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In order to improve the interfacial adhesion between PBO fiber and epoxy resin, the surface modification method of chemical treatment was employed. It was demonstrated that the interfacial shear strength (IFSS) of the micro-composite system increased by 24% compared with the control sample, which was measured by the singer fiber pull-out test. Furthermore, the surface morphology of the fiber was investigated by SEM and the wettability between the sample and water was characterized by the droplet-shape profile.

As a high-performance engineering plastic, polyimide (PI) is widely used in the aerospace, electronics and automotive industries. This paper aims to review the latest progress in the tribological properties of PI-based composites, especially the effects of nanofiller selection, composite structure design and material modification on the tribological and mechanical properties of PI-matrix composites.

The preparation technology of PI and its composites is introduced and the effects of carbon nanotubes (CNTs), carbon fibers (CFs), graphene and its derivatives on the mechanical and tribological properties of PI-based composites are discussed. The effects of different nanofillers on tensile strength, tensile modulus, coefficient of friction and wear rate of PI-based composites are compared.

CNTs can serve as the strengthening and lubricating phase of PI, whereas CFs can significantly enhance the mechanical properties of the matrix. Two-dimensional graphene and its derivatives have a high modulus of elasticity and self-lubricating properties, making them ideal nanofillers to improve the lubrication performance of PI. In addition, copolymerization can improve the fracture toughness and impact resistance of PI, thereby enhancing its mechanical properties.

The mechanical and tribological properties of PI matrix composites vary depending on the nanofiller. Compared with nanofibers and nanoparticles, layered reinforcements can better improve the friction properties of PI composites. The synergistic effect of different composite fillers will become an important research system in the field of tribology in the future.

PBO and p-aramids fibers were compared on thermal degradation in TG and DTG experiments, and PBO fiber showed the highest degradation temperature in both air and nitrogen atmosphere. Annealed under high temperature of 100°C, 200°C, 300°C and 400°C for 1.5 hours, the tenacity of these samples all decreased with the temperature, while PBO fiber showed the best tensile retention property. Whereas using the xenon arc light to simulate sunlight irradiated on the PBO and Kevlar samples for different time respectively, PBO showed the worst tensile retention property. In contrast, the p-aramid fibers showed their relatively good mechanical stability when exposed to the simulated sunlight. Therefore, the application of PBO fibers should be careful in the state of sunlight irradiation although PBO has the highest original mechanical and thermal property.

High performance aramid fibers display high tenacity, modulus and temperature resistance under various end-use applications. Since no scientific research papers on the subject of Kermel fibers are found, the thermal degradation properties of Kermel and poly-p-phenylenebenzobisoxazole (PBO) fibres are therefore compared in this paper. When heated to temperatures of 100°C, 200 °C, 300°C, and 400°C for 1.5 hours, the tenacity and extension-to-break properties of PBO and Kermel fibres both decrease with temperature, but the modulus first increases, and then decreases until 300°C. By using a scanning electron microscope (SEM) to observe the effect of heat treatment on these fibres, the morphologies of PBO and Kermel fibres exhibit fractures when they are ruptured and fibrils are found in their cores.

This paper outlines the innovations in high functional and high performance fibres for applications in protective clothing, including fibres for flame and heat protection. It also describes some typical woven and non‐woven constructions for such applications. And presents the trends in producing smart textile materials, capable of interacting with human/environmental conditions.

The paper aims to study cut resistant property of basic weft plain-knitted fabric for protective clothing.

Effects of fiber materials, fabric direction and knitting technology (sinking-depth) were explored, respectively. Cut process of fabric was tracked and the theoretical analysis was provided to evaluate energy transferring of cutting. Fiber-based cut behavior was observed by SEM images. Deformation energy stored in the loop due to yarn bending was regard as initial elastic potential energy of the fabric, which was related to loop structure.

Cut resistance of the fiber material was the dominant factor for cut resistance of weft plain-knitted fabric, while unit loop structure played a critical role in improving cut resistance.

Cut resistance of the fiber material was the dominant factor for cut resistance of weft plain-knitted fabric, while the unit loop structure played a critical role in improving cut resistance.

The paper provides theoretical support of developing flexible protective clothing.

The effects of failure mode and strain conditions of CFRP, concrete and stirrups on the shear capacity of reinforced beams bonded by geopolymer and epoxy are studied. In addition, a prediction model of the ultimate bearing capacity of CFRP-shear-strengthened beams is proposed, which considers adhesive performance parameters adhesive performance parameter ßE and FRP width parameter ßw.

This paper presents an experimental study on ultimate bearing capacity of CFRP-shear-strengthened pre-cracked beams with geopolymer and epoxy resin, which considers parameters such as impregnated adhesives types and CFRP-strengthened scheme.

The failure modes of CFRP-strengthened beams bonded by geopolymer are the combination of the CFRP-concrete interface substrate failure and fracture failure of CFRP, and that of epoxy is the local substrate failures with small area. The ultimate load of CFRP-strengthened beams is directly affected by the failure modes. The ultimate bearing capacity of CFRP-strengthened beams with geopolymer is 91.4% of that of epoxy resin. Compared with ultimate bearing capacity of CFRP-strengthened beams with U-shaped, that of complete-wrapping increases by 2.5%. Moreover, the stirrup peak strain is reduced by more than 30% in CFRP-strengthened beams bonded with geopolymer and epoxy resin in comparison with the unstrengthened beam. The existing prediction model cannot accurately predict the CFRP shear capacity contribution of strengthened beams with different CFRP-strengthened schemes and adhesive properties. The estimated results are much lower than the test data, and the deviation is much larger than 20%.

