Enhancement Of Thermal Properties Research Articles

Synthesis of Cr2O3/C3N4 doped PVA polymer membranes for optoelectronic applications

This study reports the synthesis and characterization of Cr₂O₃/g-C₃N₄ doped PVA nanocomposite membranes using a solution casting method for potential optoelectronic applications. The successful incorporation of Cr₂O₃ and g-C₃N₄ into the PVA matrix was confirmed through various analytical techniques, comprising FTIR, XRD, SEM, EDX, and XPS. The addition of Cr₂O₃/g-C₃N₄ resulted in enhanced thermal stability, as demonstrated by an increase in decomposition temperature by 25–38 °C. Optical analysis revealed a reduction in both direct and indirect band gaps, from 5.41 eV to 4.85 eV and 5.18 eV–4.65 eV, respectively, indicating modifications in the electronic structure of the composite. This enhancement in optical and thermal properties can be linked to the robust interfacial interactions between the nanofillers and the PVA matrix. The novelty of this research lies in the synergistic effect of Cr₂O₃ and g-C₃N₄, which not only improves the composite's stability and optical properties but also provides a pathway for the development of advanced materials with tunable electronic characteristics for optoelectronic devices. The results of this study contribute to the growing need for environmentally friendly, high-performance materials that can be utilized in a variety of implementations, such as sensors and flexible electronics, thereby having a positive impact on technology development and societal progress.

Simultaneous enhancement of thermal and dielectric properties of phthalonitrile resin via an organic-inorganic hybrid approach

Simultaneous enhancement of thermal and dielectric properties of phthalonitrile resin via an organic-inorganic hybrid approach

Study on enhancing mechanical and thermal properties of carbon fiber reinforced epoxy composite through zinc oxide nanofiller

This study investigates the enhancement of mechanical and thermal properties of carbon fiber reinforced epoxy composites by incorporating zinc oxide (ZnO) nanofillers. The composites were developed by adding 3–15 g of ZnO nanoparticles into the epoxy matrix and were evaluated through experimental testing. The results showed significant improvements in mechanical performance, with the maximum tensile strength of 112.49 MPa and flexural strength of 114.82 MPa at the 15 g ZnO concentration. SEM analysis revealed a reduction in void content and improved fiber-matrix adhesion, enhancing load transfer. Thermal conductivity is 13.47 W/mK, while the coefficient of linear thermal expansion is 9.29 × 10−5/°C, indicating superior thermal stability. TGA analysis demonstrated a shift in decomposition temperature from 310 to 375 °C, confirming enhanced thermal stability. These results highlight the positive influence of ZnO nanofillers on both the mechanical and thermal properties of carbon fiber reinforced epoxy composites, making them more suitable for advanced structural applications.

Enhancement of Electrical Properties and Thermal Properties of Polypropylene Composited by Copper Nanowires

Enhancement of Electrical Properties and Thermal Properties of Polypropylene Composited by Copper Nanowires

Thermal hysteresis enhancement and dispersion thermal stability in paraffin actuators: Comparison of pan-nanofibers vs metal oxide nanoparticles use

In this research, the possibility of thermal property enhancement of paraffin actuators with nanofiber and metal oxide nanoparticle addition was experimentally evaluated. Besides pure paraffin compound, paraffin mixed with the CuO, Fe3O4, ZnO, Al2O3, and electrospun polyacrylonitrile (PAN) nanofiber nanoparticles were used, and a significant hysteresis improvement at first-level measurement was observed as 24.6, 26.2, 20.0, 29.2, and 30.8 % sequentially for the samples respectively compared with pure paraffin. Thermal dispersion stability of the nanocomposites was comprehended via computer tomographic (CT) investigation. The excessive precipitation of CuO, Fe3O4, and ZnO particles in the paraffin nanocomposite was observed. Precipitation of PAN Nanofiber- and Al2O3-Paraffin nanocomposite was not visually detectable via CT throughputs. The effect of thermal dispersion stability on the hysteresis performance of the nanocomposites was also investigated to ensure long-term consistent hysteresis performance advantages in paraffin actuators. Thermal dispersion stability effect on hysteresis performance of paraffin actuators with CuO, Fe3O4, ZnO, Al2O3, and PAN nanofiber nanocomposite paraffin compounds showed losses as 14.3, 14.6, 5.8, 4.3 and 2.2 % sequentially for the samples respectively.

