Showing papers in "Composites Part A-applied Science and Manufacturing in 2018"
TL;DR: In this paper, the EMI shielding effectiveness of flexible polymer composites comprising of metals and various forms of carbon nanofillers such as carbon black, carbon nano-frillers, carbon nanotubes, graphite, graphene, graphene oxide, graphene nanosheets and graphene nanoribbons has been deeply reviewed.
Abstract: The rapid proliferation and elevated usage of electronic devices have led to a meteoritic rise in electronic pollutions such as electronic noise, electromagnetic interference (EMI) and radiofrequency interference (RFI) which leads to improper functioning of electronic devices. Metals and their alloys can serve as the best EMI shielding materials but their heavy weight, high cost and low corrosion resistance have limited their applications in EMI shielding. The emergence of flexible polymer composites have substituted the metal and metal alloy based EMI shielding materials due to their unique features such as light weight, excellent corrosion resistance, superior electrical, dielectric, thermal, mechanical and magnetic properties that are highly useful for suppressing the electromagnetic noises. In this review article, the EMI shielding effectiveness of flexible polymer composites comprising of metals and various forms of carbon nanofillers such as carbon black, carbon nanofibers, carbon nanotubes, graphite, graphene, graphene oxide, graphene nanosheets, graphene nanoribbons and graphene nanoplatelets have been deeply reviewed.
466 citations
TL;DR: In this paper, 2D hierarchical composites of nano-sized Fe3O4 particles on MXenes (TiO2/Ti3C2Tx/Fe3O 4) with different ratios were synthesized by using a moderate chemical hydrothermal reaction.
Abstract: Although two dimensional (2D) materials have already been studied as promising microwave absorption materials due to fascinating layered structure, it is hard to achieve both thin coating and excellent absorbing capability. Herein, 2D hierarchical composites of nano-sized Fe3O4 particles on MXenes (TiO2/Ti3C2Tx/Fe3O4) with different [TiO2/Ti3C2Tx]/[Fe3O4] ratios were synthesized by using a moderate chemical hydrothermal reaction. Scanning electron microscope and transmission electron microscope techniques indicated that the surfaces of MXenes were densely covered with Fe3O4 nanoparticles of ∼4.9 nm in diameter and TiO2 particles. By tuning the ratio of [TiO2/Ti3C2Tx]/[Fe3O4], microwave absorption capabilities in terms of the maximum reflection loss (RL) value and absorber thickness could be readily optimized. Specifically, the sample TiO2/Ti3C2Tx/Fe3O4-5 exhibited a remarkable absorption performance, with a maximum reflectivity of −57.3 dB at 10.1 GHz and a band range below −10 dB to over 9.1–11.1 GHz at a thickness of 1.9 mm. Therefore, our 2D MXene composites are expected to be promising candidates as ultrathin and lightweight absorbing materials.
240 citations
TL;DR: Friction stir welding/processing (FSW/P) involving temperature, mechanics, metallurgy and interaction, is a complex solid state joining and processing technology as mentioned in this paper, which has been widely applied to join aluminum alloy, titanium alloy and other materials which are difficult to weld by fusion welding.
Abstract: Friction stir welding/processing (FSW/P) involving temperature, mechanics, metallurgy and interaction, is a complex solid state joining and processing technology. FSW has been widely applied to join aluminum alloy, titanium alloy and other materials which are difficult to weld by fusion welding. The last scientific study states that FSW has potential to join thermoplastic polymers and polymer matrix composites. In this review, current understanding and development about FSW of thermoplastic polymers and polymer matrix composites, multifunctional composites fabrication as well as dissimilar FSW of metal and polymer are reviewed. Future scientific research and engineering development related to FSW/P of thermoplastic polymers and polymer matrix composites are identified.
223 citations
TL;DR: In this paper, the authors used Mo2C nanoparticles grown on reduced graphene oxide (Mo2C@RGO) to prepare the 1.5 volumetric ratio of 1.1% Mo2c@rGO/Cu composite, which exhibited a yield strength of 238 MPa, 58% and 127% higher than that of pure Cu and pure Cu, respectively.
