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[Display omitted] • The as-deposited AlCrFeCoNiCu 0.5 films were annealed at 500 °C for up to 72 h. • Four new phases were formed during the 72 h of annealing. • The formation of a new heterogeneous nanocomposite thin film was revealed. • A 30% enhancement of mechanical properties was achieved after 72 h annealing. • The as-annealed thin films exhibited superior thermal stability. High entropy alloy (HEA) films offer excellent mechanical properties due to their random solid solution structure. However, their large grain boundary volume fraction can cause thermal instability, resulting in phase decomposition that affects their high-temperature performance. Nevertheless, it remains an interesting question whether phase decomposition can be used as a processing tool to create new HEA materials. In this study, AlCrFeCoNiCu0.5 HEA thin films were fabricated and annealed at 500 °C for up to 72 h. The 72-hour annealed thin film exhibited a 30 % increase in mechanical properties, exceeding most other HEA thin films. Characterization using X-ray and electron microscopy revealed a decomposition-induced phase transformation, which produced four new phases, including Cu-rich FCC phase, Cr-rich BCC phase, and ordered B2 phase of AlNi and FeCo. The enhanced mechanical properties were due to back stress strengthening and BCC + B2 phase strengthening. The 72-hour annealed thin film also showed excellent thermal stability through a new round of annealing, exhibiting a low variation in microstructure and chemical composition after being annealed at 500 °C for 100 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Sc/Zr/Ti/Er modified Al-Cu alloy was successfully fabricated by wire-arc directed energy deposition technology. • The fine equiaxed grain structure was obtained due to the heterogeneous nucleation caused by the primary Al3X dispersoids. • Homogenization prefabricates more Al3X dispersoids, which promote the transition from θ″ to θ′ precipitate. • Homogenization ripens the existing pores, resulting in a better tensile isotropy. In this study, a novel Sc/Zr/Ti/Er-modified 2219 aluminum alloy was designed and wall-shaped components were then fabricated by wire-arc directed energy deposition (DED). Due to the heterogeneous nucleation promoted by primary Al 3 X dispersoids, the as-deposited alloy exhibits a highly equiaxed fine grain structure. Two heat treatment schedules were conducted to tailor the strength and thermal stability of the alloy. Compared with the classical T6 heat treatment, the additional homogenization step before the T6 heat treatment (HT6) prefabricated more Al 3 X dispersoids, which indirectly promoted the transition from θ″ precipitates to θ′ precipitates, resulting in a slight reduction in strength. However, this homogenization step helps to avoid the aggregation of pores by promoting pores ripening and significantly alleviates the anisotropy of ductility. In addition, the better thermal stability of the HT6 heat treated alloy is due to more Al 3 X dispersoids and finer θ′ precipitates with high coarsening resistance caused by the segregation of Sc and Mn at the θ′/Al interface during thermal exposure. In general, the wire-arc DEDed micro-alloyed 2219 Al alloy exhibits a promising combination of strength and ductility after heat treatment and its mechanical properties are superior to those of the wrought micro-alloyed Al-Cu alloys. [ABSTRACT FROM AUTHOR]

[Display omitted] • The LDHs nanofillers for PLA were successfully modified by intercalation-surface combined modification strategy. • Modified LDHs can alter the crystallinity of PLA/LDHs nanocomposites within the range of 10.1% to 47.3%. • The incorporation of organically modified LDHs simultaneously enhances the tensile strength and elongation of PLA composites. • The addition of LDHs modified through combined modification can enhance the elongation at break of PLA by up to 230%. The superior physicochemical properties of layered double hydroxides (LDHs) sets them apart from traditional polylactic acid (PLA) fillers. However, achieving efficient dispersion of LDHs within the PLA matrix poses a challenge in the fabrication of PLA/LDHs nanocomposites. In order to enhance the dispersion of LDHs in the PLA matrix and improve their compatibility with PLA, in this study sodium stearate (SS) and sodium dodecyl sulfate (SDS) were used as surface modifiers and intercalation modifiers for LDHs, respectively. Notably, the strategy of intercalation-surface combined modification for LDHs nanofillers in PLA was explored for the first time. Furthermore, the resulting PLA/LDHs nanocomposites were prepared via a sonication-assisted solution compounding method. The results indicate that the addition of LDHs modified through different methods and concentrations affects not only the thermal properties and crystallinity of the PLA/LDHs composites, but also improves the tensile strength and elongation at break of PLA. Notably, the PLA_LDH_SDS_SS_9% composite exhibited an elongation at break that was 230% higher than neat PLA. This study fills a research gap in the field of PLA/LDHs nanocomposites and establishes a significant foundation for the future preparation and application of these. [ABSTRACT FROM AUTHOR]