Foam forming of highly porous alumina ceramic paper and its enhancement of mechanical and thermal insulation properties in aerogel composites

The strength and toughness of aerogel composites can be enhanced by incorporating alumina ceramic paper as a reinforcing material. However, the production processes often suffer from issues related to poor evenness and low porosity. Herein, alumina ceramic paper with high evenness and porosity was prepared using foam forming technology and utilized as a reinforcing material for alumina-SiO2 aerogel composites. Initially, the hydroxyl groups (Al-OH) of the alumina ceramic fibers were adsorbed onto the hydrophilic moieties of bubbles via hydrogen bonding during the foam forming, which hindered the migration of the fibers and facilitated their dispersion. Subsequently, the alumina ceramic paper was fabricated through the optimization of the squeezing dehydration and defoaming processes. Finally, the alumina-SiO2 aerogel composites were formed via the sol-gel method. The alumina ceramic paper exhibited excellent multifunctional properties, including high porosity and evenness, which significantly enhanced the mechanical and thermal insulation properties of the alumina-SiO2 aerogel composites. In conclusion, highly porous alumina ceramic paper presents significant potential for application in various fields, including automotive, construction, and aerospace.

Molecular dynamics simulations of the micro mechanism of functionalized SiO2 nanoparticles and carbon nanotubes modified epoxy resin adhesives

AbstractThe bonding interface of carbon‐fiber‐reinforced polymer (CFRP)‐reinforced steel structure is a weak part, and nanomaterial‐modified adhesives are expected to improve its comprehensive performance. This paper investigates the micro‐modification mechanisms of nanomaterials on epoxy resin adhesives using molecular dynamics simulation method. It explores how the functionalized nano SiO2 and carbon nanotubes affects the thermal and mechanical properties of the epoxy resin adhesive. The models established using Materials Studio software include the pure epoxy resin adhesive model (EP) with varying degrees of crosslinking, the functionalized nano‐SiO2‐modified epoxy resin adhesive model (EP + SiO2/OH), the single‐walled carbon nanotube‐modified epoxy resin adhesive model (EP + SWNT), and the synergistic enhancements model of the epoxy resin adhesive with nano‐SiO2 and carbon nanotubes (EP + SWNT + SiO2/OH). Based on the aforementioned models, the Forcite module is used to calculate the free volume, glass transition temperature and mechanical properties of the adhesive. The results show that the degree of crosslinking effects significantly the mechanical performance of epoxy resin adhesive. A high degree of crosslinking restricts the movement of the molecular chain, enhancing the strength of the epoxy resin adhesive. Furthermore, the trend of the mechanical and thermal properties of the four models remains constant with the rise of temperature, and the properties decrease most significantly in the range of the glass transition temperature. Moreover, the epoxy resin adhesive doped with nanomaterials exhibits varying degrees of enhancement in mechanical and thermal properties. The epoxy resin adhesive reinforced with functionalized nano‐SiO2 and carbon nanotubes exhibits better properties compared to those with a single nanomaterial.Highlights The micro‐modification mechanism is revealed for nanomaterial modified epoxy resin adhesive. The degree of crosslinking effects significantly the mechanical performance of epoxy resin adhesive. The epoxy resin adhesive doped with nanomaterials exhibits varying degrees of enhancement in mechanical and thermal properties.

