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Paper is a widely used packaging material and is nowadays regaining importance, e.g., as bio-based and biodegradable material. Moreover, new technologies such as polymer-fiber composites, printed electronics and the deep drawing of paper are developing. The process stability and also the resulting quality of paper converting processes such as coating, metallization, printing, and the printing of electronics are highly affected by the hygroexpansion of paper. In order to reduce production instability and to choose and develop paper substrates with ideal characteristics, critical parameters need to be known. This paper offers an extensive overview of those parameters, starting at a molecular and microscopic level with the effect of the constituents and morphology of single fibers, before moving on to paper contents, chemical modifications and additives and finally concluding with paper production and fiber network modification. It was found that the major influences are single fiber sorption, inter-fiber contacts, microfibril angle, fiber morphology (length, width, curliness) and fiber orientation. This review gives new ideas and insights for technologists working in research, development and production optimization of paper-based products. [ABSTRACT FROM AUTHOR]

Morph-genetic C/TiN composites with cablelike structure was prepared from filter paper template through the surface sol–gel process and carbothermal nitridation reaction. The resulting materials have a hierarchical structure originating from the morphology of cellulose paper. The C/TiN composites formed the core-shell microstructure, the core is graphitic carbon, and the shell is TiN nanocoating formed by carbothermal nitridation reduction of titania with the interfacial carbon in nitrogen atmosphere. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscope were employed to characterize the structural morphology and phase compositions of the final products. [ABSTRACT FROM AUTHOR]

The editorial comments on the multi-scale predictive modelling of the composite materials' behavior. Transition of composite materials from nano to micron to meter-size is examined keeping in view the accuracy of computation and fabrication methods. The article probes the physical behavior of complex material systems under stress in terms of size, time and environment.

The article presents a list of papers related to materials science published in volumes 39, 40 and 41 of the periodical. The articles include "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan, "Thermo-Mechanical Fatigue of Shape Memory Alloys," by E. Hornbogen and "Models in Thermoluminescence," by C. Furetta and G. Kitis.

The article presents a list of review papers published in the "Journal of Materials Science". It includes "Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials," by A. Baldan, "Role of entropy of fusion in phase transformation and self-diffusion," by G. P. Tiwari, J. M. Juneja and Y. Iljima, "Models in thermoluminescence," by C. Furetta and G. Kitis, "Electrical applications of carbon materials," by D. D. L. Chung and "Hydrogen-bonded supramolecular polymers: A literature review," by G. Armstrong and M. Buggy.

The article presents a list of articles related to materials science published in volumes 39, 40, and 41. The articles include "Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials," "Observations of common microstructural issues associated with dynamic deformation phenomena: Twins, microbands, grain size effects, shear bands, and dynamic recrystal," and "Role of entropy of fusion in phase transformation and selfdiffusion."

The article presents a list of review articles published in the previous issues of the journal including "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," "Thermo-Mechanical Fatigue of Shape Memory Alloys," "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion," "Models in Thermoluminescence," and "Electrical Applications of Carbon Materials."

The article presents a list of articles published in the "Journal of Materials Science," including "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," "Thermo-Mechanical Fatigue of Shape Memory Alloys," "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion," "Synthetic Routes, Properties and Future Applications of Polymer-Layered Silicate Nanocomposites," and "Models in Thermoluminescence."

Nowadays, the scientific community emphasizes the use of reversible and non-toxic materials in the field of cultural heritage. Biopolymers are one of the alternative materials to synthetic polymers and solvents that are dangerous for human health and for the environment, applied in consolidation and coating treatment. Natural biopolymers may be divided into polysaccharide, protein, and polyester: All of them are low cost, eco-friendly, and biocompatible, besides many physicochemical characteristics such as being transparent, soluble in water, hydrogel, and film-forming, and can be easily functionalized. The addition of nanoclay, essential oil, and active molecules improves the physicochemical properties of biopolymers and proposes smart response abilities to the new composite material. This work is intended to provide an overview of the development of biopolymers by considering the most general aspects and scanning the diverse substrates of application for the conservation and protection of cultural heritage. [ABSTRACT FROM AUTHOR]

The article presents several review papers published in the Volumes 39 and 40 of the "Journal of Materials Science" including "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan, "Thermo-Mechanical Fatigue of Shape Memory Alloys," by E. Hornbogen, "Recent Developments in Polyurethane-based Conducting Composites," by J. Njuguna and K. Pielichowski, "A Review of Anode Materials Development in Solid Oxide Fuel Cells," by San Ping Jiang, Siew Hwa Chan, and "Advances in the Study on Wear of Metals by Polymers," by Si-Wei Zhang and Ren-Yang He.

Lists research papers in the volumes 39 and 40 of the "Journal of Materials Science". "Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials," by A. Baldan; "Thermo-mechanical fatigue of shape memory alloys," by E. Hornbogen; "Role of entropy of fusion in phase transformation and self-diffusion," by G.P. Tiwari, J.M. Juneja and Y. Illjima.

Presents review papers in the volumes 39 and 40 of the February 15, 2005 issue of the "Journal of Materials Science". Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials; Thermo-mechanical fatigue of shape memory alloys; Electrical applications of carbon materials,

Lists review papers published in vols. 39 and 40 of the "Journals of Materials Science" publication. "Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials," by A. Baldan; "Thermo-mechanical fatigue of shape memory alloys," by E. Hornbogen; "Models in thermoluminescence," by C. Furette and G. Kitis; "Electrical applications of carbon materials," by D.D.L. Chung.