Abstract: Mo2C nanoparticles grown on reduced graphene oxide (Mo2C@RGO) were used to prepare the Mo2C@RGO/Cu composite. The Mo2C nanoparticles played a bridging role in not only being firmly attached on RGO but also forming a semi-coherent interface with the Cu matrix, leading to strong interfacial bonding of the composites. The 1 vol% Mo2C@RGO/Cu composite exhibited a yield strength of 238 MPa, 58% and 127% higher than that of 1 vol% RGO/Cu composite and pure Cu, respectively. The strengthening mechanism of Mo2C@RGO/Cu composite relied on the dual role of Mo2C nanoparticles that not only enhanced the load transfer strengthening of RGO but also provided the possible Orowan strengthening themselves. Nevertheless, the Mo2C@RGO/Cu composite showed a drop in coefficient of thermal expansion but a reduced thermal conductivity compared to pure Cu and the RGO/Cu composite. This study provides new insights into the interface structure, strengthening mechanism and thermal behavior of carbide-modified graphene/metal composites.
178 citations
TL;DR: In this article, a novel flame retardant mechanism and model were proposed and new understanding of the role of graphene in the combustion of IFR composites was provided, which showed that the well-dispersed graphene results in significantly deteriorated limiting oxygen index and UL-94 rating.
Abstract: Surface feature of ammonium polyphosphate is modified by cation exchange reaction with piperazine, and then reduced graphene oxide nanosheets are attached to the surface of modified flame retardant via hydrogen bonding interactions. Good dispersion of graphene in the polypropylene matrix is observed. The dispersion state of graphene has an abnormal effect on the flammability results under small flame and fire behavior under forced flaming condition of intumescent flame retardant (IFR) composites. The well-dispersed graphene results in significantly deteriorated limiting oxygen index and UL-94 rating. The graphene with good dispersion is adverse to flammability results, which is in contrary to the widely-acknowledged flame retardant mechanisms. Low content of well-dispersed graphene exhibits higher reduction effect on heat release than that of poorly-dispersed counterpart. Novel flame retardant mechanism and model are proposed and new understanding of the role of graphene in the combustion of IFR is provided.
160 citations
TL;DR: In this article, the micro-cracks resistance of carbon fiber reinforced epoxy (CF/EP) laminate at 77 K was improved by using Fe3O4/GO with good paramagnetic properties.
Abstract: The epoxy nanocomposites with Fe3O4 modified graphene oxide (Fe3O4/GO) were used to influence the micro-cracks resistance of carbon fiber reinforced epoxy (CF/EP) laminate at 77 K. Fe3O4/GO with good paramagnetic properties were prepared by co-precipitation method and used to modify epoxy for cryogenic applications. Fe3O4/GO modified CF/EP laminates were also prepared through vacuum-assisted resin transfer molding (VARTM). The results show that the Fe3O4/GO can effectively improve the mechanical properties of epoxy (EP) matrix at 77 K and reduce the coefficient of thermal expansion (CTE) of EP matrix. It also can obviously improve the micro-cracks resistance of CF/EP composites at 77 K. Compared to neat EP, the CTE of Fe3O4/GO modified EP composite is decreased 51.6%. Compared to CF/EP composite, the micro-cracks density of Fe3O4/GO modified CF/EP composite at 77 K is decreased 60.0%.
156 citations
TL;DR: In this article, a highly sensitive and stretchable strain sensor based on conductive poly(styrene-butadienestyrene)/few layer graphene (SBS/FLG) composite fiber is fabricated through an easy and scalable wet-spinning process.
Abstract: High stretchability and sensitivity are the major desired requirements of strain sensors for wearable electronics applications, especially in health and medical monitoring. Herein, a highly sensitive and stretchable strain sensor based on conductive poly(styrene-butadienestyrene)/few layer graphene (SBS/FLG) composite fiber is fabricated through an easy and scalable wet-spinning process. Owing to the super flexibility of SBS matrix and the excellent electrical and mechanical properties of FLG, the SBS/FLG fiber based strain sensor revealed superior performance, including wide workable strain range (>110%), superior sensitivity (gauge factor of 160 at a strain of 50% and of 2546 at a strain of 100%), and durability. Furthermore, the mechanism behind the excellent performances of SBS/FLG fiber based sensors is discussed in detail.
