bluuebunny/crossref_metadata_2025 huggingface dataset:
The Characterization of Biodegradable Polybutylene Succinate/ Starch Blends Using HDPE-g-Acrylic Acid as a Compatibilizer
Authors: Lai S.-M. , Wu C.-S. , Liao H.-T
Published: September 2018

The properties of polybutylene succinate (PBSU)/starch blends containing 5 phr of compatibilizer, HDPE-g-acrylic acid, are discussed. X-ray diffractograms indicated some disruption of the crystal structure of PBSU with the addition of starch. The melting temperature decreased slightly with increasing amounts of starch. The added starch tended to disrupt the inter-molecular hydrogen bonding interactions between the PBSU chains in the matrix. For blends containing a certain amount of starch, the thermal stability decreased due to a relatively low heat stability of starch. As for mechanical properties, a slight increase in tensile strength was observed when the compatibilizer was incorporated in the blends. Enhanced interaction was deduced from SEM observation. Surface erosion, seen in the optical micrographs, was accompanied by a visible growth of microorganisms particularly at high concentrations of starch. The rate of biodegradation was assessed based on the decrease in tensile strength during 4 weeks of soil burial. The weight loss increased with increasing treatment times and with starch content during extended soil burial.
Preparation and Properties of Asphalts Modified with SBS/Organobentonite Blends
Authors: Wang Yun-Pu , Liu Dong-Jie , Li Yu-Feng , Wang You-Peng , Gao Jing-Min
Published: September 2018

The properties of asphalt that had been modified by adding styrene butadiene styrene block copolymers (SBS) and organobentonite clay were investigated. In asphalt mixtures, additives can be bonded to other constituents by using silane coupling agents (SCA). This improves the high-temperature storage stability, rheological properties and after-ageing properties significantly in comparison with pure SBS modified asphalts.

The improvement in high-temperature storage stability could be attributed to the organobentonite and SCA decreasing the difference in densities between SBS and asphalt. The organobentonite and SCA contents affected the rheological and low-temperature physical properties. The optimum amount of organobentonite was 2% and of SCA was 1%. These modifications also improved the after-ageing properties of the modified asphalts to some extent.
Prediction and Detection of Failures in Laminated Composite Materials Using Neural Networks - A Review
Authors: Addin A.O. , Sapuan S.M. , Mahdi E. , Othman M.
Published: September 2018

Reliable failure detection and prediction in laminated composite materials are critical for the utilization of these materials. Many quantitative techniques have been successfully researched and implemented for failure detection and prediction. Most of them are based on non-destructive methods for data collection and are quantified by using neural networks. In this paper a review of the subject is presented. The non-destructive techniques considered are limited to natural frequencies, electric conductivity, and lamb waves. The paper gives a brief introduction to each technique followed by summaries and evaluations for some relevant studies.
Fracture and Failure Behavior of Jute Fabric Reinforced Polypropylene. Effect of the Interface Modification
Authors: Acha B.A. , Karger-Kocsis J. , Reboredo M.M.
Published: September 2018

The tensile fracture and failure behavior of jute cloth (25 wt.%) reinforced polypropylene (PP) composites were studied as a function of the interface modification. The latter covered esterification of the jute and the use of lignin and maleated PP (PPMAN) as modifiers. The tensile and fracture mechanical characteristics of the composites were determined. Analysis of the emitted acoustic signals along with fractographic inspection served to trace the failure and damage development. The best property improvement was achieved by using PPMAN. The observed notch-sensitivity for the specimens was attributed to missing reinforcement homogeneity owing to the presence of insufficient jute cloth layers.
Nanocomposites Based on Thermoplastic Elastomeric Blends of Styrene Acrylonitrile and Ethylene Vinyl Acetate: Effect of Nature and Loading of Nanoclays and Dynamic Vulcanization
Authors: Patel Jaydeep , Maiti Madhuchhanda , Naskar Kinsuk , Bhowmick Anil K
Published: September 2018

A thermoplastic elastomer (TPE) is a polymeric material having rubber-like properties as well as thermoplastic-like processability. In the present work, TPE based on 30:70 w/w styrene acrylonitrile (SAN): ethylene vinyl acetate (EVA) blend was prepared. To improve the strength of the material, two types of nanoclay (Cloisite NA+ and Cloisite 10A) were added to the blend. The loading of the clays was also varied. The best mechanical properties were observed with Cloisite NA+ at 4 phr loading. The results were explained with the help of a knowledge of the morphology of the nanocomposites, as studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray dot-mapping. The dynamic mechanical properties and the diffusion behaviour of acetone through the resultant nanocomposites corroborated the observations on static mechanical properties. Dynamic vulcanization significantly improved the mechanical properties.
The Effect of Titania Content on the Refractive Index of Titania/ Polyimide Composite Films Prepared by the Sol-Gel Process SHORT COMMUNICATION
Authors: Naganuma T. , Kagawa Y.
Published: September 2018

Titania/polyimide composite films were fabricated from a polyamic acid of pyromellitic dianhydride (PMDA)/4,4'-oxydianiline (ODA) as a polyimide precursor and titanium n-butoxide by the sol-gel process. The ratio of titania weight to the combined weight of polyamic acid and titania, W, was up to 0.4, assuming complete conversion of titanum n-butoxide to titania. Refractive index dispersions and extinction coefficients of the prepared films were measured in the wavelength range from 400 to 800 nm by ellipsometer. Refractive index at a wavelength of 633 nm was increased from 1.67 for a pure polyimide to 1.77 for the titania/polyimide composite film at W=0.4.
Radiation-Induced Polymer Impregnated Sawdust-Clay-Cement Composite
Authors: Khoylou F.
Published: September 2018