Abstract An aluminum material stabilized with a 1.6 vol% of nanometric Al 2 O 3 dispersoids, named HITEMAL, was fabricated by hot extrusion of a fine atomized Al powder. The Al 2 O 3 dispersoids stemmed from a native Al 2 O 3 films on an aluminum powder surface. An extruded rod of the material was then cold-deformed out into a thin wire by rotatory swaging, hydro extrusion and rolling. Such severely deformed HITEMAL was studied as a prospective outer sheath stabilizer material for MgB 2 core superconductor wires. An emphasis was put on the effect of annealing realized at various temperatures close to the melting point of Al, which is typically applied to form an in-situ MgB 2 superconductive core, on the mechanical and electrical properties of the HITEMAL wire. A systematic investigation was performed of changes to a severely deformed Al grain structure and Al 2 O 3 dispersoids upon annealing the as-deformed wire from 595 to 655 °C for 30 min. Mechanical and electrical properties of the wire were measured at room and cryogenic temperatures. The results showed that the ultrafine-grained Al + 1.6 vol% Al 2 O 3 wire exhibited advantageous properties, and surface integrity after annealing up to 642 °C. It is thus a lightweight material of choice for outer sheaths of MgB 2 superconductors. Graphical abstract Unlabelled Image Highlights • Al wire fabricated from a fine Al powder was studied as outer sheath material for lightweight MgB 2 superconductors. • The effect of annealing realized at 595-655 °C on microstructure, mechanical and electrical properties was investigated. • The as-rolled wire showed ultrafine-grained Al structure with 1.6% of nanometric Al 2 O 3 dispersoids dispersed in Al matrix. • The Al 2 O 3 dispersoids effectively stabilized Al grain structure during annealing, and only minor Al grain growth occurred. • Wires annealed up to 642 °C showed attractive strength and electrical resistivity at room and cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Poly( l -lactide) (PLLA) is a biodegradable bioplastic that has been widely investigated for use instead of petroleum-based plastics. However, its practical applications have been limited by its brittleness. Herein, a high molecular weight triblock copolymer of poly( l -lactide)- b -poly(ethylene glycol)- b -poly( l -lactide) (PLLA-PEG-PLLA) was synthesized by ring-opening polymerization of l -lactide using stannous octoate and PEG as the initiating system. The effect of an epoxy-based chain extender on the thermal properties, melt flow index (MFI), phase morphology and tensile properties of the PLLA-PEG-PLLA were investigated and compared to PLLA homopolymer. Chain-extended PLLA-PEG-PLLA and its films were prepared by reactive melt blending and compression molding, respectively. The flexible PEG blocks significantly improved both crystallization of PLLA blocks and strain at break of PLLA-PEG-PLLA films. The chain extension can decrease MFI of both the PLLA and PLLA-PEG-PLLA but their crystallizabilities were suppressed. All the PLLA-PEG-PLLA films with and without chain extension had no phase separation. The tensile properties of PLLA-PEG-PLLA films increased by the chain extension. The results showed that the chain-extended PLLA-PEG-PLLA have potential for use as highly flexible bioplastics. [ABSTRACT FROM AUTHOR]

The microstructure design strategy is introduced to improve the mechanical property of a novel γ-Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB 2 metal matrix composite (MMC) fabricated by hot isostatic press (HIP). With increasing the content of TiB 2 from 0 to 3 wt%, the average grain size, {001} maximum texture index and average schmid factor of HIP-processed Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB 2 parts generally decrease from 27.4 μm, 7.9 and 0.43 to 22.7 μm, 4.1 and 0.38, in addition, the crystallographic texture transforms from the mixture of (001) and (111) orientations to a strong (101) orientation. The phases evolution mechanism in the HIP-processed Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB 2 parts can be divided into four steps: first of all, β phase transforms to γ and α phases, then, a small amount of new phases of TiB and TiC emerge by the diffusion of Ti and C atoms, subsequently, the β and α orderly transform to B 2 and α 2 , lastly, the B 2 , α 2 , TiB 2 , TiB and TiC uniformly distribute in the γ matrix. Both the tensile strength and strain of HIP-processed Ti-43.5Al-6.5Nb-1.5Cr-0.5C/TiB 2 components increase from 471.9 MPa and 1.7% to 653.4 MPa 2.1% with the increase of TiB 2 content from 0 to 3 wt%. [ABSTRACT FROM AUTHOR]

Conventional polyimide nanocomposites reinforced with graphene-based nanofillers usually possess excellent properties, such as high thermal decomposition temperature, enhanced tensile strength, tensile modulus, etc. However, the elongation at break of the nanocomposites is reduced. Here, we prepared N-doped graphene quantum dots/colorless polyimide nanocomposite (N-GQDs/CPI) films for the first time by in-situ polymerization, whose elongation at break is about 2 times that of the pure film. Meanwhile, the thermal properties and other mechanical properties of the films are improved. Through analyzing FT-IR, XPS, XRD, TAG SEM, etc. of N-GQDs and the films, we consider that the strengthening mechanism of matrix performance is attributed to N-GQDs' well dispersion, its small size effects and strong interface interaction with the matrix. Furthermore, at the indicative wavelength of 550 nm, the optical transmittance of the film with 1 wt% N-GQDs still maintains 79%, indicating the resulting films have excellent optical transmittance. The hydrophilic properties of the prepared films' surface is reduced, their water surface contact angle are increased from 63 ± 2.7° to 92 ± 1.7° with the content of N-GQDs increasing. This research shows that N-GQDs can enhance the various properties of polyimide and provides a high performance nanocomposite films for potential flexible substrates. [ABSTRACT FROM AUTHOR]

This work reports the effect of acrylated epoxidized soybean oil (AESO) addition on the mechanical, thermal, and thermomechanical properties of polylactide (PLA) parts obtained by injection molding. To this end, AESO, a chemically multi-functionalized vegetable oil, was incorporated into PLA during melt processing. The PLA parts with AESO contents in the 2.5–7.5 wt% range showed a remarkable enhancement in both elongation at break and impact-absorbed energy while their tensile and flexural strength as well as thermomechanical properties were maintained or slightly improved. Additionally, the AESO-containing PLA parts presented higher thermal stability and lower crystallinity. The improvement achieved was ascribed to a dual effect of plasticization in combination with a chain-extension and/or cross-linking process of the PLA chains by the highly reactive acrylate and epoxy groups present in AESO. The use of AESO thus represents an environmentally friendly solution to obtain toughened PLA materials of high interest in, for instance, rigid packaging, automotive or building and construction applications. [ABSTRACT FROM AUTHOR]

