Higher Tensile Modulus Research Articles

Fabrication, Mechanical Characterization and Interfacial Properties of Okra Fiber Reinforced Polypropylene Composites

In this study, an attempt has been taken to manufacture okra fiber (OF) composites with varying the fiber content ranging from 25-65% on total weight of the composites and polypropylene (PP) was preferred as matrix material. To fabricate the composites untreated and mercerized fibers were selected. A systematic study was done to observe the mechanical behaviors of the composites such as tensile, impact and bending properties. It was found that treated (mercerized) fiber composites exhibited improved mechanical properties than that of untreated fiber composites. Maximum tensile strength (TS) and bending strength (BS) was examined 38.5 MPa and 72.5 MPa respectively, whereas the highest tensile modulus (TM) and bending modulus (BM) was observed 675 MPa and 5.4 GPa respectively. The optimum impact strength (IS) and hardness value was found to be 22.87 KJ/m2 and 97 (Shore-A) for mercerized fiber composites containing 45% fiber. The composite samples were exposed to different intensities of γ radiation (2.5 kGy–10.0 kGy) and found significant improvement in the mechanical properties up to 5.0 kGy dose. Water absorption, degradation properties due to heat and soil medium of the composites were also performed. The interfacial property was examined by Microscopic Projector and Scanning Electron Microscope (SEM) and found that the interfacial bonding between matrix material and fiber was enhanced due to the treatment of fibers which authenticate the found mechanical characteristics of the composites.

Ultrahigh‐Strength Ultrahigh Molecular Weight Polyethylene (UHMWPE)‐Based Fiber Electrode for High Performance Flexible Supercapacitors

AbstractFlexible fiber‐based supercapacitor (FSC) with excellent electrochemical performance and high tensile strength and modulus is strongly desired for some special circumstances, such as load‐bearing, abrasion resistant, and anticutting fabrics. Here, a series of ultrahigh‐strength fiber electrodes are prepared for flexible FSCs based on ultrahigh molecular weight polyethylene fibers, on which the polydopamine, Ag, and poly (3,4‐ethylene dioxythiophene): poly(styrenesulfonate) are deposited in sequence. The modified fiber‐based electrode exhibits superhigh strength up to 3.72 GPa, which is the highest among fiber‐based electrodes reported to date. In addition, FSCs fabricated with the optimized fiber electrode shows a specific areal capacity as high as 563 mF cm−2 at 0.17 mA cm−2, which corresponds to a high areal energy density of ≈50.1 µWh cm−2 at a power density of ≈124 µW cm−2. The specific areal capacity only decrease 8% after 1000 times bending test, indicating the outstanding bending performance of this composite fiber electrode. Furthermore, several FSCs can be connected in series or in parallel to get higher working voltage or higher capacity respectively, which demonstrates its potential for broad applications in flexible devices.

Investigation the influences of geotextile on reducing the thermal reflective cracking using XFEM

A 3D extended finite element model (XFEM) was constructed to investigate the thermal reflective cracking propagation and anti-cracking characteristic of geotextile. Influence factors of tensile modulus and placement location of geotextile were analysed. A temperature cycling test in the material test system was utilised in this work to validate the XFEM. Thermal simulations were performed considering the influences of solar radiation, air convection and air radiation. It has been found that crack initiated and propagated as temperature declining in earlier cycle, and crack length being fixed because of no more severe temperature variation based on maximum principal stress criterion. Geotextile with high tensile modulus had a significant influence on reducing the crack propagation compared with low tensile modulus geotextile or unreinforced situation. Geotextile placing at the bottom of asphalt surface had the best crack resistance influence, and geotextile placed at one-fourth depth from asphalt course bottom was more efficient than placed at other locations in terms of anti-crack propagation.

Size Effect of Defects on the Mechanical Properties of Graphene

Graphene, a two-dimensional material, has been studied and utilized for its excellent material properties. In reality, achieving a pure single-crystalline structure in graphene is difficult, so usually graphene may have various types of defects in it. Vacancies, Stone-Wales defects, and grain boundaries can drastically change the material properties of graphene. Graphene with vacancy defects has been of interest because it is a two-dimensional analogy of three-dimensional porous materials. It has efficient material properties, and can function as a part of modern devices. The mechanical properties have been studied by using molecular dynamics for either a single vacancy defect with various sizes or multiple vacancy defects with same defect ratios. However, it is not clear which one has more influence on the mechanical properties between the size of the defects and the defect ratio. Therefore, we investigated the hole-size effect on the mechanical properties of single-crystalline graphene at various defect ratios. A void defect with large size can have a rather high tensile modulus with a low fracture strain compared to a void defect with small size. We numerically found that the tensile properties of scattered single vacancies is similar to that of amorphous graphene. We suspect that this is due to the local orbital change of the carbon atoms near the boundary of the void defects, so-called the interfacial phase.