The preparation of a new composite material has been achieved by the impregnation of sawdust-clay-cement mixtures with unsaturated polyester resins containing styrene and in one case, methyl methacrylate (MMA) monomers, followed by exposure to Co-60 gamma radiation to induce graft copolymerisation of the polyester/monomer mixture. The most suitable impregnation time and radiation dose have been determined for two polyester compositions. The high compression strength and bending modulus show that the final material produced was comparable in mechanical properties with high strength concrete. Hydration of the sawdust-clay-cement mixture after moulding for between 1 and 28 days decreased the porosity of the composite because the hydration products were deposited within the pore-spaces. The effect on the mechanical properties of the resin content, which in turn affects the porosity, was greater than that of the hardening of the cement component after hydration.
Conductive Polyaniline/Poly (Epichlorohydrin-co-Ethylene Oxide) Blends Prepared in Solution
Authors: Abbas Zaid K. , Barton Stephen J. , Foot Peter J.S. , Morgan Huda
Published: September 2018

Blends of poly (epichlorohydrin-co-ethylene oxide) rubber (Zeon Hydrin® C2000L) and polyaniline doped with dodecylbenzenesulfonic acid (PAni-DBSA), containing different weight fractions of PAni were cast from solution. Solubility parameters for both PAni-DBSA and Hydrin® were calculated and found to be comparable, favouring some degree of miscibility. Conductive transparent films were formed by casting onto PTFE substrates. Conductivities of cast films were found to be in the region of 10−7 S.cm−1 for 1% wt PAni-DBSA. Electrical conductivities increased as the wt % of PAni-DBSA was increased, showing a percolation threshold as low as 1% wt with highest conductivity achieved at 50%. Decomposition steps of conductive blends were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal stability of the blends was influenced by the ratio of PAni-DBSA to Hydrin®. The effect of composition on the glass transition in the blends was determined using thermomechanical analysis (TMA).
E-Glass/Polypropylene Pultruded Nanocomposite: Manufacture, Characterisation, Thermal and Mechanical Properties
Authors: Roy Samit , Hussain Farzana , Narasimhan K. , Vengadassalam K. , Lu H.
Published: September 2018

The manufacture of continuous fibre-reinforced nanocomposites, E-glass reinforced in a polypropylene (PP) matrix with and without nanoclay, by pultrusion is discussed. Thermal and mechanical characterisation of nanocomposites has been performed and compared with traditional microcomposites. Also, the nanocomposites were characterised by Transmission Electron Microscopy (TEM) and Optical Micrography (OPM). Compressive strength of pultruded polypropylene nanocomposites was improved by improving the yield strength of the surrounding matrix in shear and reducing fibre misalignment in the composite through optimisation of manufacturing process variables. TGA and DSC results show that nanoclay improves thermal stability without any deviation in glass transition temperature and melt temperature. Initially, polypropylene and nanoclay were melt intercalated using a single-screw extruder and the pultruded nanocomposite was fabricated using extruded pre-impregnated (pre-preg) tapes. Compression tests were performed as mandated by ASTM guidelines. OPM was used to examine the failure surfaces. TEM revealed an intercalated morphology. Significant improvements were achieved in compressive strength and compressive modulus with relatively low nanoclay loadings. Mechanical tests were performed for baseline pultruded PP nanocomposite with 0 wt% nanoclay and modified pultruded PP nanocomposite with 3 wt% nanoclay. The tests showed significant improvements in compressive strength (~122%) and shear strength (~60%) in modified pultruded PP nanocomposites in comparison with baseline properties. Uni-axial tensile tests showed a minor increase in tensile strength (~3.4%). Multi-scale simulations of nanoclay/polymer interface behaviour are currently in progress in order to understand the strength enhancement mechanism.
Rheological Properties of Aminosilane Surface Treated Short Glass Fibre Reinforced Polypropylenes. Part 1: Steady Shear and Oscillatory Flow Properties in Molten State
Authors: Nishitani Y. , Sekiguchi I. , Hausnerova B. , Zdrazilova N. , Kitano T.
Published: September 2018

The effect of surface treatment on the rheological properties of 20 and 40 wt.% short glass fibre reinforced polypropylenes (GF/PP) and of the same composites containing maleic anhydride modified polypropylene (GF/mPP/PP) were investigated. Glass fibres were surface-treated by aminosilane coupling agent (ASC, γ-aminopropyltriethoxysilane). Steady state shear and dynamic properties in the molten state were measured using a cone and plate type rotational viscometer.

Surface treatment increased the rheological properties of the molten composites. This trend was more pronounced for composites containing modified PP. In the case of the GF/PP materials the increase was monotonous for all measured functions, while in the case of the GF/mPP/PP ones, the parameters representing elasticity showed peaks at 0.5 wt.% ASC. The Cox-Merz empirical law was found to be applicable to untreated GF/PP and GF/mPP/PP composites at low shear rates (angular frequencies), where the materials showed Newtonian plateaux.

