bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology and Electrical Conductivity of Polystyrene Sulfonic Acid-Graphite Nanosheet Composites
Authors: Yu Chaosheng , Li Bin
Published: September 2018

Polystyrene sulfonic acid (PSS) was prepared by sulfonating polystyrene (PS), obtained by emulsion polymerisation of styrene. Sulfonate groups were introduced on the phenyl groups of PS. Nanocomposites were prepared by dispersing nanoscale graphite (NanoG) in PSS aqueous solution with the aid of sonication, and casting the dispersion on a plastic film. The sulfonate anions on PS resulting from the ionisation of sulfonic acid groups facilitated the dispersal of NanoG carrying the positive charges. Scanning electron microscopy was used to characterise the morphologies of expanded graphite, NanoG and the nanocomposites, and the results showed that the graphite sheets varied in thickness from 40 to 70 nm. Transmission electron micrographs revealed that the PSS was intercalated into the sub-layers of nanoG homogeneously. The electrical conductivity of the nanocomposites reached 1.25 × 10−4S.cm−1 at a concentration of 0.2 vol.% and the electrical conduction phenomenon could be interpreted by classic percolation theory.
Flexural, Morphological and Thermal Properties of Poly(Lactic Acid)/ Organo-Montmorillonite Nanocomposites
Authors: Shyang Chow Wen , Kuen Lok Sook
Published: September 2018

Poly(lactic acid) (PLA)/organo-montmorillonite (OMMT) nanocomposites were prepared by using solution intercalation and melt intercalation methods. For solution intercalation method, toluene was used as solvent. For melt intercalation method, PLA/OMMT composites were prepared by using single-screw extruder. The flexural properties of PLA/OMMT composites have been studied by using three point bending tests. Comparisons between the flexural properties of PLA/OMMT nanocomposites prepared by both methods have been carried out. The microstructures of the PLA/OMMT nanocomposites were assessed by Field Emission Scanning Electron Microscopy (FESEM) and X-ray Diffraction (XRD) analysis. The thermal properties of PLA/OMMT nanocomposites have been characterized by using Differential Scanning Calorimeter (DSC). The flexural modulus of PLA/OMMT nanocomposites prepared by both solution intercalation and melt intercalation methods increased significantly by the addition of OMMT. For both methods, it was found that the optimum flexural properties of the PLA nanocomposites was achieved at 1 wt.% OMMT loading. The dispersion of OMMT in the PLA prepared by solution intercalation is better than that of melt intercalation method. This is attributed to the ease of intercalation of PLA chain into the OMMT layered silicate during the solution intercalation process. XRD results revealed that intercalation of OMMT layered silicate occurred in the PLA matrix.
Thermal Degradation of Elastomer Based Nanocomposites
Authors: Sadhu Susmita Dey , Rajeev R.S , Bhowmick Anil K.
Published: September 2018

The thermal degradation behavior of nanocomposites based on Styrene Butadiene Rubber (SBR), Polybutadiene Rubber (BR) and Acylonitrile Butadiene Rubber (NBR) with 19%, 34% and 50% acrylonitrile contents respectively, and sodium montmorillonite (designated as N) and octadecyl amine modified sodium montmorillonite (designated as OC) clays have been investigated. The thermal degradation pattern depends on the type of the matrix and the clay, polarity of rubber and loading of the filler. In general with the addition of the modified clay, there is a significant change in thermal stability. For example, there is a shift of Tmax, (the temperature at which rate of degradation is maximum) towards higher temperature and a decrease in the rate of degradation. The activation energy of degradation calculated from the Flynn-Wall-Ozawa method increases with the loading of the clay up to 4 parts. Filler loading beyond 4 parts in NBR with 34% acrylonitrile content causes a decrease in the Tmax value. The degradation rate for the same rubber in air is generally higher than that of the same in the nitrogen atmosphere. The results have been explained by using X-ray data.
Synthesis and Characterization of Bis(3-Vinyl Ester-2-Hydroxy Propane) Ether-Terminated Poly(Dimethylsiloxane) Toughened Epoxy-Clay Hybrid Nanocomposites
Authors: Chozhan Chinnakkannu Karikal , Alagar Muthukaruppan , Gnanasundaram Periyannan
Published: September 2018