Here we review and summarize the groundbreaking scientific researches of the late Professor Larry L. Hench, including several of his key discoveries in materials science and engineering. First, we provide a statistical overview of his exceptional scientific performance using Scopus, Web of Science, and other Web sites to extract statistical data on his scientific publications and patents. Professor Hench achieved an exceptionally high h-index of 77 (Scopus) for the field of materials science and engineering, which resulted from his 340 research papers, 210 conference papers, 41 patents, 24 books, 4 editorial notes, and 3 biographies starting in 1967. Then, we summarize and highlight his seminal articles, books, and patents in several research areas, such as bioactive glasses, optical gel glasses, biocomposites/coatings, glass-ceramics, biophotonics, advanced ceramics, semiconducting and ionic conducting glasses, glass corrosion, and nuclear waste disposal. Prof. Hench not only discovered the first man-made material to form a chemical bond with bone and initiated a whole new field-bioactive glasses and glass-ceramics-but also made several other important scientific discoveries. It is quite clear that he was one of the most influential materials scientists/engineers of all time! We hope that this review is not only useful for all persons interested in materials science and engineering but also encourages students and younger investigators to make use of this accumulated knowledge to design novel materials and discover new applications for glasses and ceramics. [ABSTRACT FROM AUTHOR]

With development of present energy-saving society, lightweight and green development in the automotive and aerospace industries have put forward urgent demands for heat-resistant cast aluminum alloys. Present cast aluminum alloys are of lightweight and have excellent mechanical properties when serving in ambient environment. However, when serving at temperatures of 200–300 ℃ or even higher, the alloys inevitably soften and the high-temperature mechanical properties decline rapidly, hardly meeting the requirements for high-performance equipments. This paper summarizes the development process of classic heat-resistant aluminum alloys, especially the microstructural characteristics of heat-resistant cast aluminum alloys in the past decade, and reviews the current microstructure tuning strategies of heat-resistant aluminum alloys from the aspects of intrinsic heat resistance of the second phases, phase interface modification, diffusion-controlled phase transition, grain boundary stabilization and composite material design. Finally, we propose the prospects for the future development of heat-resistant aluminum alloys. [ABSTRACT FROM AUTHOR]

Carbon materials have excellent thermophysical properties, and different dimensions of carbon materials are attractive candidates for enhancing high-performance aluminum matrix composites for thermal management. This paper reviews the preparation processes of carbon/aluminum composite materials in various dimensions and summarizes the main factors affecting the thermal conductivity of carbon/aluminum composites from the perspectives of metal matrix, reinforcement, and interface. Finally, we summarize the experimental progress of interfacial modification of different carbon/aluminum composites and put forward the future research direction in this field. [ABSTRACT FROM AUTHOR]

As a class of thermosetting resins with exceptional overall performance, cyanate esters have not received sufficient attention for their potential applications in 3D printing. In this paper, polytetrafluoroethylene micropowder is used for the first time as a thixotropic agent to regulate the rheological properties of liquid bisphenol E cyanate monomer for direct ink writing of cyanate ester resins in 3D printing. Due to their appropriate compatibility, the mixed inks exhibit high storage modulus and shear-thinning behavior, enabling the printed structures to maintain their shape well during printing and subsequent curing processes. The printed samples have good mechanical strength and excellent thermal stability. At the same time, the presence of polytetrafluoroethylene endows the composite materials with low dielectric constant and hydrophobicity. The latter property leads to high hygrothermal stability of the composites. The cyanate ester-polytetrafluoroethylene composite developed here offers a reliable method for 3D printing high performance cyanate ester, efficiently enhances the processibility of the cyanate ester based materials. [ABSTRACT FROM AUTHOR]

This paper investigated the specific compressive strength (specific strength) of fly ash-based geopolymer composites with four hardwood extractives and two softwood extractives, as well as specific wood extractives. Additionally, the effect of the portion of pine wood (i.e., sapwood and heartwood) and wood pretreatment with NaOH were considered. Geopolymer paste (with extractives) and geopolymer wood composites (GWCs) were cured at 60 °C for 24 h. The samples were stored in a climate chamber (20 °C, 65% RH) for 7 days before finally testing under compression. From the results, the specific strengths of geopolymers with hardwood extractives were not significantly affected. However, geopolymers containing pine extractives showed the most significant reduction in specific strength. There were no significant differences in the specific strengths of geopolymers containing polyphenols and resin acid. Generally, geopolymers containing fatty acids recorded the lowest specific strengths. There was no difference between the GWCs with untreated sapwood and heartwood. However, the wood pretreatment led to a 21% and 10% increase in the specific strengths of GWCs with sapwood and heartwood, respectively. The findings of this study form the basis for improved GWCs production and a wide range of applications for green composite materials. [ABSTRACT FROM AUTHOR]