A novel lightweight organic aerogel-impregnated low-density carbon/carbon (C/C) composite was produced through vacuum impregnation using carbon-bonded carbon fibre (CBCF) as substrate and resorcinol-furfural (RF) aerogel as infiltrant. Microstructural analysis showed that fibres in CBCF were uniformly coated with a thin layer of aerogels, acting as the supporting skeletons, to strengthen the aerogel matrix. The as prepared RF-C/C possessed low densities between 0.26 and 0.37 g/cm 3 , relatively high compressive strength, ranging from 0.45 to 3.27 MPa, and low thermal conductivities of 0.105 to 0.350 W/(mK) at room temperature. Furthermore, good thermal ablative and insulative properties (recession rates as low as 0.082 mm/s and internal temperature peaks below 90 °C at 38 mm in-depth position as the surface temperature exceeded 2000 °C) under an atmospheric re-entry condition. From mentioned above, RF-C/C present huge application prospects in heat preservation and thermal protection field, especially in energy-saving and aerospace. [ABSTRACT FROM AUTHOR]

Polyetherimide (PEI) is a high performance thermoplastic polymer that retains its properties at elevated and cryogenic temperatures. Nanofiller reinforced PEI used in aerospace structures will substantially reduce the payload. This study attempts to optimize nanofiller content and process parameter for melt compounding of PEI/acid ( COOH) functionalized MWCNTs (Multi-walled Carbon Nanotube) nanocomposite using Response surface methodology (RSM). Face Centered Central Composite Design (FCCD) with two factors viz. MWCNT content and extrusion screw speed at three levels each is used to model and optimize nanocomposite properties relevant to aerospace applications. FTIR spectrum confirmed the functionalization of MWCNTs while morphological analysis confirmed the dispersion of MWCNTs. COOH-MWCNTs reinforced composite showed enhanced thermal and mechanical properties along with better retention of properties upon exposure to gamma irradiation and atomic oxygen. These properties were modeled with non-linear quadratic equations using regression analysis and verified by validation experiments. Optimization for performance of nanocomposites for aerospace application has been revealed by overlapping the contour plots within the practical constraints to recognize the combination of factor ranges. [ABSTRACT FROM AUTHOR]

The use of dispersions of poly(vinyl alcohol) PVA and detonation nanodiamond (DND) as novel inks for 3D printing of variously shaped objects using a layer-by-layer additive manufacturing method is reported. In parallel with the nanocomposites preparation, we designed a 3D printing apparatus and settled protocols for the shaping of hybrid materials, choosing PVA-DND inks as a model system to test the performances of the 3D apparatus. Along with material design and preparation, we discuss the main factors influencing the quality of the final printed objects and enlighten the importance of the matching between the chemical/physical properties of the materials to be extruded and the characteristics of the 3D printer. The thermal and mechanical properties of the printed systems have been tested by Differential Scanning Calorimetry and Contact Resonance Atomic Force Microscopy. The analysis of the mechanical properties of the 3D printed objects evidenced, for 0.5% w/w , 1% w and 5% w DND-loaded nanocomposites, values of mean indentation modulus that are 22%, 44% and 200% higher, respectively, than that of the unloaded PVA. The results of the present research, indicate that an appropriate methodology is able to print PVA-DND nanocomposites in well-defined and shaped structures, suitable for a variety of possible applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The various AM-ed high-heat-flux copper alloys CuCrZr and CuCrNb alloys are built by different processes, including L-PBF, EB-PBF, LP-DED, AW-DED and HLADED processes. The optimization of building parameters, the approaches to enhance the absorptivity of copper alloys are stressed. • The microstructure, crystallographic texture, and precipitates of AM-ed CuCrZr and CuCrNb alloys are summarized. The precipitates mainly include Cr, Cu x Zr y , and ZrO 2 particles for AM-ed CuCrZr, and Cr and Cr 2 Nb particles for AM-ed CuCrNb alloys, respectively. • The mechanical and thermal properties of various AM-ed CuCrZr and CuCrNb alloys are presented, including anisotropic properties, the effect of heat treatments on the properties and the properties at high temperature. Additive manufacturing (AM) has gained attention in recent decades. Due to excellent mechanical and thermal properties, pure copper and its alloys are widely in nuclear and aerospace industries. CuCrZr and CuCrNb are precipitation hardenable alloys. The present work provides a comprehensive overview of current research works on CuCrZr and CuCrNb alloys built by various AM processes (especially laser powder bed fusion, L-PBF). Due to high reflectivity for near infrared laser and high thermal conductivity, it is still challenging to build copper alloys by conventional L-PBF process. Therefore, three approaches to enhance the absorptivity of the alloys have been discussed. The microstructure, including texture and precipitates have been discussed. The mechanical, electrical and thermal properties at room temperature and high temperature, anisotropic properties, and post-heat-treatments have been discussed in the review. In addition, the outlook of the AM-ed CuCrZr and CuCrNb alloys has been highlighted. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compact and nanogranular ZrCu/O films were deposited by pulsed laser deposition and annealed to investigate thermal stability. • Nanogranular films crystallize at 300 °C, while the crystallization of compact films occurs >420 °C. • The Young's modulus and hardness increase with annealing temperatures due crystallization process, reaching 180 and 14 GPa for nanogranular films. • The residual stresses of compact films increase with annealing temperature, while for nanogranular ones they reach a maximum at 420 °C, indicating a complete crystallization. • The evolution of structural/mechanical properties is studied, considering film morphology, local chemistry and free volume. Binary ZrCu nanocomposite amorphous films are synthetized by pulsed laser deposition (PLD) under vacuum (2 × 10−3 Pa) and 10 Pa He pressure, leading to fully amorphous compact and nanogranular morphologies, respectively. Then, post-thermal annealing treatments are carried out to explore thermal stability and crystallization phenomena together with the evolution of mechanical properties. Compact films exhibit larger thermal stability with partial crystallization phenomena starting at 420 °C, still to be completed at 550 °C, while nanogranular films exhibit early-stage crystallization at 300 °C and completed at 485 °C. The microstructural differences are related to a distinct evolution of mechanical properties and residual stress, with compact TFMGs showing the highest values of Young's modulus (157 GPa), hardness (12 GPa), strain rate sensitivity (0.096), and local residual stress (+691 MPa) upon annealing at 550 °C, while nanogranular films reach the maximum values of mechanical properties at 485 °C followed by relaxation at higher temperatures due to complete crystallization. We show that PLD in combination with post-thermal annealing can generate different families of amorphous films with varying nanoscale morphologies, resulting in tunable mechanical properties and thermal stability, which can thus be used for designing novel film configurations for different fields of application. [ABSTRACT FROM AUTHOR]