UV-Blocking Synthetic Biopolymer from Biomass-Based Bifuran Diester and Ethylene Glycol.

A furan-based synthetic biopolymer composed of a bifuran monomer and ethylene glycol was synthesized through melt polycondensation, and the resulting polyester was found to have promising thermal and mechanical properties. The bifuran monomer, dimethyl 2,2′-bifuran-5,5′-dicarboxylate, was prepared using a palladium-catalyzed, phosphine ligand-free direct coupling protocol. A titanium-catalyzed polycondensation procedure was found effective at polymerizing the bifuran monomer with ethylene glycol. The prepared bifuran polyester exhibited several intriguing properties including high tensile modulus. In addition, the bifuran monomer furnished the polyester with a relatively high glass transition temperature. Films prepared from the new polyester also had excellent oxygen and water barrier properties, which were found to be superior to those of poly(ethylene terephthalate). Moreover, the novel polyester also has good ultraviolet radiation blocking properties.

Ultrastiff, Thermoresponsive Nanocomposite Hydrogels Composed of Ternary Polymer–Clay–Silica Networks

Anomalous increases in mechanical stiffness and tensile strength were achieved in a poly(N-isopropylacrylamide) nanocomposite gel (NC gel) by incorporating a small amount of silica through the sol–gel reaction of tetraethyl orthosilicate in the polymer–clay network. The resulting NC-Si gels, with ternary polymer–clay–silica structures, exhibited very high tensile moduli (∼3500 kPa) and strengths (∼1700 kPa), as well as well-defined thermoresponsive swelling/deswelling behavior, through the incorporation of 0.2–2.5 wt % silica (relative to the gel weight). The reinforcing efficiency of in situ formed silica in the NC gel is more than 50 times that of clay, while the incorporation of preformed silica nanoparticles led to no observable changes in mechanical properties. The controllable range of hydrogel tensile mechanical properties was significantly extended by the preparation of NC-Si gels. The ternary polymer–clay–silica network structure was proposed on the basis of optical transmittance, TEM, EDS, and 2...

Preparation and characterization of near-stoichiometric silicon carbon fibres.

Near-stoichiometric SiC fibres (CVC-S fibres) were successfully prepared by pyrolysing chemical-vapour-cured polycarbosilane fibres under hydrogen and subsequent heat treatment in inert atmosphere at 1500 °C. The composition and properties of the obtained fibres were determined by Auger electron spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, tensile strength testing, and X-ray diffraction analysis. The results reveal that the CVC-S fibres with C/Si of 1.06 and O of 1.11 wt% have high tensile strength (2.6 GPa), high tensile modulus (321 GPa), and a highly crystalline structure (crystallite size, ∼14 nm.) In addition, the high-temperature behaviour of the CVC-S fibre was also investigated via heat treatment in argon and air at different temperatures. In particular, the fibres retain ∼2.2 GPa of their original strength after heating at 1600 °C for 1 h under argon. When argon was replaced by air, the tensile strength of the fibres could still be maintained at ∼1.1 GPa after annealing at 1400 °C. The more economical and practical approach along with the excellent performance of the obtained fibres render the CVC-S fibres promising materials for high-temperature applications.

Influence of the Woven Structure on the Initial Fracture Behavior of Roving Glass Fabric Reinforced Composites

In this paper, investigation on the initial fracture behavior was carried out on roving glass woven fabric reinforced composites which were manufactured by hand lay-up method. Two kinds of roving glass woven fabrics of different FAW (Fabric Area Weight) and crimp ratio, Type A of 570 g/m2 and Type B of 800 g/m2, were adopted as reinforcement in this study. Tensile test was conducted and tensile properties were discussed on specimens of 6 degrees 0°/5°/10°/80°/85°/90°. The initial fracture behavior was observed on 0 degree and 90 degree and the fracture mechanism was compared and discussed among 5°/10°/80°/85°. The results showed that Type B has higher tensile modulus and tensile strength than that of Type A. And different initial fracture behaviors between two kinds of materials was observed and analyzed, which indicated that the crimp ratio plays an important role of woven fabric reinforced composites in fracture mechanism.