150 citations
TL;DR: In this paper, a continuous carbon fiber 3D printer was used to produce composite composite core shapes with honeycomb, rhombus, rectangle, and circle core shapes as a single piece.
Abstract: Many modern aircraft components are made from carbon fiber reinforced polymer sandwich structures with two outer skins possessing high tensile and compressive strengths separated by a lightweight core that provides shear stiffness. However, the conventional manufacturing method involves a complicated and costly bonding process. This study used a continuous carbon fiber 3D printer to manufacture sandwich structures with honeycomb, rhombus, rectangle, and circle core shapes as a single piece. The functional properties of the sandwich structures were quantified by shape evaluations and three-point bending tests. Three-point bending tests showed maximum load and flexural modulus increased as effective density increased for all core shapes, but the rhombus core shape was the strongest. Because the mechanical properties depended on the core shape, continuous carbon fiber 3D printers can be used to flexibly design core shapes that satisfy the desired strength and stiffness.
150 citations
TL;DR: In this paper, the authors investigated the key driving mechanisms and damage evolution of the compressive failure of laminated composites containing BVID using compression after impact and indentation (CAI) tests.
Abstract: The damage tolerance of Carbon Fibre Reinforced Polymer (CFRP) to Barely Visible Impact Damage (BVID) is a critical design limiter for composite structures. This study investigated the key driving mechanisms and damage evolution of the compressive failure of laminated composites containing BVID using compression after impact and indentation (CAI) tests. Experiments were carried out on two similar quasi-isotropic laminates: [45 2 /90 2 /0 2 /−45 2 ] 2S and [45/90/0/−45] 4S . Matrix cracking and delaminations were introduced by either low-velocity impact or quasi-static indentation tests prior to the CAI tests. The full-field displacement during CAI as well as the moment of rupture was captured by 3D Digital Image Correlation (DIC). The effect of ply-blocking and influence of factors, such as impact energy, delamination area and surface indentation, on compressive failure was studied. Previously validated high-fidelity finite element (FE) numerical models for the indentation and impact events were then used to investigate the damage evolution during CAI failure.
142 citations
TL;DR: In this paper, the impact of the fiber orientation on mechanical properties and thermal conductivity of 3D-printed polypropylene (PP) composites filled with short carbon fibres was investigated.
Abstract: For composites based on polypropylene (PP) filled with short carbon fibres (CF), extrusion-based additive manufacturing provides a promising and cost-effective manufacturing technique that utilises the flow-induced orientation of the fibres for their targeted alignment through the control of the printing direction. This study investigates the impact of the fibre orientation on mechanical properties and thermal conductivity of 3D-printed PP composites filled with short-CF. Provided a homogeneous fibre-dispersion and a good fibre-matrix adhesion, the composites showed considerably improved mechanical properties compared to neat PP regardless of the fibre orientation. However, for the different printing orientations, a strong anisotropy in terms of flexural and impact properties and thermal conductivity was observed. For example, it was found that the thermal conductivity along the printing and, thus, the fibre direction was three times higher than perpendicular to that direction. The present work provides a key to the fabrication of parts with tailored, orientation-dependent properties.
140 citations
TL;DR: In this paper, the paraelectric SrTiO3 nanofibers (ST NFs) and poly(vinylidene fluoride) (PVDF) were prepared by a solution cast method.
Abstract: Inorganic/polymer nanocomposite films have attracted pronounced attention for electric energy storage applications since their high power energy density and fast charge-discharge ability. In this work, the flexible nanocomposite films composed by the paraelectric SrTiO3 nanofibers (ST NFs) and poly(vinylidene fluoride) (PVDF) were prepared by a solution cast method. The ST NFs, synthesized by an electrospinning method, were coated with a dense and robust dopamine layer which could effectively improve the filler-matrix distributional homogeneity and compatibility. The composite film with an optimized filler content illustrates a high discharge energy density of 9.12 J/cm3 at 360 MV/m, which is about 625% over the biaxially oriented polypropylenes (BOPP) (1.2 J/cm3 at 640 MV/m). Moreover, the composite film shows a superior power density of 2.31 MW/cm3 and ultra-fast discharge speed of 178 ns. Therefore, the present approach might be extended to the fabrication of similar polymeric nanocomposites for high-performance capacitor energy storage devices.
