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In this paper, polypyrrole (PPy) composites (PPy-BC) filled with boron carbide (BC) at different ratios were synthesized for the sorption of carcinogenic methyl orange (MO) dye from aqueous media. In sorption experiments, first, optimum process parameters including operating time (0–210 min), adsorbent mass (0.01–0.30 g/50 mL), concentration (10–50 mg/L), and pH (2–12) were determined. The raw data obtained from the sorption tests were applied to the various isotherms and the Langmuir model showed the best results. From Langmuir isotherm model, the maximum sorption capacities for pristine BC, pristine PPy, and PPy-BC-10 composite were calculated as 208.3, 285.7, and 222.2 mg/g at 25 °C, pH 7, and 10–50 mg/L, respectively. It was determined that the sorption process followed the pseudo-second-order kinetic and the chemisorption process occurred. From the enthalpy values, it was determined that the process was endothermic for pristine BC (+ 40.82 kJ/mol) and pristine PPy (+ 27.33 kJ/mol), and exothermic for PPy-BC-10 (− 7.48 kJ/mol). It can be said that the sorption process of MO dye on composites can be realized by electrostatic interactions, π–π interactions, H-bonding, and pore diffusion. All results showed that the prepared composites could be used as an efficient and potential adsorbent in the sorption of anionic pollutants from an aqueous environment. [ABSTRACT FROM AUTHOR]

As a directly net-shaped structure, 3D woven variable thickness composite plate is different from the constant thickness structure in terms of the changing weft yarn sizes and resulting various warp yarn direction. To investigate the mechanical behavior of this structure, a finite element (FE) model was proposed in this paper on the basis of author's previous geometric model illustrating the characterized details. Mesh convergence was studied to determine the size of element in compromise of accuracy and efficiency. Linear displacement rather than periodic boundary conditions were applied due to the thickness change. For the validation of presented FE model, a sample variable thickness plate in 3D layer to layer weave style was tested under tensile load in warp direction whose thickness was changed in this direction by the change of weft yarn size. The strain was monitored with the help of Digital Image Correlation (DIC) system. The results showed that the predicted homogenized stiffness in warp direction decreased with the thickness increasing, in agreement with the observation from experiments. The maximum error between the predicted stiffness and the measurements of typical segment (TS) in variable thickness region of the plate is 12.05 % while the minimum error is 0.7 %. [ABSTRACT FROM AUTHOR]

Developing efficient and effective oil/water separation materials with both high treatment flux and rejection by a low cost and simple way have been the main goal pursued by researchers. In this paper, a porous metal foam (Ni foam plate and slice) with high strength is selected as the substrate and bacterial nanocellulose fiber (BNC) is used as hydrophilic fibers for modification. Driven by concentration difference, we constructed Ni foam/BNC composite, where the BNC fibers could insert into the foam body and regulate the pore size of foam by only changing the fiber content. This enables the intrinsic large pores of the pristine Ni foam to decrease quickly while maintaining high porosity. Compared to the thick Ni foam plate, the stacks composed of thin Ni foam slices with various pore sizes can effectively separate different oil/water mixtures (i.e. layered oil/water mixtures, oil/water emulsions with and without surfactant) solely by gravity with high treatment flux and satisfactory oil rejection. Furthermore, the modified Ni foams show good reusability only through ethanol washing. The modified Ni foams could be used in the situations with severe water impact and large pressure difference owing to their high compressive modulus. It is expected that this facile pore size adjustment technology can provide us an easy scaled up method to construct filtering materials with high strength and oil/water separation efficiency. [ABSTRACT FROM AUTHOR]

