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This study focussed on the development of fully biodegradable composites based on polybutylene succinate (PBS) in combination with raw materials from different processing stages of the pulp and paper industry. Sulfite pulp (SP), kraft pulp (KP) and screened sludge residue (SL) from wastewater treatment plants (WWTP) were investigated as reinforcing fibres contributing to a circular economy. We report a comparative study of the physicochemical properties and mechanical performance of PBS composites reinforced with these cellulosic raw fibres and commercial pure microcrystalline cellulose (MC). The composites were characterised in tensile strength, elongation at break, modulus of elasticity, water absorption and wettability. The incorporation of the fibres into the polymer matrix was also investigated using torque rheometry. Critical concentrations were obtained with maximum incorporation in the range of 15–20 wt% for SP/KP and 25–30 wt% for SL. SP and KP composites showed at least as good physicochemical and mechanical properties as MC at the concentrations studied (0–20 wt%). SP-composites showed the highest tensile strength and modulus of elasticity. It was shown that these fibres from the pulp and paper industry can be used as reinforcement for PBS matrices without additional chemical purification and provide a valuable alternative to commercial microcrystalline cellulose. [ABSTRACT FROM AUTHOR]

The diagnostics of materials, elements and structures after fire exposure are very complicated. Researchers carrying out such diagnostics encounter difficulties at the very beginning, e.g., how to map fire conditions. In this publication, the authors focused on the analysis of the fibre-cement composite used as facade cladding. The fibre-cement boards are construction products used in civil engineering. The fibre-cement boards are characterised by two phases: the matrix phase and the dispersed phase. The analysis of fibre-cement composite was performed using non-destructive methods. The use of non-destructive methods in the future will allow for the analysis of facades after fires without the need to obtain large elements, which will significantly reduce costs while increasing safety. The aim of the work was to determine internal changes in the microstructure of fibre-cement boards after exposure to fire. The degraded samples were compared with reference samples in the evaluation of the microstructure. An analysis was performed using a scanning electron microscope, images of backscattered electrons (BSE) and maps obtained using Energy Dispersive X-ray Spectroscopy (EDX), which allowed conclusions to be drawn. The observed changes were presented in the form of photos showing changes in the composition of the plates, and they were commented on. It should be noted that fire temperatures act destructively, and a number of changes can be observed in the microstructure. The results of the work indicate that, in the future, the use of non-destructive methods will make it possible to assess the degree of degradation of the façade after a fire. [ABSTRACT FROM AUTHOR]

In recent years, the interest in using fiber reinforced composites (FRC) has increased due to their potential to replace traditional materials in various applications. The advantages of polymer composites from natural fibres are: biodegradability, high performance, market availability and low price. This article is based on a review that discusses both polymer composite materials and typical applications by other authors on fiber reinforced composites (FRCs).

This study investigated the effect of the number of filaments on the tensile properties of high tensile strength polyacrylonitrile-based (T1000GB) and high modulus pitch-based (K13D) carbon fiber epoxy-impregnated bundle composites. In addition, the Weibull statistical distributions of the tensile strength were evaluated. The results clearly demonstrate that the tensile strength of the bundle composites increased with the increasing number of filaments in the case of a smaller number of filaments, ultimately reaching a maximum value. In contrast, for a larger number of filaments, the tensile strength decreased with the increasing number of filaments. In addition, for a smaller number of filaments, the Weibull modulus of the bundle composites increased with an increase in the number of filaments, whereas it remained constant in the case of a larger number of filaments.

In recent years, the interest in using fiber reinforced composites (FRC) has increased due to their potential to replace traditional materials in various applications. The advantages of polymer composites from natural fibres are: biodegradability, high performance, market availability and low price. This article is based on a review that discusses both polymer composite materials and typical applications by other authors on fiber reinforced composites (FRCs). [ABSTRACT FROM AUTHOR]

ZrSiO 4 demonstrates applicability as the SiC/SiC interphase. Via a non-hydrolyzed sol-gel method, the pyrolysis product, synthesis condition, and the formation effectiveness of the ZrSiO 4 coating on SiC fibers were investigated. Mini-SiC/SiC composites with two layers of ZrSiO 4 interface coatings were oxidized to preliminarily verify their oxidation resistance effect. [ABSTRACT FROM AUTHOR]