This work addresses to the preparation of biocomposites resulting from the combination of different biodegradable aliphatic polyesters with cork (30 wt.%). The lignocellulosic biomass with closed cellular structure was compounded with poly(L-lactic acid) (PLLA), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), poly-ε-caprolactone (PCL) and starch-poly-ε-caprolactone (SPCL) blend using a twin-screw extruder prior to injection moulding into tensile samples. The physico-mechanical and thermal properties of the matrices and the bio-based cork composites were investigated. This study shows that the addition of cork contributes to produce lightweight materials using PLLA and PHBV matrices and promotes an increase on the stiffness of PCL. The fracture morphology observations showed good physical cork–matrix bonding with absence of voids or cavities between cork and the bio-based polyesters. Cork increases the crystallinity degree of the biocomposites. These findings suggest that the cork–polymer biocomposites are a viable alternative to develop more sustainable composite materials, such as automotive interior parts and bio-based caps for wine bottles as it has been shown as proof-of-concept. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of various steatite ceramics with porosities up to 30% using different types and concentrations of renewable plant fiber products. • 3D X-ray microscopy enabled a non-destructive investigation of isolated pores (≤350 µm) and large pore structures (greater than 1000 µm). • Extracted pore network models facilitated the characterization of the specific pore parameters induced by the different pore-forming agents and contents. • The use of the longer fiber product (≤350 µm) indicated a limitation of the processability at concentrations around 10 wt%. • Experimentally validated effective medium modeling gave access to the thermo-mechanical properties in dependence of pore space parameters. A large number (greater than 150) of porous steatite ceramic rods were prepared using different types of renewable plant fiber products as pore-forming agent with mass contents ranging from 2 to 10%. In addition, dense steatite ceramics were synthesized for comparison within a gas furnace at sintering temperatures between 1300 and 1350 °C. High-resolution 3D X-ray microscopy facilitated a non-destructive, direct investigation of the three-dimensional pore space and microstructure. By using image-based pore space analysis, various pore space parameters, such as, e.g., pore volume, pore-size distribution, and pore connectivity were determined. In addition to the characterization of the pore space, phase analysis, structural and chemical investigations were carried out by X-ray powder diffraction, electron microscopy, Fourier-transform infrared, Raman and X-ray spectroscopy. Finally, to evaluate the influence of characteristics on the physical properties, elastic, strength and thermal properties were determined. With the increase of porosity, the flexural strength and thermal conductivity values decrease from σ f = 123 ± 8 to 37 ± 5 MPa and λ = 3.22 ± 0.02 to 1.77 ± 0.02 W/(m·K), respectively. The obtained experimental results were discussed by means of micromechanical models, highlighting the effect of pore-space morphologies on the physical performance of porous steatite ceramics. [ABSTRACT FROM AUTHOR]

A new type of composite based on phthalonitrile resin reinforced with silicon carbide (SiC) microparticles was prepared. For various weight ratios ranging between 0% and 20%, the effect of the micro-SiC particles on the mechanical and thermal properties has been studied. Results from thermal analysis revealed that the starting decomposition temperature and the residual weight were significantly improved upon adding the reinforcing phase. At the maximum micro-SiC loading, dynamic mechanical analysis (DMA) showed an important enhancement in both the storage modulus and glass transition temperature ( T g ), reaching 3.1 GPa and 338 °C, respectively. The flexural strength and modulus as well as the microhardness were significantly enhanced by adding the microfillers. Tensile test revealed enhancements in the composites toughness upon adding the microparticles. Polarization optical microscope (POM) and scanning electron microscope (SEM) analysis confirmed that mechanical and thermal properties improvements are essentially attributed to the good dispersion and adhesion between the particles and the resin. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate and characterize various properties of experimental composition prepared from graphitic carbon nitride (g-C 3 N 4 ), wood flour (WF) and polypropylene (PP). g-C 3 N 4 with different concentrations (1 wt.%, 3 wt.%, 5 wt.% and 10 wt.%) were used as reinforcing filler for wood plastic compositions (WPCs). Maleic anhydride grafted polypropylene (PP-g-MA) was added as a coupling agent to increase the interaction between the components. Water absorption, morphology, physical, mechanical and thermal properties of the as-prepared composites were evaluated. The results showed that the tensile modulus of the composite was increased by 142.9% with increasing of g-C 3 N 4 contents to 5 wt.%, reaching approximately 498 MPa compared to WPC. Moreover, the flexural and tensile strengths reached their maximum values when the concentrations of g-C 3 N 4 were 1 wt.% and 3 wt.%, respectively. When maintaining the g-C 3 N 4 at a low concentration, it was well dispersed in the WPC with thin plate shape. However, when more g-C 3 N 4 (3–10 wt.%) was introduced, the enhancing effect began to diminish because of the agglomeration of g-C 3 N 4 which caused poor interfacial adhesion. The water absorption results showed a lower value with the addition of 1 wt.% g-C 3 N 4 , and the thermal tests showed that the degradation temperature shifted to higher value clearly after the addition of g-C 3 N 4 . Besides, with the addition of g-C 3 N 4 improved the outward color compared to the control sample. [ABSTRACT FROM AUTHOR]