Owing to the high demand for electronic devices and electric vehicles, a huge effort has been directed to the exploration and development of new batteries with good cycling stability, satisfactory high specific capacity and safety. In this paper, we report the designed synthesis of the vanadium oxide with mixed valence H2V3O8 and the composite H2V3O8/PEDOT:PSS using low cost and easy hydrothermal method. Electrochemical activity of the vanadium oxyhydroxide H2V3O8 and the composite H2V3O8/PEDOT:PSS as cathodes materials for high performance lithium–ion batteries was evaluated vs. Li+/Li at various current rates. Compared with pure H2V3O8, composite H2V3O8/PEDOT:PSS cathode exhibits higher specific capacity (390 mAh g−1 at 0.05 A g−1 whereas, an initial discharge capacity of 300 mAh g−1 is observed at 0.3 A g−1), more excellent rate performance and longer cycle life. The composite H2V3O8/PEDOT:PSS cathode delivers excellent specific capacity of ca. 390 mAh g−1 and a 97.5% capacity retention are achieved even after 350 cycles at current density of 0.05 A g−1. Higher electrochemical capacity and stability of the new composite cathode are mainly ascribed to a cooperative effect between the conductive polymer (PEDOT:PSS) with good electrical conductivity and the unique nano-sized H2V3O8 rods with short diffusion pathway for lithium ions diffusion. [ABSTRACT FROM AUTHOR]

Focuses on the preparation of stable inkjet-printable carbon nanotube (CNT)-based ink by special method using multi-walled carbon nanotubes (MWNT). Observation of sub-agglomerates in the MWNT agglomerate; Assessment of the relationship between MWNT concentration and resistance of printed strips; Success of the preparation of the stable CNT-based ink.

This paper reviews a literature survey on the usage of volcanic particle materials as an alternative filler material in polymer composites. Also, it highlights different types of volcanic particle materials and their potential effect on the performance of polymer composites. The review begins with Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis of different volcanic materials. Then, it reviews the thermal and mechanical properties of polymer composites that filled with different volcanic particle materials such as volcanic ash, pumice, perlite, and tuff. Reviewed articles have demonstrated that volcanic particle materials can serve as a polymer composite filler. However, there are several factors such as volcanic particle type, size, surface treatment, dispersion, filler concentration, and interfacial interaction with polymer matrix that should be considered and optimized to achieve a balanced polymer composite with its desired properties. Further, the review provides some insights on the gap in the research of volcanic particle material in polymer composites. In particular, the research of volcanic particle materials in different kind of polymers especially bio-based and recycled ones according to the cost-effective and green applications was suggested to be focused. [ABSTRACT FROM AUTHOR]

The heat transfer performance of the graphene network in the polymer is not so satisfactory due to the high interfacial thermal resistance between layered graphene. This paper constructs partially stacked graphene sheets models with random vacancies by the molecular dynamics to investigate the effect of vacancy coverage rate, stacking length and stacking forms on the heat transfer coefficient. The results indicate that the heat transfer coefficient of the whole system mainly depends on the effective thermal conductivity of the stacking region. As the vacancy coverage rate increases, the effective thermal conductivity of the stacking region increases rapidly and then decreases slowly due to the synthetic effect of the interfacial thermal resistance and in-plane thermal resistance. Further studies reveal the positive correlation between the stacking length and the effective thermal conductivity of the stacking region. However, the effective thermal conductivities of models with different stacking lengths converge to a similar value approximately at a high vacancy coverage rate. Finally, the stacking form is proved to have a slight influence on the effective thermal conductivity. This work is of practical importance for the design and application of graphene networks in composites materials. [ABSTRACT FROM AUTHOR]

The detection method with potential ability to diagnose drugs in human serum rapidly, highly sensitivity and selectivity is of vital importance for clinical diagnosis. In this paper, an electrochemical sensor on the basis of composite material modified by zeolitic imidazolate framework (ZIF) on carbon nanofiber (CNF) surface is constructed, which is used for ultra-sensitive determination of adrenaline (AD). CoMnZIF-CNF combines the good conductivity of carbon nanofibers and the high electrocatalysis of CoMnZIF, which can improve the reaction activity and the sensing effect of adrenaline. The proposed sensor shows a good linear relationship between AD concentration from 5 to 1000 μM, and the detection limit is 0.22 μM. Meanwhile, CoMnZIF-CNF demonstrated the remarkable selectivity, significant repeatability and stability, as well as excellent reproducibility. Besides, through the analysis of AD in serum electrolyte, the practicability of the sensor was evaluated and the recovery rate was between 97.51 and 102.53%. On the basis of the results, the prepared sensor has a vital application prospect in detecting AD in actual sample analysis. [ABSTRACT FROM AUTHOR]

Traditional epoxy resin materials are widely used in coatings, composite materials, electronic packaging materials, etc. They are usually made of unsustainable fossil resources and cannot be recycled under mild conditions. Degradable thermosetting resins with dynamic covalent structure provide a potential solution to this conflict. In this paper, using biomass energy vanillin, m-xylylenediamine and 1, 6-hexanediamine as raw materials, two dynamic imine bond curing agents were synthesized, and then cured with DGEBA to prepare two bio-based imine epoxy vitrimers. The thermal and mechanical properties of two imine epoxy vitrimers were studied and compared in detail. Results showed that the two types of polymers exhibit excellent thermal stability and solvent resistance. At the same time, the tensile strength, modulus and elongation at break were comparable to or even better than those of conventional bisphenol A epoxy resin. In addition, due to the hydrolysis of the dynamic imine bonds, vitrimers had degradable characteristic, and its degradation also exhibited temperature, solvent and acidity dependence. More importantly, the recyclable carbon fiber reinforced polymer composites made of these two vitrimers could be completely degraded under weak acid conditions, and the nondestructive recycling of carbon fiber composites could be realized. We envision that this vitrimers with simple process, excellent comprehensive properties and degradability will make it a potential candidate for applications in sustainable structural materials. [ABSTRACT FROM AUTHOR]