TL;DR: In this paper, poly(glycidyl methacrylate) (PGMA) chains were grafted onto the surface of hexagonal boron nitride (h-BN) by using a simple free radical polymerization.
Abstract: Surface modification of chemically-inert hexagonal boron nitride (h-BN) to reduce its interfacial thermal resistance remains problematic, thereby hindering its application in thermal conductive composites. Here, poly(glycidyl methacrylate) (PGMA) chains were grafted onto the surface of h-BN by using a simple free radical polymerization. The prepared PGMA grafted h-BN (h-BN-PGMA) was incorporated into epoxy (EP) to enhance the thermal conductivity of EP composites. Adding 3, 9 or 15 vol% of h-BN-PGMA into EP leads to 60%, 203% or 505% increase s in thermal conductivity, respectively. Meanwhile, the surface modification of h-BN is benefit to enhance the compatibility between the fillers and EP matrix, which reduces the apparent viscosity of composite materials. Furthermore, compared with EP/h-BN, EP/h-BN-PGMA composites with the same filler-loading exhibit higher storage modulus and glass transition temperature. Additionally, the dielectric constant of the composites hardly depends on the testing frequency while the dielectric loss maintained at a very low level.
TL;DR: In this paper, a bioflame retardant, calcium magnesium phytate (CaMg-Ph), was synthesized via the reaction of calcium chloride and magnesium chloride with phytic acid from renewable source.
Abstract: A bio-flame retardant, calcium magnesium phytate (CaMg-Ph), was synthesized via the reaction of calcium chloride and magnesium chloride with phytic acid from renewable source. Poly(lactic acid) (PLA) biocomposites were fabricated using CaMg-Ph as a bio-sourced phosphorous additive combined with acid-treated carbon nanotubes (CNT). The thermal, mechanical and flame retardant properties of PLA biocomposites were evaluated by thermogravimetric analysis (TGA), tensile and cone calorimeter tests. The addition of the combinations (19 wt% CaMg-Ph and 1 wt% CNT) into PLA resulted in a slight increase in tensile strength (52.8 MPa), compared to 20 wt% CaMg-Ph (50.4 MPa), indicating the reinforcement effect of the CNT. The addition of 10, 20, and 30 wt% CaMg-Ph led to significant reduction in PHRR by 22%, 33%, and 38% respectively with a similar trend in THR. PLA/CaMg-Ph19/CNT1 showed lower PHRR (35.0%) and higher char yield (18.4 wt%) compared to PLA/CaMg-Ph20, suggesting the preferable flame retardant properties.
TL;DR: In this article, shear-stiffening gel (STG) was introduced into shear thickening fluid (STF)-impregnated-Kevlar® woven fabric to improve the impact resistance.
Abstract: In this work, shear-stiffening gel (STG) was introduced into shear thickening fluid (STF)-impregnated-Kevlar® woven fabric (Kevlar/STF) to improve the impact resistance. The STF filled within the yarns of Kevlar and the STG covered the Kevlar/STF to form Kevlar/STF/STG composite. The STG in the Kevlar/STF/STG not only protected STF but also improved the impact resistance of the fabric because of its excellent shear-stiffening characteristics. A series of experiments including the yarn pull-out test, the split Hopkinson pressure bar impact test, rod penetration test, and knife cutting test were carried out to verify the enhancement effect. The improvement mechanism of the impact resistance for the Kevlar/STF/STG was studied. Under the similar anti-impact performance, the Kevlar/STF/STG possessed lower weight than the Kevlar and its strong impact resistance originated from the synergetic effect among the STF, STG and Kevlar. Therefore, the Kevlar/STF/STG exhibited broad potential in the soft body armor.
TL;DR: In this paper, a shift-speed ball milling (SSBM) was used to construct GNS/aluminum composites with high tensile strength of 295 MPa.