A bis(3-vinyl ester-2-hydroxy propane) ether-terminated poly(dimethylsiloxane) (BVHPDMS), was synthesized from diglycidyl ether-terminated poly(dimethylsiloxane) and acrylic acid, and its structure was confirmed by FTIR, 1H and 13C NMR spectra. DGEBA epoxy resin was toughened with BVHPDMS using DDM as curing agent. The formation of BVHPDMS and its chemical reaction with epoxy resin was determined by FTIR. Epoxy and BVHPDMS toughened epoxy systems were further modified with organophilic montmorillonite clay. Organoclay filled hybrid BVHPDMS-epoxy resin castings were characterized for their thermal and mechanical properties. The introduction of 10% BVHPDMS into 5% organoclay filled epoxy resin improved the impact strength by 37.5% compared with unmodified epoxy resin system. The nanocomposites exhibited higher storage modulus (increased from 3060 to 3757 MPa) than unmodified epoxy resin. The presence of d001 reflections of the organophilic MMT clay in the XRD pattern of the cured product indicated the development of an intercalated clay structure. The heterogeneous morphologies of the BVHPDMS toughened epoxy and BVHPDMS toughened epoxy-clay hybrid systems were ascertained by SEM analysis.
Smart Polymeric Membranes: Self-Control of Pore Size Induced by Variations in pH
Authors: Estrada R. , Rodríguez R. , Castaño V.M.
Published: September 2018

A new kind of synthetic membrane was designed that has the ability to adjust the pore diameter in a wide range of sizes (from 0.8 to 22.3 μm) just by changing the pH of the aqueous media where they are immersed; in this way changing the pH can externally control the pore size of these membranes. A non-linear mathematical model, based on the overlap of charged particles, was developed to explain the behavior of the adjustment of pore size when the pH was varied. This model fits correctly the oscillatory behavior of the pore size as a function of pH. It has been reported by us that a similar behavior was found when the external temperature is changed. It is then possible to design smart membranes which respond to external parameters like temperature or pH.
Monitoring the Degree of Conversion of Cyclic Butylene Terephthalate Using Dielectric Analysis
Authors: Archer E. , McIlhagger A.T. , McIlhagger R. , Quinn J.P. , Mallon P. , Brádaigh C.Ó
Published: September 2018

Dielectric analysis (DEA) is the most common technique used to determine the state of cure in-process for many thermosetting resins systems such as epoxies, polyesters, polyurethanes, polyimides, silicones, bismaleimides, and phenolics. The objective of this work is to investigate the processing characteristics of cyclic butylene terephthalate (CBT) (supplied by Cyclics Corporation) which polymerises to form a thermoplastic, polybutylene terephthalate (PBT). This paper reports on the interim results of ongoing experimental investigations in which DEA is used to correlate the process cycle to composite structural features and mechanical performance of a complex composite part. Through adjustments in process cycle, the significant processing parameters have been identified which optimise the production of thermoplastic PBT composite parts. The recorded ion viscosity is used to indicate change in material viscosity, conversion rate and process time. These results have been analysed and presented as a guide for correct process control.
Water Absorption of Lignocellulosic Phenolic Composites
Authors: Lai Jau Choy , Ani Farid Nasir , Hassan Azman
Published: September 2018

The main objective of this study is to investigate the effect of filler content and filler size on the water absorption behaviour of phenolic composites filled with oil palm shell flour, rice husk flour and coconut shell flour. Lignocellulosic phenolic composites with three different filler sizes (<38 μm, 38–75 μm and 75–150 μm) and at three different filler loadings (30%, 45% and 55%) were prepared using a two-roll mill before being hot pressed. A pure Novolak sample was produced via the same method. The water absorption rate at different times, the diffusion coefficients, and the kinetic parameters k and n of the samples were calculated. All the samples exhibited a Fickian diffusion mechanism The water absorption rate and the quantity of water absorbed by the composites increased noticeably with increasing filler loading due to the hydrophilic nature of the lignocellulosic fillers. However, filler size does not significantly influence these properties.
Effect of Silica Sol-Modified Nano-Calcium Carbonate on Polyurethane(Urea) Dispersions and their Films
Authors: Dongya Yang , Fengxian Qiu
Published: September 2018