This paper describes a study on the development of novel lightweight and highly flexible composites for electromagnetic interference (EMI) shielding applications. The weft-knitted fabrics produced by using polyester/cotton, polyester/cotton-copper, and polyester/cotton-stainless steel composite yarns with metal deposition and without metal deposition were tested to determine the EMI shielding effectiveness (SE). The surface structures of all composite fabric samples were observed by stereomicroscope. The state of the presence of metal particles on the metal deposited composite fabric was studied by field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) analyzer. The EDX analyses confirmed the presence of metal particles, and the FESEM analyses revealed uniformly deposited metal particles on the surface of composite fabrics. The EMI shielding was also evaluated using vector network analyzers in the frequency range of 8–12 GHz for all samples. The highest value of EMI SE in this research for the composite fabric with the metal deposited sample was achieved to 19.53–23.95 dB. Moreover, the breathability and the durability of produced fabrics were characterized by air permeability, moisture regains, abrasion resistance, and washing fastness. The results of EMI shielding, durability, and breathability tests confirmed their potential for use as an excellent material for EMI shielding in wearable textiles for commercial applications. [ABSTRACT FROM AUTHOR]

With superior vibration alleviation property, mineral-filled polymer composite (MFPC) has attracted more attention in the field of mechanical manufacturing. However, the application of MFPC is limited by its inferior mechanical strength. Straight-line and special-shaped Mo fibers were respectively added into MFPC to improve its mechanical properties in the paper. The influences of fiber shape and matrix performance on interface bonding property of fiber-matrix were studied systematically. And the effects of fiber shape and fiber content on compressive and flexural strength of MFPC were separately discussed. Finite element analysis was employed to further verify experimental results. Compared with straight-line fiber, both pulling ability and interfacial bonding strength of special-shaped Mo fiber are greatly improved when mass ratio r of resin and curing agent is identical. For the same fiber, interface bonding strength of r=4:1 is obviously greater than that of r=7:1. The maximum mechanical strength is achieved when mass fraction of fibers is 1.2 %. Mechanical properties of MFPC reinforced by special-shaped fibers are much better than those reinforced by straight-line fibers. By contrast, the reinforcing effect of M-shaped fibers is optimal, followed by N-shaped, U-shaped the third, and V-shaped the minimum, which consists with the results of finite element simulation. [ABSTRACT FROM AUTHOR]

In this paper, Co/Al2O3 composite nanofibers with different Co content are fabricated by electrospinning combined with selective reduction. By controlling the Co content in the composite nanofiber, not only the fiber's morphology, but also the magnetic properties can be well adjusted to meet different applications' requirements. The magnetic hysteresis loops of composite nanofiber show two different types of shape, typical ferromagnetism and wasp-waisted ferromagnetism. Interestingly, the saturation magnetization, which has a close relationship with the content of magnetic component, is not simply shows an increasing tendency with the increases of Co content in the composite fiber. For the Co content below 50 wt%, the Ms value increases with the Co content. After that, the saturation magnetization decreases to a valley value at near 60 wt% Co content, then increases again. The coercivity also shows the same tendency. The results indicate that the dipolar coupling interaction plays a key role in the magnetic property adjustment of Co/Al2O3 composite nanofiber. [ABSTRACT FROM AUTHOR]

In this paper, Co/Al2O3 composite nanofibers with different Co content are fabricated by electrospinning combined with selective reduction. By controlling the Co content in the composite nanofiber, not only the fiber's morphology, but also the magnetic properties can be well adjusted to meet different applications' requirements. The magnetic hysteresis loops of composite nanofiber show two different types of shape, typical ferromagnetism and wasp-waisted ferromagnetism. Interestingly, the saturation magnetization, which has a close relationship with the content of magnetic component, is not simply shows an increasing tendency with the increases of Co content in the composite fiber. For the Co content below 50 wt%, the Ms value increases with the Co content. After that, the saturation magnetization decreases to a valley value at near 60 wt% Co content, then increases again. The coercivity also shows the same tendency. The results indicate that the dipolar coupling interaction plays a key role in the magnetic property adjustment of Co/Al2O3 composite nanofiber. [ABSTRACT FROM AUTHOR]

Delamination is the most common failure mode in laminated composites, due to the reduced strength in the through-the-thickness direction. This paper describes the development of core-and-effect textured glass yarns for improving the bonding strength of laminated glass woven fabric composites. Air-jet texturing introduces bulk and loops in the yarn which provides more contact surface between the fibers and the resin. However, the yarn tenacity decreases after texturing because of the reduced alignment of the filaments. The effects of texturing air pressure, yarn overfeed ratio, yarn linear density and core-sheath ratio were studied in this paper. The tenacity of glass yarns decreased significantly after the texturing process. The reduction was smaller for yarns with a higher core linear density. The effects of texturing air pressure on the tenacity were found to be insignificant. [ABSTRACT FROM AUTHOR]