Polymeric materials reinforced with synthetic fibres such as glass, carbon, and aramid provide advantages of high stiffness and strength to weight ratio as compared to conventional construction materials, i.e., wood, concrete, and steel. Despite these advantages, the widespread use of synthetic fibre-reinforced polymer composite tends to decline because of their high-initial costs, their use in non-efficient structural forms, and, most importantly, their adverse environmental impact. The banana fibres were chemically modified through contact with 10 wt % sodium hydroxide solutions for 45 minutes. Polymeric composites with different fibre lengths were prepared through the hand lay-up process at room temperature. Prepared composites exhibited better mechanical and thermal properties. The tensile strength increased with an increasing fibre length of the banana fibre in epoxy matrix composites, due to the stronger interfacial interactions between the treated fibres and the epoxy matrix. These effects occurred due to the morphological and chemical changes in the treated fibre surfaces, which promote better adhesion between the fibres and the epoxy matrix. [ABSTRACT FROM AUTHOR]

Background: There is a lack of reliable methods to obtain valid measurements of the tensile response of high performance materials such as fibre composites, ceramics and textile products at high rates of strain. Objective: We propose and assess two new test techniques aimed at measuring valid tensile stress versus strain curves at high and ultra-high strain rates. Methods: We conduct detailed, non-linear explicit Finite Element (FE) simulations of the transient response of the test apparatus and specimen during the tests and we develop simple analytical models to interpret the test measurements. We consider two test techniques: one based on the split Hopkinson bar apparatus, and suitable for strain rates of up to 1000 /s, and a second technique relying on projectile impact and aimed at measurements at strain rates higher than 1000 /s. Results: The simulations are successfully validated using test data at strain rates of order 200 /s and then used to predict the test performance at strain rates up to approximately 5500 /s. We find that both techniques can give valid stress versus strain curves across a wide range of strain rates. Conclusions: We identify the limits of both techniques and recommend optimal measurement strategies for dynamic testing of materials with different ductility. [ABSTRACT FROM AUTHOR]

Bioactive ions (Mg, Sr, Zn) doped carbonated hydroxyapatite powders (dHAp) and pure carbonated hydroxyapatite (HAp) powders were prepared by wet chemical precipitation method. The bioactive ions were incorporated into the HAp matrix by co-precipitation from solution containing the appropriate amount of chloride salt of different ions. The morphology of pure HAp was mainly needle-like in nanometre size and the particles were disordered showing quasi-amorphous structure. The ion doping changed the morphology of particles, the dHAp particles had distorted spheroid shapes. Owing to the ion addition, the crystallinity of particles decreased. Particle aggregations can also be observed in both types of samples. HAp and dHAp loaded biopolymer polyvinylpyrrolidone (PVP) composite materials have also been developed by novel electrospinning technique. It has been shown that both the HAp and dHAp particles can be successfully incorporated into the PVP fibre web matrix and simultaneously the bioceramic powders were attached to the surface of polymer fibres. The surface of fibres was not fully covered with the particles. The ceramic powder addition to the polymer solution caused the polymer fibres to become more entangled and the diameters of fibres varied over a wider range compared to the base polymer fibres without bioceramic powder addition. [ABSTRACT FROM AUTHOR]

This work compares the photocatalytic performance of powder and supported bismuthoxychloride (BiOCl) catalysts. Semiconducting nanoparticles (NPs) were immobilised onto cotton fibres (Cot) to prepare photoactive hybrid materials (Cot-BiOCl) for application in environmental remediation and facilitate catalyst recovery. The cotton modification was accomplished using simple in situ methodologies of reactant impregnation followed by BiOCl synthesis in water at room temperature. Using this methodology, it was possible to load 14 mg of BiOCl NPs per gram of modified cotton. The as-prepared material absorbs mainly in the UV range. However, after an easy in situ light sensitisation of the BiOCl, and due to the formation of oxygen vacancies on the catalyst surface, the sensitised material (BiOCl UV) starts to absorb in the visible range. Its bandgap energy, E g , shifts from 3.37 to 1.99 eV thus allowing its use under visible light. The photoluminescence (PL) analysis suggests lower recombination rate of the electron-hole pairs conferring enhanced photoactivity to the self-sensitised BiOCl. Under UV–visible light irradiation the Cot-BiOCl photocatalytically degraded a range of collagen dyes with high efficiency, ≥ 73% in 1 h. After light sensitisation, the modified cotton fibres also allow a swift degradation of collagen dyes at a lower cost under visible light irradiation, 88 ≥ removal % ≥ 45, within 3 h. Additionally, the composite reutilisation and the contribution of the substrate architecture on the composite stability is highlighted. The approach used, along with the high activity of the catalyst, displays better economic viability for application in industrial pollutant removal by enabling efficient use of solar light, and an easy and swift catalyst recovery. [ABSTRACT FROM AUTHOR]

