Characterization Of Thermal Properties Research Articles

Characterization of Optical, Thermal, and Viscoelastic Properties of Pollenkitt in Angiosperm Pollen Using In-Line Digital Holographic Microscopy.

Pollen grains are remarkable material composites, with various organelles in their fragile interior protected by a strong shell made of sporopollenin. The outermost layer of angiosperm pollen grains contains a lipid-rich substance called pollenkitt, which is a natural bioadhesive that helps preserve structural integrity when the pollen grain is exposed to external environmental stresses. In addition, its viscous nature enables it to adhere to various floral and insect surfaces, facilitating the pollination process. To examine the physicochemical properties of aqueous pollenkitt droplets, we used in-line digital holographic microscopy to capture light scattering from individual pollenkitt particles. Comparison of pollenkitt holograms to those modeled using the Lorenz-Mie theory enables investigations into the minute variations in the refractive index and size resulting from changes in local temperature and pollen aging.

A Novel Oscillatory Thermal Response Test Method for Efficient Characterization of Ground Thermal Properties: Methodology and Data Analysis

A Novel Oscillatory Thermal Response Test Method for Efficient Characterization of Ground Thermal Properties: Methodology and Data Analysis

A Novel Microfiber Cellulose from Paederia foetida Stems: Characterization of Physical, Morphology, Thermal, and Chemical Properties

A Novel Microfiber Cellulose from Paederia foetida Stems: Characterization of Physical, Morphology, Thermal, and Chemical Properties

Thermal behavior of dry-cast concrete blocks masonry walls at elevated temperatures

This study aims to contribute to a better understanding of the behavior of masonry structures in the event of a fire, addressing a critical gap in both local and international standards and design guidance. Particularly in Brazil, the widespread adoption of structural masonry contrasts with the absence of national standards for evaluations at high temperatures, mainly due to the scarcity of research on the subject, potentially leading to severe consequences for life safety and property losses. This paper addresses a comprehensive study on the thermal behavior of dry-cast hollow concrete blocks masonry at high temperatures. The study combines both experimental and numerical analyses and involves underexplored topics, including characterization of thermal properties at elevated temperatures of commonly used blocks, post-fire condition of masonry's components, and determination of isotherms in the masonry cross-section in scenarios with one or both faces of the wall exposed to fire (separating and non-separating walls). Despite differences in the physical characteristics of the concrete used in block production, the temperature dependency of thermal properties obtained during experiments showed similar to that in Eurocode 2. Numerical and experimental results also indicate a low influence of block strength and mortar joints on the temperature evolution within the masonry. A key finding refers to a relatively fast temperature increase during heating due to the small thickness of the shells and webs of the blocks, thus impacting the performance of masonry structures in fire.

Combining linear-scaling quantum transport and machine-learning molecular dynamics to study thermal and electronic transports in complex materials

We propose an efficient approach for simultaneous prediction of thermal and electronic transport properties in complex materials. Firstly, a highly efficient machine-learned neuroevolution potential (NEP) is trained using reference data from quantum-mechanical density-functional theory calculations. This trained potential is then applied in large-scale molecular dynamics simulations, enabling the generation of realistic structures and accurate characterization of thermal transport properties. In addition, molecular dynamics simulations of atoms and linear-scaling quantum transport calculations of electrons are coupled to account for the electron-phonon scattering and other disorders that affect the charge carriers governing the electronic transport properties. We demonstrate the usefulness of this unified approach by studying electronic transport in pristine graphene and thermoelectric transport properties of a graphene antidot lattice, with a general-purpose NEP developed for carbon systems based on an extensive dataset.

Pulsed ultrasound assisted extraction of alternative plant protein from sugar maple leaves: Characterization of physical, structural, thermal, electrical, and techno-functional properties

Plant proteins are gaining in popularity and are increasingly being considered as an alternative to animal protein, thus a sustainable, yet comparable source of plant protein is highly recommended. To this end, the current study was conducted to investigate the structural, thermal, physical, and functional attributes, as well as the volatile profile of sugar maple leaves (SML) protein. To this end, SML protein was extracted by homogenization (10000 rpm, 5 min) pretreated ultrasound-assisted extraction (120000 J, 60% amplitude, 5:5 pulse, 25 °C, and 15 min) at varying pH (8−10) and compared with conventionally extracted SML protein. Among the different protein extracts, sonicated extract (pH9) provided a good protein yield (up to 7%) having higher protein content (210 mg Bovine serum albumin/g dry matter), thermal stability (onset of denaturation temperature:114 °C), and functional properties (solubility, emulsion capacity, water holding capacity, and antioxidant activity). On contrary, the characteristic green aroma, caused by 3-hexen-1-ol and nonanal, was found higher in sonicated protein extracts than that of macerated extracts. Having said that, this study showed the versatile properties of SML protein fractions that can be used as plant-based food ingredients.