Tee-joints are the weakest links in the composite pipelines under internal pressure. In this paper, the internal pressure behavior of Tee-joint composites reinforced with integrated weft-knitted preforms was studied. For this purpose, a multiscale approach was developed on meso-and macro-scales using the homogenized finite element method and ABAQUS Commercial package. Three repetitive unit cells (RUC) of the weft-knitted composite were investigated on the mesoscale. Using the result of the mesoscale simulation, the internal pressure behavior of integrated and non-integrated Tee-joint composites was simulated on the macroscale. A burst pressure test was carried out on the prepared samples. The numerical and experimental results showed that the integrated Tee-shape preforms improve the internal pressure resistance of the Tee-joint composite so that the resistance against internal pressure of integrated Tee-joint composites is at least 40% higher than non-integrated Tee-joints. [ABSTRACT FROM AUTHOR]

Sandwich structures are state of the art for construction of lightweight structures with high mechanical load capacity. Beside established core materials like foams, honeycombs or wood, napcore material is an interesting option when economic production costs or the possibility to integrate extra functionality are criteria in addition to specified mechanical values. Napcore material is made from a two-dimensional resin-impregnated knitted fabric that is shaped into a threedimensional nap structure and stabilized by the cured resin matrix. In this paper the mechanical behavior under low velocity impact loads of sandwich structures made with napcores from aramide textile and phenolic resin is investigated and compared with components containing honeycomb cores. [ABSTRACT FROM AUTHOR]

In this paper, a novel strategy was used to prepare the bamboo fiber (BF)/polypropylene (PP) composites which greatly improved the distribution of BF. Both the raw and alkali treated BF were utilized for the fabrication of composites and silane coupling agent was used to improve the adhesion of BF and PP. The effects of BF content and the alkali treatment of BF on mechanical, thermal, morphological, dynamic mechanical properties and water absorption were studied. The Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the hydrophilic nature of raw BF was significantly reduced by alkali treatment. In addition, the mechanical properties and the water absorption of the composites were found to increase with the increment of BF loading. Most importantly, the mechanical properties of the alkali treated BF showed much higher values than that of raw BF while the water absorption of alkali treated BF was much lower than that of raw BF. The results indicated the interaction of fiber-matrix was greatly improved by the alkali treatment. Moreover, from the Scanning Electron Microscopy (SEM) images, it further proved that the distribution of BF was improved by the way of papermaking to premix BF and PP fiber. The Dynamic mechanical thermal analysis (DMA) results showed that the storage modulus of the composites was increased with further increase in BF content. [ABSTRACT FROM AUTHOR]

In this paper, the short carbon fiber (SCF)/PP composite foams with fine open cell were prepared with batch foaming technique using supercritical CO. The effects of SCF contents, saturation pressure and depressurization rate on the cell morphology were studied. The experimental results indicate that the cell morphology of foamed composites was significantly influenced by the SCF contents and saturation pressure. It is found that the cell size increased and cell density decreased with the increment of SCF contents while the saturation pressure had the opposite effect. However, depressurization rate showed little impacts on the cell morphology due to the presence of SCF. [ABSTRACT FROM AUTHOR]

The present paper is concerned with the effect of cork and rice husk ash micro particles fillers on the mechanical properties (flexural resistance, fracture toughness, impact absorbed energy, elastic and viscous moduli) of polyester based composite. Composite sheets were hand molded using weight filler fractions of 1, 2.5, and 5 %. Flexural strength of filled materials was much lower than the polyester matrix, with more pronounced effect for cork powder, decreasing significantly with filler content increases. Fracture toughness decreases also on the filled composites. Using cork powder fracture toughness decreases significantly when filler content increases, while for rice husk ash filler a slight increase was observed. Both fillers improve absorbed impact energy, peaking at about 2.5 % of filler content. Best improvements were obtained using rice husk ash powder, reaching about 30 %. Both fillers increase glass transition temperature and the maximum use temperature and also the elastic modulus compared with polyester. It can be concluded from this study that the used agro-waste materials are attractive reinforcements from the standpoint of their mechanical properties. [ABSTRACT FROM AUTHOR]