Nanoindentation technology is an advanced method to explore the microscopic mechanical properties of layer or block materials. Grid nanoindentation coupled with statistical analysis is effective to give an insight into multiphase materials just like cement paste, mortar and concrete. However, traditional statistical methods, such as deconvolution analysis and Gaussian Mixture Model (GMM), are limited by the nondeterminacy of normal distribution assumption, computational instability due to random selection of initial values, and some problems induced by large amount of calculation. In this paper, clustering analysis, an advanced analysis method for mixed data and widely used in machine learning field, is developed to deal with grid nanoindentation test data. Calculation results suggested that K-medoid clustering is suitable and highly efficient to explain grid nanoindentation tests. Furtherly, clustering method is more robust than deconvolution analysis and GMM when data size is reduced. In addition, normal distribution assumption is not always available for the mechanical properties of some mineral phases in cement pastes. This work offers a new optional mathematical tool to interpret and understand the multiphase properties of cementitious materials probed by grid nanoindentation technology. [ABSTRACT FROM AUTHOR]

The research presented in this paper aims to improve on the accuracy and computational efficiency of previously reported stochastic models for predicting the electromechanical properties of conductive polymer composite (CPC) materials with nanoparticle constituents. The proposed approach provides a means of quantifying the degree of particle dispersion in a mixture—a parameter that is most often reported as qualitative- and process-specific. CPC-based sensors have recently garnered attention in the field of structural health monitoring due to their atomic similarities with composite materials that are an increasingly popular commodity among numerous industries. In this study, CPCs composed of carbon black nanoparticles and phenolic-based resin epoxy are manufactured and characterized both experimentally and via computational methods. A high-fidelity stochastic modeling solution is proposed to estimate electromechanical properties of such CPCs. Qualitative analysis on the fidelity of the stochastic model is demonstrated. The potential uses for the model and validation techniques are discussed. [ABSTRACT FROM AUTHOR]

Nickel-based superalloys such as Hastelloy X (HX) are widely used in gas turbine engines for their exceptional oxidation resistance and high-temperature strength. The addition of ceramic reinforcement further enhances these superalloys' mechanical performance and high-temperature properties. For this reason, this paper investigates the microstructure and mechanical property of laser powder bed fusion (LPBF) additively manufactured HX–1 wt% WC (tungsten carbide) composite specimens. The results demonstrate that the LPBF-fabricated composite was observed to have several pores and microcracks, whilst only pores were detected in the as-fabricated pure HX. Compared to the fabricated pure HX, the tensile yield strength of such HX composite parts was increased by 13% without undue sacrifices to ductility, suggesting that the very limited number of microcracks were not sufficient to degrade the mechanical performance. The significantly increased dislocations were considered to be the primary contributor for the mechanical performance enhancement in the LPBF-fabricated composite material. The findings offer a promising pathway to employ LPBF process to fabricate advanced microcrack-free composites with high-strength through a careful selection of ceramic reinforcement materials. [ABSTRACT FROM AUTHOR]

Piezoresistivity is an electromechanical effect characterized by the reversible change in the electrical resistivity with strain. It is useful for electrical-resistance-based strain/stress sensing. The resistivity can be the volumetric, interfacial or surface resistivity, though the volumetric resistivity is most meaningful scientifically. Because the irreversible resistivity change (due to damage or an irreversible microstructural change) adds to the reversible change that occurs at lower strains, the inclusion of the irreversible effect makes the piezoresistivity appear stronger than the inherent effect. This paper focuses on the inherent piezoresistivity that occurs without irreversible resistivity changes. The effect is described by the gage factor (GF), which is defined as the fractional change in resistance per unit strain. The GF can be positive or negative. Strong piezoresistivity involves the magnitude of the fractional change in resistivity much exceeding the strain magnitude. The reversible effect of strain on the electrical connectivity is the primary piezoresistivity mechanism. Giant piezoresistivity is characterized by GF ≥ 500. This critical review with 209 references covers the theory, mechanisms, methodology and status of piezoresistivity, and provides the first review of the emerging field of giant piezoresistivity. Piezoresistivity is exhibited by electrically conductive materials, particularly metals, carbons and composite materials with conductive fillers and nonconductive matrices. They include functional and structural materials. Piezoresistivity enables structural materials to be self-sensing. Unfortunately, GF was incorrectly or unreliably reported in a substantial fraction of the publications, due to the pitfalls systematically presented here. The most common pitfall involves using the two-probe method for the resistance measurement. [ABSTRACT FROM AUTHOR]