In this study, the low Ag-content Sn-1.5Ag-0.7Cu (SAC157) lead-free solder was modified for advance electronic components with minor additions of Bi. The microstructure, melt properties and tensile behavior after and before compositional modifications were investigated. From microstructures evaluation, 1 wt% Bi addition to SAC157 significantly enhanced the solid solution effect of Bi and refined needle-like Ag3Sn and plate-like Cu6Sn5 particles as well as extended the eutectic area, which raised the mechanical strength and Young's modulus to about 1.5 times of SAC157 solder. With increasing Bi addition to 3 wt%, the cubic-shaped Bi precipitates and enlarged eutectic area cause a dramatic increase of ultimate tensile strength, yield strength and Young's modulus to about 2.2-2.6 times of the SAC157 alloy, although the elongation was maintained at the SAC157 level. The peak flow stress during deformation can be correlated with temperature and strain rate by a hyperbolic-sine equation. The activation energy for SAC157 alloy was increased from 58.2 kJ/mol to 101.7 and 109.0 kJ/mol when doped with 1.0 and 3.0 wt% of Bi, indicating the change of dominant deformation mechanism from dislocation pipe diffusion to lattice self-diffusion. Besides, the addition of Bi not only reduced the solidus temperature (Tonset) and eutectic temperature (Tm), but also decreased the undercooling even though the pasty rang is slightly increased. [ABSTRACT FROM AUTHOR]

[Display omitted] • A W-Cu composite coating was deposited on the graphite flakes by combing the impregnation reduction and ultrasonic-assisted electroless plating. • The W-Cu composite coating can enhance the GFs/Cu interfacial bonding from the simple mechanical connection to the mechanical-metallurgical synergy. • For the GFs(7 W-Cu)/Cu composites, the in-plane flexural strength and TC reached 189.6 ± 3.8 MPa and 929.8 ± 5.0 Wm−1K−1, respectively. Carbon materials reinforced copper matrix composites with excellent mechanical properties, high thermal conductivity (TC) and suitable coefficient of thermal expansion (CTE) are expected to meet the urgent need for the thermal management materials with structural stability and efficient heat dissipation in civil and military fields. In this work, the tungsten-copper (W-Cu) composite coating was deposited on the graphite flakes (GFs) by the impregnation-reduction and ultrasonic-assisted electroless plating. Meanwhile, the W-Cu coated GFs reinforced Cu matrix composites (GFs(W-Cu)/Cu) were also prepared by the vacuum hot-pressing sintering. Based on the microstructure and surface analysis, the interfacial bonding has changed from the simple mechanical connection to the mechanical-metallurgical synergy. As for the three-point bending and uniaxial tensile tests, the largest in-plane, through-plane flexural strength and tensile strength of the GFs(W-Cu)/Cu composite can achieve the values of 189.6 ± 3.8, 172.3 ± 4.2 and 91.9 ± 2.6 MPa, respectively. Among the GFs(W-Cu)/Cu composites, the ultrahigh in-plane TC and lowest through-plane CTE can reach 929.8 ± 5.0 Wm−1K−1 and 6.3 ± 0.2 ppmK−1 respectively, and the better thermal response rate can be 0.67 °C·s−1. In conclusion, an effective way to develop the structural and functional integrated carbon-based thermal management materials can be provided. [ABSTRACT FROM AUTHOR]

Abstract: Polypropylene (PP) is one of the most common thermoplastic materials in the world. There is a need to recycle the large amount of this used material. To overcome the environmental problems, related to the polymer waste, PP was recycled and used as a matrix material in different composites that can be used in high value applications. In this paper, composites made of recycled polypropylene (RPP) reinforced by glass fibres and/or wood flour of the palm tree were prepared, characterized and modeled. The mechanical and thermal properties of these recycled polymer matrix composites (RPMCs) were measured experimentally and modeled theoretically. The mechanical properties included tensile modulus, tensile strength and hardness, whereas thermal properties included thermal stability, melting and crystallinity percentage content were studied. In addition we applied the functionally graded materials concept, the elastic finite element analysis of a layered functionally graded pressurized pipe, which is one of the practical industrial applications, was accomplished in order to have some insight on the performance of such RPMCs. The results reveal that the desired mechanical and thermal properties met the requirements of a wide range of practical applications which can be attained by adding the considered fillers. Also, the proper selection of the layers of the pressurized pipe, which was made of RPMCs, led to decrease of the induced stresses and accordingly increased the operational safety. [Copyright &y& Elsevier]