In order to develop composites with better mechanical properties and environmental performance, it becomes necessary to increase the hydrophobicity of the natural fibers and to improve the interface between matrix and natural fibers. Graft copolymerization of natural fibers is one of the best methods to attain these improvements. Only few workers have reported the use of graft copolymers as reinforcing material in the preparation of composites. So in the present paper, we report the preparation of graft copolymers of flax fibers with methyl acrylate (MA) using Fenton’s reagent (FAS-H2O2) as redox system. Synthesized flax-g-poly(MA) was characterized with FTIR, TGA/DTA, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. Composites were prepared using flax-g-poly(MA) as a reinforcement and phenolformaldehyde (PF) as the binding material. Mechanical properties of phenol-formaldehyde composites were compared and it has been found that composites reinforced with flax-g-poly(MA) showed improvement in mechanical properties. Composites reinforced with flax-g-poly(MA) showed better tensile strength (235 N) and compressive strength (814 N) in comparison to composites reinforced with original flax fiber which showed lesser tensile strength (162 N) and compressive strength (372 N). Composites reinforced with flax-g-poly(MA) shows the improved MOR, MOE, and SP. [ABSTRACT FROM AUTHOR]

Both the chicken eggshell (ES) and rice husk (RH) represent environmental, and pollution issues. Incorporating both of them, with minimum processing procedures, in various useful applications is a major contribution in solving such problems. In this research, unsaturated polyester (UP) was doped with different percentages (5–25 wt.%) of fine (ES) to form one (UP-ES) composite system. The (UP-ES) system was reinforced with a fixed 10 wt.% of (RH), which represents an agricultural waste produced in tonnage, to fabricate the second system. X-ray diffraction (XRD) analysis emerged that the (ES) is forming from calcium carbonate (CaCO3) resembling typically the mineral one. The addition of (ES) enhanced both the mechanical characteristics of (UP) resin in terms of tensile strength, elongation %, tensile modulus, impact strength, flexural strength from 26.33 to 33.77 MPa, from 3.30 to 3.60 MPa, from 2000 to 2406.67 MPa, from 1.25 to 2.42 kJ/m2, from 64.93 to 75.07 MPa, and the thermal stability from 335.75 to 346.24 °C, respectively. This inclusion of (ES) also promoted both the limiting oxygen index (LOI) and dielectric constant (εr) of (UP) from 17.25 to 23.50 % and from 6.76 to 11.02, respectively. The addition of (RH) to (ES-UP) composite, generally, gave the same attitude for the properties like what in the (ES-UP) system other than the remarkable extra-increase in the (εr). Also, (RH) elevated the water absorption (%) of (ES-UP) composite by the action of its hydrophilic nature. It is concluded that the incorporation of both (ES) and (RH) reduces the final cost of the composite and solves one of the great environmental disposal issues. [ABSTRACT FROM AUTHOR]

In this study, composites of carbon fiber (CF) with poly vinyl chloride (PVC), poly(ε-caprolactone) (PCL), and 1:1 ratio of PVC/PCL blend were prepared. The composites were characterized by ATR-IR, SEM-EDX, XRD, and Electrical Resistivity techniques. Ozawa-Flynn-Wall (OFW) method was used to calculate the activation energy (Ea) of the composites from thermogravimetry (TG) curves. The activation energies of CF/PVC, CF/PCL, and CF/Blend composites were 89 kJ/mol, 61 kJ/mol, and 72 kJ/mol, respectively. From the DSC curves, it was determined that glass transition (Tg) values of composites prepared with CF were higher than pure polymers. Additionally, CF/Blend had a melting temperature of 54.8 C due to the dissolution of PVC in the molten PCL. In SEM images, it was clearly seen that the polymer matrix consisting of PVC and PCL was attached to the CF surfaces. The XRD results showed that the peak (002) at 2θ=25 ° represents the characteristic CF, while another peak (110) at 2θ=22 ° denotes the CF/PCL composite. The electrical resistivity of CF/PVC, CF/PCL and CF/Blend composites were 0.1714, 0.0873, and 0.0318 Ω mm, respectively. [ABSTRACT FROM AUTHOR]