Geopolymer alternative to epoxy as an adhesive is feasible and effective for CFRP reinforcement. Furthermore, the accuracy is improved by introducing parameters about adhesive properties based on the existing prediction model. The estimated results are in excellent agreement with the test data, and the deviation is controlled within −12.80%, and the model is suitable for predicting the shear capacity of FRP-strengthened beams with ßf = 90° in shear capacity database.

Since columns are critical structural elements, they shall withstand hazards without any considerable damage. In the case of a fire, although concrete has low thermal conductivity compared to other construction materials, its properties are changed at elevated temperatures. Most critically, the residual compressive strengths of reinforced concrete columns are significantly reduced after fire exposure. Validation of the worthiness of rehabilitating concrete structures after fire exposure is highly dependent on accurately determining the residual strengths of fire-damaged essential structural elements such as columns.

In this study, eight reinforced-concrete columns (200 × 200 × 1,500 mm) that were experimentally examined in a prior related study have been numerically modelled using ABAQUS software to investigate their residual compressive strengths after exposure to different durations of standard fire (i.e. one and two hours) while subjected to different applied load ratios (i.e. 20 and 40% of the compressive resistance of the column). Outcomes of the numerical simulations were verified against the prior study's experimental results.

In a subsequent phase, the results of a parametric study that has been completed as part of the current study to investigate the effects of the applied load ratios show that the application of axial load up to 80% of the compressive resistance of the column did not considerably influence the residual compressive strength of the shorter columns (i.e. 1,500 and 2,000-mm high). However, increasing the height of the column to 2,500 or 3,000 mm considerably reduced the residual compressive strength when the load ratio applied on the columns exceeded 60 and 40%, respectively. Also, when the different columns were simulated under two-hour standard fire exposure, the dominant failure was buckling rather than concrete crushing which was the typical failure mode in most columns.

The outcomes of the numerical study presented in this paper reflect the residual compressive strength of RC columns subjected to various applied load ratios and standard fire durations. Also, the parametric study conducted as part of this research on the effects of higher load ratios and greater column heights on the residual compressive strength of the fire-damaged columns is practical and efficient. The developed computer models can be beneficial to assist engineers in assessing the validity of rehabilitating concrete structures after being exposed to fire.

This paper aims to explore the preparation and tribological performance of MoS₂ nanoparticles supported on fly ash (FA) microparticles.

FA was activated by NaOH, oleic acid and HCl to obtain three modified FA samples. Nano-MoS₂ was deposited on them to form MoS₂/FA additives for poly-α-olefin (PAO) modification. Tribological tests were conducted on a reciprocating rig through the ball-on-disk friction manner. Using X-ray diffraction, scanning electron microscope, energy dispersive spectrometer, Raman spectrometer and element analyzers, the products and their lubrication mechanisms were characterized.

At 1.5 Wt.%, nano-MoS₂ and MoS2/FA could remarkably improve the tribological properties of PAO. The nano-MoS₂ deposited on the HCl-activated FA presented better lubrication performance than nano-MoS₂. It could reduce friction and wear by approximately 27% and approximately 66%, respectively. The lubrication of MoS₂/FA can be attributed to the formation of MoS₂ and carbon containing lubricating film.

FA was applied as a supporter to prepare MoS₂/FA lubricants. The reuse of FA, a solid waste, is important for environmental protection. Moreover, MoS₂/FA is more economical than nano-MoS₂ as a lubricant, because it contains approximately 71% of low-cost FA.

Polymeric particulate composites with thermoplastics, especially polypropylene (PP) matrix with mineral fillers, are of great practical importance due to their simple possibility of modifying mechanical properties and reducing the price/volume ratio of the resulting material. Both filler properties and interface properties have a great effect on the mechanical properties, primarily on stiffness and toughness, of the resulting composite material. Good final dispersion of the filler particles also plays a very important role. To reach the best adhesion and distribution of the particles, various procedures are carried out for activation of the particles. Therefore, the purpose of this paper is to investigate and discuss the effect of using plasma as a tool for treating commercially available CaCO₃ nanoparticles in PP matrix.

The effect of the composite structure on its mechanical properties was studied from an experimental as well as a theoretical point of view. For an experimental study, four PP matrix were chosen. For use as filler, the commercially available precipitated surface-treated calcium carbonate was chosen. The composites were prepared with 5, 10, and 15 wt% of fillers. The sequence of expositions of plasma was chosen to verify the optimal treatment duration. The filler particles were characterized by several structure analytical methods. The composite mechanical properties were characterized by tensile, bending, impact, and creep tests. The deformation behavior of the three-phase composite with homogeneously distributed coated particles was numerically simulated on a microscopic scale.

The main conclusions of this work can be summarized as follows: with the use of plasma to the precipitated calcium carbonate, composites with well-dispersed particles can be prepared; the surface modification using plasma is done mainly by grafting –OH groups onto the particles’ surface; a synergetic effect of modifier enhancing the performance was observed; performance modifier increases the resistance against viscoelastic strain; and the size of the particles and their volume content generally lead to increase in the macro modulus of the composite.

Plasma, as a tool for treating the inorganic fillers, enables to destroy the agglomerates in composite, which is the basic way on how to optimally utilize the synergetic effect of composite with PP matrix.