A series of novel aqueous polyurethane(urea) (PUU)/silica sol-modified nano-calcium carbonate (CaCO3) hybrid dispersions were prepared using an in situ dispersion technique. Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) examinations indicated that the modified nano-CaCO3 particles were mostly covered or partially inlaid on the surface of PUU particles or in the PUU matrix. PUU/modified nano-CaCO3 hybrid dispersions with lower modified nano-CaCO3 content (≤15%) exhibited low viscosity, small particle size and excellent stability. The rheological features revealed that this hybrid PUU dispersion belonged to pseudoplastic fluids. In addition, the incorporation of modified nano-CaCO3 could also enhance the mechanical properties of PUUs dramatically through the reinforcing effect of inorganic CaCO3. The better water resistance of PUU/modified nano-CaCO3 hybrid films proved that modified nano-CaCO3 could be used as effective modifiers for PUUs, and this method provided an efficient way to incorporate silica sol-modified nano-CaCO3 in the PUU matrix.
Polycarbonate-Carbon Nanofibers Composites: An Electron Spin Resonance Study
Authors: Chipara Mircea , Brittain William J. , Lau Kin-tak , Chipara Magdalena Dorina
Published: September 2018

Electron spin resonance investigations on polycarbonate loaded with various amounts of carbon nanofibers (ranging from 0% to 10%) are reported. A complex resonance spectrum was recorded. The spectrum was assigned to the convolution of resonance lines originating from the conducting electrons delocalized over the metallic domains of nanotubes, of free radicals generated during the polymer processing, and of catalyst's traces. The shape of resonance spectra originating from conducting electrons delocalized over the metallic domains of nanotubes was accurately fitted by a Lorentzian-like shape. The correlation between the measured DC resistivity of these samples and the relevant parameters of the resonance spectrum (line width, g-factor, and ratio between the amplitude of the absorption and dispersion components) was investigated. The saturation of the ESR line, at room temperature is reported.
Modeling the Effect of Strain Rate on the Mechanical Properties of HDPE/Clay Nanocomposite Foams
Authors: Jo Choonghee , Naguib Hani E.
Published: September 2018

A constitutive model considering the effect of strain rate on the mechanical properties of semicrystalline polymer/clay nanocomposite foams was studied. Also, the influence of crystallinity on the effect of strain rate was incorporated in the model. High density polyethylene (HDPE)/clay nanocomposite foam was manufactured by a batch foaming process. Intercalated clay structures in the nanocomposite were investigated by means of transmission electron microscope (TEM), and the crystallinity of the material was measured using differential scanning calorimeter (DSC). Also, foam morphologies were studied by using scanning electron microscope (SEM). The favorable effect of nanoclay on the foaming was increased as crystallinity decreases. Also, the influence of crystallinity on the foaming decreased at high clay contents. The tensile strength of the foams increased linearly to the logarithmic scale of strain rate. The Young's modulus of the foams was reinforced by increasing the crystallinity. However, the rate of increase in the modulus was blunted as strain rate increases. Also, the Young's modulus increased gradually with increasing the strain rate, but the rate of increase diminished as crystallinity increases. This combining effect of strain rate and crystallinity on the Young's modulus was modeled and a viscoelastic stress-strain behavior of the foam was also proposed. The proposed constitutive model was validated by experiments.
Preparation, Surface Morphology, and Thermal Stability of Polyamide 6 Composite Nanofibres by Electrospinning
Authors: Cai Yibing , Tao Dan , Wei Qufu , Gao Weidong
Published: September 2018

This work reports the preparation of the polyamide 6 (PA6)/organically modified montmorillonite (O-MMT) composite nanofibres by a facile compounding and electrospinning. The O-MMT was firstly dispersed in N,N-dimethyl formamide and then compounded with PA6 which was dissolved in formic acid. The composite solution was electrospun to form PA6/O-MMT composite nanofibres. The structures and morphology of the composite nanofibres were characterised by scanning electron microscopy (SEM), x-ray photoelectron spectra (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the O-MMT layers were well exfoliated within the composite nanofibres and were oriented along the fibre direction. The homogeneous and cylindrical composite nanofibres showed decreased fibre diameters owing to the enhanced conductivity of the polymer solution. The results characterised by thermogravimetric analyses (TGAs) showed that the loading of O-MMT improved the thermal stability of the composite nanofibres.
Compatibility Study of Polyamide 6/Polyvinylpyprrolidone Blend by Viscometry, Melting Point Depression and Morphological Analysis
Authors: Zhang Shi Jie , Huang Xian Bo , Zhang Ming Qiu , Zhao Jian Qing
Published: September 2018