Unveiling the enhancement of thermal fatigue properties of FeCrB alloy induced by in-situ particles

In order to overcome the inferior thermal fatigue (TF) properties of FeCrB alloy, FeCrBTi alloy containing in-situ formed particles has been developed. This study systematically investigated the enhancement mechanism induced by in-situ particles through the TF experiment. Results demonstrated in-situ particles not only directly alter the crack propagation path but also refine the microstructure, thereby contributing to stress reduction and improving mechanical properties. Furthermore, in-situ particles promote the formation of a compact and adhesive oxide scale. Therefore, the TF properties of FeCrBTi alloy are 3.1 times higher compared to FeCrB alloy. This research shed a novel light on the improvement of TF resistance of tool steels.

Optical, thermal, and electrical characteristics of cashew gum/Polypyrrole/zinc oxide nanocomposites for next‐gen optoelectronics

AbstractIn this electronic era, there is a demand to switch from conventional polymers to conducting biopolymers. We developed conducting biopolymer nanocomposites of cashew gum (CG) and polypyrrole (PPy) with zinc oxide (ZnO) nanofillers [CG/PPy/ZnO] via in‐situ oxidative polymerization using a sustainable solvent. These nanocomposites were characterized using Fourier‐transform infrared spectroscopy (FTIR), UV–visible spectroscopy, field emission scanning electron microscope (FE‐SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The FTIR signal at 855 cm−1 confirms the successful inclusion of ZnO nanofillers into the biopolymer. UV–vis absorption of the blend nanocomposite increases with the nanoparticle doses. Among the various blend nanocomposites, the least bandgap energy was observed for 7 wt% ZnO loading. FE‐SEM revealed homogeneous dispersion of ZnO nanofillers in the CG/PPy blend at 7 wt% ZnO. TGA and DSC demonstrated that the CG/PPy/ZnO nanocomposites have better thermal stability and glass transition temperature than the pure polymer blend, indicating enhanced thermal properties. The CG/PPy/7 wt% ZnO showed the highest conductivity, 4.62 times greater than the pristine blend at 100 Hz. Dielectric constant, activation energy, AC conductivity and dielectric loss measurements demonstrated that the nanocomposites outperformed the pure polymer blend. Complex impedance analysis revealed increased impedance with rising temperature. Overall, CG/PPy/ZnO nanocomposites exhibit superior optical, morphological, thermal, electrical, and dielectric properties, making them promising for energy storage and optoelectronic applications.Highlights Ecofriendly synthesis of CG/PPy/ZnO nanocomposites Enhancement in optical, structural, and thermal properties of CG/PPy/ZnO Dielectric properties and temperature‐dependent AC conductivity are summarized. Blend nanocomposite shows higher AC conductivity and dielectric constant CG/PPy/ZnO nanocomposites are suitable for energy storage applications

Enhancement of thermal and mechanical properties of PMMA nanocomposites by adding spark plug ceramic waste

In this research, poly methyl methacrylate (PMMA) resin was used as a base material and spark plug ceramic waste (CW) particles as a support material with different weight ratios (0%, 1%, 2%, 4%, 6%, 10%, 14%, and 20%) to study the thermal and mechanical properties through diffraction examination. FE-SEM surface structure images showed that the fracture surface of the (94% PMMA +6%CW) nanocomposite sample manifests a good distribution of particles at low and high levels. The result showed that the thermal conductivity (K) slightly increased until it reached the maximum value (0.6 watt/m.ºC) at the ratio (86%PMMA +14%CW). For the impact strength, it was noticed that the impact strength of PMMA increases with the increased weight ratios (1, 2, 4, 6, 10, 14, and 20%) of fine powder of ceramic waste compared with pure PMMA to reach the maximum value (6.02 kJ/mm2) at the sample (94% PMMA +6%CW) under L.C. Moreover, after 30 days of submersion in water, the PMMA reinforced with ceramic waste particles had enhanced impact strength. The shore D-number readings for all of the samples showed an increase as a result of the findings of nanocomposite compared with PMMA pure, where the sample (94% PMMA+6%CM) attained the greatest shore D numbers (87 H.NO). The compressive strength at the weight percentage (99% PMMA + 1% CW) was somewhat reduced. Then the compressive strength increased till it reached its maximum value (29.94 MPa) at the weight percentage (94% PMMA + 6% CW).