Transition metal phosphides have received extensive attention as anode materials of sodium ion batteries due to their high theoretical specific capacity and low redox potentials. However, the large volume change during the insertion/extraction of sodium ions often leads to a poor electrochemical performance and thus limits their practical application. Herein, we rationally designed three-dimensional hierarchical Ni5P4 nanospheres wrapped by rGO nanostructures (Ni5P4@rGO) through a sequential hydrothermal synthesis and phosphidation of highly folded spherical α-Ni(OH)2. The graphene nanosheets can effectively prevent the collapse of spherical α-Ni(OH)2 and aggregation of Ni5P4 active materials during phosphidation. Besides, the strong coupling between the nickel phosphide and graphene layers leads to excellent electrochemical performance of Ni5P4@rGO composite as anode materials of SIBs, delivering a specific capacity of 304 mA h g–1 at 0.2 A g–1 after 200 cycles. The strategy developed in this paper may shed light on the morphology-controlled synthesis of transition metal phosphides with high performance for energy storage devices. [ABSTRACT FROM AUTHOR]

The expansion of the optical response range and the high photoelectron holes separation and the transfer efficiency are prerequisites for the excellent hydrogen evolution performance of the catalyst. In this paper, amorphous CoSx is combined with rare-earth complex LaMnO3 and under the characterization of SEM, TEM, XRD and XPS, the successful synthesis of the composite catalyst was demonstrated; characterization results by UV–Vis, BET and electrochemical workstations show that the composite material exposes more active sites, and the close contact interface formed between the two effectively improves the separation and transmission of photogenerated carriers, and the ability of the composite material to sense light is also significantly enhanced. After optimizing the hydrogen production conditions of the composite catalyst, the hydrogen production under visible light (≥ 420 nm) for 5 h reached 458.8 μmol, which was about 6.8 and 4.5 times that of pure LaMnO3 and CoSx, and the hydrogen evolution stability of the material is very good. Studies have shown that amorphous CoSx is a good material that can replace precious metals for hydrogen production. [ABSTRACT FROM AUTHOR]

In this review, recent progress in the mechanical, thermal and interfacial properties of graphene/CNT multiphase polymer composites is examined. Progress in the mechanical and thermal properties of CNT (1D) and graphene (2D) nanostructure materials is also reviewed and compared. Furthermore, this review highlights the improvements in the mechanical, thermal and interfacial properties of two- and three-phase composites, owing to the addition of graphene/CNT. In particular, analysis of several notable papers on hybrid composites (graphene/CNT) provides an intensive review of synergetic effects on the overall properties of the corresponding composites. This holistic review describes an improved interface between fibers and a nanofiller-reinforced matrix. Although the presence of nanofillers even at low loadings confers an overall improvement in composite properties, the exact ratios of individual fillers and combined forms remain to be discussed in depth. Finally, potential applications, current challenges and future perspectives for use of these multiphase composites are discussed with regard to their extraordinary capabilities and promising developments in graphene/CNT family-based composite materials. [ABSTRACT FROM AUTHOR]

There has been much effort to provide eco-friendly and biodegradable materials for the next generation of composite products owing to global environmental concerns and increased awareness of renewable green resources. An increase in the use of natural materials in composites has led to a reduction in greenhouse gas emissions and carbon footprint of composites. In addition to the benefits obtained from green materials, there are some challenges in working with them, such as poor compatibility between the reinforcing natural fiber and matrix and the relatively high moisture absorption of natural fibers. Green composites can be a suitable alternative for petroleum-based materials. However, before this can be accomplished, there are a number of issues that need to be addressed, including poor interfacial adhesion between the matrix and natural fibers, moisture absorption, poor fire resistance, low impact strength, and low durability. Several researchers have studied the properties of natural fiber composites. These investigations have resulted in the development of several procedures for modifying natural fibers and resins. To address the increasing demand to use eco-friendly materials in different applications, an up-do-date review on natural fiber and resin types and sources, modification and processing techniques, physical and mechanical behaviors, applications, life-cycle assessment, and other properties of green composites is required to provide a better understanding of the behavior of green composites. This paper presents such a review based on 322 studies published since 1978. [ABSTRACT FROM AUTHOR]

Natural fibers are particularly interesting from a materials point of view since their morphology has been tailored to enable a wide range of macroscopic level functions and mechanical properties. In this paper, we focus on mussel byssal threads which possess a morphology specifically designed to provide a hysteretic yet resilient large strain deformation behavior. X-ray diffraction studies have shown that numerous natural fibers have a multi-domain architecture composed of folded modules which are linked together in series along a macromolecular chain. This microstructure leads to a strong rate and temperature dependent mechanical behavior and one which exhibits a stretch-induced softening of the mechanical response as a result of the underlying morphology evolving with imposed stretched. This paper addresses the development of a constitutive model for the stress–strain behavior of the distal portion of mussel byssal threads based on the underlying protein network structure and its morphology evolving with imposed stretched. The model will be shown to capture the major features of the stress–strain behavior, including the highly nonlinear stress–strain behavior, and its dependence on strain rate and stretch-induced softening. [ABSTRACT FROM AUTHOR]