The purpose of this work was to develop the high-performance ultra-high molecular weight polyethylene (UHMWPE) fibers reinforced rigid polyurethane (RPU) composites. UHMWPE fibers were electroless deposited by copper to form the copper oxides on the fiber surface. The results showed that the copper oxides-coated UHMWPE fibers had the positive effects on the mechanical properties of the composites. Compared with neat RPU, the tensile strength, tensile modulus, bending strength, and impact strength of copper oxides-coated UHMWPE fibers/RPU composites were increased by 20.4 %, 39.7 %, 11.0 % and 15.8 %, respectively. Interlaminar shear strength (ILSS) was also increased by 14.9 %. The dynamic mechanical analysis (DMA) proved the reinforcing effect of copper oxides-coated UHMWPE fibers. Both strength and toughness were increased mainly due to the metal oxides deposited on the fiber surface. On one hand, the copper ions and oxygen ions on the UNMWPE fiber surface could react with oxygen and hydrogen in polyurethane to form chemical bonds. On the other hand, the copper oxides increased the crack propagation path to improve the toughness of the material. [ABSTRACT FROM AUTHOR]

Due to the ultralow density and high specific area, nanofibrous sponges show great potential in the field of filtration and separation. To prepare nanofibrous sponges for high temperature smoke filtration, polytetrafluoroethylene (PTFE) was chosen due to its corrosion resistance and high temperature resistance. PTFE nanofiber prepared via electrospinning shows irregular concave-convex pores in the fiber body, which can improve the specific surface area and further enhance filtration performance. However, sponges made of PTFE nanofiber suffered from severe shrinkage, which limited the development in sponge products. In this study, polyimide (PI) nanofiber converted from polyamic acids (PAAs) nanofiber was introduced into the PTFE sponges to reinforce the dimensional stability. The parameters that influenced the morphology, porosity, shrinkage ratio, and thermodynamic properties of the composite sponges were also investigated. Moreover, the filtration performance of the composite sponges was tested. Results indicated that PTFE/PI composite nanofiber sponges possessed high porosity (94.34–98.12 %), excellent thermal stability (above 550 °C), and decent filtration efficiency (the maximum filtration efficiency reached 99.97 % to PM 2.0) were prepared, which demonstrated the potential in the field of high-temperature filtration. [ABSTRACT FROM AUTHOR]

In the present work tensile, flexural, impact and hardness properties of sorghum bicolor, sisal fiber and jute reinforced with polyester composites are described for the first time. The hybrid composite plates are fabricated for different fiber weights by hand lay-up method. To investigate the mechanical attributes tensile, flexural, impact and hardness tests were performed as per ASTM standard. The mechanical test results revealed a regular trend of an increase in tensile, flexural, impact and hardness properties to adding natural fibers. Good adhesion between the natural fibers and the polyester matrix is also responsible for the effective resistance capability. Further, thermal stability and thermal decomposition of the composite material observed by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The work concludes that sisal, jute, and sorghum bicolor fiber have high potential as reinforcement for composite production. This type of composite material can be useful for automobiles, industrial applications and construction fields. [ABSTRACT FROM AUTHOR]

We prepared itaconic acid based dispersants (IBDs) by the copolymerization of itaconic acid with acrylic acid, acrylamide, or vinyl sulfonic acid, and compared the efficacy of the IBDs on carbon fiber (CF) dispersion in a water-based system, against that of sodium dodecyl sulphate (SDS) which is widely used as a dispersing agent. The procedure to fabricate nonwoven CF (NCF)/PP composites using IBDs includes the following steps: the synthesis of IBDs, the dispersion of CFs in water by the IBDs, the formation of a NCF, and hot pressing of NCF with polypropylene (PP) layer. We determined the tensile, thermal properties, and the electrical conductivity of non-woven CF/PP composites. It was found that using IBDs as a CF dispersing agent led to the CF/PP composites having better tensile, thermal, and electrical properties, as compared to when SDS was used as a dispersing agent. [ABSTRACT FROM AUTHOR]