Abstract: Graphene nanosheet (GNS)/aluminum composites were fabricated via shift-speed ball milling (SSBM), consisting of a long-term low-speed ball milling (LSBM) and a short-term high-speed ball milling (HSBM). During the early stage of LSBM, Al powders were flattened into flakes, while the agglomerated GNSs were gradually dispersed onto Al flakes. After an inflection point of LSBM time, the dispersed GNSs got re-agglomerated and seriously damaged due to the accumulated work-hardening of Al flakes. During HSBM, the GNS/Al flakes were cold-welded into lamellar-structured particles, preserving the GNS dispersion states. It was demonstrated that the 0.5 vol.% GNS/Al composites via SSBM with 6 h LSBM had proper combination of ultrafine-grained Al matrices with well-preserved, uniformly-dispersed GNSs. Exceptional properties were achieved with a good ductility of 13.5% at a tensile strength of 295 MPa. Therefore, such flake powder metallurgy via SSBM proved to be a smart and effective fabrication strategy for nano-reinforced metal matrix composites.
TL;DR: In this article, a review of state-of-the-art research carried out on the effect of nano titanium dioxide (NT) on the properties of cementitious composites is presented.
Abstract: Nano titanium dioxide (NT) as a zero-dimensional nano material has received widespread attention from both industry and research communities due to its distinguished physical and chemical properties. Much research work indicated that NT can modify material structures, thus providing a new approach to develop high-performance, durable, multifunctional, and environmentally friendly cementitious composites. This paper reviews state-of-the-art research carried out on the effect of NT on the properties of cementitious composites and aims to provide a comprehensive insight into possible development of NT-engineered cementitious composites. The detailed introductions on the processing, microstructures (hydration products and pore structure), properties (hydration, workability, density, mechanical properties, shrinkage, functional properties and durability) and applications of NT-engineered cementitious composites are presented. Finally, the risks, challenges and future development of NT-engineered cementitious composites are discussed.
TL;DR: In this article, the authors report a method through silver-deposition on the surface of the fillers to create a silver nanoparticle "bridge" to decrease the interfacial thermal resistance between fillers.
Abstract: Polymer composites with high thermal conductivity have a great potential application in modern electronics, due to their light-weight, easy process, low cost and stable physical and chemical properties. Nevertheless, most polymer composites commonly possess unsatisfactory thermal conductivity, primarily because of the high interfacial thermal resistance between inorganic fillers. Herein, we report a novel method through silver-deposition on the surface of the fillers to create a silver nanoparticle “bridge”, to decrease the interfacial thermal resistance between fillers. The results demonstrate that the out-of-plane thermal conductivity of the epoxy resin/sphere alumina composites is increased to 1.304 W m−1 K−1, representing an improvement of 624% compared with pure epoxy resin. This strategy provides an insight for the design of thermally conductive polymer composites with potential to be used in next-generation electronic packaging.
TL;DR: In this article, a new fabrication approach was proposed to prepare carbon nanotube (CNT) composite powders and utilize them for SLS process, which could offer an effective method to fabricate the CNT/Polymer composite with electrically conductive segregated structures.
Abstract: Additive manufacturing such as selective laser sintering (SLS) offers the strategies to create 3D complex components with desirable mechanical, electrical and thermal properties using the composite powders as feeding materials. This work proposes a new fabrication approach to preparing carbon nanotube (CNT) composite powders and utilizes them for SLS process. As compared with the hot-compression process, the SLS process could offer an effective method to fabricate the CNT/Polymer composite with electrically conductive segregated structures. At a small loading range of CNTs (
TL;DR: In this article, the authors reported the design and synthesis of tunable electromagnetic (EM) absorbers by encapsulating graphite into SiC nanowires, which achieved a maximum reflection loss of −22 dB at 16.8 GHz with a small thickness of 1.7mm.
Abstract: This paper reports on the design and synthesis of tunable electromagnetic (EM) absorbers by encapsulating graphite into SiC nanowires. The hybrid nanowires with controllable dielectric and microwave absorption properties are employed for achieving tunable EM absorbers. The synthesis of the graphite/SiC hybrid nanowires was conducted by electrospinning and high temperature annealing. By simply controlling annealing temperature, the hybrid nanowires annealed at 1300 °C present a maximum reflection loss (RL) of −22 dB at 16.8 GHz with a small thickness of 1.7 mm and an effective absorption bandwidth (RL
TL;DR: In this article, a 5083Al matrix composites reinforced with graphene oxide (GO) and graphene nanoplates (GNPs) have been prepared by the pressure infiltration method.