In this paper, porous SiC f /SiC composites are prepared by chemical vapor infiltration of SiC matrix on stitched fibrous preforms with different fabrics laminate structure. The microstructure of the fibrous preforms before and after infiltration of SiC matrix and the permeability and the regeneration efficiency of the porous SiC f /SiC composites with different laminate structure have been determined. Experimental results show that the porous SiC f /SiC composites with twill fabrics laminate structure exhibits a higher permeability with a higher volume porosity and mean pore diameter. In comparing the regeneration ability of two types laminate structure filter medium, as expected, the twill fabrics laminate structure exhibits a better regeneration efficiency than the plain fabrics laminate structure due to its higher air permeability. [ABSTRACT FROM AUTHOR]

Structural components made of fibre-reinforced materials are frequently used in engineering applications. Fibre-reinforced composites are multiphase materials, and complex mechanical phenomena take place at limit conditions but also during normal service situations, especially under fatigue loading, causing a progressive deterioration and damage. Under repeated loading, the degradation mainly occurs in the matrix material and at the fibre-matrix interface, and such a degradation has to be quantified for design structural assessment purposes. To this end, damage mechanics and fracture mechanics theories can be suitably applied to examine such a problem. Damage concepts can be applied to the matrix mechanical characteristics and, by adopting a 3-D mixed mode fracture description of the fibre-matrix detachment, fatigue fracture mechanics concepts can be used to determine the progressive fibre debonding responsible for the loss of load bearing capacity of the reinforcing phase. In the present paper, a micromechanical model is used to evaluate the unixial or multiaxial fatigue behaviour of structures with equi-oriented or randomly distributed fibres. The spatial fibre arrangement is taken into account through a statistical description of their orientation angles for which a Gaussian-like distribution is assumed, whereas the mechanical effect of the fibres on the composite is accounted for by a homogenization approach aimed at obtaining the macroscopic elastic constants of the material. The composite material behaves as an isotropic one for randomly distributed fibres, while it is transversally isotropic for unidirectional fibres. The fibre arrangement in the structural component influences the fatigue life with respect to the biaxiality ratio for multiaxial constant amplitude fatigue loading. One representative parametric example is discussed.

Quasi-static mechanical properties of aramid fibres reinforced natural rubber/SBR composites are comprehensively investigated via scanning electron microscopy (SEM), uniaxial tensile tests, multi-step stress relaxation, and the Mullins experiment. The strength, stiffness, viscoelasticity, and Mullins effect of composites are analysed, and the micro failure mechanism is also explored. It is shown that the samples appear similar to a laminate plate with random short fibres in a plane. The results of the uniaxial tensile tests indicate that the tensile strength and elongation at failure decrease, while the stiffness increases following the addition of a small amount of aramid fibres into the rubber matrix. The multi-step relaxation and Mullins experiments reveal that the aramid-short-fibres weaken the viscoelasticity of rubber composites. Finally, the strain energy of the composite is divided into four parts, and one part is considered with respect to its application to the study of interface destruction between the matrix and fibre. [ABSTRACT FROM AUTHOR]

Natural fiber-reinforced geopolymer has attracted wide attention in construction and building materials due to its low cost, low density, and excellent mechanical properties. Cellulose, hemicellulose, and lignin are the three basic components of natural fibres, and were investigated to reveal their influence on the metakaolin-based geopolymer. Comparative evaluations were investigated via morphology analysis and mechanical strength analysis. The results showed distinct microstructures and mechanical properties of the geopolymer-based materials with cellulose, hemicellulose, and lignin, respectively. A low content (5 wt%) of lignin, cellulose, and hemicellulose enhanced the flexural and compressive strength of pure geopolymer. Higher lignin and hemicellulose led to the porous morphology, lower density, and brittle fractures of geopolymer-based composites, which reduced the flexural and compressive strength in these geopolymer-based composites. It was noted that the degree of geopolymerization was clearly lowered by the alkaline degradation of hemicellulose. With the increase in cellulose content, in contrast, the denser structure and fewer pores of the geopolymer matrix were detected, as well as ductile failures of geopolymer-based composites. Good bonding was also shown between the geopolymer matrix and cellulose fibres without remarkable degradation. The results of this study will facilitate a better understanding of the effect of lignocellulosic biomass in natural fibre-reinforced geopolymers and should serve as the basis for further research and applications. [ABSTRACT FROM AUTHOR]