Glass fiber, GF, which was first hydroxylated and silanized, was incorporated into epoxy resin modified with amino-terminated hyperbranched polymer (ATHBP) to obtain high performance composite. The effects of GFs content on the mechanical properties of composites were investigated, discussing the results from flexural, tensile, and impact tests. The composites revealed noticeable improvement in flexural strength, tensile strength as well as impact strength but slow decrease in elongation at break, compared to the epoxy/ATHBP thermoset. FESEM morphology results indicated the good compatibility between epoxy matrix and GF in the appearance of ATHBP and showed that the toughening mechanism was mainly attributed to the stress transfer mechanism. [ABSTRACT FROM AUTHOR]

Growing interest in sound absorbing materials in industrial applications is their maximized low frequency properties. This research focused on improvement of sound absorption characteristics of layered nonwoven composites. Two different nonwoven structures as polyester and polyester/polyamide blend, were selected as top layer of the bilayered structure. Combinations of a control top layer and a variety of base layers were tested for their sound absorption properties and the effect of using; 1) polyester or 2) polyester/polyamide top layer was investigated. Development of composites with microfibrous layer of 70 %Polyester/30 %Polyamide fibers backed with either of 70 %wool/30 %bi-component polyester, 70 %Cotton/30 %Polyester or 70 % equivalent blend of acrylic, cotton, polyester and 30 % polypropylene nonwoven fibers, provided exceptional sound absorption properties at low frequencies. Macrofibrous layer of polyester fibers backed with 70 %wool/30 %bi-component polyester fibers improved sound absorption properties at all frequency ranges. [ABSTRACT FROM AUTHOR]

Fibrous plants are available in abundance in nature and are a renewable resource. The development of high performance composites from a cheap natural fiber, such as water hyacinth ( Eichhornea crassipes) is particularly beneficial from an economic point of view. Remarkable, thermosetting resins such as polyester are used widely as a composite matrix due to polyester resins present a good dimensional stability, thermal stability, and good mechanical properties. For this study, some composites from water hyacinth fiber and polyester resin were prepared by using solution impregnation and hot curing methods. The composites were prepared by varying fiber percentages (5, 10, 15, and 20 wt%). These were characterized by FTIR and DSC analysis. Additionally, the elastic modules (MOE) from static test according to ASTM (D143-94) and by dynamic test from Sylvates Duo were obtained. Mechanical properties such as flexural strain and compression strength parallel of the different composites were analyzed. Thus, composites which had a concentration of water hyacinth in the range of 5 to 10 wt% yielded the best results. Additionally, the analysis showed no evidence of a negative effect on mechanical and thermal properties of the composite by addition of water hyacinth to the polyester resin. Furthermore, the results showed that water hyacinths fibres presented a competitive reinforcement quality when they were compared with other natural fibers, as such jute, abaca, and rice straw. [ABSTRACT FROM AUTHOR]

The mechanical and thermal behavior of compression molded jute/polypropylene (PP) composites were studied by evaluating tensile strength (TS), bending strength (BS), tensile modulus (TM), bending modulus (BM), impact strength (IS), thermogravimetric (TG/DTG) and differential thermal analysis (DTA). A chemical modification was made to jute fabrics using N,N-Dimethylaniline (DMA) in order to improve the interfacial adhesion between the fabrics and matrix. It was found that jute fabrics on treatment with N,N-Dimethylaniline (DMA) significantly improved the mechanical properties of the composites. Thermal analytical data of PP, both treated and untreated jute fabrics as well as composites revealed that DMA treatment increased the thermal stability of the fabrics and composite. DMA treatment also reduced the hydrophilic nature of the composite. DMA treated jute composite was found less degradable than control composite under water, soil and simulated weathering conditions. [ABSTRACT FROM AUTHOR]