Modification, Blending, Characterization, and Investigation of Thermal Properties, pH Response of Chitosan-based Polymer Extracted from Labeo rohita Scales

Modern shrimp farming began in India during the late 1980s in response to increasing global demand for shrimp and government policies aimed at promoting seafood exports. Corporate entities provided the necessary capital to build hatcheries, farms, and processing plants. However, a survey revealed that the major waste materials generated by these shrimp processing industries in India have become a major problem. In the present work, chitin is extracted and purified from the scale of fish Labeo rohita and modified into chitosan. Chitosan and polyvinyl alcohol (PVA) were blended in various ratios to prepare a composite material and films. The blended material was characterized using fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and a few other analyses to understand the polymer’s nature. The work demonstrated that fish scales can serve as a valuable raw material for chitin, chitosan and these polymer-based products. Chitosan, being easily accessible, cost-effective, and biodegradable, has wide-ranging applications in fields like clinical, biomedical, food industry, pharmaceuticals, polymer industries, etc., proper preparation of chitin, chitosan and combination with suitable compounds can lead to desired outcomes.

Encapsulation of bioactive compounds extracted from haritaki pulp (Terminalia chebula Retzius): characterization of physical, thermal, and morphological properties

The bioactive compounds of haritaki (Terminalia chebula Retzius) were microencapsulated using zein and starch as the encapsulating agents, utilizing both conventional (encapsulator) and advanced (freeze drying) techniques.

Comprehensive characterization of physicochemical, thermal, compositional, and sensory properties of cold-pressed rosehip seed oil

In this study, cold-pressed rosehip seed oil was fully characterized. Acidity and oxidation levels were near the limit values or slightly exceeded them and improvement in the storage conditions was suggested. The oil started to crystallize at -45.25 °C, and melt at -25.56 °C. Linoleic acid (51.1%), β-sitosterol (84.6%), γ-tocopherol (773.76 µg/g) and rosmarinic acid (31.38 µg/g) were determined as major fatty acid, sterol, tocopherol and phenolic compound, respectively. For the first time, aromatic volatile compounds and sensory descriptive terms were determined for cold-pressed rosehip seed oil. Sixty-seven volatile compounds were detected and L-limonene was found to be a major volatile compound. According to the sensory analysis, timber/kindling and raw vegetable tastes/aromas were found to be relatively dominant. Consequently, it is thought that rosehip seeds can be used as a raw material for edible and nutritionally-rich cold-pressed oil production and/or as source oil for functional food preparations.

Numerical Analysis of the 200-m Length Borehole Heat Exchanger for the Precise Characterization of Flow Rate and Thermal Properties

Numerical Analysis of the 200-m Length Borehole Heat Exchanger for the Precise Characterization of Flow Rate and Thermal Properties

Morphological and Thermal Analysis of Poly(L-lactic acid)/ Carboxymethyl Cellulose Bio-composites

Poly (L-lactic acid) (PLLA) and carboxymethyl cellulose (CMC) are derived from renewable resources and both have excellent properties such as biocompatibility and biodegradability. Applications of PLLA are restricted for some of its inadequate physical properties such as low glass transition temperature, relatively low melting point, high crystallization temperature, slow crystallization rate, and poor heat stability. This study aims to prepare and characterize a renewable bio-composite with more adequate properties for applications by solution casting of different PLLA, and CMC ratios. CMC was prepared from microcrystalline cellulose (MCC) of mustard stalks (agricultural wastes) and the yield was about 78%. The samples were analyzed via Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetric (DSC), wide-angle X-ray diffraction (WAXRD), and scanning electron microscopy (SEM) for spectroscopic and thermal properties characterization. The interaction between carboxylate groups of CMC surfaces and the terminal hydroxyl, terminal carboxyl, and carbonyl groups of PLLA through hydrogen bonds caused the shift and broadening of the band of FTIR spectra. The decomposition temperature of CMC was increased and formed excellent bio composites with PLLA. Composite crystallinity varied with the percentages of the CMC. The fibrous form of CMCs is present in the SEM micrograph indicating cellulose's fibrous structure was not affected by carboxymethylation. In composites, the surfaces of CMC fibers are layered and different from the reported results of SEM micrographs of PLLA/MCC composites. PLLA/CMC performs better in thermal properties but its mechanical characteristics cannot be determined owing to a limitation where the composite was too brittle and not able to undergo tensile testing.