(Invited) 3D Printing-Assisted Casting of Conducting Polymers for Bioelectronics

3D structured conducting polymers, known for their high conductivity, low impedance, and tunable form factor, are promising candidates for various bioelectronics applications. However, achieving a balance between structural complexity, electrical conductance, and processing generality has been challenging in these materials. In this talk, I will discuss our efforts to address this trade-off through 3D printing-assisted casting. Light-based 3D printing is used to create hollow molds, providing structural complexity and design freedom, whereas the casting nature imparts material versatility. The casting molds are made of superabsorbent polymers and printed in a partially hydrated state. Their dehydration provides significant enhancement in feature resolution and excellent thermal and mechanical properties, making them versatile for casting. After casting, over-hydration of the molds facilitate their energy-efficient removal. Using poly(3,4-ethylenedioxythiophene) (PEDOT) as a model system, complex architectures such as octet and truncated octahedron can be achieved. Compositing silver flakes with PEDOT through a thermal injection process leads to prints with conductivity over 6000 S/cm and high environmental stability. This method can potentially be applied to other hard-to-print soft materials and composites.

PEBAX® 5533D Formulation for Enhancement of Mechanical and Thermal Properties of Material Used in Medical Device Manufacturing

The medical device industry is constantly innovating in the search for materials that demonstrate superior performance, better intrinsic characteristics, profitability, and a positive impact on potential patients. The thermoplastic polymer resin Pebax® 5533D is one of the most widely used commercial materials for manufacturing medical device parts due to its easy processability. However, its mechanical and thermal properties require improvements to mitigate identified manufacturing defects, such as a decrease in material flexibility, high susceptibility to moisture, and thermal degradation during processing. Therefore, this study integrated different materials, such as plasticizers and filler additives, to produce a polymer compound prototype formula as a solution technique to enhance the current material’s performance. Modifying mechanical and rheological properties allows to evaluate the impacts on the polymeric material’s flexibility and thermal behavior. This was achieved by processing mixed additives using injector-molding equipment to obtain equal-molded samples of every formula. In addition, material characterization was performed to determine the variations in the samples’ crystallization, flexural strength, and moisture content. Calcium stearate was determined to be the most significant component serving as a mechanical resistance modifier and thermal stabilizer alongside calcium chloride as a moisture content reducer combined with Pebax® 5533D.

Highly Anisotropic Thermally Conductive Dielectric Polymer/Boron Nitride Nanotube Composites for Directional Heat Dissipation.

An ideal dielectric material for microelectronic devices requires a combination of high anisotropic thermal conductivity and low dielectric constant (ɛ') and loss (tan δ). Polymer composites of boron nitride nanotubes (BNNTs), which offer excellent thermal and dielectric properties, show promise for developing these dielectric polymer composites. Herein, a simple method for fabricating polymer/BNNT composites with high directional thermal conductivity and excellent dielectric properties is presented. The nanocomposites with directionally aligned BNNTs are fabricated through melt-compounding and in situ fibrillation, followed by sintering the fibrous nanocomposites. The fabricated nanocomposites show a significant enhancement in thermal properties, with an in-plane thermal conductivity (K‖) of 1.8 Wm-1K-1-a 450% increase-yielding a high anisotropy ratio (K‖/K⊥) of 36, a 1700% improvement over isotropic samples containing only 7.2 vol% BNNT. These samples exhibit a 120% faster in-plane heat dissipation compared to the through-plane within 2 s. Additionally, they display low ɛ'of ≈3.2 and extremely low tan δ of ≈0.014 at 1kHz. These results indicate that this method provides a new avenue for designing and creating polymer composites with enhanced directional heat dissipation properties along with high K‖, suitable for thermal management applications in electronic packaging, thermal interface materials, and passive cooling systems.