Highlights: [•] Increasing fiber content decreased tensile strength and strain. [•] Tensile modulus was increasing with increase in fiber content. [•] SEM showed fiber/matrix poor adhesion. [•] Impact strength was decreasing with increase in fiber content. [•] Lower thermal stability with increase in fiber content was observed. [Copyright &y& Elsevier]

Highlights: [•] Distillers grains (DG) was demonstrated as effective filler for PBS. [•] The incorporation of DG improved the elastic modulus of PBS. [•] The incorporation of DG increased the crystallinity rate of PBS. [•] The incorporation of DG decreased the damping property of PBS. [•] The incorporation of DG increased the flame retardancy of PBS. [Copyright &y& Elsevier]

Highlights: [•] Using waste crab shells to develop high-performance composites by simple method. [•] Combining the anatomic analysis of crab shell with the design of composite. [•] Introducing a 4-step all-mechanical treatment to prepare ultra-long chitin fiber. [•] Incorporation of chitin nanofiber improves properties of PMMA/Chitin composite. [Copyright &y& Elsevier]

Highlights: [•] Glass/epoxy, carbon/epoxy and hybrid laminated were manufactured and characterized. [•] Physical, thermal, mechanical and wear properties of such composites were discussed. [•] The impact of hygrothermal aging on the strength of all composites was studied. [Copyright &y& Elsevier]

Highlights: [•] Modified graphite flakes/carbon black filled SBR and SBR/BR blend were synthesized. [•] Mechanical and thermomechanical properties of the composites were widely studied. [•] Composites with improved antiskid property and low rolling resistance were obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new strategy was proposed to make PVA/rGO composites by solvothermal reduction. [•] The solvent acted not only as a reducing agent but also as a good stabilizer. [•] The homogeneous dispersion of rGO sheets in the PVA matrix was achieved. [•] The crystallinity of PVA/rGO nanocomposites was investigated. [•] Mechanical properties and thermal stability were greatly improved by adding rGO. [Copyright &y& Elsevier]

Highlights: [•] Bamboo charcoal (BC) was used as reinforcing filler of wood-plastic composites. [•] BC could have strong interfacial interaction in the wood-plastic composites (WPCs). [•] The BC-WPC composites displayed lower water absorption properties. [•] The BC-WPC composites displayed higher flexural, tensile and thermal properties. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel natural fiber reinforced recycled poly (ethylene terephthalate) composite was prepared. [•] Mechanical performance and thermal behavior of the composites were investigated. [•] Composites with improved toughness and strength were achieved. [ABSTRACT FROM AUTHOR]

Highlights: [•] We found an indirect approach for in situ Young’s modulus and CTE for particle. [•] In situ particle properties are substantially different from their bulk properties. [•] In situ particle Young’s modulus is found to be close to nanoindentation result. [ABSTRACT FROM AUTHOR]

Abstract: This study treats the combined effects of both particle sizes and particle loading on the mechanical and thermal properties of polypropylene (PP) composites reinforced with Nut-shells of Argan (NA) particles. Three range sizes of particles were used in the presence of a polypropylene matrix grafted with 8wt.% of a linear block copolymer based on styrene and butadiene coupling agent, to improve adhesion between the particles and the matrix. The composites were prepared through melt-blending using an internal mixer and the tensile specimens were prepared using a hot press molding machine. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and tensile tests were employed to characterize the composites at 10, 15, 20 and 25wt.% particle contents. Results show a clear improvement in Young’s modulus from the use of particles when compared to the neat PP, a gain of 42.65%, 26.7% and 2.9% at 20wt.% particle loading, for particle range 1, 2 and 3, respectively. In addition a notable increase in the Young’s modulus was observed when decrease the particle size. The thermal stability of composites exhibits a slight decrease (256–230°C) with particles loading from 10 to 25wt.%, against neat PP (258°C). [Copyright &y& Elsevier]

Abstract: In this study, poly(butylene succinate)/hollow glass microsphere (PBS/HGM) composites were prepared with various HGM contents. The phase morphology, melting and crystallization behavior, mechanical properties and thermal stability of PBS/HGM composites were investigated in detail. Regarding the thermal properties, it was observed that the incorporation of HGM increased the crystallization rate and thermal stability of PBS without affecting the crystalline structure of the composite. With the increase of HGM content from 5wt% to 20wt%, the storage modulus and complex viscosity values increased continuously, while the density of the composite monotonously decreased. Moreover, the modulus of the specimens increased from 330MPa to 470MPa. The results showed that, although raw HGM was used without any modification, the HGM played an important role in improving the properties of PBS. [Copyright &y& Elsevier]

Abstract: Polymer blending has become an important field in polymer research and especially in the area of recycling. In this research the target was to reduce the polymer waste problem. Therefore, recycled high density polyethylene (rHDPE) and virgin isotactic polypropylene (vPP) blends containing upto 30wt% of vPP have been prepared by melt compounding method using injection molding at 220°C. The thermal properties, thermal degradation and the mechanical properties of the polymer blends were studied using differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), and tensile testing method. DSC study shows that in all the blends there are two melting peaks, one around the melting temperature of rHDPE and another one around the melting point of vPP, indicating that vPP is not well dispersed into the rHDPE matrix. The changes in the heat of fusion for the rHDPE/iPP polymer blends versus vPP content suggests that incorporating vPP affects the crystallinity of the system. TGA analysis of the polymer blends shows that parts of rHDPE with 95/5 upto 80/20 of vPP are mostly stable composition which brings about valuable stabilization to the rHDPE. Tensile testing shows that there is strong correlation between the thermal properties and the tensile behavior of rHDPE/vpp blends. [Copyright &y& Elsevier]