Abstract: In the present work, 5083Al matrix composites reinforced with graphene oxide (GO) and graphene nanoplates (GNPs) have been prepared by the pressure infiltration method. Regardless of the graphene types, no peaks of Al4C3 phase have been detected by the XRD analysis. However, needle-like Al4C3 phase has been observed in the GO/5083Al and the GNPs/5083Al composites, while the content of the Al4C3 phase in the GNPs/5083Al composite was much lower. Furthermore, the segregation of Mg element at the surface of the GNPs has been found in the GNPs/5083Al composite, implying the inhibition effect of Mg element on the formation of the Al4C3 phase. It has been found that the yield strength of the composites was slightly improved by the addition of the GO and GNPs, and the GNPs/5083Al composite demonstrated 14% increment in the tensile strength. Meanwhile, the pulling-out of the GO and GNPs have been observed.
TL;DR: In this article, a review on the latest strategies of microstructure engineering of graphene for highly thermal conductive composites is summarized and both fabrication methods and theoretical simulations are discussed.
Abstract: Heat management is more and more crucial challenge since the development of modern electronic devices towards miniaturization and high dense integrity. Highly thermal conductive composites based on graphene are ideal heat-dissipating materials for their excellent heat dissipation ability, outstanding mechanical properties as well as low coefficient of thermal expansion. Numerous efforts have been made towards the development of graphene-based polymeric composites with high performance. Furthermore, it has been demonstrated that microstructure engineering of graphene-based construction of three-dimensional networks and high orientation is extremely important to improve the properties of composites. In this review, the research progress on the latest strategies of microstructure engineering of graphene for highly thermal conductive composites is summarized. Both fabrication methods and theoretical simulations are discussed. Finally, development and perspectives of highly thermal conductive composites are presented.
TL;DR: In this article, E-glass fibers were coated with graphene oxide by electrophoretic deposition, while reduced graphene oxide (rGO) coated fibers were obtained by subsequent chemical reduction, and the fiber-matrix interfacial shear strength increased for both GO and rGO coated fibers.
Abstract: An engineered interphase can improve the mechanical properties of epoxy/glass composites simultaneously inducing a piezoresistive response. To prove this concept, E-glass fibers were coated with graphene oxide (GO) by electrophoretic deposition, while reduced graphene oxide (rGO) coated fibers were obtained by subsequent chemical reduction. The fiber-matrix interfacial shear strength (measured by the single-fiber fragmentation test) increased for both GO and rGO coated fibers. Unidirectional composites with a high content of both uncoated and coated fibers were produced and mechanically tested under various configurations (three-point bending, short beam shear and mode-I fracture toughness, creep). Composites with coated fibers performed similarly or better than composites prepared with uncoated fibers. Finally, composites with rGO coated fibers were tested for their piezoresistive response under both static and dynamic conditions. The electrical resistance changed proportionally to applied strain thus confirming the possibility of using composites with rGO coated fibers as strain sensors in load-bearing components.
TL;DR: In this article, a sizing procedure was utilized in 3D printing of continuous fiber reinforced thermoplastic composites (CFRTPCs) process to improve their interfacial performance.
Abstract: A sizing procedure was utilized in 3D printing of continuous fiber reinforced thermoplastic composites (CFRTPCs) process to improve their interfacial performance. The sized carbon fiber (SCF) reinforced PA6 (SCF/PA6) was successfully printed, exhibiting 42.2% higher interlaminar shear strength (ILSS) than that of virgin carbon fiber (VCF) reinforced PA6 (VCF/PA6). The influence of sizing and printing process on interfacial performance and fracture patterns was studied systematically. Weak interfacial performance with large fiber pull-out was observed in VCF/PA6. Strong interfacial performance with fiber cut-off arose in SCF/PA6 under excessive forming pressure. They were both detrimental to mechanical properties. Moderate interfacial performance with finite fiber pull-out in SCF/PA6 under decent forming pressure achieved maximum 82% and 246% increasement in flexural strength and modulus respectively. The interface optimization strategy for 3D printed CFRTPCs was set up, which could speed up the technological progress for practical industrial applications.