Modification of biodegradable thermoplastic cassava starch/kapok fiber incorporated by tartaric acid and processed by compression molding technique

Thermoplastic starch has been attracted due to its availability, biodegradability, and processability. However, its poor tensile properties, high hydrophilicity and lack of antibacterial activity are still the major concerns for many applications. In current study, several thermoplastic cassava starch samples (THPCS), reinforced with kapok (KP) fibers and modified by varying levels of tartaric acid (TA), a natural organic acid, were prepared to enhance their limitations. All samples were mixed and shaped using an internal mixer and a compression molding machine, respectively. The modified THPCS samples were characterized using analytical techniques such as FTIR, SEM and TGA. Morphology, water uptake, mechanical properties, biodegradability, and antimicrobial performance of various samples were also evaluated. IR peak positions of O–H stretching as well as O–H bending were clearly observed for shifting to lower wavenumbers with the addition of KP fibers or KP fibers/TA, indicating of new H-bond formation. In addition, the use of KP fibers caused the enhancement of mechanical strength and thermal properties including the reduction of water uptake. Moreover, THPCS/KP fiber sample modified by TA presented surface smoothness, good biodegradability, and antibacterial performance against both Staphylococcus aureus and Escherichia coli.

0D/2D Co-Doping Network Enhancing Thermal Conductivity of Radiative Cooling Film for Electronic Device Thermal Management.

The radiative cooling has great potential for electronic device cooling without requiring any energy consumption. However, a low thermal conductivity of most radiative cooling materials limits their application. Herein, a multishape codoping strategy was proposed to achieve collaborative enhancement of thermal conductivity and radiative properties. The hBN-coated hollow SiO2 particles were prepared based on electrostatic self-assembly technology, which were then mixed with hBN platelets and doped into a poly(vinylidene fluoride-co-hexafluoropropylene) substrate. Discrete dipole approximation theory was employed to reveal the mechanism and optimize the particle size. The results showed that the multishape codoping method can significantly improve the radiative performance, with 94.9% reflectivity and 91.2% emissivity. In addition, this zero-dimensional and two-dimensional composite doping structure facilitated the formation of a thermal conduction network, which enhanced the thermal conductivity of the film up to 1.32 W m-1 K-1. The high thermal conductivity radiative cooling film can decrease the heater temperature from 58.8 to 31.3 °C, with a further reduction of temperature by 7.2 °C compared to the radiative cooling substrates with low thermal conductivity. The net cooling power of the film can reach 102.5 W m-2 under direct sunlight. This work provides a novel strategy for high-efficiency electronic device cooling.

Decoding the role of bismuth oxide in advancing structural, thermal, and nuclear properties of [B2O3–Li2O–SiO2]-Nb2O5 glass systems

This paper investigates the pivotal role of bismuth oxide (Bi₂O₃) in the enhancement of nuclear safety, structural, and thermal properties of glasses, specifically in the BNLS system. BNLS system has the formula [B2O3–Li2O–SiO2]-Nb2O5(20-x)–(Bi2O3)x (where x = 0.0,5.0,10.0,15.0 and 20.0 mol%). Through a comparative study, the potential advantages, and limitations of integrating Bi₂O₃ in place of traditional elements are highlighted, emphasizing its importance in the field of advanced glass materials. FTIR analysis showed the presence of Bi–O vibrations of the tetrahedral [BO4] groups and the Bi–O–Bi linkages. DSC testified the glass formation with increasing thermal stability of the formed glass with the inclusion of Bi2O3 into the glass system. Through the quantification of the Gamma Linear Attenuation Coefficient (GLAC) and Gamma Mass Attenuation Coefficient (GMAC), the work identifies the attenuation behavior against varying photon energies. Notably, a concentration-dependent rise in attenuation characteristics is observed, with BNLS20 exhibiting the most potent radiation shielding. Glass Half-Value Layer (GHVL) parameters and Mass Gamma Photon Penetration (GMFP) were measured, reinforcing that glasses with higher Bi2O3 concentrations and lower GHVL are better attenuators. The transmission factor (ln(I/Io)) was also studied, confirming that BNLS20 possesses the most effective radiation shielding capabilities. This research establishes that adding Bi₂O₃ to the [B2O3–Li2O–SiO2]-Nb2O5 glass system markedly improves its thermal stability and radiation shielding capabilities. BNLS20, in particular, emerges as a standout for radiation protection, surpassing both other BNLS variants and conventional shielding materials, thereby positioning it as an exceptional choice for advanced nuclear safety applications.