In this study, barnacle-like manganese oxide (MnO 2 ) decorated porous carbon nanofibers (PCNF) were synthesized using electrospinning and the chemical precipitation method for high-performance asymmetric supercapacitors. The porous structure of PCNF was acquired using poly(styrene- co -acrylonitrile) in the electrospinning solution. In order to obtain the optimized barnacle-like MnO 2 on PCNF (MnO 2 -PCNF), the barnacle-like MnO 2 was synthesized using different synthetic times (namely, 1.5, 3.0, and 7.0 min) of the chemical precipitation. Among them, the optimized MnO 2 -PCNF for 3.0 min exhibited the well-dispersed MnO 2 on the PCNF with the nano-size of 190–218 nm. The optimized MnO 2 -PCNF showed the superior specific capacitance of 209.8 F g −1 at 10 mV s −1 and the excellent high-rate performance of 160.3 F g −1 at 200 mV s −1 with the capacitance retention of 98.7% at 100 mV s −1 for 300 cycles. In addition, electrochemical performances of asymmetric cell (constructed activated carbon and MnO 2 -PCNF) showed the high specific capacitance of 60.6 F g −1 at the current density of 0.5 A g −1 , high-rate capacitance of 30.0 F g −1 at the current density of 10 A g −1 , and the excellent energy density of 30.3–15.0 Wh kg −1 in the power density range from 270 to 9000 W kg −1 . The enhanced electrochemical performance can be explained by the synergistic effects of barnacle-like MnO 2 nanoparticles with a high active area related to high specific capacitance and well-dispersed MnO 2 with a short ion diffusion length related to the excellent high-rate performance. [ABSTRACT FROM AUTHOR]

In this study, bamboo fibres from Bambusa Vulgaris species were used as reinforcement materials for acrylic emulsion polymer modified concrete to determine their engineering properties and elemental compositions. Moisture absorption, density and percentage voids were investigated as well as the compressive strength, flexural strength and split tensile strength at 28, 45 and 60 days of air curing. Acrylic polymers reduced moisture intake, increased the densities and led to another increase in percentage of voids but composite samples with bamboo fibre inclusions at 1.5% and 10% polymers with 1.5% fibre an 15% polymers showed better physical properties than those with polymers only. Compressive and split tensile strength tests had similar results of optimum strength at 45 days while flexural strength test had optimum value at 60 days of air curing. This showed that the properties of unreinforced concrete could be improved through addition of fibres and polymers for use in structural applications.

Environmental issues have motivated researchers to replace synthetic fibres with natural fibres in the fabrication of polymer composites. However, natural fibres demonstrate weak mechanical or thermal properties which limit their different applications. Researchers have suggested fabrication of hybrid composites in order to improve the mechanical and thermal properties of natural fibre-based composites. Hybrid composites are made up by two or more fibres in one matrix or two polymer blends and with one natural fibre reinforcement. By hybridising one natural fibre with another natural fibre/synthetic fibre in one matrix, the resulting composite is a unique product (hybrid composites) that displays better mechanical and thermal properties in comparison with individual fibre-reinforced polymer composites. The advantages of developing hybrid composites are that they are more reliable for different applications and more environmental friendly. In this review paper, we present some recently published works related to mechanical and thermal properties of natural/natural fibres, and natural/synthetic fibre-based hybrid composites. Hybrid composites are one of the emerging fields in material science which has attracted attention for their different engineering applications. [ABSTRACT FROM AUTHOR]

In this study, bamboo fibres fromBambusa Vulgarisspecies were used as reinforcement materials for acrylic emulsion polymer modified concrete to determine their engineering properties and elemental compositions. Moisture absorption, density and percentage voids were investigated as well as the compressive strength, flexural strength and split tensile strength at 28, 45 and 60 days of air curing. Acrylic polymers reduced moisture intake, increased the densities and led to another increase in percentage of voids but composite samples with bamboo fibre inclusions at 1.5% and 10% polymers with 1.5% fibre an 15% polymers showed better physical properties than those with polymers only. Compressive and split tensile strength tests had similar results of optimum strength at 45 days while flexural strength test had optimum value at 60 days of air curing. This showed that the properties of unreinforced concrete could be improved through addition of fibres and polymers for use in structural applications. [ABSTRACT FROM AUTHOR]