Abstract: A series of melt processed clay filled-PP/PET immiscible blends were analyzed in terms of thermal and mechanical properties combined with a theoretical analysis using a mechanical model for probing nanoclay localization in the blends influenced by blend composition, nanoclay content and type of matrix (PET-rich and PP-rich). According to the results obtained from DSC technique, it was shown that localization of nanoclay in the blend systems can be detected by analyzing changes in crystallization temperature and crystallinity of polymer components of the blend systems. From the tensile test results, it was revealed that tensile strength of the blend systems was affected by localization of nanoclay in the matrix phase, only. There was observed no compatibilization effect of nanoclay localized at interface of the blends, on mechanical properties improvement. Also, it was revealed that localization of nanoclay particles in matrix phase resulted in their more efficiency to increase tensile modulus than that localized in disperse phase. However, this efficiency was still dramatically low as compared to that predicted by Hui–Shia model. [Copyright &y& Elsevier]

Abstract: The reduction in harmful destruction of ecosystem and to produce low cost polymeric reinforced composites, the researchers are emerging with policies of manufacturing the composites using natural fibres which are entirely biodegradable. These policies had generated safe strategies to protect our environment. The utilization of bamboo fibres as reinforcement in composite materials has increased tremendously and has undergone high-tech revolution in recent years as a response to the increasing demand for developing biodegradable, sustainable, and recyclable materials. The amalgamation of matrix and natural fibres yield composite possessing best properties of each component. Various matrices used currently are soft and flexible in comparison to natural fibres their combination leads to composite formation with high strength-to-weight ratios. The rapid advancement of the technology for making industry products contributes consumer the ease of making a suitable choice and own desirable tastes. Researchers have expanded their expertise in the product design by applying the usage of raw materials like bamboo fibre which is stronger as well as can be utilized in generating high end quality sustainable industrial products. Thereby, this article gives critical review of the most recent developments of bamboo fibre based reinforced composites and the summary of main results presented in literature, focusing on the processing methodology and ultimate properties of bamboo fibres with polymeric matrices and applications in well designed economical products. [Copyright &y& Elsevier]

Abstract: Polyethylene (PE), polypropylene (PP) and their blends have attracted a lot of attention due to their potential industrial applications. Therefore, the current work has been carried out with the main objective of investigating the impact of the thermal aging/treatment and blend ratio (composition range) on the mechanical (tensile and hardness) and thermal characteristics (using thermogravimetric analysis in a dynamic air atmosphere) of PE, PP and PE/PP binary blends. Samples of PE/PP blends containing 100/00, 75/25, 50/50, 25/75 and 0/100wt.% were prepared via injection moulding technique and thermally treated/aged at 100°C for 0, 2, 4, 7, 14days. The tensile measurements indicated that the yield strength and the modulus decrease with increasing PE content. It was also observed that PE, PP and their blends deform in ductile modes. They undergo a uniform yielding over a wide range of deformation, which is followed by strain hardening and then failure. The strain to break for pure PE is found to be much higher than that for pure PP and for their blends, intermediate values have been observed. The hardness measurements have also revealed that increasing PE content in PE/PP blends reduced the hardness value of PP, however, thermal aging at 100°C has not affected the polymers hardness which holds also true for the tensile properties, showing a good correlation between tested mechanical properties. The thermogravimetric analysis (TGA) in a dynamic air atmosphere and derivative thermogravimetric analysis (DTA) were conducted to study the thermal degradation and stability of thermally unaged and aged PE, PP and PE/PP blends in terms of the initial (T d and T d(1%)) and final (T d(99%)) decomposition temperatures and maximum decomposition rate temperature (T max). All polymers start to decompose at no less than 365°C. As for mechanical properties, the blend ratio has affected the thermal properties however, aging time has not. [Copyright &y& Elsevier]

[Display omitted] • A novel high-entropy oxide (YYHEO) was engineered with significant mass disorder. • YYHEO exhibited glass-like low thermal conductivity (1.27 W/m∙K). • YYHEO exceeded typical substitutional solid solubility limit even with a significant atomic size difference (>50%). • YYHEO shows thermal stability even at elevated temperature (1500 ° C) without any phase degradation. • Thermophysical properties were compatible with YSZ (CTE: 10.08 × 10−6 K−1, E : 218.21 ± 3.64 GPa and H : 14.42 ± 0.5 GPa). An entropy-stabilization strategy was applied to engineer a novel thermal insulating material by establishing a single-phase solid solution with the formula of (Y 1/2 Yb 1/2) 2 (Ti 1/3 Zr 1/3 Hf 1/3) 2 O 7 (YYHEO). Structural analysis revealed that this material exceeded the typical substitutional solubility limit, even with a significant atomic size difference, where the conventional determination rule was defied. YYHEO exhibited a lower glass-like thermal conductivity due to its highly disordered crystal structure and the specific design strategy. The coefficient of thermal expansion and mechanical properties (e.g. elastic modulus and hardness) were comparable to conventional materials, suggesting that YYHEO is a promising candidate for application as a new thermal insulating material. [ABSTRACT FROM AUTHOR]

Carbon–carbon reinforced aluminum composites with different content of pyrolytic carbon and carbon fibers were manufactured. Porous carbon–carbon preforms in sandwich structure are composed of unidirectional T300 carbon fibers and carbon felt encapsulated and connected by Cpy sheaths. The characterizations of C–C/A1 composites were investigated. The obtained thermal conductivity (κ) reaches 128 W/m K and CTE of samples varies in a wide range. Mechanical properties are analyzed through three-point bending. The effects of graphitization are investigated. Graphitization of carbon–carbon preforms strengthens bonding between carbon fibers and Cpy sheaths so that the characterizations of composites are changed. [Copyright &y& Elsevier]

