Thermal Properties Research Articles

Sequence of monomers and position of stereocenters matter for thermal properties of stereocontrolled oligourethanes.

Polyurethanes are commodity materials used for multiple applications. In recent years, a new category of polyurethane material has emerged, characterized by the lack of polymer molar mass distribution, control of the monomer arrangement in the chain, and even full stereocontrol. Various multistep synthesis strategies have been developed to fabricate sequence-defined polyurethanes. However, synthesizing stereocontrolled polyurethanes with a controlled sequence is still a challenge. Polyurethanes with structural precision, as represented by biopolymers, i.e. proteins or nucleic acids, have opened new application directions for these groups of materials. It has been shown that polyurethanes can be used as biomimetics, information carriers, molecular tags, and materials with strictly controlled properties. Precise synthesis of macromolecules allows us to fine-tune the properties of polymers to specific needs. Therefore, it is essential to collect information on the sequence-structure relationship of polymers. In our work, we present synthetic pathways to make sequence and stereo-defined oligourethanes. We demonstrate that structural details, i.e., the monomer sequences and position of the stereocenter, have a tremendous effect on the thermal properties of model oligourethanes. We show that the introduction of chirality by constitutional isomerization can be used to program the thermal characteristics of polymers, which are key features for material applications.

Influence on solar PV performance integrated with heat sinks and nano-enhanced phase change material

The inevitable advancement of solar photovoltaic (PV) system performance highly relies on temperature control, which enhances electrical efficiency. The objective of this study is to enhance electrical efficiency by incorporating phase change material of HS36 (PCM) and nano enhanced PCM (NePM). The thermal properties of PCM were improved by adding graphene flakes (GF) into PCM to enhance the thermal transfer rate between the PV panel and PCM. The phase change properties and thermal conductivity of PCM with different concentrations of GF were assessed. The results indicated that the 0.9 wt.% NePCM exhibited the highest thermal conductivity enhancement of 47% in solid states and a significant reduction in latent heat by 9.4% during freezing compared to pure PCM. The effect of cooling on PV performance was studied using a reference panel, integrated with a heat sink containing PCM (PV/PCM) and NePCM (PV/NePCM). Outdoor experiments were conducted using a 10 W panel, and the results for the use of PCM showed a reduction in temperature and an improvement in efficiency. The findings revealed that attaching a heat sink and integrating the PV panel with pure PCM and NePCM reduced the temperature by 8.65°C and 10.04°C, respectively, and improved efficiency by 11.65% and 12.15%, respectively. It can be concluded that the proposed thermal management method for PV systems offers a viable solution for increasing daily average electrical generation with maximum efficiency.

Degradation characteristics of 3D printed continuous fibre-reinforced PA6/chopped fibre composites in simulated saltwater

AbstractThis paper investigates the performance of continuous fibre-reinforced 3D printed components in salt water medium at room temperature. Markforged® Mark Two 3D printer was employed to fabricate standard specimens made of Onyx and reinforced Onyx specimens with continuous carbon, high-strength high-temperature glass, and Kevlar fibres. Aging process was conducted to characterize the long-term effect of salt water on the mechanical behaviour of fibre-reinforced 3D printed samples. Several mechanical tests including tensile, 3-point bending test and indentation testing have been carried out on the dry and aged standard samples to evaluate tensile strength, flexural strength, micro-hardness, and modulus of elasticity in micro-scale. The mechanical tests revealed the degradation and loss in mechanical properties of the printed samples after aging in salt water. The data highlighted that Onyx samples without continuous fibres experienced the most significant reduction in both tensile (33.54%) and flexural (63.47%) strengths after 1 year, while continuous carbon fibre-reinforced Onyx samples showed comparatively lower strength reductions (28.46% in tensile strength and 18.73% in flexural strength). Optical and scanning electron microscopy were performed to investigate the fracture behaviour of the tested specimens. In addition, the DSC assessment showed a slight change in the thermal properties of aged specimens.