PLA reinforced with modified chokeberry pomace and beetroot pulp fillers. Effect of oligomeric chain extender on the properties of biocomposites

Agri-food waste is an exciting way to use as a polymer filler. It is an ecological option for cutting down the material cost, especially relatively expensive biodegradable plastics. In this paper, lignocellulosic residues of chokeberry pomace (CP) and beetroot pulp (BP) are grafted with lactic acid oligomers (OLAs) in direct condensation of lactic acid (LAc) into the lignocellulosic backbone. Biocomposites with modified and unmodified fillers were prepared using poly (lactic acid) (PLA) matrix. Additionally, the influence of an epoxy-based chain extender (Joncryl® ADR 4468 (ADR)) on the properties of the biocomposites mentioned above was checked. SEM was used for the characterisation of modified and unmodified fillers. The success of the grafting reaction was confirmed by FTIR and 1HNMR analyses. DSC, DMA and TGA was applied for the characterisation of thermal properties of produced biocomposites. The influence of chemical modification and introduction of ADR to the biocomposite on water absorption, rheological and mechanical properties were tested. Moreover, the reaction between ADR and the lignocellulosic backbone of the CP filler was studied by FTIR analysis. Results showed, that modification of the filler using OLAs has a significant influence on reducing water absorption by 48.3 and 56.5 % for CP and BP biocomposites, respectively. The tensile strength increased after the modification and introduction of ADR. The chemical treatment of the filler causes an increase in the tensile strength by about 29 and 8 % compared to unmodified CP and BP fillers, respectively. 0.75 % of ADR in CP/PLA biocomposite allowed for an increase in tensile strength by 51 %. Rheological study showed that presence of ADR compensates the consequences of hydrolysis and segment exchange of the PLA chains caused by water and OLAs, respectively. Results are promising for the production of ecological biocomposites with satisfying mechanical, thermal and rheological properties compared to biocomposites with unmodified lignocellulosic filler.

Synthesis, characterization and determination of thermal properties of shape stabilized n-pentadecane based composite phase change materials including graphitic carbon nitride/alumina fillers for latent heat storage applications

Recently, Phase Change Materials (PCMs) has attracted significant interest for thermal energy storage (TES), which is a rational and convenient energy storage method. In the present work, new composite PCMs were prepared by performing easy impregnation process in which n-pentadecane was selected as PCM. For this, emulsion templated porous polymer composites were synthesized and employed as the frameworks to obtain new composite PCMs. To improve the heat transfer characteristics, the support matrices were prepared by loading of 1 wt% thermal conduction enhancer fillers namely, graphitic carbon nitride (g-C3N4), graphitic carbon nitride/alumina (g-C3N4/Al2O3) and alumina (Al2O3). The chemical structure, thermal stability and specific surface area characteristics of the frameworks were examined by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry (TG) and Brunauer–Emmet–Teller (BET) surface area analyses. Furthermore, the morphology and distribution of the fillers were explored with Scanning Electron Microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Additionally, improvements in the thermal conduction properties of the composite matrices were determined through the tests performed based on the T-history method. Moreover, the examinations on the thermal properties of the obtained composite PCMs were carried out using Differential Scanning Calorimetry (DSC). It was found that the reductions in supercooling temperatures (ΔT) were observed for the synthesized composite PCMs compared to degree of supercooling of pristine n-pentadecane. According to the obtained results, the synthesized composite PCMs can be employed in the cold thermal energy storage (TES) applications considering their appropriate properties and favorable TES capacities between 79.49 kJ/kg and 121.50 kJ/kg.