This paper presents the effects of microfibre contents on mechanical properties of fly ash-based geopolymer matrices containing glass microfibres at 0, 1, 2 and 3 mass%. The influence of glass microfibres on the fracture toughness, compressive strength, Young's modulus and hardness of geopolymer composites are reported, as are the microstructural properties investigated using scanning electron microscopy. Results show that the addition of 2 mass% glass microfibres was optimal, exhibiting the highest levels of fracture toughness, compressive strength, Young's modulus and hardness. The results of the microstructural analysis indicate that the glass microfibres act as a filler for voids within the matrix, making a dense geopolymer and improving the microstructure of the binder. This leads to favourable adhesion of the composites, and produces a geopolymer composite with good mechanical properties, comparable to pure geopolymer. The failure mechanisms in glass microfibre-reinforced geopolymer composites are discussed in terms of microstructure. [ABSTRACT FROM AUTHOR]

To enhance the thermo-electrical properties of liquid silicone rubber (LSR) in applications, the carbon fibres (CFs) modified by multiwall carbon nanotubes (MWCNT) on the surfaces were used as the fillers. The MWCNT-modified CFs (MPCFs) were analysed by Fourier transform infrared spectra, thermogravimetric analysis, scanning electron micrograph and energy dispersive X-ray spectroscopy. It was found that MWCNT were successfully adsorbed onto the surface of CFs. The MPCFs functioned as conductive fillers in LSR for thermal and electrical conductivity application and exhibited significant enhancement. The effects of MPCFs loading on thermal conductivity and volume resistivity of LSR composites were investigated in detail. Results of this work revealed that the MPCFs/LSR composites possessed a thermal conductivity of 0.73 W m−1 K−1with 14 vol.-% filler loading, approximately 3.48-fold higher than that of pure LSR substrate. And with the increase of MPCFs loading, the least volume resistivity of MPCFs/LSR composites is 10 Ω cm. Besides, compared with that of neat LSR, the tensile strength of MPCFs/LSR composites increased 0.913 MPa. [ABSTRACT FROM PUBLISHER]

We report the effect of cationic polyacrylamide (CPAM) addition on the structural assembly of silica nanoparticles (NPs) within a nanocellulose fibre matrix. Paper like composites are fabricated by first forming complexes of NPs with CPAM, then adding those to a suspension of nanocellulose fibres; followed by filtration, pressing and drying of the final suspension. Complementary small angle X-ray scattering (SAXS) and microscopy (SEM, TEM) investigations of these composites showed a lognormal bimodal distribution of NP sizes. Data analysis allows understanding interparticle interactions within assemblies of SiO 2 NPs at the nanometer scale with respect to different dosage of CPAM. Increasing CPAM dosage increases retention of NPs within the cellulose matrix with stronger interparticle interactions and produces composites with smaller pores. The correlation length of NPs, indicative of the size of the NP clusters increased from 30 to 70 nm as the CPAM dosage increased from 16.5 to 330 mg/g NPs. Retention and assembly of SiO 2 NPs by varying CPAM dosage results from the balance of different interaction forces between NPs, CPAM and nanocellulose fibres. Understanding the effect of CPAM dosage on the various NP and composite structural conformations enables us to engineer novel hierarchically and functional cellulose based structured materials. [ABSTRACT FROM AUTHOR]

Short carbon fibre (C f ) reinforced silicon carbide (SiC) composites with 7.5 wt% alumina (Al 2 O 3 ) as sintering additive were fabricated using spark plasma sintering (SPS). Three different C f concentrations i.e. 10, 20 and 30 wt% were used to fabricate the composites. With increasing C f content from 0 to 20 wt%, micro-hardness of the composites decreased ~28% and fracture toughness (K IC ) increased significantly. The short C f in the matrix facilitated enhanced fracture energy dissipation by the processes of crack deflection and bridging at C f /SiC interface, fibre debonding and pullout. Thus, 20 wt% C f /SiC composite showed >40% higher K IC over monolithic SiC (K IC ≈4.51 MPa m 0.5 ). Tribological tests in dry condition against Al 2 O 3 ball showed slight improvement in wear resistance but significantly reduced friction coefficient (COF, μ) with increasing C f content in the composites. The composite containing 30 wt% C f showed the lowest COF. [ABSTRACT FROM AUTHOR]

A simple and effective process combining pressure and gyration has been developed and used to jet-out composite fibres containing graphene nanoplatelets. Thermoplastic polyurethane and phenolic resin polymers were used as matrices. Processing parameters such as rotation speed, pressure and polymer concentration had a marked influence on the composite fibre diameter. Focussed ion beam milling and etching verified the effective incorporation of the graphene nanoplatelets into the composite fibres. Morphological, rheological, physico-chemical and thermal properties of the composite fibres were evaluated to identify possible applications for them. [ABSTRACT FROM AUTHOR]