Carbon fiber‐reinforced thermoplastic synthesized by the hypercrosslinking reaction of polyether ether ketone

AbstractRecently, thermoplastic resins were used as matrix to synthesize carbon fiber‐reinforced thermoplastic (CFRTP) for recycling it easily. In this study, a CFRTP with excellent mechanical properties and heat resistance was synthesized using a polyether ether ketone (PEEK) as a matrix resin. The PEEK resin was modified to form cross‐linked structures through Friedel–Crafts reaction alkylation. The synthesis temperature of CFRTP was optimized considering the mechanical properties of PEEK, and its heat resistance was enhanced because of the cross‐linked structures. Further, the cross‐linked PEEK resin was partially used as a matrix resin, and the mechanical properties of the CFRTP were enhanced. We plan to develop a method for recycling CFRTP using PEEK and crosslinked PEEK for synthesizing C/C composites by focusing on the high heat resistance of the crosslinked PEEK containing a large amount of carbon and reducing mass loss after heat treatment.Highlights CC bonds were introduced into the polyether ether ketone (PEEK) resin by Friedel–Crafts reaction alkylation. Thermal properties of PEEK were enhanced by hypercrosslinking reaction. Optimization of synthesized temperature was investigated to fabricate carbon fiber‐reinforced thermoplastic (CFRTP). Mechanical properties were enhanced CFRTP modified with hypercrosslinking reaction.

Ancient and historical cooking pots and food: an eternal communion. A topical review

AbstractThis contribution provides a topical view at and review of traditional clay‐based utilitarian cooking pots that were used for millennia to prepare, serve, display, and distribute foodstuff. Key mechanical and thermal properties of ceramic cooking vessels will be discussed and strategies of property optimization outlined. In addition, some important chemical changes food constituents undergo during cooking will be explained. Mass‐produced ancient ceramic cooking pots from Neolithic Mesopotamia have revolutionized the art of cooking by allowing foodstuff to be processed in water. As an example of successfully optimizing the properties of cooking vessels, emphasis is being given to Indigenous prehistoric North American ware of the Mississippian culture (c. 800 to 1600 CE) that show impressively how ancient potters overcame the technological challenges posed by essentially unsuitable smectite‐rich clays with extreme plasticity and high swell–shrink ratio by adding copious amounts of burnt mussel shells as temper material.

Influence of Silica Nanoparticles on the Physical Properties of Random Polypropylene

Influence of Silica Nanoparticles on the Physical Properties of Random Polypropylene

Effects of volume fraction of short-cut quartz fibers on mechanical and thermal properties of SiO2f/SiO2 composites

Effects of volume fraction of short-cut quartz fibers on mechanical and thermal properties of SiO2f/SiO2 composites

Multiphoton Lithography of Interpenetrating Polymer Networks for Tailored Microstructure Thermal and Micromechanical Properties.

Multiphoton lithography (MPL), an emerging truly 3D microfabrication technique, exhibits substantial potential in biomedical applications, including drug delivery and tissue engineering. Fabricated micro-objects are often expected to undergo shape morphing or bending of the entire structure or its parts. Furthermore, ensuring precise property tuning is detrimental to the realization of the functionality of MPL microstructures. Herein, novel MPL materials based on interpenetrating polymer networks (IPNs) are presented that effectively combine the advantages of acrylate and epoxy systems. IPNs with varying component ratios are investigated for their microfabrication performance and structural integrity with respect to thermal and micromechanical properties. A variety of high-resolution techniques is applied to comprehensively evaluate IPN properties at the bulk, micron, and segmental levels. This study shows that the MPL laser scanning velocity and power, photoinitiator content, and multi-step exposure can be used to tune the morphology and properties of the IPN. As a result, a library of 3D MPL IPN microstructures with high 3D structural stability and tailored thermal and micromechanical properties is achieved. New IPN microstructures with Young's moduli of 3-4MPa demonstrate high-to-fully elastic responses to deformations, making them promising for applications in morphable microsystems, soft micro-robotics, and cell engineering.

Synergistic modification of hot-melt extrusion and nobiletin on the multi-scale structures, interactions, thermal properties, and in vitro digestibility of rice starch

BackgroundRice starch has high digestibility due to its large carbohydrate content. Synergistic modification of hot-melt extrusion (HME) and additives such as flavonoids, hydrocolloids, proteins, lipids, and other additives has the tendency to retard the rate of starch hydrolysis. Hence, the current investigation aimed to study the combined effect of the HME-assisted addition of nobiletin (NOB, 0, 2, 4, and 6%) on the multi-scale structures, interactions, thermal, and digestibility characteristics of rice starch.MethodsThe study employed density functional theory calculations and an infrared second derivative of an Fourier-transform infrared (FTIR) spectrometer to analyze the interactions between NOB and starch. The physicochemical properties of the starch extrudates were characterized by FTIR, 13C nuclear magnetic resonance, X-ray diffraction, and differential scanning calorimetry, while the digestibility was evaluated using an in vitro digestion model.ResultsHME was found to disrupt the crystalline structure, helix structure, short-ordered structure, and thermal properties of starch. The interaction between NOB and starch involved hydrophobic interactions and hydrogen bonds, effectively preventing the molecular chains of starch from interacting with each other and disrupting their double helix structure. The addition of NOB led to the formation of a highly single-helical V-type crystalline structure, along with the formation of ordered structural domains. Consequently, the combined treatment significantly enhanced the ordered structure and thermal stability of starch, thus effectively leading to an increase in resistant starch and slowly digestion starch.DiscussionThe study underscores that synergistic modification of HME and NOB holds promise for enhancing both the nutritional value and functional properties of rice starch. These findings offer valuable insights for developing high-quality rice starch products with broader applications.