Compatibility of the blends of polyamide 6 (PA6) and polyvinylpyrrolidone (PVP) was investigated by solution viscosity measurement, melting point depression and morphological analysis. The viscosity data were discussed by using ΔB and Δb criteria [Formula: see text], where b11 b22 and b12 characterize the interactions between polymer molecules (1-1, 2-2 and 1-2), respectively. ΔB and □b ≥ 0, miscible; ΔB and Δb < 0, immiscible). From melting point data of the PA6 component, the polymer-polymer interaction parameter χ12 = −0.069 was derived through the simplified Nishi-Wang equation. The results revealed that PA6 formed a partially compatible blend with PVP. This conclusion was further evidenced by morphological analysis.
Emulsion Polymerisation of St/BuA Stabilised with a PEG-containing Graft Copolymer
Authors: Guo Linlin , Gao Ge , Liu Xiaoli , Liu Fengqi
Published: September 2018

An amphiphilic graft copolymer comprising poly(ethylene oxide) (PEG) grafts was synthesised and characterised. It was used to stabilise the emulsion polymerisation of St or BuA. The effectiveness of this PEG-containing graft copolymer in stabilising St/BuA emulsion polymerisation was studied. Finally, stable dispersions of polystyrene microspheres were used as templates, and polystyrene microspheres were coated with Fe3O4 by in situ reaction of Fe3+ and Fe2+ in the presence of OH−. No additional treatments were needed in the process.
Phase Morphology and Rheological Behavior of in-situ Polymerized Nylon 11/Nylon 66 Composites
Authors: Guo Qiwen , Jiang Jiuxing , Cai Yanli
Published: September 2018

In this paper, the nylon 11/nylon 66 alloys were synthesized by in situ polymerization method. For comparison, the blends of nylon 11 and nylon 66 was also fabricated through melt extrusion. The phase morphology of nylon 11/nylon 66 alloys was invested by scanning electron microscope (SEM), differential scanning calorimetry (DSC) and atomic force microscope (AFM) techniques. The rheological behavior was studied on advanced rheometric exnylonnsion system. The SEM and DSC results show that the amorphous nylon 66 is embedded in crystalline nylon 11 matrix and the interface in between them is not clear in nylon 11/nylon 66 alloys, while two separated phases are clearly present in the nylon 1/nylon 66 blends. The AFM results reveal that the crystallinity of nylon 11 is very low, where the plate-like crystals are dominant. However, the introduction of nylon 66 promotes the crystallization of nylon 11 thus the crystals of nylon 11 become smaller. The complex viscosity and viscoelastic modulus are improved in comparison with nylon 1/nylon 66 blends.
Synthesis of Poly(1,4-cyclohexanedimethyl-1,4-cyclohexanedicarboxylate) as the Matrix Resin for Transparent Composites
Authors: Yuhong Chen , xi Li , Maosheng Zhan
Published: September 2018

PCCD polymers were prepared by melt polycondensation of 1,4-cyclohexanedimethanol (CHDM) and 1,4-cyclohexanedicarboxylic acid (CHDA) in the presence of titanium tetrabutoxide (TBT) as catalyst in a successive two-step polymerization. In the first stage, the effect of esterification temperature and stirring rate on reaction degree were investigated. The impact of reaction temperature on reaction degree was more obvious than that of stirring rate. The optimal esterification temperature and optimal stirring rate was 220 °C and 150 r/min respectively. In the second stage, the reaction conditions such as molar ratios of CHDM to CHDA and polymerization temperature were controlled for the optimum results. Mn of PCCD polymers increased with increasing initial molar ratio of CHDM to CHDA firstly, got its maximum when initial molar ratio reached 1.004:1, and then decreased when initial molar ratio exceeded 1.004:1. The polymerization temperature of 275 °C can lead to high molecular weight PCCD polymers (Mn>30,000). Finally PCCD/glass composites were studied, and it was shown that the composites maintain high transmittance and low haze like those of pure PCCD but possess better mechanical and thermal properties.
Physical-mechanical and Morphological Properties of Cellulose Reinforced Composites from Recycled Jute Woven Cloth
Authors: Yang Yuqiu , Yu Ying , Ota Tomoko , Tanaka Yutaka , Nishida Ryuiti , Kawabata Shinichiro , Hamada Hiroyuki
Published: September 2018