As for ASC surface treated materials, GF/mPP/PP followed the same trend. On the other hand, GF/PP exhibited a higher complex viscosity than the steady state shear one over the whole range of angular frequencies (shear rate) covered by the experiments. Surface treatment enhanced apparent yield stress, as did increasing the glass fibre content. The effect of the latter was more pronounced in the case of the GF/mPP/PP series. The viscosities of the re-mixed composites became lower than those of the original ones, and the difference between untreated and ASC treated systems was detectable only in the case of the complex viscosity of the GF/mPP/PP sample.
Influence of Flame Retardant and Glass Fibre on Non-Isothermal Crystallisation Behaviour of Pa66
Authors: Li Liping , Li Bin , Tang Fei
Published: September 2018

The authors studied the influence of melamine polyphosphate flame-retardant (MPP-FR) and glass fibre on the non-isothermal crystallisation behaviour of a polyamide (PA66) by differential scanning calorimetry (DSC). The glass fibre reinforced PA66 (PA66/GF) and its reinforced flame retarded equivalent (PA66/GF/FR) were prepared using a twin-screw extruder. The experimental results demonstrated that the MPP-FR increased the crystallisation rate and decreased the supercooling required for crystallising nucleation. The glass fibres increased the crystallisation rate and the amount of supercooling.

Avrami analysis showed that the non-isothermal crystallisation of PA66 and its composites followed the Avrami equation. The activation energy for the transport of macromolecular segments to the growing surface was calculated by using the Kissinger method based upon DSC data, and the calculated activation energies were 243.5 kJ·mol−1, 201.1 kJ·mol−1 and 305.9 kJ·mol−1 for PA66, PA66/GF and PA66/GF/FR, respectively. The activity of nucleation for GF and MPP-FR were 0.87 and 0.79 respectively, calculated by Dobreva's method. The results indicate that the MPP-FR has more effective ability to promote heterogeneous nucleation than GF.
Free Vibration Analysis and Optimal Design of a Cantilevered Adhesively Bonded Composite Tubular Single Lap Joint
Authors: Apalak M. Kemal , Yildirim Mustafa
Published: September 2018

This study reports the most effective design parameters for the three-dimensional free vibration and modal stress state of an adhesively bonded cantilevered composite tubular single lap joint. The effects of fibre angle, fibre volume fraction, overlap length, tube thicknesses and inner tube radius on the first ten natural frequencies and mode shapes of the adhesive tubular joint were investigated, using the back-propagation Artificial Neural Network (ANN) method. In order to train and test the proposed artificial neural network models used to predict the first ten natural frequencies, as well as the corresponding modal strain energies, a series of free vibration and stress analyses was carried out. The finite element method was used for random values of the design parameters, such as the fibre angle, the fibre volume fraction, the overlap length, the tube thicknesses and the inner tube radius. The ANN models indicated that increasing each of all the design variables resulted in increases in the first ten natural frequencies as well as in the modal strain energies, whereas increasing the inner tube thickness reduced the natural frequencies but increased the modal strain energies. The fibre angles above 20° and the inner tube radius were more effective design parameters than the overlap length and the outer tube thickness. The Genetic Algorithm indicated completely different values of the design parameters of an optimal joint based on three objective functions, in which i) the natural frequency only was maximised, ii) the modal strain energy was minimised and iii) the previous objective functions were balanced. Thus all design parameters were maximised as possible except the inner tube thickness, and the fibre volume fraction became optimal at 70%.
Bond Behaviour of Frp Reinforcing Bars in High-Strength Steel Fibre-Reinforced Concrete
Authors: Won Jong-Pil , Park Chan-Gi , Kim Hwang-Hee , Lee Sang-Woo , Won Cheol
Published: September 2018

Current design trends for structures require the increased use of high-strength concrete, which has a compressive strength of over 80 MPa. Its enhanced strength, however, leads to brittle failure problems, which have been resolved by adding steel fibres. Fibre-reinforced polymer (FRP) is actively being studied to resolve the corrosion problems encountered with steel reinforcing bars in concrete structures exposed to adverse environmental conditions. In this study, we experimentally evaluated the bond behaviour of FRP reinforcing bars in high-strength steel fibre-reinforced concrete. A high-strength concrete mix was created with a target strength of over 80 MPa, and steel fibre was added. The FRP reinforcing bars had an increased pullout load with a slow gradient, and the slope of the pullout load reduction curve remained small after the maximum pullout load was reached. In addition, the bond strength increased as steel fibre was added to the FRP reinforcing bar.
The Design and Manufacture of Advanced 3D Woven Hybrid Composite Materials
Authors: Quinn J.P. , McIlhagger A.T. , McIlhagger R. , Ridgeway K. , Ganeshmal M , King R.S. , Stewart G.
Published: September 2018

This paper describes a feasibility study to assess the viability and potential benefit of 3D woven textile reinforcements with metallic yarns integrated into the structure. It reports the results from a study of the manufacture and mechanical testing of hybrid 3D woven composite materials. The hybrid structures were manufactured using carbon fibre and aluminium wire, and subsequently impregnated with a two-part aerospace resin system. Details are given concerning the manufacturing issues with hybrid materials, and the results from mechanical testing of the first of these novel hybrid structures are examined. In addition there is a discussion of possible future developments in this area.