A comprehensive study on the thermal properties and chemical characterization of 1,3,5‐trinitroso‐1,3,5‐triazine (R‐Salt)

Abstract1,3,5‐trinitroso‐1,3,5‐triazine (R‐Salt) is an insensitive energetic that has previously been used as an improvised explosive. The work presented here is a comprehensive study on the thermal properties and chemical characterization of R‐Salt. Thermal analysis was performed via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) which found both crude and recrystallized R‐Salt have similar thermal properties but the selected lid impacted both the thermal profile and onset temperature. Chemical characterization performed via Raman, Fourier‐transform Infrared (FT‐IR), nuclear magnetic resonance (NMR) spectroscopy and high‐resolution mass spectrometry indicate that recrystallization does not quantitatively improve the purity of crude R‐Salt., The reported NMR 2D‐HSQC, FT‐IR, and Raman spectra are the first to be reported within the published literature, as to the authors’ knowledge.

Study on Mechanical Properties of Polymer Composites Filled with Nano Egg-shell Powder

Polymeric materials, when reinforced with synthetic fibers like glass, carbon, and aramid, offer notable advantages including increased stiffness and strength-to-weight ratio compared to conventional materials such as wood, concrete, and steel. Among these options, glass fiber stands out due to its affordability and widespread availability. Glass fiber reinforced polymer composites exhibit moderate mechanical properties, which can be significantly enhanced by incorporating nano fillers like eggshell powder. This study explores the utilization of nano eggshell powder as well as methods for effectively integrating nano fillers into polymer composites to create value-added products. Four types of composites, varying in weight proportions of nano eggshell powders, were prepared using the hand lay-up technique for mechanical and thermal characterizations. Various mechanical properties including tensile strength, flexural strength, impact behavior, as well as thermal properties via TGA and DMA analysis were investigated. The results indicate that incorporating the optimal amount of nano fillers significantly improves the overall strength of glass fiber reinforced composite materials, leading to cost savings of over 30%. This suggests that nano eggshell fillers hold great potential in composite manufacturing, particularly for substituting high-cost glass fibers in low load-bearing applications.

Modified Release 3D-Printed Capsules Containing a Ketoprofen Self-Nanoemulsifying System for Personalized Medical Application.

This study explores the realm of personalized medicine by investigating the utilization of 3D-printed dosage forms, specifically focusing on patient-specific enteric capsules designed for the modified release of ketoprofen, serving as a model drug. The research investigates two distinct scenarios: the modification of drug release from 3D-printed capsules crafted from hydroxypropyl methylcellulose phthalate:polyethylene glycol (HPMCP:PEG) and poly(vinyl alcohol) (PVA), tailored for pH sensitivity and delayed release modes, respectively. Additionally, a novel ketoprofen-loaded self-nanoemulsifying drug delivery system (SNEDDS) based on pomegranate seed oil (PSO) was developed, characterized, and employed as a fill material for the capsules. Through the preparation and characterization of the HPMCP:PEG based filament via the hot-melt extrusion method, the study thoroughly investigated its thermal and mechanical properties. Notably, the in vitro drug release analysis unveiled the intricate interplay between ketoprofen release, polymer type, and capsule thickness. Furthermore, the incorporation of ketoprofen into the SNEDDS exhibited an enhancement in its in vitro cylooxygenase-2 (COX-2) inhibitory activity. These findings collectively underscore the potential of 3D printing in shaping tailored drug delivery systems, thereby contributing significantly to the advancement of personalized medicine.