Physical Properties of Novel Kenaf Short Fiber Reinforced Bulk Molding Compounds (BMC) For Compression Moulding

The recent trends have seen natural fiber reinforced composites (NFRC) garnering a large following due to their low density, commercially viability, low health risk, high tensile strength and modulus and renewability. Many have attempted toapplythe NFRC in automotive and other practical applications. This paper discusses the physical properties such as the Gel time, specific gravity, and also the volumetric shrinkage of a recently developed kenaf reinforced bulk molding compound with unsaturated polyester matrix. It has been found that the specific gravity declines as the fiber loading increases all fiber length. The highest was the BMC reinforced with 9 mm kenaf short fiber with 1.81. It has also been found that the Gel time increases proportionally to the loading of the fiber due to the fibers absorbing the heat released during bond formation. And a compression molding technique was used to study the shrinkage of the respective materials. It can be concluded that both fiber loading and fiber length plays a significant part in the physical properties of the composites

Effect of fiber volume fraction on the thermal and mechanical behavior of polylactide‐based composites incorporating bamboo fibers

ABSTRACTBiodegradable composites reinforced with natural fibers are emerging as advanced materials in structural applications. In this work, green biocomposites are fabricated using hot pressing molding technique, polylactic acid selected as a matrix. The samples are prepared with different fiber volume fractions (30%, 40%, and 50%). Tensile tests are conducted on the specimens to investigate the composite mechanical behavior, and the influences of fiber content on the morphological and thermomechanical properties are evaluated using scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. There are higher tensile modulus and lower elongation at break for composites with increasing fiber content, respectively. Much variation in the tensile strength is observed when the fiber content is varied, which could be attributed to fiber agglomerations that affect the dispersion of fibers in the matrix, as evidenced by fracture surfaces. Thermal tests demonstrate that the increment of fiber content enhances the glass transition temperature and crystallization temperature of composites. Besides, a comparative analysis of the composites is performed, and the properties of the treated fiber composites are found to be improved compared to those from untreated fibers. Detailed analysis confirms the possibility of the addition of bamboo fibers to a biodegradable matrix for a specific application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46148.

Properties of HDPE/Biodegradable Polymer Blends Using Modified Rubber

Biodegradable blends consisting of poly(lactic acid) (PLA), poly(butylene adipate-coterephthalate) (PBAT) and epoxidized natural rubber (ENR) were blended in two proportions at PLA/PBAT/ENR ratios of 70/10/20 and 70/20/10. Then, blends these biodegradable polymers (PLA/PBAT/ENR) with HDPE at various ratios of 20/80, 10/90 and 5/95 wt%, the mechanical and morphological properties were investigated. Tensile tests of PLA/PBAT/ENR blends revealed high tensile strength and modulus but low elongation compared with HDPE. The tensile strength, elongation at break and impact strength of HDPE/biodegradable polymer blends decreased with increasing biodegradable polymer contents. Morphological properties of HDPE/biodegradable polymer blends were investigated by scanning electron microscope, which showed smoother surface of HDPE/biodegradable (70/10/20) than those of (70/20/10) polymer blends according to ENR compatibilization effect.

Synthesis and Study of Organosoluble Aromatic Cardo (co)polyamides and Their Application in the Optical Fiber Primary Coating Technology

A series of organosoluble aromatic cardo copolyamides (PA) with chlorine and carboxylic side groups has been synthesised by low‐temperature polycondensation in N‐methyl‐2‐pyrrolidone (N‐MP) solution and their properties have been estimated. The obtained polymers are differed in high molar masses (ηinh = 0.7 ÷ 1.8 dL/g) and demonstrate the following thermal characteristics: 300 °C < Tg < 390 °C; 425 °C < T10% < 510 °C (in air). PA films are characterized by high tensile strength (100 ÷ 230 MPa) and modulus (1.6 ÷ 2.3 GPa). It was stated the obtained PAs form the high quality coatings with good adhesion to the optical fiber surface without any additional coupling agent. The fibers with elaborated PA coatings demonstrate high thermal stability. The study of the optical fiber bending strength before and after thermal tests has shown that this parameter decreases by 10% only after prolonged exposure to high temperatures, namely, 72 h at 200–300 °C. Some samples withstand more than 1 h treatment at 350 °C without any changes of the optical fiber bending strength.