Some preliminary data within this paper was used in a presentation at TexComp-8 Nottingham, October 2006.
Ldpe/Agave Fibre Composites: Effect of Coupling Agent and Weld Line on Mechanical and Morphological Properties
Authors: Leduc Simon , Ureña José Ricardo Galindo , González-Núñez Rubén , Quirarte Juan Ramos , Riedl Bernard , Rodrigue Denis
Published: September 2018

Natural fibre composites based on Agave fibres (Agave tequilana) and low-density polyethylene (LDPE) were produced by injection moulding. Maleic anhydride grafted polyethylene (MAPE) was also added to study the effect of fibre content, coupling agent addition, and weld line presence on mechanical properties. It was found that tensile and flexural moduli increased with fibre concentration while they decreased for impact strength. In all cases, MAPE addition enhanced the effect up to an optimum content between 2 and 5% on a fibre weight basis. The presence of a weld line substantially reduced tensile properties and this effect could be interpreted in terms of molecular entanglement and orientation changes.
Influence of Adjustable Grafted Side Chains on the Non-Isothermal Crystallisation of a Ternary-Monomer Solid Phase Graft Copolymer of Polypropylene
Authors: Haoqun Hong , Hui He , Demin Jia , Ben Hua , Gengdong Lin
Published: September 2018

A solid phase graft copolymer with an adjustable structure was prepared by grafting maleic anhydride, methyl methacrylate and butyl acrylate onto polypropylene (PP). How the grafted side chains affected the crystallisation of the graft copolymer was studied by differential scanning calorimetry and polarised optical micrographs. Results show that the grafted side chains not only promoted heterogeneous nucleation but also hindered the whole crystal growth of the copolymers. The Jeziorny method and Mo method were successful in describing the non-isothermal crystallisation kinetics. The Jeziorny method showed that the Avrami exponent ranged from 2 to 3, indicating that the crystal tended to grow in a three-dimensional mode. The Mo method showed that the graft copolymer (known here as PPTM) needed a lower crystallisation rate than PP to attain the same crystallinity at unit time, due to the hetero-nucleation of the grafted side chains. Meanwhile, the hetero-nucleation of the grafted side chains caused a decrease in the crystallisation half-time and in the spherulite size of PPTM. Hindrance of the grafted side chains was shown by the incomplete crystallisation images and by the increase in the non-isothermal crystallisation activation energy of PPTM.
The Influence of Fe/Feo Mixture on the Molecular Fluctuation Networks of Polybutyleneterephthalate
Authors: Ozden S. , Borukayev T.A.
Published: September 2018

The failure mechanism of high-density polybutyleneterephthalate (PBT) was improved by the addition of highly dispersed Fe/FeO particles to the polymer. The impact strength of PBT was measured and the results were used to model the physical structure and failure mechanism of PBT. Fractal analysis was used to investigate the molecular changes caused by the presence of the modifier. The addition of the modifier decreased the free volume, increased the density of the fluctuation network of molecular chains, increased the interphases between crystalline and amorphous phases, and improved the packing of the molecules. The best results were obtained for the addition of 0.05% Fe/FeO.
Functional Polymer Nanocomposites
Authors: Faupel Franz , Zaporojtchenko Vladimir , Strunskus Thomas , Greve Henry , Schürmann Ulrich , Takele Haile , Hanisch Christian , Chakravadhanula Venkata Sai Kiran , Ni Na , Gerber Andreas , Quandt Eckhard , Podschun Rainer
Published: September 2018

While extensive research has been carried out in the field of structural polymer-based nanocomposites much less investigations have been concerned with polymer nanocomposites for functional applications. Among the functional nanomaterials, nanocomposites consisting of metal nanoparticles dispersed in a dielectric matrix are of particular interest due to their novel functional properties offering hosts of new applications. Here, polymers are attractive as matrix, and several approaches have been reported to incorporate metal nanoparticles into polymers. The present review is concerned with the preparation of polymer-based nanocomposites by vapor phase co-and tandem deposition and the resulting functional properties. The techniques involve evaporation and sputtering, respectively, of metallic and organic components and inter alia allow the preparation of composites which contain alloy clusters of well defined composition. Emphasis is placed on soft-magnetic high frequency materials with cut-off frequencies well above 1 GHz and on optical composites with tuned plasmon resonances suitable for ultra thin color filters, Bragg reflectors, and other devices. In addition, antibacterial coatings and sensors for organic vapors are addressed. The latter take advantage of the steep drop of the electrical resistivity at the percolation threshold. First results are also reported on the incorporation of photo-switchable molecules into nanocomposites near the percolation threshold. Moreover, a novel approach to produce magnetic nanorods is presented.
Polyhedral Oligomeric Silsesquioxane (POSS)-Modified Thermoplastic and Thermosetting Nanocomposites: A Review
Authors: Zhao Jianqing , Fu Yi , Liu Shumei
Published: September 2018

Polyhedral oligomeric silsesquioxane (POSS) nanoparticles have been successfully incorporated into thermoplastic and thermoset polymers via copolymerization, grafting, blending, surface bonding, or other transformations. A great promise in the development of a wide range of POSS-containing nanocomposites with diversely improved properties has been displayed. Thermal properties, viscoelastic properties, mechanical strengths, dielectric constants, surface hydrophobicity and flame-retardancy of the nanocomposites are easily varied to target properties by adjusting POSS structure, crosslink density, processing condition, etc. Investigations on the effects of POSS molecular geometry, composition, and concentration on physical and mechanical properties of resultant POSS-modified thermoplastic and thermosetting nanocomposites have been carefully reviewed in this article.
The Study on the Microstructures and High Performances of Melt Blending Polyurethane/Multiwalled Carbon Nanotubes Composites
Authors: Jiang Fengdan , Wu Sizhu , Wei Yongji , Zhang Liqun , Hu Guohua
Published: September 2018