The variation of arrangement of micro-structural entities (i.e. inclusions) influences local properties of composites. Thus, there is a need to classify and quantify different micro-structural arrangements. In other words, it is necessary to identify descriptors that characterize the spatial dispersion of inclusions in random composites. On the other hand, Delaunay triangulation associated with an arbitrary set of points in a plane is unique which makes it a good candidate for generating such descriptors. This paper presents a framework for establishing a methodology for characterizing microstructure morphology in random composites and correlating that to local stress field. More specifically, in this paper we address three main issues: correlating microstructure morphology to local stress fields, effect of clustering of inclusions on statistical descriptors identified in the paper, and effect of number of realizations of statistical volume elements (SVEs) on statistical descriptors. [ABSTRACT FROM AUTHOR]

This paper describes the development of eco-friendly bamboo and wood fibre cement composites from agriculture wastes for applications in the housing and building industries, and for sustainable infrastructure regeneration. Bamboo flakes and fibres from oil palm tree fronds were produced and tested for their sugar content and effect on the setting and strength development of the portland cement matrix. To counteract the adverse effects on cement hydration, chemical accelerators, cement replacement materials or a combination of both were used in the manufacture of the composite boards. With the bamboo, the composition of the particleboard was optimized in terms of bamboo–cement ratio and the type and amount of chemical admixture to produce a composite with satisfactory strength and dimensional stability. For the production of wood fibre cement composites, cement replacement materials such as fly ash, rice husk ash and latex were used in conjunction with chemical admixtures to counteract the adverse effect on the hydration characteristics of the cement matrix. Tests were then carried out to optimize the amount and type of cement replacement material and chemical admixtures to produce boards with adequate strength and dimensional stability. All the strength and dimensional stability tests reported in the paper were carried out according to Malaysian Standard MS 934. The paper emphasizes the need for holistic design combining chemical admixtures, cement replacement materials and modern production technology to produce a wide range of cement-bonded composite boards, which will satisfy international standards and can be widely used for infrastructure regeneration. [ABSTRACT FROM AUTHOR]

As a new metal forming technology, the liquid infiltration and semi-solid extrusion process can produce various composite parts, such as tubes, bars, and shaped products, in a single process. In this paper, the liquid infiltration and semi-solid extrusion process for forming a composite tube is simulated by means of thermal rigid-plastic quasi-coupling FEM method. The key technologies such as the handling of liquid phase zone, the transition between liquid and solid phase zones, the grid re-meshing method and the establishment of the boundary condition have also been studied. Based on the FEM simulation software developed by the authors and the grid re-meshing technology, the distribution of stress field, strain field and deformation force in the liquid infiltration and semi-solid extrusion process for forming composite tubes are obtained. The deformation force simulation results accord with the experimental data, indicating the reliability of the system. Therefore, the present research is theoretically valuable in the product quality control and the process parameter choice. [ABSTRACT FROM AUTHOR]

Since potassium hexatitanate whisker is often used for the filler of composites or as a catalyst, its surface is very important. In this paper the surface morphology and structure of potassium hexatitanate fiber has been observed by AFM. The potassium hexatitanate fiber shows that its surface has different “lamellas”. In addition, we obtained the temperature dependence of the linear expansive ratios along a, b, c 3 directions of the cell by molecular dynamics simulation. The simulation result shows that the linear expansive ratios along the 3 directions are almost the same. Therefore, the periodical surface structure is not generated by the shrinkage along 3 directions in the cooling process of the K2O·6TiO2 whisker preparation. The surface structure is believed to be related to the mechanism of crystal growth of the K2O·6TiO2 whisker and is consistant with the “liquid melt inducing” model [22]. [ABSTRACT FROM AUTHOR]

This paper reports on the post-processing disintegration of melt-infiltrated aluminum-carbon nanotube (Al-CNT) composites. The paper shows that un-optimized processing conditions can lead to the deterioration of the consolidated composite into micro-scale powder over time. Extensive characterization of the disintegration process over unprecedented post-processing times of ~2.5 years was conducted. The effect of post-processing time on the morphological and phase changes is discussed. The paper points to the importance and need to evaluate the long-term properties of Al-CNT composites. [ABSTRACT FROM AUTHOR]

This paper presents a new, simple, accessible and environmentally friendly method to prepare gold-reduced graphene oxide composites (Au/rGO) with gold concentration of 2.5 wt%, 5 wt% and 10 wt%. The Au/rGO materials with low Au concentration present AuNPs of low dimensions and proved good catalytic activity for formic acid (FA) decomposition in aqueous solution. The most of the structural characteristics are not dependent of the gold content such as: large surface area (234-278 m2 g−1), good crystallinity of graphenes, few layers of carbon in the graphene support (5-6 layers), medium density of structural defects in graphene, the presence of remanent oxygenated groups on the graphene surface, very good dispersion of AuNPs on both sides of the graphene sheets. The AuNPs size instead is strongly dependent on the Au concentration: The smallest nanoparticles were obtained for Au2.5/rGO (3-5 nm) and the largest for Au10/rGO (10-14 nm). The position of the energy levels (conduction band and valence band) relative to the Fermi level also changes with the Au content. [ABSTRACT FROM AUTHOR]