Theoretical realization of Mo2P; a novel stable 2D material with superionic conductivity and attractive optical properties

Mo2P as a new member of the advancing two-dimensional (2D) materials family has been theoretically identified in this study. We conducted extensive density functional theory calculations to explore the crystal structure, dynamical stability, mechanical response, electronic structure and optical properties. Mo2P was found to be metallic with the Fermi energy locating at the d bands of transition metal Mo. A high reflectivity of ∼100% at low energies less than 1eV was observed, introducing Mo2P as a potential candidate for photonic and optoelectronic applications such as transmitting electromagnetic waves devices. Our calculations confirm that the novel 2D structure is dynamically stable and can withstand at high temperatures including 1000K. Mo2P was found to yield high tensile strength and elastic modulus of 12GPanm and 56GPanm, respectively. We particularly evaluated the application of Mo2P as an anode material for Li and Na-ion rechargeable batteries. The open-circuit voltages of 0.88–1.06V and 0.94–0.09V were predicted for Li and Na ions storages, respectively, which are desirable for commercial anodic materials. Interestingly, our calculations predict remarkably low diffusion energy barriers of 50meV and 17meV for Li and Na adatoms, respectively, promising to achieve ultrafast charging/discharging. The findings provided by this study can motivate further experimental and theoretical studies to probe new 2D crystals made from phosphor and transition metals with 2H and 1T atomic structures.

Crack Analysis of Fixed Support Fibre Glass Composite Beam Based on Natural Frequencies

A Fibre reinforced composites (FRCs) is a composite material made by plastic matrix and reinforced with thin fibres having high tensile strength and high flexural modulus. It is also known as fibre reinforced polymer (FRP) or glass reinforced plastic (GRP). The typical applications of FRCs include marine, aircraft, automotive industries, medical applications, building constructions, sports equipment and many industrial products. In this study specifically E-Glass epoxy resin composite beam is selected because of its high strength, high rigidity, less failure possibility, low cost and easy availability. This study aims to describe the presence of crack in fibre glass composite beam. The crack analysis is to be performed in order to analyze the crack before the failure, which influences characteristics like modes of vibration and natural frequencies. A numerical study is conducted to investigate the free vibration response using finite element method. To understand the phenomenon of crack generation and its approximate location, FFT analysis is to be done along with its validation on FEA.

Properties of grafted wood flour filled poly (lactic acid) composites by reactive extrusion

Composites of poly(lactic acid) with wood flour which was grafted by melt extruding with methyl acrylate in the presence of benzoyl peroxide (BPO) were investigated. The modification of filler (WF-g-PMA) was carried out to enhance the filler-matrix interactions, while the treated component was characterized by infrared spectrum. Properties of binary (PLA/WF, PLA/WF-g-MA) composites were analyzed as a function of the grafting monomer amount by scanning electron microscopy, differential scanning calorimeter, thermogravimetric analysis, water absorption and mechanical tests. Compared with the untreated system (PLA/WF), all treated composites showed higher interfacial compatibility as a result of chemical bonding between WF and grated monomer. All composites showed higher tensile modulus and lower strength and elongation at break as compared to pure PLA; grafting modification with methyl acrylate led to an increased stiffness and decreased water absorption of the composites because of an enhanced filler-matrix interfacial compatibility.

Metallic-like thermal conductivity in a lightweight insulator: Solid-state processed Ultra High Molecular Weight Polyethylene tapes and films

Ultra High Molecular Weight Polyethylene with a reduced number of entanglements can be stretched in the solid state both uni- or biaxially to produce highly oriented tapes and films. The chain orientation, in combination with the reduced number of chain ends, is responsible for the high tensile modulus and tensile strength of the drawn materials, and, as we report here, also for the high thermal conductivity achieved through lattice movements. A property such as thermal conductivity in an electrical insulator makes UHMWPE tapes and films of great applicative interest. In-plane laser-flash thermal analysis has been applied to measure the thermal diffusivity of samples of different molecular weights stretched both uni- and biaxially, and a strong correlation has been found between the drawing ratio and the resulting in-plane thermal conductivity. Values of at least 40 W/m K have been achieved for UHMWPE having Mw comprised between 2 and 10 million, while higher values of 65 W/m K are observed for the higher Mw samples having relatively lesser number of chain ends. Surprisingly the biaxially stretched samples also show in-plane conductivity, with the highest value reaching 18 W/m K, comparable to stainless steel.