A melt blending process was employed to prepare nanocomposites based on thermoplastic polyurethane (TPU) and multiwalled carbon nanotubes (MWNT). The content of MWNT filled in TPU was increased till 40 phr (parts per hundreds of rubber). The morphological, structural and mechanical properties of the resulting TPU nanocomposites were systematically investigated using scanning electron microscope (SEM), transmission electron microscope (TEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), dynamic mechanical thermal analysis (DMTA) and tensile testing. The results indicated that the unmodified MWNT were dispersed finely and uniformly in the TPU matrix beyond expectation, and the microphase separation structures of the TPU nanocomposites were slightly affected by the presence of MWNT. The mechanical properties of the TPU nanocomposites containing various amounts of MWNT at both room temperature and 120 °C were studied, which demonstrated that the modulus of TPU were greatly increased and the high temperature tensile strength of TPU was also prominently improved when MWNT content is higher. Moreover, the TPU nanocomposites exhibited improved thermal and electrical conductivities that might mean the TPU/MWNT nanocomposites have potential application as multifunctional materials.
Injection Moulding of Long-glass-fibre-reinforced Poly(ethylene Terephthalate): Influence of Processing Conditions on Flexural and Impact Strengths
Authors: Cilleruelo L. , Lafranche E. , Krawczak P. , Pardo P. , Lucas P.
Published: September 2018

This paper aims to identify the main parameters that influence the mechanical properties of long-glass-fibre-reinforced poly(ethylene terephtalate) parts in order to optimise the potential of these composites. A Taguchi design of experiments (DOE) was used for this purpose. The shape of the injection-moulded specimen was representative of the complexity of industrial parts (presence of sharp frontal and tangential steps). The mechanical properties (bending and Charpy impact tests) were measured at different locations in the part in order to highlight anisotropy. Variance analysis has shown that holding pressure, injection speed, and mould temperature are the most effective processing parameters. It has also shown that the optimised parameter sets that lead to the highest flexural strength on the one hand and the highest impact strength on the other hand are different, the polymer melt and mould temperatures being opposite. Finally, microstructure analysis has shown a fibre content gradient along the flow axis, which is greatly amplified by the presence of geometrical accidents (frontal and tangential steps) including the reorientation of fibres in the flow direction at the end of the parts.
Integration of Single-Walled Carbon Nanotubes into a Single Component Epoxy Resin and an Industrial Epoxy Resin System
Authors: Guan J.W. , Ashrafi B. , Martinez-Rubi Y. , Zhang Y. , Kingston Christopher T. , Johnston A. , Simard B.
Published: September 2018

Single-walled carbon nanotubes (SWCNT) exhibit amongst the best mechanical, thermal and electrical properties of any known material. With their very high aspect ratios, SWCNT are well-suited to making ultra-light multifunctional structural composites. In this work, covalent chemistry is used to integrate SWCNT into a single component epoxy resin (aerospace grade MY0510) as well as an industrialized epoxy resin system for sporting goods. In particular, reduced SWCNT react directly with epoxide groups to create direct connections to the resin backbone. As the reduction process naturally exfoliates the SWCNT bundles, excellent dispersion is readily obtained. Substantial mechanical property improvements of the modified resin and carbon fibre composites have been observed through well-controlled processing. Their mechanical properties, specifically impact resistance, compression after impact strength and fracture toughness of the modified resin and fibre composites are discussed.
Effect of the Periodic Distributions of Carbon Nanotube on Homogenized Effective Stiffness for Nanotube Reinforced Polymer Composites
Authors: Luo Dong-mei , Yang Hong , Zhou Ying-long , Zhu Wen-liang
Published: September 2018

By means of the virtual work theory and asymptotic expansion homogenization method (HM) with rigorous mathematically multi-scale perturbation theory, an improved homogeneous integral equation with simple and precise periodic boundary conditions is obtained to predict the homogenized effective stiffness of carbon nanotubes (CNTs) reinforced composites. Two and three dimensional CNTs-composites are analyzed by the proposed model. The present results with special ratio between longitudinal and transverse intervals for nanotubes (Tf/Hf) are compared well with those from empirical Halpin-Tsai and Mori-Tanaka approaches, which indicate that the present analysis has a relatively wide range to consider the effects of CNTs distribution on macroscopic mechanical properties of CNTs-composites. The results show that it is possible to design composites with high stiffness by considering a reasonable ratio between longitudinal and transverse intervals for discontinuous carbon nanotubes.
Preparation, Morphology and Properties of Nano-silica-alumina Co-doped Polyimide Three-layer Composite Films
Authors: Weng Ling , Liu Lizhu , Yang Liqian , Lin Jiaqi
Published: September 2018

A series of novel nano-silica-alumina co-doped polyimide (PI/nano-SiO2-Al2O3) three-layer composite films were prepared via combination of sol-gel process and ultrasonic-mechanical method. The effects of different inorganic phase contents and different Si/Al weight ratio on the properties of composites were investigation. The amination process of PI composite films was analyzed by Fourier transform infrared (FT-IR), and the inorganic phases’ morphology and its distribution in composite films were observed by scanning electron microscopy (SEM). Results indicated that a homogeneous dispersion of SiO2-Al2O3 particles was obtained when the inorganic phase content was below 6 wt.%. The thermal and mechanical properties of the three-layer composite films were measured and compared to the pure PI. It was also observed that when Si/Al weight ratio was 4:1 and the total inorganic phase weight content reached 4 wt.%, the composite film had the highest tensile strength, which was 30% higher than pure PI. Moreover, the electric breakdown strength of composite films was examined and its effective factors were analysed.
Effect of Arc Spraying Power on the Microstructure and Mechanical Properties of Pb-Sn Coating Deposited onto Carbon Fiber Reinforced Epoxy Composites
Authors: Wang Rongguo , Song Dajun , Liu Wenbo
Published: September 2018