Thermal and Elastic Properties of an A2/B2 Refractory High Entropy Superalloy and Its Constituent Phases

Thermal and Elastic Properties of an A2/B2 Refractory High Entropy Superalloy and Its Constituent Phases

Mechanical, thermal, chemical, and physical properties of sponge gourd outer skin fiber-reinforced vinyl ester composites

Mechanical, thermal, chemical, and physical properties of sponge gourd outer skin fiber-reinforced vinyl ester composites

A renewably sourced, circular photopolymer resin for additive manufacturing.

The additive manufacturing of photopolymer resins by means of vat photopolymerization enables the rapid fabrication of bespoke 3D-printed parts. Advances in methodology have continually improved resolution and manufacturing speed, yet both the process design and resin technology have remained largely consistent since its inception in the 1980s1. Liquid resin formulations, which are composed of reactive monomers and/or oligomers containing (meth)acrylates and epoxides, rapidly photopolymerize to create crosslinked polymer networks on exposure to a light stimulus in the presence of a photoinitiator2. These resin components are mostly obtained from petroleum feedstocks, although recent progress has been madethrough the derivatization of renewable biomass3-6 and the introduction of hydrolytically degradable bonds7-9. However, the resulting materials are still akin to conventional crosslinked rubbers and thermosets, thus limiting the recyclability of printed parts. At present, no existing photopolymer resin can be depolymerized and directly re-used in a circular, closed-loop pathway. Here we describe a photopolymer resin platform derived entirely from renewable lipoates that can be 3D-printed into high-resolution parts, efficiently deconstructed and subsequently reprinted in a circular manner. Previous inefficiencies with methods using internal dynamic covalent bonds10-17 to recycle and reprint 3D-printed photopolymers are resolved by exchanging conventional (meth)acrylates for dynamic cyclic disulfide species in lipoates. The lipoate resin platform is highly modular, whereby the composition and network architecture can be tuned to access printed materials with varied thermal and mechanical properties that are comparable to several commercial acrylic resins.

Effect of Reaction Layers on Internal Stresses in Co‐Fired Multilayers of Calcium Manganate and Calcium Cobaltite

A widespread recovery of waste heat requires a cost‐effective production of thermoelectric generators. Thermoelectric oxides are predestined for use at high temperatures. For manufacturing reasons, a multilayer generator design will be easily scalable and cost‐effective. To evaluate the potential of ceramic multilayer technology for that purpose, a multilayer of the promising thermoelectric oxides calcium cobaltite (Ca3Co4O9), calcium manganate (CMO, CaMnO3), and glass–ceramic insulation layers is fabricated. Cracks and reaction layers at the interfaces are observed in the microstructure. The compositions of these reaction layers are identified by energy‐dispersive X‐ray spectroscopy and X‐ray diffraction. Mechanical and thermal properties of all layers are compiled from literature or determined by purposeful sample preparation and testing. Based on this data set, the internal stresses in the multilayer after co‐firing are calculated numerically. It is shown that tensile stresses in the range of 50 MPa occur in the CMO layers. The reaction layers have only a minor influence on the level of these residual stresses. Herein, it is proven that the material system is basically suitable for multilayer generator production, but that the co‐firing process and the layer structure must be adapted to improve densification and reduce the tensile stresses in the CMO.

Exploring the potential of fly ash cenosphere—capric acid composite phase change material in concrete incorporating supplementary cementitious material

AbstractIncreasing demand for energy globally, with the building sector being a significant contributor to energy consumption, is a major issue. To address this, efforts are being made to make buildings more energy efficient, including lowering the demand for heating, ventilation, and air conditioning to decrease energy demand. Phase change material (PCM) functions as a latent heat energy storage material that absorbs heat energy while transforming its phase from solid to liquid and then releases the heat energy when it transforms from liquid to solid state. Integrating PCM into building materials can considerably enhance their energy storage density. In this study, the potential of using fly ash cenosphere—capric acid (CeCA) composite PCM in concrete is evaluated. The mechanical, durability and thermal properties of the CeCA blended concrete were investigated. Furthermore, the CeCA‐concrete is enhanced with auxiliary cementitious substance, namely ground granulated blast furnace slag (GGBS). The optimal proportion of CeCA was determined to ensure a balance of compressive strength and thermal conductivity. The results indicated that the compressive strength of the CeCA blended concrete lowered with an increase in the percentage of CeCA. The thermal conductivity of the concrete specimen was lowered by 33.14% at a 25% incorporation of CeCA, resulting in improved thermal performance. The incorporation of GGBS has enhanced the mechanical and durability performance of CeCA‐Concrete. The optimal concrete specimen was found to be 25% CeCA +40% GGBS, which had greater thermal efficiency than the control specimen with similar strength performance. The findings were validated by field emission scanning electron microscopy analysis of the concrete specimen.