Applying additive manufacturing technology to the principles of fibre reinforcement of hydrogels, we have fashioned weak hydrogels into mechanically enhanced composites. We combined the extracellular matrix-like structure of gelatin-methacrylamide (GelMA) and GelMA/hyaluronic acid-methacrylamide (HAMA) hydrogels with highly oriented poly(ε-caprolactone) (PCL) fibres fabricated by Melt Electrospinning Writing (MEW) to achieve fibre-reinforced GelMA/HAMA composites with improved compressive properties. Stacked fibres with lay-down patterns of 0°–90° and 0°–60°–120°, and spacing of 400 and 800 μm were prepared by MEW. These defined fibrous structures were infiltrated with hydrogels, namely GelMA (10%) and GelMA/HAMA (0.125%, 0.25% and 0.5%) in custom-made moulds and crosslinked by a reduction–oxidation initiating system (ammonium persulphate/tetramethylethylenediamine). Mechanical properties and deformation characteristics of the constructs were evaluated under uniaxial compression loading conducted at 37 °C in culture media with an integrated camera. Reinforced constructs showed more than a 35-fold-increase of the compressive Young’s modulus. However, the compressive Young’s moduli were highly strain-rate dependent. The fibre reinforcement has a particular impact on the Poisson’s ratio of the composite constructs, decreasing from values of approximately 0.4 to 0.01. The high interfacial surface area between the fibre structure and the hydrogel matrix is believed to be one of the main factors responsible for the significant increase in the mechanical properties of the constructs. In summary, we have found that reinforcement of hydrogels with defined MEW fibre architectures achieves an outstanding increase in the mechanical properties at high strain rates. [ABSTRACT FROM AUTHOR]

Structural components made of fibre-reinforced materials are frequently used in engineering applications. Fibre-reinforced composites are multiphase materials, and complex mechanical phenomena take place at limit conditions but also during normal service situations, especially under fatigue loading, causing a progressive deterioration and damage. Under repeated loading, the degradation mainly occurs in the matrix material and at the fibre-matrix interface, and such a degradation has to be quantified for design structural assessment purposes. To this end, damage mechanics and fracture mechanics theories can be suitably applied to examine such a problem. Damage concepts can be applied to the matrix mechanical characteristics and, by adopting a 3-D mixed mode fracture description of the fibre-matrix detachment, fatigue fracture mechanics concepts can be used to determine the progressive fibre debonding responsible for the loss of load bearing capacity of the reinforcing phase. In the present paper, a micromechanical model is used to evaluate the unixial or multiaxial fatigue behaviour of structures with equi-oriented or randomly distributed fibres. The spatial fibre arrangement is taken into account through a statistical description of their orientation angles for which a Gaussian-like distribution is assumed, whereas the mechanical effect of the fibres on the composite is accounted for by a homogenization approach aimed at obtaining the macroscopic elastic constants of the material. The composite material behaves as an isotropic one for randomly distributed fibres, while it is transversally isotropic for unidirectional fibres. The fibre arrangement in the structural component influences the fatigue life with respect to the biaxiality ratio for multiaxial constant amplitude fatigue loading. One representative parametric example is discussed. [ABSTRACT FROM AUTHOR]

Kenaf fibre reinforced polyester biocomposites fabricated by hand lay-up technique by using propionic and succinic anhydride-modified kenaf fibres. Chemical structure, mechanical, thermal and morphological properties of kenaf fibres reinforced polyester biocomposites evaluated. The Fourier transform infrared study of modified kenaf fibres carried out to look at changes in functional groups after modification. It confirmed from Fourier transform infrared spectroscopy the variation in positions of functional groups. The mechanical (tensile, flexural and impact) property results revealed that biocomposites with modified kenaf fibres exhibited better properties as compared to untreated kenaf fibres-reinforced polyester biocomposites. Morphological studies show that treated kenaf biocomposites show better fibre/matrix interaction. Thermal analysis results of modified biocomposites exhibited higher initial and final decomposition temperatures. Modified biocomposites display less char residue as compared with unmodified kenaf fibres reinforced polyester composites. [ABSTRACT FROM AUTHOR]

In this work microgel-PVA composite fibres are prepared by means of an electrospinning process using aqueous solutions of poly(vinyl alcohol) (PVA) and poly( N-vinylcaprolactam)-based microgels. The optimal parameters are defined to fabricate homogenous composite fibres in which the microgels are embedded into a PVA matrix. It is demonstrated that the fibres can be physically and chemically crosslinked. The fibre morphology is visualised and its properties investigated by differential scanning calorimetry, DSC, thermo-gravimetric analysis, TGA, and isothermal moisture sorption analysis. The results show that the thermo-sensitive properties of the microgels are retained inside the fibres and that the degree of swelling and the moisture sorption kinetics can be tuned by changing the temperature. [ABSTRACT FROM AUTHOR]