In this study, Pb-Sn coatings were deposited on carbon fiber reinforced epoxy composites (CFRE composites) by means of plasma spraying as a permeation barrier in the applications of composite pressure vessels. The bonding strength of the Pb-Sn coatings-substrates with different plasma spraying power was tested on a RGD-5 tensile testing machine. The microstructures of the as-sprayed coatings have been examined by scanning electron microscopy (SEM), respectively. The result showed that the melting extent and the bond strength of the coatings were evidently improved with the increasing of spraying power. Observation of fracture surfaces shows that carbon fiber bundles can bond well with Pb-Sn coatings using 42 kW spraying power.
MD Simulation of Single-wall Carbon Nanotubes Employed as Container in Self-healing Materials
Authors: Liu Wenbo , Liu Yang , Wang Rongguo
Published: September 2018

Promising self-healing models enclosing styrene molecules into carbon nanotubes (CNTs) are proposed because of the unique hollow structure and predominant properties of CNTs. The nanotubes filled with healing agent are embedded in an epoxy matrix which contains catalyst particles capable of polymerizing the healing agent. When a micro crack forms in the matrix and ruptures the wall of single-wall nanotube (SWNT), the healing agent escapes from SWNT. The polymerization of healing agent is triggered once it contacts with the catalyst which is embedded in polymer matrix, and rebind the damaged site. Then the healing process is completed. One of the key points of this self-healing process is whether the healing agents can escape from the wall of SWNTs. In order to probe whether the feasibility of this system, models have been set up using molecular dynamics. The results of our simulations have shown that the healing agents can escape from the SWNTs in 5 ps, and the number of escaped styrene molecules depends on temperature and the density of the styrene molecules that filled into nanotube.
Buckling Behavior of Compression-loaded Advanced Grid Stiffened Composite Cylindrical Shells with Reinforced Cutouts
Authors: Jingxuan He , Mingfa Ren , Qizhong Huang , Shanshan Shi , Haoran Chen
Published: September 2018

In this paper, the buckling behavior of an advanced grid stiffened (AGS) composite cylindrical shell with a rectangular cutout is systematically investigated using the finite element method. The effects of reinforcement dimension of cutout on the non-linear response of the AGS composite cylindrical shell are described. The simulational results illustrate the complex non-linear response of a compression-loaded AGS composite cylindrical shell with an unreinforced cutout. In particular, a local buckling response occurs on the shell near the cutout which is caused by local skin deformations near the cutout. In general, reinforcement around a cutout in a compression-loaded AGS composite cylindrical shell can eliminate the local buckling response near the cutout and increase the global collapse load of the shell. However, simulational results illustrate that which reinforcement configurations can cause an unexpected increase in the magnitude of local deformations in the shell and cause a reduction in the global collapse load. A parameter study, including the orientation, thickness and size of cutout reinforcement in the AGS composite cylindrical shells, was conducted to improve the buckling response characteristics by determining a set of appropriate parameters.
Synthesis and Optoelectronic Properties of Novel Fluorene-based Copolymer for Red Light-emitting Diodes
Authors: Liu Zhitian , Hu Shuangqiang , yang Baolong , Wu Shuangquan , Wang Zixing , Zhang Chi , Hu Zhao
Published: September 2018

Novel copolymer derived from ethoxylated fluorene and 4,7-dithienyl-2,1,3-benzothiadiazole was successfully synthesized by palladium(0)-catalyzed Suziki coupling reactions. Optoelectronic properties of the copolymer were characterized by elemental analysis, NMR, UV absorption, photoluminescence (PL), and electroluminescence (EL). The films of the copolymer showed DBT-dominant red emissions. EL devices of the copolymer with a sandwich configuration of ITO/Polymer/Al displayed exclusive DBT emissions peaked at around 655 nm with the CIE coordinate of (0.67, 0.32). The polymer layer contained a conjugated copolymer that emits red light, trimethylolpropane trimethacrylate (TMPTMA), a low vapor pressure highly crosslinkable liquid, and lithium trifluoromethane sulfonate (LiTf) at a weight ratio of 20:40:1. A dynamic p-i-n junction was formed in thin films of light emitting polymers admixed with an ionically conductive medium. The PLEC device was turned on at relative low voltage 3.2 V and the brightness reached up to 1200 cd/m2 at 8 V.
Miscibility Investigation of Polycarbonate/Poly(arylether Ketone) Containing 1,4-Naphthalene Blends
Authors: Jiang Dong , Zhang Xiao-Ran , Ma Yan-Mei , Wang Zhong-Dong
Published: September 2018

The blends of polycarbonate (PC) and Poly (aryl ether ketone) containing 1,4-Naphthalene (NA-PAEK) were prepared by melt mixing in a Brabender-like apparatus. The specimens for measurements were made by compression molding under pressure and then were water-quenched at room temperature. The miscibility behavior of PC with NA-PAEK was examined using differential scanning calorimeter (DSC), scanning electron microscope (SEM), and density.
Preparation and Characterization of Poly(vinyl alcohol) Based Polyampholyte Membrane
Authors: Yu Lijuan , Meng Pingrui , Liu Shenghuan , Wang Xiaohui , Zhange Yanmei , Yu Haoqiang
Published: September 2018