Recently, carbon fiber composites have been widely used as structural reinforcement materials of buildings, replacing reinforcing bars or concrete. And the increase in use of super fibers such as aramid and high strength PE, which is aimed at improving the reinforcement properties, has resulted in a demand for a resin system with excellent mechanical and thermal properties. In this research, a fiber-reinforced composite has been produced by using the super fibers such as carbon fiber or aramid fiber, reinforcement resin and the silica hybrid compound containing epoxy group. This study was carried out to confirm the effect of the silica hybrid on mechanical properties, heat resistance and adhesion strength of a fiber-reinforced epoxy composite, which was produced by blending silica or introducing silica hybrid through covalent bonds. And the silica hybrid containing epoxy group, which may be introduced to the structure of fiber-reinforced epoxy composite through covalent bonds caused by reaction with a hardener, has been used, so that the heat resistance and adhesion strength could be improved. [ABSTRACT FROM AUTHOR]

Carboxymethyl cellulose (CMC) is a cellulose derivative having water-soluble property, biodegradability, and biocompatibility. It has been used in various medical applications as forms of gel, film, membrane, or powder. In this study, composite CMC nonwovens were produced, by a wet-laid nonwoven process, to improve the wet strength of carboxymethyl cellulose nonwovens. Followed by preparing the CMC fibers from cotton fiber, the composite CMC nonwovens composed of CMC fibers and PE/PP bicomponent fibers were manufactured by using 85/15 % v/v of ethanol/water solution as a dispersion medium. Structural analyses of CMC fibers, such as XRD, TGA, FT-IR, and degree of substitution indicated that CMC fibers were successfully produced. The wet strength of CMC nonwoven was dramatically increased by blending with the PE/PP fibers without sacrificing the key properties for wound dressing materials such as liquid absorption, gel blocking and liquid retention. It is expected that the composite CMC nonwovens will be a good candidate for wound dressing materials for mild exudate condition. [ABSTRACT FROM AUTHOR]

In this study, the effect of processing parameters such as temperature, pressure, time of compaction process and areal density on high-velocity impact behaviour of high performance polyethylene fibre cross-ply composites were investigated by Taguchi method. Samples were made through high temperature and pressure compacting process and morphology and interlayer adhesive of samples were investigated by scanning electron microscopy “SEM and T-peel test, repectively. Taguchi method was used to plan a minimum number of experiments. Statistical analysis, analysis of variance (ANOVA), was also employed to determine the relationship between experimental conditions and yield levels. ANOVA was applied to calculate sum of square, variance, ratio of factors variance to error variance and contribution percentage of each factors on response. A hemispherical tip type projectile was used for high velocity impact tests and the depth of trauma as the response factor was measured after impacting test. Results showed that when the temperature, pressure, and time of compacting process were 125 °C, 3 MPa, and 30 min for the composite sample with 7.4 kg/m 2 areal density, the trauma depth was decreased to its lowest value. [ABSTRACT FROM AUTHOR]

Composites consisting of polyurethane (PU)/carbon nanotubes (CNTs) have been successfully prepared by solution mixing method. CNTs were modified through mechano-chemical reaction to increase the compatibility with PU via hydrogen bondings. SEM microphotographs proved that modified CNTs (M-CNTs) became shorter and FTIR spectra showed that hydroxyl groups had been introduced to the surface of M-CNTs. SEM images of PU/M-CNTs composites also proved that M-CNTs were effectively dispersed in PU matrix. Mechanical property tests showed that addition of M-CNTs could significantly improve the tensile properties of PU/M-CNTs composite (breaking strength enhancement ratio for composite with 5.0 wt% M-CNTs was 103.81 %). The thermal stability of composites with M-CNTs was also improved. The initial degradation temperature enhancement was 19.9 oC for the composite with 0.5 wt% M-CNTs. Electrical property tests showed that the electrical properties were improved by adding M-CNTs. The volume conductivities increased 3 and 5 orders of magnitude for the composites with 5.0 wt% and 10 wt% M-CNTs, respectively. The addition of M-CNTs had little effect on the elastic properties of the composites. [ABSTRACT FROM AUTHOR]