Strong, bacteriostatic and transparent polylactic acid-based composites by incorporating quaternary ammonium cellulose nanocrystals

Renewable natural fibers (e.g., cellulose nanocrystals (CNCs)) are being applied for reinforcing bio-based polylactic acid (PLA). For improvement in the interfacial compatibility between CNCs and PLA and the dispersibility of CNCs, a quaternary ammonium salt-coated CNCs (Q-CNCs) hybrid was prepared in this study based on an esterification self-polymerization method, and such hybrid was further utilized as a new strengthening/toughening nanofiller for producing the Q-CNCs-reinforced PLA composite. The results confirmed that quaternary ammonium salt coatings could efficiently enhance CNCs/PLA interfacial compatibility via mechanical interlocking and semi-interpenetrating networks. Attributing to the synergistic effect of quaternary ammonium salts and CNCs, a considerable enhancement in processing, mechanical, and thermal properties was gained in the obtained Q-CNCs-reinforced PLA composite. With the addition of 0.5 wt% Q-CNCs, the tensile strength, Young's modulus, and elongation at break of the Q-CNCs-reinforced PLA composite was raised by approximately 23 %, 37 % and 18 %, respectively; compared with pure PLA, the obtained composite had excellent bacteriostatic properties and good transparency. This work discusses the development of high-performance, low-cost and sustainable PLA-based composites on a potential application in packaging materials.

Thermal Property Enhancement of a Novel Shape-Stabilized Sodium Acetate Trihydrate-Acetamide/Expanded Graphite-Based Composite Phase Change Material

Thermal Property Enhancement of a Novel Shape-Stabilized Sodium Acetate Trihydrate-Acetamide/Expanded Graphite-Based Composite Phase Change Material

Improving thermal stability of starches native cross-linked with citric acid as a compatibilizer for thermoplastic starch/polylactic acid blends

This study aimed to enhance compatibility and thermal stability between thermoplastic starch (TPS) and polylactic acid (PLA) by incorporating citric acid-grafted starch (CA–Starch) at different concentrations (1 and 5%) with varying degrees of substitution for starch derived from sweet potatoes and yams (DY). Blends were produced using a constant TPS/PLA weight ratio of 60:40, both with and without a compatibilizer. The blending process was carried out using a torque rheometer under two distinct conditions. The results exhibited reduced particle sizes in TPS60/PLA40/CA–Starch blends, as evidenced by SEM images displaying improved interaction and smoother surfaces. Significantly, one of the properties that experienced substantial improvement was the compatibility between TPS and PLA, as indicated by reduced phase segregation within the blends. This improvement manifested in enhanced surface morphology, smaller particle sizes, and greater homogeneity in the blends. Additionally, an enhancement in thermal properties, particularly thermal stability, was observed with higher CA content. This study underscores that the incorporation of CA–Starch not only enhances compatibility but also improves thermal stability in TPS60/PLA40 blends, offering potential for the development of biocompatible materials with superior performance.Graphical abstract

Publisher's Note: “Phase change-related thermal property characterization and enhancement in carbon-based organic phase change composites” [Appl. Phys. Rev. 11, 021322 (2024)

Publisher's Note: “Phase change-related thermal property characterization and enhancement in carbon-based organic phase change composites” [Appl. Phys. Rev. <b>11</b>, 021322 (2024)