Poly(vinyl alcohol)-g-poly(sodium allylsulfonate/acrylamide) (PVA-g-PSAS/AM) were synthesized by free radical polymerization. The PVA-g-PSAS/AM was degraded into poly(vinyl alcohol)-g-poly(sodium allylsulfonate/vinylamine) (PVA-g-PSAS/VA), which was PVA based polyampholyte (PBPA). The PBPA homogeneous membrane was characterized by FT-IR and SEM. The isoelectric point of PBPA was pH=6. Surface hydrophilicity of membranes was examined by automated contact angle measurement device. At 90 °C, the PBPA membrane showed a separation factor of 991 and a flux of 1140g/(m2·h) for 90 wt.% ethanol aqueous solution, while about 1491 and 970 g/(m2·h) for 90 wt.% isopropanol aqueous solution.
Simulation of a Flexible Polymer Confined between Two Parallel Surfaces
Authors: Li Hong , Qian Chang-Ji , Luo Meng-Bo
Published: September 2018

The conformational properties of a lattice self-avoiding polymer chain confined between two parallel impenetrable surfaces are simulated using Monte Carlo method. The statistical conformation size of polymer can be scaled by polymer chain length N and distance D between two surfaces. Chain is nearly free at large scaled distance Δ = D/Nνb with ν = 0.58 the scaling exponent and b = 1.42 mean bond length. Then it is squeezed along normal direction to surface at intermediate Δ, and at last it spreads out along surface at small Δ. For attractive surfaces, the chain is adsorbed at low temperature. For small D, we find an abnormal temperature dependence of chain size due to chain adsorbed to both surfaces simultaneously.
Sky-white Temperature/pH-sensitive Nanocomposite Microgels with Lower Size and Good Temperature-Sensitivity
Authors: Zhanga Qingsong , Li Xuewei , Chen Li
Published: September 2018

Adopting inorganic nanoclay (lithium magnesium silicate hydrate, LMSH) as physical crosslinking agent, a kind of novel temperature/pH double-sensitive nanocomposite microgels based on N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) were synthesized by using surfactant- free emulsion polymerization method. As a comparison, the traditional poly(NIPAM- co-AAc) microgel using N,N’-methylene-bis-acrylamide(MBA) as chemical crosslinker was prepared by same method. The chemical structure, shape, particle size and phase transition behavior of two kinds of microgels were confirmed by FTIR, XRD, SEM and DSC respectively. The results show that nanocomposite microgel was successful prepared under LMSH severing as physical crosslinker, and the prepared nanocomposite microgel dispersions present sky-blue state, different from oyster white of microgels crosslinked by MBA. The nanocomposite microgels crosslinked by LMSH present good spherical shape with hydrodynamic diameter less than 430 nm, which is much smaller than that of microgels crosslinked by MBA. In addition, the microgels crosslinked by LMSH show same good temperature-sensitivity. With increasing temperature from 20 to 50°, turbidity value increases, but lower than that of poly(NIPAM- co-AAc) microgel. Although a 7 mol.% ratio of AAc/NIPAM was used, the volume phase transition temperature of microgels still keeps at about 31° because of crosslinking structure of LMSH platelets.
Influence of Wear and Thermal Deformation on Machined PEEK Plastic Bush and Ti Crank Shaft
Authors: Koike Hitonobu , Kida Katsuyuki , Kanemasu Kenji , Santos Edson Costa , Rozwadowska Justyna , Uryu Megumi , Saruwatari Kenichi , Honda Takashi
Published: September 2018

In biped walking humanoid robot, toughness, durability and lightweight of joint parts are crucial factors due to parts’ constant exposure to high torque and loads. Such ergonomically challenging conditions create the need for joint systems comprising independent elements capable of keeping the component operable for long periods of time. In our work, we focused on wear and thermal deformation in two different grades of both poly-ether-ether-ketone (PEEK) and polyoxymethylene (POM) plastic bushes. The components used for investigation were bushes typically employed in speed reduction devices in joint models for biped walking humanoid robots. In such joint systems, plastic bushes are directly connected to a crankshaft, playing an important role in the robot's movement ability. In order to acquire the knowledge of how to build more efficient systems, the influence of the titanium crankshaft roughness on the frictional heat occurring between the shaft and the polymer bush as well as the input axis-output axis backlash require close examination. Based on Rolling Contact Fatigue test, we established the optimal machining conditions for the crank shafts and bushes. Also, superior to other tested polymers as far as glass transition temperature, wear toughness and thermal deformation are concerned, PEEK was found to be the best suiting material for our investigation.
Preparation of Monolithic Epoxy Resin-2-methylimidazole Porous Material for Adsorption/Electrosorption of Cu(II)
Authors: Wang Sui , Tao Yan-Ling , Zhang Rui-Feng
Published: September 2018