In the present review, the recent progress in describing the intricacies of mechanical and thermal properties of all types of graphene- and modified graphene-based polymer nanocomposites has been comprehensively examined. The effectiveness of microscopy bouquet for the intrinsic characterization of graphene family and their composites was clearly demonstrated in this research. Furthermore, the utility of the dynamic mechanical analysis and thermo-gravimetric analysis employed for thermal characterization that has been reported by various researchers was exhaustively analyzed in this paper. This research primarily focused on the analyses of several good articles concerned with hybrid graphene composites and the synergetic effect of graphene with other nanofiller to assess its effect on the mechanical properties of its corresponding composites. Such systematic analysis of previous literatures imparted a direction to the researchers about the solution of improved interfacial properties as well as the enhanced dispersion into the vicinity of the matrix. This current research has suggested that the presence of the graphene filler even at very low loadings has shown considerable improvement in the overall mechanical properties of graphene. Further studies to optimize the value of the filler need to be addressed in order to gain complete understanding of the properties of graphene. The potential applications, current challenges, and future perspectives pertaining to these nanocomposites were elaborately discussed in the current study with regard to the multi-scale capabilities and promising developments of the graphene-family-based nanocomposites materials. [ABSTRACT FROM AUTHOR]

Metal-zeolite composite catalysts have found numerous applications in adsorption, gas separation, petroleum refining and chemical industry. The key issue in the design of these catalysts is localization of the metal within the zeolite structure. This paper focuses on a new approach to the synthesis of nickel-zeolite composite catalysts selectively containing metal nanoparticles inside the zeolite pores. In the catalysts prepared by conventional impregnation, metal particles from the external surface of the zeolites were selectively removed by extraction with bulky polymer molecules of poly-4-styrenesulfonic acid. The method is particularly suitable for the ZSM-5 zeolite with relatively narrow micropores. The nickel zeolite catalysts were tested in hydrogenation of toluene and 1,3,5-tri-isopropyl benzene (TIPB). The removal of nickel particles from the zeolite external surface leads to a considerable decrease in the hydrogenation rate of the bulky TIPB molecules, while toluene hydrogenation rate was affected to a much lesser extent and was almost proportional to the nickel content. The proposed methodology can be extended to other types of microporous catalysts. [ABSTRACT FROM AUTHOR]

In this study, a novel and excellent structure-damping composites (PVDF&PDA-CF3D/EP) with high damping and mechanical properties were prepared by coating double layers of polyvinylidene fluoride (PVDF) and polydopamine (PDA) on the surface of the three-dimensional braided carbon fibers (CF3D). The dynamic mechanical analysis and logarithmic decrement measurements were employed to determine the damping characteristic of composites. Results show that there is an increase of approximately 160% in the damping factor of PVDF&PDA-CF3D/EP at low temperature and low strain, compared with that of CF3D/EP. The shear strength of the composites was performed to investigate the synergy effects of PVDF&PDA on the improvement in the interfacial bonding strength between fibers and epoxy matrix. Owing to the optimum of the interface, the flexural strength, flexural modulus and impact strength of PVDF&PDA-CF3D/EP increase by 22%, 11.8% and 18.1%, respectively, compared with those of PVDF-CF3D/EP. Finally, the synergic reinforcing mechanism on the damping and mechanical properties of the composites is discussed in the paper. Therefore, this work provides a general path to make good structure-damping composites which possess great potential application in the industrial field. [ABSTRACT FROM AUTHOR]

Effective thermal conductivity models for nanosheet-based composites are less common than those for composites containing spherical nanoparticle. A novel theoretical model for effective thermal conductivity is proposed aiming to the sheet-like nanoparticle polymer composites in this paper, and comparative analysis is made with other relevant models as well as experimental data. The effective thermal conductivity of the anisotropic nanoparticle is obtained by analysing the differential equations of a sheet-like nanoparticle with an interphase layer in both in-plane and through-plane directions in a cylindrical coordinate system. Then the present model is established based on the Nan’s model and the solutions of these differential equations. The present model which contains the effects of detailed geometry and anisotropy of nanosheet as well as interphase layer are analysed and validated with other models and experimental data. The results of present model are in good agreement with some available experimental results. [ABSTRACT FROM AUTHOR]

This paper is the second of a two-part series assessing the feasibility of using the J-integral with full-field deformation data from digital image correlation (DIC) to characterize toughness in continuous fiber, SiC/SiC ceramic matrix composites (CMCs). In part I, line and area integral adaptations of the J-integral were validated with analytical and experimental deformation fields. It was found that variability in experimental data and contour truncation at the crack wake introduced error and path-dependency, but this could be mitigated through data filtering. In this paper, the line and area integral methods were evaluated for cross-ply and longitudinal CMC tensile specimens. It is demonstrated that these approaches cannot be used for quantitative characterization, but can be successfully used to examine qualitative trends. For both architectures, area integral measurements of the potential energy release rate, J, were larger (and arguably more accurate) than line integral measurements. Resistance curves were characteristic of tough materials, but the stress intensity magnitudes were larger in the longitudinal laminates than the cross-ply (for equivalent crack extension). Experimentally derived bridging laws showed that fiber bridging tractions were largest in the cross-ply laminates, which was attributed to a lower volume fraction of longitudinal fibers. Quantitative, single-value measurements of fracture toughness could not be established since (1) noise in the DIC data masked strain signals indicative of first matrix cracking, and (2) widespread matrix cracking rendered the J-integral invalid (regardless of size and position, the boundaries of the line and area contours inevitably intercepted microcracks). Rather, gross estimates of toughness and stress intensity factors were made under the assumption that the limitations in the spatial resolution of the DIC data essentially transforms regions with fine microcracking along the contour into continuous regions of elastic deformation. When evaluated with the J-integral, the smoothed deformation fields manifest as resistance curves indicative of a tough material. Thus, the J-integral was valuable for qualitative assessments of toughening mechanisms in the CMCs. [ABSTRACT FROM AUTHOR]