Crafting high‐performance polymer‐integrated solid electrolyte for solid state sodium ion batteries

AbstractThe development of modern solid‐state batteries with high energy density has provided the reliable and durable solution needed for over‐the‐air network connectivity devices. In this study, a NASICON‐type Na3Zr2Si2PO12 (NZSP) ceramic filler was prepared using the sol‐gel method and then a polymer‐integrated solid electrolyte consisting of polyethylene oxide (PEO), NZSP, and sodium perborate (SPB) was prepared by Stokes' solution casting process. Through physico‐chemical and electrochemical characterization techniques, the morphology, electrochemical, and thermal properties of the prepared solid electrolyte sample were carefully studied. The PEO/NZSP/SPB electrolyte developed for all‐solid‐state sodium‐ion batteries (ASSSBs) exhibited a strong ionic conductivity, a large window for electrochemical stability, and was effective in controlling the growth of sodium dendrites. Furthermore, the polymer‐integrated solid electrolyte showed impressive rate capability, high discharge capacity (73.2 mAh g−1) at 0.1 mA cm−2, and good faradaic efficiency (98%) even after 100 cycles. These results reveal that the PEO/NZSP/SPB electrolyte is a potential and inevitable candidate for the evolution of high‐performance rechargeable ASSSBs.

Evaluation of thermal comfort and air permeability properties of Lyocell blended drapery fabrics

PurposeThe paper aims to provide an investigation about the effect of weft yarn type on thermal comfort and air permeability properties of Lyocell blended drapery fabrics.Design/methodology/approachThe paper evaluates the effect of weft yarn type on thermal comfort and air permeability properties of Lyocell blended drapery fabrics. Twill drapery fabrics with 18 Tex linen warp yarn where two types of weft yarns were utilized respectively with the order of “A” yarn and “B” yarn. 58 Tex Lyocell Linen blended first weft yarn (A yarn) was kept constant and the second weft yarn (B yarn) varied in different yarn structures and yarn count. Thermal comfort properties such as thermal conductivity, thermal resistivity, thermal absorptivity, fabric thickness were measured by means of Alambeta device. Correlation matrix between the thermal properties was also displayed. Air permeability results were obtained by using SDL Atlas Digital Air Permeability Tester Model M 021 A. One way analysis of variance (ANOVA) test was performed in order to investigate the effect of weft yarn type on thermal comfort and air permeability properties of Lyocell blended drapery fabrics.FindingsIn this paper, weft yarn type was found as a significant factor on some of the thermal comfort properties such as thermal conductivity, thermal resistivity, thermal absorptivity, fabric thickness and on the air permeability properties.Originality/valueThere are limited works related to evaluation of some thermal comfort and air permeability properties of Lyocell blended drapery fabrics.

Reinforcing effects of ground tyre rubber on physical, mechanical, and thermal properties of polyethylene terephthalate

This study examines the use of waste and recyclable polyethylene terephthalate (rPET) along with micro-sized ground tire rubber (GTR) to produce a polymer matrix composite (PMC) material. The PMC materials are made in a Twin-screw extruder, with different ratios of rPET to GTR ranging from 90:10 to 50:50. In order to assess the performance of the newly created rPET-GTR matrix composite materials, the physical, mechanical properties are empirically observed. The thermal properties and crystallinity (Xc) of PMC materials are analysed using DSC. SEM and microscopic imaging are used to determine the characteristics of rPET-GTR composite materials, including elemental compositions like carbon, oxygen, and silicon. The functional group and chemical structure are confirmed through IR spectra analysis using FTIR techniques. The inclusion of micro-sized GTR has shown a significant effect on the physical (density = 1.306 - 1.208 g/cm3, water absorption = 1.76%–10.74%, and melt flow index = 8.12 - 12.79 gm/10 min), mechanical (tensile strength = 52.78 – 73.58 MPa, impact strength = 110.64 - 138.44 J/m, hardness = 56.14 - 76.37, and flexural modulus = 66.23 - 106.32 MPa), and thermal (melting temperature = 220.25°C–192.57°C, Xc = 20.30 to 30.58%) properties of rPET. These studies all work together to improve the performance of waste rPET and GTR materials by repurposing them. It helps to promote sustainability, cost-effectiveness, and expands the range of applications (automotive parts, building materials, sports equipment, electrical insulation and prosthetics) for rPET-based composites with potential uses in the polymer industries.