A new monolithic porous polymer was successfully prepared by using epoxy resin (bisphenol A diglycidyl ether, EP), 2-methylimidazole (2-MZ) as curing agent and polyethylene glycol (PEG-1540) as porogen. The reaction-induced phase separation of this system was successfully controlled by the weight ratio of EP-MZ-PEG (2.0:0.27:2.8) and other reaction conditions. The stepwise polymerization completed at 100 °C for 11 h without disturbance mode. The porogen was removed and the monolithic material with macro-through-pores was obtained. The synthesized polymer was characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The prepared material was found to be more efficient for Cu(II) adsorption as compare to Co(II) and Ni(II) in aqueous water. Furthermore, it was then used as the working electrode connected with a direct high-voltage power supply, and a platinum wire was used as counter electrode. The experimental conditions including the adsorption/desorption time, pH value, adsorption/electrosorption mode, and voltage were investigated and optimized, and a new method for Cu(II) removal was established. After adsorption at pH 6, the stirring speed of 400 rpm and the voltage below 120V for 1 h, the loaded Cu(II) was then eluted with 3 mL of 5% HNO3 solution for 10 min, and determined with inductively coupled plasma atom emission spectrometry (ICP-AES). The results showed that the adsorption rate was improved significantly by the electrically enhancing means, and the recovery was > 95%.
Sandwich Oil-absorptive Materials by a Semi-interpenetrating Resin Based on Poly(Butyl Methacrylate)-inter-Poly(Hydroxyethyl Methacrylate) in Poly(Ethylene Terephthalate) Nonwoven Cloth
Authors: Zhao Jian , Xiao Changfa , Xu Naiku , Feng Yan
Published: September 2018

A linear polymer was synthesized by suspension polymerization using butyl methacrylate (BMA) monomer and benzoyl peroxide (BPO) initiator. The resulting PBMA was interpenetrated into PHEMA crosslinking networks in N, N-dimethylacetamide (DMAc), using HEMA (hydroxyethyl methacrylate) as monomer, divinylbenzene (DVB) as crosslinking agent. After the reaction terminated, the mixed solution was made into sandwich oil-absorptive materials. The influence of the crosslinking agent and the mass ratio of PBMA and HEMA on the semi-interpenetrating (semi-IPN) structure and properties were analyzed by scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR) and dynamic mechanical thermal analyzer (DMA), while swelling behaviour and gel fraction were also researched. Crosslinking density measurements were also carried out and calculated by Flory-Rehner theory. The results showed that with an increase of DVB, the semi-IPN exhibited a higher gel fraction. The glass temperature (Tg) was evaluated by DMA. Oil-absorptive properties were tested according to ASTM (F726-81). The highest oil absorptivity of sandwich oil-absorptive materials was 15.5 g/g to 10% crude oil diluted with toluene when the DVB content was 2%wt. (based on HEMA monomer weight) with PBMA/HEMA (70/30 by weight).
The Bearing Strength of Pin Loaded Woven Composites Manufactured by Vacuum Assisted Resin Transfer Moulding and Hand Lay-Up Techniques
Authors: Sevkat Ercan , Brahimi Malek , Berri Sidi
Published: September 2018

The bearing strength of pin-loaded woven glass-fibre reinforced epoxy composites was investigated. To understand the effect of manufacturing methods on bearing strength of pin loaded composites, specimens manufactured using Vacuum Assisted Resin Transfer Moulding (VARTM) and hand lay-up methods were tested under tensile loading. In addition, the effects of geometrical parameters such as diameter of pin-hole (d), edge distance to pin hole diameter ratio (e/d) and, width to pin-hole diameter ratio (w/d) on the bearing strength of pin-loaded composites were studied. It was observed that specimens manufactured using VARTM method sustained more load compared to specimens manufactured using the hand lay-up method. Geometrical parameters were found to be very influential on the failure modes, bearing strength and magnitude of sustained loads.
Rheology, Flexure and Thermomechanical Characterization of Epoxy/CNF Nanocomposites: Effect of Dispersion Techniques
Authors: Hosur Mahesh , Barua Rajib , Zainuddina Shaik , Kumar Ashok , Trovillion Jonathan , Jeelani Shaik
Published: September 2018

The aim of this study is to investigate the optimum technique to disperse vapour grown carbon nanofibres (VGCNFs) in SC-1 epoxy uniformly and to evaluate their effect on the performance of SC-1 epoxy. In this study, ultrasonication and Thinky mixing methods were used either in isolation or in combination with 3-roll shear mixing. To achieve better dispersion, VGCNF was tested either by mixing with SC-1 resin directly or premixed with a solvent and then mixed with SC-1 resin after evaporating the solvent. Flexural tests were performed to evaluate mechanical performances, and the results exhibited 25.60% and 8.88% improvement of flexural strength and modulus, respectively over neat epoxy with only 0.2 wt.% loading. Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) indicated improvement in storage modulus, Tg, inflection temperature and residue content respectively over neat SC-1 epoxy. The high viscosity found by rheological analysis prevents their ubiquitous use in fibre reinforced composites. Thermal and mechanical properties at higher loading conditions were seen either to reduce or not significantly improve. These results indicate that the methods used for dispersion are suitable for low weight percent loading only.
In-vitro Response of Fibroblasts to Poly-L-lactide Composite Materials Containing Bovine Bone
Authors: He Zeqiang , Xiong Lizhi
Published: September 2018

This study aimed to investigate the interaction between fibroblastic cells and poly-L-lactide (PLLA) composite film containing bovine bone. The effects of PLLA/bovine bone on cell cytotoxicity, attachment, proliferation and differentiation of fibroblasts in-vitro were investigated. The results of cytotoxicity tests showed that cells cultured in extracts of PLLA/bovine bone and on the surface of composites showed normal growth and proliferation, and mineralization nodules were observed for fibroblasts cultured in PLLA/bovine bone extract at day 7 by using von Kossa staining and tetracycline staining. Compared with pure PLLA materials, bovine bone in the PLLA composites facilitated both adhesion and proliferation of rat fibroblasts on the PLLA/bovine bone composite film. In conclusion, these results suggest that the introduction of bovine bone may improve the cell response involved in the osteogenesis and thus may be beneficial to further modify poly-L-lactide as a better bone repairing material.