Abstract: Radially polarized piezoelectric fibers are now considered to be used in smart composites. The piezoelectric layers in these fibers are generally anisotropic in the transverse direction and therefore difficult to analyze when dynamic loads are involved. The present paper presents a theoretical study of the dynamic behavior of radially polarized cylindrical piezoelectric layers between isotropic elastic media. A new interphase model is developed to provide simple yet accurate evaluation of the dynamic response of such anisotropic elastic layers. Unlike the traditional interface-spring model, the current interphase model satisfies the equations of motion of the layers and can provide reliable prediction of the stress and displacement. A comparison between the developed model, the interface-spring model and the finite element analysis is conducted. The results clearly show the advantages of the current model over the traditional interface-spring model in simulating anisotropic layers. Numerical examples based on this interphase model for different interphase thicknesses, loading frequencies and material combinations are presented to evaluate the dynamic behavior of multilayered elastic media. [Copyright &y& Elsevier]

Abstract: This article examines the development of a laser pretreatment method for glass fibre reinforced polypropylene surfaces for industrial applications. This work aims to create a reproducible surface for bonding low-energy polypropylene which adheres very poorly to most adhesives and forms to the matrix material for plastic composites. The combination of glass fibres with polypropylene in the form of hybrid yarns is intended to produce a low-cost and powerful engineered fibre composite with applications in high-technology industries. The key process is bonding the engineered fibre composite without modifying the material properties. This is done by adhesive bonding. For this purpose, various pretreatment processes were examined and compared, for example, surface degreasing, plasma pretreatment for final cleaning and activation, the use of peel ply and laser pretreatment. The laser pretreatment serves two purposes: the defined generation of different surface structures and the exposure of glass fibres to be able to exploit the adhesive properties of glass surfaces. Moreover, two processes of artificial aging were performed to simulate potential boundary conditions during future use thus ensuring well-founded assessment of the pretreatments. Possible maximum initial adhesive strength is not the only key factor in favour of a decision to use adhesive bonding. Rather is the resistance to aging in real ambient conditions relevant for the long-term usage and stable bonding behaviour. Finally, the surface pretreatment methods are compared with each other, assessed and critical issues of surface pretreatment and material are validated. [Copyright &y& Elsevier]

Glass fibre composites were recycled by microwave pyrolysis. The glass fibres recovered were evaluated as a reinforcement agent for polypropylene (PP). Samples were prepared with a micro-compounder and the resulting compounds were evaluated with tensile testing, flexural testing, Charpy impact testing and scanning electron microscopy (SEM). The adhesion between fibre and glass was relatively poor, and an attempt was made to improve it. Various coupling agents were evaluated, in addition to the use of maleic anhydride-grafted PP (MA-PP). Tests showed that MA-PP had a relatively strong effect on the mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: Non-oxide CMCs based on pyc-coated SiC-fibres (Tyranno SA3™) as well as novel amorphous ceramic fibres in the quaternary system Si–B–C–N (named SiBNC-fibres) were manufactured via polymer infiltration and pyrolysis process. Two different fibre architectures were applied: 0|90° unidirectional (UD) cross-ply and 0|90° plain weave fabric layer. UD cross-ply reinforced CMCs exhibit much more uniformly distributed filaments leading to better infiltration efficiency in resin transfer moulding process. Bending strength and fracture behaviour are strongly influenced by fibre architecture: UD cross-ply reinforced CMCs show higher bending strengths and less non-linear behaviour compared to plain weave fibre reinforcement. In tensile test there is no evidence of an influence of fibre architecture. Mechanical properties of unexposed SiCpyc/SiCN and SiBNCpyc/SiCN strongly correlate with fibre properties. After exposure to air (T =1100°C, 20h), a significant decrease of mechanical properties could be observed, caused by complete oxidation of pyc-fibre coating interfered with silica formation. [Copyright &y& Elsevier]

Abstract: Borides and carbides of early transition metals are considered a class of promising materials for several applications, the most appealing ones being in the aerospace and energy sectors. The present work is mostly focused on toughening of UHTCs through incorporation of SiC chopped fibers. Mechanical properties of reinforced composites are compared to those of un-reinforced, whisker- and particle-reinforced materials and the effect of different kinds of sintering aids is studied. Addition of fibers allows toughness to be increased from 3–4MPam1/2 (for un-reinforced materials) to 5.0–6.2MPam1/2. The high temperature behavior is also investigated both in air furnace and in arc jet facility. Eventually, a paragraph is dedicated to potential of UHTCs as sunlight absorbers for future solar concentrating systems operating in the high temperature regime. [Copyright &y& Elsevier]