Characterization and optimization of thermal properties of rice straw and Furcraea foetida fiber reinforced polymer composite for thermal insulation application

The majority of the materials used in the building insulation are non-biodegradable polymeric materials. The continuous use of these polymers will not only cause environmental pollution but can also trigger health hazards in living beings. Therefore, in this study a sustainable composite material is prepared to limit the consumption of polymers by reinforcing them with rice straw agro-wastes and Furcraea foetida based natural fibers. The thermal stability, conductivity, transmittance, resistance, specific heat capacity and the flammability properties of the fabricated composite are evaluated. It is observed from the study that the composite with 20 wt% of rice straw showed the lowest thermal conductivity of 0.128 W/m oC which is 29.67% lower compared to neat epoxy material and was thermally stable up to 248 °C. Also, the thermal transmittance of the composite was reduced by 29.66% and it showed a thermal resistance of 0.154 m2oC/W at a temperature of 70 °C. The composite with the highest concentration of rice straw showed maximum specific heat of 3.22 J/g oC and it showed lower flammability with an average burning rate of 5.67 mm/min. The hybridization of composite with rice straw (15 wt%) and Furcrea foetida (20 wt%) fiber improved the strength of the composite and also it showed thermal conductivity of 0.132 W/m oC and was thermally stable up to a temperature of 272 °C.

A review of the use of infrared thermography in building envelope thermal property characterization studies

International standards used to carry out building envelope energy audits such as ISO 9869 rely on using heat flux meters (HFM) and temperature sensors on indoor and outdoor walls in-situ as inputs in calculations to determine thermal properties. Obtaining these measurements may be restrictive, expensive, and time-consuming. By contrast, obtaining temperature measurements using infrared thermography (IRT) is accessible, inexpensive, and quick. For these reasons, an auditing methodology which could solely use IRT to perform most building audits would be beneficial on many fronts. However, this practice is unfavored as it is viewed as being unprecise and involves considering numerous environmental factors which may be inaccurate and difficult to model. The present review article serves as a critical analysis of measurement techniques and models currently used in energy auditing research, detailing their advantages, drawbacks, and accuracy, and examines how, with improvements in methodology and with proper environmental modeling, IRT imagery could be used in place of HFM in building envelope auditing standards such as ISO 9869, potentially saving time, effort, and costs in related research and commercial activities.

Comprehensive thermal properties of ternary eutectic molten salt/nanoparticles composite phase change materials for high–temperature thermal energy storage

Chlorine and fluorine salts are very promising thermal storage media for high–temperature thermal energy storage (TES) systems. In this study, NaCl–KCl–NaF/nanoparticles composite phase change materials (CPCMs) were employed by an advanced high–temperature and high–pressure reactor. NaCl–KCl–NaF was adopted as the BS, while CuO and Al2O3 nanoparticles have been uniformly dispersed in different ratios to generate CPCMs from the base salt (BS). Microscopic characterization, thermal properties characterization, and economic analysis of CPCMs and the BS were performed. The findings revealed that the best results were obtained when the BS was added with 0.5 wt percent Al2O3 and 0.5 wt percent CuO nanoparticles, CPCMs have improved solid/liquid thermal conductivity by a factor of 3.70 and 1.84, and TES density by a factor of 1.13, while reducing the cost per unit of TES density by approximately 26.8%. In addition, the CPCMs and BS possess excellent operating temperature range and thermal stability, whereby they are applicable in high–temperature TES systems.

Investigation and characterization of dielectric, thermal, and chemical properties of recycled high‐density polyethylene blended with virgin polyethylene

AbstractDielectric performance of post‐consumer recycled HDPE blended with virgin HDPE was investigated to evaluate the possibility of using these materials for the insulation of electrical wires and cables. The presence of organic and inorganic impurities was investigated using thermal and chemical methods (TGA, DSC, and EDX). The characterization of impurities revealed different amount of inorganic impurities in recycled material that was depending on the execution of melt filtration by the recycler to prepare the recycled material. Higher values of both dielectric losses and dielectric constant were observed for post‐consumer recycled PE, with the dielectric loss of recycled material almost 17 times higher than the one of virgin PE at power frequency (60 Hz). The short‐term breakdown strength of post‐consumer recycled HDPE was observed to be slightly lower than that of virgin PE. The experimental result showed that blending the recycled stream with virgin materials was effective in order to enhance dielectric properties of recycled material. In this regards, dielectric losses decreased by almost 50% when 50% of virgin HDPE was added to the recycled material. In addition, breakdown strength was improved when virgin HDPE was added.

Thermal Conductivity of 3C/4H-SiC Nanowires by Molecular Dynamics Simulation.