Composite coatings of polyamide/graphene: microstructure, mechanical, thermal, and barrier properties

This effort reports on novel fluorinated polyamide (FPA) and polyamide 1010 (PA1010)-based blends and graphene reinforced nanocomposite. PA1010/FPA (80:20) blend was opted as matrix material on the basis of molecular weight, thermal, and shear stress performance. Graphene was obtained through in situ chemical method of graphene oxide reduction. PA1010/FPA/Graphene nanocomposites was developed using various graphene loadings (up to 5 wt.%). Thin film coatings were prepared on glass substrate. Consequently, the PA1010/FPA/Graphene attained regular spongy morphological pattern. PA1010/FPA/Graphene 3 also showed improved T0 and Tmax of 534 and 591 °C relative to the neat blend (T10 423 °C; Tmax 551 °C). Limiting oxygen index measurement indicated better non-flammability of PA1010/FPA/Graphene 1–3 nanocomposite series (57–60%) relative to the blend series (28–31%). UL94 tests also showed V-0 rating for nanocomposites. Furthermore, PA1010/FPA/Graphene 3 nanocomposite revealed significantly high tensile strength (62 MPa), flexural modulus (1690 MPa), and adhesive properties to be utilized as coating materials. The nanocomposite coatings also displayed outstanding barrier properties against O2 and H2O compared with neat blends.

Mechanical and Thermal Properties of Kenaf Fiber Reinforced Polypropylene/Magnesium Hydroxide Composites

This paper presents a study of the mechanical and thermal properties of kenaf fiber (KF) reinforced polypropylene (PP)/magnesium hydroxide (MH) composites. Pure PP samples show low tensile, flexural and flame retardant properties. It was found that KF and MH filler insertion improved the properties of PP composites. The incremental addition of KF fiber between 0 and 20 weight percent in composites results in higher tensile modulus and decomposed mass loss at onset temperature, but lower tensile strength, elongation, flexural strength and onset temperature. Addition of 25 wt% KF produces slightly higher flexural strength. Increasing the volume of MH filler in the composites caused lower strength, tensile modulus and elongation, but higher onset temperature and 2ndpeak temperature in thermogravimetric analysis (TGA) testing. Increasing the KF content in the PP matrix resulted in lower mass residue. Increasing the KF content in composites containing MH increased the mass residue at the end of the testing.

Sensor yarns for real-time in situ detection of damage behavior for the purpose of structural health monitoring of textile-reinforced thermoset composites: development of a continuous wet-chemical silvering process for high-performance filament yarn

High-performance textile yarns such as glass filament (GF) yarn will be used as the base material for the development of sensor yarns because glass filament yarns offer both high tensile strengths and moduli of elasticity, as well as high melting temperatures and elongation. A new continuous wet-chemical metallization process has been developed for GF yarns on a laboratory scale to achieve special properties such as electrical conductivity. The aim of the work is to develop a continuous wet-chemical silver plating process for the GF-filament yarn in order to achieve electrical conductivity on the GF-surface. The process was carried out continuously in order to metallize the GF, which is sensitive to the shear force. A homogeneous, completely covered and adhered silver layer on the GF yarn surfaces was obtained by the application of this technology. The surface morphology was been determined by light and scanning electron microscopy to assess the silver layer properties such as structure, homogeneity, and cracking. The chemical structure of the surfaces was analyzed by means of energy dispersive x-ray spectroscopy. For structural analysis, GF yarns were investigated using a Fourier transform infrared spectrometer. The dispersive and polar component of the surface energy of the sized and silvered GF yarn was measured by using a single fiber Tensiometer K100. The silver layer thickness and the silver content were determined after the metallization. Textile physical tests of the tensile strength, elasticity modulus, elongation at break, and yarn fineness of the single GF yarns as well as GF bundle were carried out.

Production of Tensioner Pulley from Nylon-Glass Fiber Composites

This paper shows the feasibility of replacing the SPCC steel with glass fiber reinforced Nylon composites for the manufacturing of tensioner pulley. Three series of Nylon (Nylon 66, Nylon 46 and Nylon 46 with PTFE) reinforced with 30wt% of glass fiber were investigated. Finite Element Analysis (FEA) was carried out to simulate the stress distribution and to predict the maximum stress located on the pulley component. It was found that all Nylon composites had higher tensile modulus than SPCC steel, while the SPCC steel exhibited higher tensile strength. FEA demonstrated that the maximum stress on Nylon composite pulley was lower than the SPCC steel pulley, however these stresses were higher than yield stress of materials. The addition of supporting rib can reduce the stress concentration to lower the yield stress of materials. Finally the performance of Nylon composite pulley was considered. Pulley with plain-surface bearing was meet the criteria for endurance test, however, the interfacial adhesion between bearing and Nylon composite pulley can be improved by glued and gouged surface. According to the experimental results, glass fiber reinforced Nylon composites can be the representative materials of replacing SPCC steel for tensioner pulley.