Abstract: Calcium phosphate cements (CPC) consist of one or more calcium orthophosphate powders, which upon mixing with water or an aqueous solution, form a paste that is able to set and harden after being implanted within the body. Different issues remain still to be improved in CPC, such as their mechanical properties to more closely mimic those of natural bone, or their macroporosity to favour osteointegration of the artificial grafts. To this end, blends of CPC with polymer and ceramic fibres in different forms have been investigated. The present work aims at providing an overview of the different approaches taken and identifying the most significant achievements in the field of fibre-reinforced calcium phosphate cements for clinical applications, with special focus on their mechanical properties. [Copyright &y& Elsevier]

Abstract: The paper discusses the development of the advanced polymer composite material applications in the building and civil/structural infrastructure over the past three to four decades. It endeavours to identify and prioritise the important in-service research areas which are necessary to improve the understanding of the behaviour of FRP materials and FRP structural components. The paper demonstrates the types of structures which have been developed from the FRP composite material and the most advantageous way to employ composites in civil engineering. The material has extraordinary mechanical and important in-service properties which when combined with other materials are utilised to improve the stiffness/strength, durability, the whole-life cost benefit and the environmental impact. The paper concludes by summarising key successes of the advanced polymer composite in the civil infrastructure and suggests areas in which, if they are employed innovatively, FRP composites could be used with great advantage. [ABSTRACT FROM AUTHOR]

In this paper, the spinning of polypropylene (PP)/montmorillonite (MMT) composites, as well as the structure and selected mechanical properties of composite fibres are presented. In the experimental work the commercially available organically modified montmorillonites Cloisite 15A (C15A) and Cloisite 30B (C30B) were used. The organoclays were incorporated into the matrix of PP fibres in the form of concentrated PP/organoclay dispersion before spinning. The rheological properties of concentrated PP and PP/organoclay dispersion were investigated to estimate the melt mixing of these components and spinning conditions. A positive effect of both organoclays on the geometrical and structural non-uniformity of PP composite fibres was found. MMT acts as a nucleating agent in PP and can affect the crystallisation rate and supermolecular structure of PP fibres. PP composite fibres formed at a maximum draw ratio showed a higher tensile strength (tenacity) and Young's modulus in comparison with unmodified fibres. [ABSTRACT FROM AUTHOR]

Abstract: It has previously been shown possible to use highly oriented polypropylene (PP) tapes to create self-reinforced (all-PP) composites. It is desirable to understand the relationship between tape processing parameters and the mechanical properties and thermal stability of the tapes, as these tape properties will govern the ultimate properties of the all-PP composite. In this paper, the effects of the tape drawing parameters such as draw ratio (λ), drawing temperature and thermal annealing on the final mechanical properties, density and dimensional thermal stability of the tapes are presented. PP tapes drawn to λ =17 possess tensile moduli of ∼15GPa and tensile strengths of ∼450MPa. PP tapes with high draw ratios, λ >9.3, show a decrease in density, a change from transparent to opaque appearance and increased dimensional thermal stability with increasing draw ratio. The results of an investigation into the effects of a thermal annealing step, targeted at improving the dimensional thermal stability of these highly oriented PP tapes, are also presented. [Copyright &y& Elsevier]

Abstract: In this paper, results presented concern both the chemical and physical behaviours of hemp fibres in lime-based mineral matrix in order to better understand the role of chemical modifications of cellulosic fibres in the evolution of the macroscopic properties, essentially mechanical ones, of such composite materials. The role of fibres surface treatment has been also studied through various chemical treatments applied on hemp fibres. In a first step, the influence of such treatments on the fibre characteristics has been investigated by several means, such as scanning electron microscopy, thermal analysis, X-ray diffraction and FTIR spectroscopy, in order to evaluate their consequences on the fibre behaviour itself. Secondly, an attempt to characterise the influence of the various chemical treatments of fibres on the mechanical behaviour of hemp reinforced lime-based composites has been completed by a three points bending testing campaign. According to the results, it seems that the modifications induced by specific chemical treatments (EDTA, NaOH) on fibres play a major role in the strengthening of the lime/fibres interface but also in the improvement of the overall stiffness of the composite (with respect to the one reinforced by untreated fibres) most probably related to a specific stiffening process of the fibre itself. [Copyright &y& Elsevier]