Silicon carbide (SiC) is a promising material for thermoelectric power generation. The characterization of thermal transport properties is essential to understanding their applications in thermoelectric devices. The existence of stacking faults, which originate from the "wrong" stacking sequences of Si-C bilayers, is a general feature of SiC. However, the effects of stacking faults on the thermal properties of SiC are not well understood. In this study, we evaluated the accuracy of Tersoff, MEAM, and GW potentials in describing the thermal transport of SiC. Additionally, the thermal conductivity of 3C/4H-SiC nanowires was investigated using non-equilibrium molecular dynamics simulations (NEMD). Our results show that thermal conductivity exhibits an increase and then saturation as the total lengths of the 3C/4H-SiC nanowires vary from 23.9 nm to 95.6 nm, showing the size effect of molecular dynamics simulations of the thermal conductivity. There is a minimum thermal conductivity, as a function of uniform period length, of the 3C/4H-SiC nanowires. However, the thermal conductivities of nanowires weakly depend on the gradient period lengths and the ratio of 3C/4H. Additionally, the thermal conductivity of 3C/4H-SiC nanowires decreases continuously from compressive strain to tensile strain. The reduction in thermal conductivity suggests that 3C/4H-SiC nanowires have potential applications in advanced thermoelectric devices. Our study provides insights into the thermal transport properties of SiC nanowires and can guide the development of SiC-based thermoelectric materials.

Characterization of the Optical and Thermal Properties of Cardiac Tissue as a Function of Temperature.

In this work, we devised the first characterization of the optical and thermal properties of ex vivo cardiac tissue as a function of different selected temperatures, ranging from room temperature to hyperthermic and ablative temperatures. The broadband (i.e., from 650 nm to 1100 nm) estimation of the optical properties, i.e., absorption coefficient (μa) and reduced scattering coefficient $({\mu ^{\prime}}_s)$, was performed by means of time-domain diffuse optics. Besides, the measurement of the thermal properties was based on the transient hot-wire technique, employing a dual-needle probe to estimate the tissue thermal conductivity (k), thermal diffusivity (α), and volumetric heat capacity (Cv). Increasing the tissue temperature led to variations in the spectral characteristics of μa (e.g., the redshift of the 780 nm peak, the rise of a new peak at 840 nm, and the formation of a valley at 900 nm). Moreover, an increase in the values of ${\mu ^{\prime}}_s$ was assessed as tissue temperature raised (e.g., for 800 nm, at 25 °C ${\mu ^{\prime}}_s = 9.8{\text{ c}}{{\text{m}}^{{\text{ - 1}}}}$, while at 77 °C ${\mu ^{\prime}}_s = 29.1{\text{ c}}{{\text{m}}^{{\text{ - 1}}}}$). Concerning the thermal properties characterization, k was almost constant in the selected temperature interval. Conversely, α and Cv were subjected to an increase and a decrease with temperature, respectively; thus, they registered values of 0.190 mm2/s and 3.03 MJ/(m3•K) at the maximum investigated temperature (79 °C), accordingly.Clinical Relevance- The experimentally obtained optical and thermal properties of cardiac tissue are useful to improve the accuracy of simulation-based tools for thermal therapy planning. Furthermore, the measured properties can serve as a reference for the realization of tissue-mimicking phantoms for medical training and testing of medical instruments.

Protic dialkylammonium-based ionic liquids as promising solid-solid phase change materials for thermal energy storage: Synthesis and thermo-physical characterization

The widespread deployment of renewable energies such as solar and wind implies the parallel development of energy storage systems to deal with their intermittency. Storing renewable energy as thermal energy is one of the alternatives under constant research. In this regard, phase change materials (PCMs) are able to store large amounts of energy at a nearly constant temperature in the form of latent heat. Nevertheless, most of these PCMs undergo solid-liquid transitions, which hamper their implementation due to leaking issues, forcing the need for containment and increasing the final cost of the TES system.Therefore, a class of PCMs possessing solid-solid transitions has emerged to avoid these problems, the so-called organic ionic plastic crystals (OIPCs). Currently, the scientific literature and the number of OIPCs available for TES are rather scarce. Herein, we present the synthesis, the structural, and the thermo-physical characterization of nine OIPCs based on the dioctylammonium cation combined with different organic and inorganic acids as the anions. Particular attention has been paid to the most characteristic thermal properties of PCMs (latent heat, transition temperature, subcooling, thermal conductivity, and energy storage density), evaluating their thermal stability and the reliability of the most promising materials over thermal cycling as well. Among the prepared OIPCs, 3 of them, [DOA][NO3], [DOA][Cl], and [DOA][FOR], exhibited promising properties with remarkable solid-solid transition enthalpies of 156.6 J/g (at 41.4 °C), 101.2 J/g (at 20.0 °C) and 58.4 J/g (at 29.7 °C), respectively. These 3 OIPCs showed high potential to be used and integrated as PCMs in TES systems at temperatures below 45 °C.