect to the stress relaxation conditions are discussed in detail.The simulation results of the full-scale models show that the shrinkage of glue lowers the level of induced tension stresses in the paint layers in the central area of the painting due to the inward bowing of the stretcher. The inward deformation of the stretcher can be 4.5 times as large in a painting with a glue layer as in one without. This indicates the difficulty in forming cracks near the center of paintings purely by desiccation; however, in close-up cross-section model, cracks of 20 μm in length could still be observed in the ground exposed to an extreme RH change of 90% to 10%.The analysis of cross-section models with the full geometrical complexity for the corners showed that multiple cracks are likely to form in ground and paint layers in the corners when desiccated by 40%; RH 50–10%. Furthermore, in extreme cases with stiffer ground/paint such as zinc white, cracks can form from smaller drop in RH; RH 50% to 35%. Such cracks are form in the ground layers, and therefore, are not initially visible as they are positioned below the uncracked paint layer. This result can be the possible explanation for cracks in the ground, which are initially invisible with the naked eye, but can be revealed with X-radiographs.The results support the hypothesis that fluctuations in relative humidity can cause hidden cracks in the lower layers, which can eventually propagate further into the upper-lying paint layers of paintings. The cracks typically form when the desiccation reaches a 40% drop, but in cases of brittle materials the drop causing cracks can be lower. The actual RH drop causing cracks depends on the specific material composition.

Formulation of Fast Dissolving β-Glucan/Bilberry Juice Films for Packaging Dry Powdered Pharmaceuticals for Diabetes.

The aim of this study was to develop fast dissolving films based on β-glucan and bilberry juice due to the bioactive potential of β-glucan and antidiabetic effect of bilberry juice. The benefit of incorporation of bioactive compounds into the films is due to the removal of unnecessary excipients and to confer protection as well as increase stability and shelf life to the packaged product. Due to the fast dissolving requirements of the European Pharmacopeia, which reduced the dissolution time from 180 to 60 s, indicating less than a minute, hygroscopic materials, such as sodium alginate and a suitable plasticizer, such as glycerin were incorporated. Moreover, the influence of ingredients and surfactants, such as soybean oil was studied in the design of fast dissolving films. Additionally, the steady state rate water vapor transmission rate (WVTR), water vapor permeability (WVP), and FT-IR spectroscopy tests were performed at high resolution to ensure the reliability of the films and composition as well as to validate the results. Our data suggest that the addition of surfactants contributed to the development of fast dissolving films without influencing the diffusion of water vapor. Low levels of WVTR and short dissolution time made from β-glucan and bilberry juice are a convenient candidate for packaging dry powdered pharmaceuticals for diabetes.

Discrimination between softwood and hardwood based on hemicellulose content obtained with portable nuclear magnetic resonance

Wood is a hygroscopic material that can reach an equilibrium moisture content when ambient temperature and relative humidity are constant. Moisture affects all properties of wood, as well as its preservative treatment. The hygroscopic behavior of wood can be attributed to the hydroxyl groups of its constituents. Since hemicellulose shows the greatest water affinity, it can be considered the main responsible for the ingress of water into the wood mass. Below the fiber saturation point, wood moisture is only stored in the cell walls. Proton Nuclear Magnetic Resonance (NMR) is a relative method used for the evaluation of moisture content distribution in wood and NMR relaxation is an excellent tool to study the hygroscopic behavior of different woods below the fiber saturation point. This work aimed to test the hypothesis of discriminating among softwoods and hardwoods of different botanical species and identifying further sub-clusters of woods based on the NMR proton spin–spin (T2) and spin–lattice (T1) relaxation times of their cell wall water in the hygroscopic moisture range. Importantly, the study was performed using a portable low-cost NMR instrument with which it is possible to investigate wood samples of any size. The main result of this study was that at RH = 94% the relaxation time T2,2, associated with the cell wall bound water, can be used as a marker to discriminate among softwoods and hardwoods.Graphical abstract

Thermo-physical properties measurements of hygroscopic and reactive material (zeolite 13X) for open adsorptive heat storage operation

The determination of the thermo-physical properties (density, specific heat capacity, and thermal conductivity) of hygroscopic and reactive solid materials, as those applied in sorption thermochemical heat storage systems, is not trivial. Lack of precision in the measurement and contradictory results make it difficult to enter these thermal parameters in the programs used for simulating the functioning and operating scenarios of thermochemical heat storage devices. For this reason, different techniques have been applied and compared in order to improve the accuracy of the measurement. In particular, there was a difference in thermal conductivity (about 30%) between the hot disc experiments and the others, as well as a higher dispersion of the experimental data (MAD > 19%). The same was found for specific heat capacity (MAD ≈14%). Hence, the transient hot disk method is not suitable for estimating thermal conductivity and the specific heat capacity of this type of material. Nevertheless, this technique enables a good estimation of the thermal effusivity. The thermal conductivity and the specific heat capacity were investigated by the hot wire method and by TG-DSC, respectively. A slight increase in specific heat with temperature was observed, but in the range of 70–95 °C, this value is constant at 913 J kg−1 K−1. The applied methodology was validated by comparing the experimental and calculated thermal effusivity values.