• Highly filled PBT/alumina composites were toughened via reactive processing. • Excellent thermal conductivity and strength were preserved after modification. • Percolating network and yield behavior were determined by three rheological criteria. • More stable phase structure was confirmed via creep-recovery test after reactive compatibilization. • Improved toughness was attributed to interfacial interaction and stress transfer. Unlabelled Image High filler content is the prerequisite for imparting specific properties to polymeric composite. However, serious mechanical properties degradation happened in this kind of material due to the inevitable reduction of material cohesion. In this work, highly filled poly(butylene terephthalate)/ alumina (PBT/Al 2 O 3) composites were modified by directly melt mixing with a reactive compatibilizer ethylene–methyl acrylate–glycidyl methacrylate terpolymer (E-MA-GMA). The modified samples presented greatly enhanced elongation at break and impact response, simultaneously preserved their tensile strength and high thermal conductivity. The reactive compatibilization between PBT and Al 2 O 3 spheres was confirmed by SEM, FTIR, and rheology characterizations. Three rheology criteria plots demonstrated that the filler percolating network and apparent yield behavior occurred in the ternary PBT/Al 2 O 3 /E-MA-GMA composites melt. It is believed that enhanced particle-matrix interfacial interaction and stress transfer caused by E-MA-GMA endowed this highly filled composite improved toughness. This study suggests the potential application of E-MA-GMA elastomer to resolve the mechanical properties degradation in highly filled polymeric composites. [ABSTRACT FROM AUTHOR]

As phase change functional polymer composites, polydimethylsiloxane (PDMS) and paraffin composites exhibit excellent performance on temperature dependent thermal and mechanical properties. In this paper, PDMS/paraffin composites with uniform microstructure are prepared by the melting mixing method with paraffin as filler and PDMS as matrix. The modification of PDMS by paraffin components owns both advantages on excellent flexibility and heat absorption capacity. Systematic experiments results are performed to illustrate the DSC specter, stress-strain curves and other properties varying with temperature. The obtained composites can be an ideal material for soft thermal management substrate of flexible electronics or phase change heat sink of batteries and this study might be helpful for the design and fabrication in the wide potential applications. Image 1 • Composites thermal management mechanism is paraffin solid-liquid phase transition that absorbing exceeding heat energy. • Composites comprising 30 wt % paraffin can be used as flexible thermal management substrate for epidermal electronics. • Phase transition, thermal management and transmittance change of the composites occur at the paraffin melting point. • Paraffin melting is the reason for viscoelastic transition and transmittance change with temperature. [ABSTRACT FROM AUTHOR]

Selective Laser Melting (SLM) is an Additive Manufacturing (AM) process based on the local fusion of powdered metal. SLM requires support structures that enable heat transfer and structural support during fabrication while being frangible to enable removal. Despite the criticality of support structures, very little quantitative data exists to characterise their behaviour. AlSi10Mg is an important SLM alloy which is particularly appropriate for laser applications due to its ease of processing. Block support structures are the most versatile of the commercially implemented support structure designs. This research presents an experimental study of the mechanical strength and numerical analysis of the thermal behaviour during SLM fabrication of ALSi10Mg block support structures. It was found that: support structure peel strength is significantly lower than normal strength due to fundamentally different failure mechanisms; support strength is influenced by height; and, reduced support spacing increases heat transfer and load bearing capability. Design equations were generated to enable prediction of the strength of a given support structure. This previously unavailable data allows AM designers to unambiguously specify support structures that are optimal for a specific design scenario. Furthermore, these insights potentially allow the redesign of block support structures such that response is independent of geometry. Unlabelled Image • Analysis of the mechanical strength and thermal properties of AlSi10Mg block support structures fabricated by SLM. • The peel strength of a support structure is significantly less than its tensile strength. • The strength of a support structure is inversely proportional to its height. • Reducing support spacing increases heat transfer capability. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM), particularly Selective Laser Melting (SLM) has enabled development of lattice structures with unique properties. Through control of various parameters lattice structures can produce unique mechanical, electrical, thermal and acoustic properties, and have received much research attention. Despite the increasing volume of published data on the mechanical response of specific SLM lattice structures, there exists no overarching analysis. This work addresses this identified deficiency by providing a comprehensive summary of the experimental data reported on the mechanical response of SLM lattice structures. The design, fabrication and performance of SLM lattice structures are reviewed and the quality of data reported is analysed to inform best-practice for future studies. This comprehensive data summary enables meta-analysis of the reported mechanical performance of SLM lattice structures, providing insight into the bounds of their technical capabilities. Correlations were identified between the relative density and mechanical properties of many unit cell topologies consistent with the predictions of the Gibson-Ashby model, indicating its usefulness in describing and predicting the behaviour of SLM lattice structures. This review provides designers with a compiled resource of experimental data and design for AM tools to inform future design applications of SLM lattice structures and facilitates their further commercial adoption. Unlabelled Image • A review of the design, fabrication and mechanical performance of Selective Laser Melting (SLM) lattice structures. • Reported data on the mechanical performance and properties of a broad range of SLM lattice structures is compiled. • Meta-analysis of reported data allows insights into the applicability of the Gibson-Ashby model to SLM lattice structures. [ABSTRACT FROM AUTHOR]