The concept of reinforcing soil with natural fibers was originated in ancient times. However, short natural and synthetic fiber soil composites have recently attracted increasing attention in geotechnical engineering for the second time. Consequently in this work, shear behavior of fiber reinforced soil composite was modeled by using force-equilibrium method. The proposed model indicated that fiber percentage, fiber diameter, fiber aspect ratio, Elastic Modulus of fiber, coefficient of friction between fiber and matrix, the thickness of shearing zone and vertical compressive stress determine the shear resistance of a fiber reinforced soil composite. In the next step, a set of laboratory direct shear tests was performed on different samples including both neat soil and fiber reinforced treatments. In order to compare model outputs and experimental results, it was necessary to measure the coefficient of friction between fiber and soil. Therefore, a novel apparatus based on fiber pull-out test was designed to determine the interfacial shear stress between fiber and soil. Since, soil considers as a soft material and its mechanical properties depend on vertical stress, therefore, the Instron Tensile Tester was modified to provide fiber pull-out test through the soil matrix. Consequently, the proposed model adequately predicted shear behavior of fiber reinforced soil composite based on fiber pull-out test results. [ABSTRACT FROM AUTHOR]

The effects of the material and treatment parameters on airflow resistivity and normal-incidence sound absorption coefficient of alkalized three layered nonwoven composites have been studied. The material parameters included fiber size and porosity. The treatment factors included the temperature, duration and concentration. The alkalized composite was a three-layered nonwoven sandwich structure consisting layers of Polypropylene/Hemp/Polypropylene. Alkalization treatment has been found to result in a loss of basis weight and a decrease in air flow resistivity. Among treatment factors, only temperature was found to be a statistically-significant factor on air flow resistivity. Higher-temperature alkalization leads to higher air flow resistivity compared to the lower-temperature treatment. Alkalization at higher temperature and higher concentrations gives better results in normalized sound absorption performance compared to lower-temperature and lower-concentration treatments, respectively. [ABSTRACT FROM AUTHOR]

The objective of this investigation was to evaluate the mechanical, thermal stability and viscoelastic behaviors of experimental PP composites made from wheat straw and PP-g-MA coupling agent. Four levels of wheat straw, 10, 20, 25 and 30 wt % and two levels of coupling agent, 0 and 3 % wt were mixed with PP in rotary type mixer and injection molding process, respectively. Tensile characteristics and impact strength, thermal gravity and dynamic mechanical and thermal analysis of the samples were evaluated. Based on the results, it was observed that the tensile properties increased and impact strength decreased with the increase in the fiber loading from 10 % to 30 %. Further, the composites treated with PP-g-MA exhibited improved mechanical properties which confirmed efficient fiber-matrix adhesion. DMT analysis showed that the PP composites made of 30 % wheat straw containing 3 % PP-g-MA showed the highest E' and lowest tan δ than the untreated ones. Also, the thermal stability of wheat straw was lower than PP and as filler content in the composites increased, the thermal stability decreased and the ash content increased. [ABSTRACT FROM AUTHOR]

simple method to decorate carbon nanotubes (CNTs) with silver nanoparticles was developed to enhance the electrical conductivity of CNTs. The acid-treated CNTs were suspended in the silver acetate solution, ammonia solution was then added, and the CNTs decorated with silver nanoparticles (Ag@CNTs) were produced. The Ag@CNTs were dispersed in polyvinyl alcohol (PVA) to fabricate electrically conducting polymer composites. The electrical, thermal and mechanical properties of the composites were measured. The electrical conductivity of the composites containing 0.8 % (o.w.f.) Ag@CNTs was more than four orders of magnitude higher than those of pristine and functionalized CNTs respectively, which confirmed the effectiveness of the Ag@CNTs as conducting filler. However, the improved electrical conductivity led to somewhat decrease of mechanical properties of PVA/Ag@CNTs composites. [ABSTRACT FROM AUTHOR]

There have been many interests in using natural fibers as substitutes for glass fibers to prepare fiber reinforced composites. Flax fibers, due to their specific strength, have been a hot issue in this field. The focus of this research work is to manufacture flax fiber reinforced low melting point PET composites directly from nonwoven mats. No consolidation methods are applied to the carded nonwoven mats before the hot-press molding. The effects of operating parameters like carding method, molding temperature, molding time, etc. on the mechanical properties of composites have been investigated. Results show it is a facile and cost-saving method to produce composites specifically in the application areas like automobile interior ornament and decoration materials, etc. [ABSTRACT FROM AUTHOR]