TL;DR: In this article, the thermally conductive coefficient (λ) of the BN/DCPDCE/BADCy composite with 30% BN fillers was improved to 0.64 W/mK, about 3 times in comparison to that of pristine DCPDCE and BN composite.
Abstract: DCPDCE/BADCy hybrid resin and BN fillers were performed to fabricate the thermally conductive BN/DCPDCE/BADCy composites. When the molar ratio of DCPDCE/BADCy was 0.4/0.6, the dielectric constant (e) and dielectric loss tangent (tgδ) value of the DCPDCE/BADCy hybrid resin was decreased to 2.92 and 5.08 × 10−3, respectively. Impact and flexural strength was increased to 10.7 kJ/m2 and 100.7 MPa, respectively. And the heat-resistance index (THRI) was 201.6 °C. Furthermore, the thermally conductive coefficient (λ) of the BN/DCPDCE/BADCy composite with 30 wt% BN fillers was improved to 0.64 W/mK, about 3 times in comparison to that of pristine DCPDCE/BADCy hybrid resin. Compared to that of Maxwell and Russell models, our proposed thermally conductive model could predict the experimental λ values more precisely. THRI value was enhanced from 201.6 °C (Pristine DCPDCE/BADCy hybrid resin) to 206.6 °C. Moreover, the BN/DCPDCE/BADCy composite with 10 wt% BN presented the optimal impact strength (11.7 kJ/m2) and flexural strength (108.4 MPa).
TL;DR: In this paper, an amine-terminated macromolecular chain (ATBN) was covalently grafted on expanded graphite (EG) surface using 4,4′-methylene diphenyl diisocyanate as coupling agent.
Abstract: Amine-terminated macromolecular chain (ATBN) were covalently grafted on expanded graphite (EG) surface using 4,4′-methylene diphenyl diisocyanate as coupling agent. The functionalization result of the amine-terminated EG (AEG) was demonstrated by various analysis techniques. The AEG was incorporated into the epoxy (EP) matrix to form EP/AEG nanocomposites by interlayer polymerization in the EG interval layers. The grafted ATBN chains on the AEG surfaces can not only enhance the interfacial adhesion of the filler and EP matrix, but can also act as hardener to react with the EP chains covalently to further toughen the fabricated EP nanocomposites. The thermal stability, thermal conductivity, thermos-mechanical, and rheological properties of the EP/AEG nanocomposites were comprehensively studied. The results showed that the novel-designed AEG can significantly enhance the thermal conductivity of the EP composites. Moreover, the as-designed composites show superior thermal stability and thermo-physical properties, making them potentially useful as thermal management materials in electronic devices.
TL;DR: In this paper, the state of knowledge in the characteristics of the interface between the carbon nanotubes and the polymer matrix is presented, focusing on the progress of the relationships between interfacial characteristics and nanocomposite properties.
Abstract: Recent research on the interfacial characteristics of carbon nanotube-polymer nanocomposites is reviewed. The state of knowledge in the characteristics of the interface between the carbon nanotubes and the polymer matrix is presented. Emphasis is placed on the progress of the relationships between interfacial characteristics and nanocomposite properties. Research methodologies used in studying the characteristics of the interface are described. Challenges and opportunities associated with the characterization of the interface are discussed. Critical issues in the research on the interactions at the interface are reviewed, and the advantages and disadvantages of covalent and non-covalent functionalization of carbon nanotubes are delineated. Furthermore, how the properties of the nanocomposites depend on the characteristics of the interface is discussed. The latest developments of the techniques for interface characterization are reviewed, and the strengths and limitations of these techniques are discussed. Potential topics of oncoming focus are finally highlighted.
TL;DR: In this article, a ternary hybrid of carbon nanotubes/graphene oxide/MoS2 was prepared via hydrothermal method, and its microstructure, phase composition, and enhancement effect on the tribological properties of epoxy were investigated systematically.