For 3D-printing circuits, highly electrical conductive composite filaments were prepared through thin-film transition technique and hot extrusion-drawing. In the filaments, flaky silver powders with nanoscale thickness and smooth flat surface were used as electrical conductive phase, and thermoplastic polyvinyl butyral was used as binder phase. The thermal properties of the electrical conductive composites were studied by thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectrophotometric. Results showed that the electrical conductive composites possessed highly thermal stability up to 350 °C. Moreover, the scanning electron microscopy revealed that thin-film transition technique made the flaky silver powders in the cured conductive films present a face-to-face contact pattern and the well-ordered orientation remain in the composite filaments, which could greatly decrease the volume resistivity of composite filaments. The as-prepared composite filaments showed a low volume resistivity of 7.02 × 10−4 Ω cm at only 55 wt% (11.08 vol%) of flaky silver powder filling rate. The solvent-free 3D printing used composite filaments show low volume resistivity and well mechanical properties that prove the potential application in 3D-printing circuits. [ABSTRACT FROM AUTHOR]

A strong strain hardening ability in ultra-high strength spring steel 60Si2CrVAT was achieved by the design of multiphase microstructures using a quenching-partitioning-tempering process. The microstructure consisted of ~ 70% martensite/bainite and ~ 30% retained austenite, which was obtained at an optimized partitioning temperature of 380 °C. The corresponding yield strength ratio and the product of strength and elongation were 0.81 and 34,828 MPa%, respectively. Interestingly, this sample exhibited a double-stage strain hardening characteristic with a concave-down shape, which was distinct from that of the other samples. The excellent performance of the ultra-high strength spring steel was mainly due to the interactions between the multiple phases and the stability of the retained austenite during cold deformation. This paper provides a new way of obtaining a strong strain hardening ability in ultra-high strength steels, which is expected to be applicable to the cold coiling process. [ABSTRACT FROM AUTHOR]

Polymer composite materials are being increasingly used in primary load-bearing structures in several advanced industrial fields such as aerospace vessels, railway wagons and mega-scaled wind turbines where detection of subcritical damage initiation can significantly reduce safety issues and maintenance costs. It is therefore crucial to inspect these composite structures in order to assess their structural health and to ensure their integrity. Non-destructive testing techniques (NDT) are used for this purpose, making it possible to monitor mechanical damage of composite materials under in situ or ex situ service conditions. This paper reviews the capabilities of the most common NDT techniques used to inspect the integrity of composite materials. Each technique has a detection potential and cannot allow a full diagnosis of the mechanical damage state of the material. Thus, depending on the occurring damage mechanism and the conditions of use, one technique will be preferred over another, or several techniques should be combined to improve the diagnosis of the damage state of the structures. [ABSTRACT FROM AUTHOR]

Adequate micro-modeling for composites is the basic and key precondition for their property prediction. This study takes fiber-reinforced composites (FRCs) as an example and focuses on the linkages among fiber content, porosity and aggregation in the microstructure of composites, as well as their effect on the overall mechanical properties. A novel two-parameter agglomeration model is developed to take both the tightly packed filler assemblies and the porosity into account, in which the fiber weight fraction is used as an independent variable to express the volumetric composition. Meanwhile, an improved two-scale approach based on Mori-Tanaka (M-T) homogenization theory is utilized to predict the effective properties of FRCs. Three typical FRCs: three-dimensional (3D) randomly distributed FRCs, two-dimensional (2D) randomly distributed ones and unidirectionally (UD) distributed ones, are investigated in detail. The proposed model and method are validated by available experimental data. A parametric study reveals that due to the synergistic influence of fiber content, porosity and local aggregation, a maximum stiffness of FRCs can be achieved by making fibers uniformly dispersed in the matrix and setting the fiber weight fraction to be a certain transition value, which is characterized as a best possible condition with high fiber content and low porosity. [ABSTRACT FROM AUTHOR]

This paper presents the results obtained for the effects of the loading rate and of the testing temperature on the mechanical properties, particularly on the stiffness and on the ultimate tensile strength, of a geopolymer reinforced with glass or carbon fibres. HIGH-SILICA geopolymer powder from CLUZ- CYECH and two reinforcement fibres (glass fibres—type AR and carbon fibre - HTS 5631) were used. The displacement rate is varied from 0.02 until to 2 mm/s and the testing temperature is increased from the room temperature until the temperature of 300 °C. For the case of geopolymers reinforced with carbon fibres and glass fibres, the increase of the displacement rate from 0.002 to 2 mm/s led to an improvement on the ultimate flexure strength of about 33 and 31%, respectively. The same dependency was observed for the stiffness, with variations of loading rate of 39 and 53%, for carbon fibres and glass fibres, respectively. Increasing the room temperature until the temperature of 300 °C decreases significantly both the ultimate strength and the flexure stiffness for both reinforcements. However, a major drop on both the stiffness and the strength occurred up to 150 °C. [ABSTRACT FROM AUTHOR]