Abstract: A novel ternary hybrid of carbon nanotubes/graphene oxide/MoS2 was prepared via hydrothermal method, and its microstructure, phase composition, and enhancement effect on the tribological properties of epoxy were investigated systematically. Results revealed EP-CNTs/GO/MoS2 possessed the lowest friction coefficient and wear rate than EP and its other composite coatings reinforced by single filler or binary hybrids. In particular, its friction coefficient and wear rate were 0.042 and 3.44 × 10−5 mm3/Nm, respectively, which were reduced by up to 90% and 95% compared to those of pure-EP. And this was mainly attributed to uniform dispersion of CNTs, GO, MoS2 in CNTs/GO/MoS2 hybrid, and load-carrying capacity of CNTs and GO, self-lubricating effect of MoS2, as well as formation of transfer film onto counterpart surface.
TL;DR: ZIF@MgAl-LDH hybrids were synthesized by zeolitic imidazolate frameworks (ZIF) and MgAl layer-layered double hydroxide (LDH) via electrostatic interactions as discussed by the authors.
Abstract: ZIF@MgAl-LDH hybrids were synthesized by zeolitic imidazolate frameworks (ZIF) and MgAl-layered double hydroxide (MgAl-LDH) via electrostatic interactions. Their structure and morphology were systematically characterized. Then, ZIF@MgAl-LDH hybrids were added to epoxy resin (EP) to study their effects on the thermal properties and fire resistance of the material. The results of TGA showed that ZIF@MgAl-LDH could improve the char yield of the EP composites. The cone calorimetry, smoke density tests, limiting oxygen index (LOI) and UL94 vertical burning test showed that ZIF@MgAl-LDH effectively improved the flame retardancy and smoke suppression of EP. Furthermore, the laser Raman spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS) results of the char residue showed that ZIF@MgAl-LDH promoted the formation of a char layer with high graphitization and thermal oxidation resistance, which was conducive to the reduction of the fire hazards. This simple treatment of EP may expand its fire safety applications.
TL;DR: In this article, bio-based dopamine was employed toward exfoliating bulk hexagonal boron nitride (h-BN) with hydrogen bond action and imparting a highly active surface.
Abstract: The potential prospect of hexagonal boron nitride (h-BN) in the fields of polymer composites is severely limited by undesirable exfoliation efficiency and chemical inertness. Herein, bio-based dopamine was employed toward exfoliating bulk h-BN with hydrogen bond action and imparting a highly-active surface. With assistance of polypodamine, SnO2 nanoparticles were in-situ synthesized and strengthened the interfacial interaction between h-BN and epoxy (EP) matrix. The integrated function of metal oxide/h-BN toward flame retardant and smoke suppression of polymer materials was firstly studied and obtained, in term of reduced peak heat release rate (decreased by 41.1%), lower total heat release (decreased by 30.1%), and suppressed total smoke production (decreased by 21.6%). In addition, the mechanism for enhancements on flame retardant and smoke suppression of EP composites was systematically investigated. Such a design route simultaneously achieves the exfoliation and functionalization of h-BN, thus offering an active platform for further functionalization modification.
TL;DR: In this paper, a short carbon fiber reinforced poly-ether-ketone (SCF/PEEK) and 2060-T8 aluminum alloy were joined via friction stir welding with co-controlling shape and performance.
Abstract: Short carbon fiber reinforced poly-ether-ether-ketone (SCF/PEEK) and 2060-T8 aluminum alloy (AA2060-T8) were joined via friction stir welding with co-controlling shape and performance. The high-quality surface integrity and joint formation were acquired based on a tapered thread pin with the triple facets, a stationary shoulder and a new lap configuration of the SCF/PEEK and the AA2060-T8 at the upper and lower sides. An intimate contact formed at the AA2060-T8 and the SCF/PEEK interface. The macro/micro-mechanical interlocking and the chemical bond attributed to the main bonding mechanisms. Decreasing heat input was beneficial to eliminating the welding defects and improving the load bearing of the joint. The maximum tensile shear strength was 33 MPa. This work indicates that friction stir welding with co-controlling shape and performance has the feasible and potential to join thermoplastic and metal.