In this study, the jute cloth from recycled coffee bags was used to fabricate ecologically friendly composites by hand lay up molding technique. As the primal investigation, the effect of moisture contents of the jute cloth on the mechanical properties of the composites was discussed based on the results of 3 point bending and Izod impact tests. Additionally, The Dynamic mechanical analysis (DMA), and the thermogravimetric (TGA) were also performed to investigate the thermal properties of the composites. The results suggested that the moisture content of jute cloth did not affect significantly on the thermal behaviors. However bending and Izod impact tests’ results showed that the mechanical properties of composites deceased with the decrease of the moisture content. On the other hand, the composite with low moisture content had relative higher initial fracture stress which was considered affected by better interfacial between natural fiber and polymer.
Tensile Properties of Z-pins Reinforced Laminates
Authors: Dan Ma , Yong Li , Tao Sun , Lin Fan , Peng Wang , Jun Xiao
Published: September 2018

The delamination toughness of Z-pins reinforced laminates could be improved significantly and in-plane mechanical properties of the laminates were degraded with a few of Z-pins inserted in the through-thickness direction. The influence of Z-pin inserted parameters and moisture absorption condition on the tensile properties of the laminates was experimentally studied. The results showed that Z-pins can change microstructure and the original stress-strain state of the Z-pinned laminates, and the tensile strength and modulus of the laminates were obviously influenced. The tensile modulus of the Z-pinned laminates decreased with the increasing of Z-pins’ diameter and volume content, while it increased with that of Z-pins’ angle. The moisture absorption rate and balanced moisture content of Z-pinned laminates increased due to Z-pin inserted, which eventually resulted in accelerating degradation of performance of composites laminates.
Research on Depolymerisation and Regeneration of Epoxy Resin Cured with Anhydrides
Authors: Xie Fang , Huang Longnan , Wang Xinbo , Li Bin , Ma Jinhuan
Published: September 2018

The recovery and utilization of thermosetting resins without any pollution is always concerned in the FRP (Fiber Reinforce Plastic) industry. Based on the theory that the ester exchange reaction between alcoholic hydroxyl and ester groups will occur in existence of catalyst, a new technology was developed to recycle bisphenol-A epoxy resin cured with anhydrides. The orthogonal experiments were carried out and influence factors were analyzed in order to get a higher decomposition ratio of epoxy resin. Decomposed products were analysed with FTIR and were further applied to prepare regenerated resin by mixing with fresh epoxy resin. The degree of three-dimensional network and mechanical properties of original and regenerated resins were measured and compared. The results showed that the decomposition ratio could reach 98% while heated at 180 °C with the NaOH catalyst in ethylene glycol (EG) for 7 hours and the properties of the regenerated resin were good.
Theoretical Prediction of the Stiffness and Failure Strength of Stitched Foam-Core Sandwich Composites
Authors: Ma Yuanchun , Han Haitao , Lu Zixing , Lu Wenshu , Qiu Tao , Guo Junhong
Published: September 2018

Based on the microstructure, a novel theoretical method was proposed to predict the equivalent stiffness and failure strength for stitched foam-core sandwich composites. Experimental studies on stiffness and failure strength were also carried out. Considering the different thickness increment of the laminated face-panels for different stitching density and the influence of the stitching angle to the width of the resin pocket zone, a modified fiber distortion model was developed to evaluate the stiffness of stitching laminated face-panels by a combined series-parallel model. As for the prediction of failure strength, the composite face-panels were analyzed by the classical laminate theory and the local wrinkling failure of the face panel was also considered. A bridging model was adopted to analyze the stress of the stitched foam-core, and the failure strengths were predicted with proper failure criteria for different constitutive materials. The equivalent stiffness and failure strength of stitched foam-core sandwich composite panels were obtained under fat-wise loading, edge-wise loading, three point bending and transverse shear loading, respectively. The predicted results showed a good agreement with the experimental results and the finite element results, which demonstrated the validity of the present theoretical method.
Numerical Analysis of Buckling and Delamination Growth for Stiffened Composite Laminated Plates with Piezoelectric Actuators
Authors: Rui-xiang Bai , Liang Wang , Zhanjun Wu , Hao-ran Chen
Published: September 2018

The buckling and delamination propagation behavior in delaminated piezoelectric stiffened composite plates subjected to combined applied voltage and compressive loading are studied. The cohesive element for the non-linear finite element software ABAQUS is used to simulate the interface of the delamination region in the composite plates. The numerical simulation is conducted by using piezoelectric solid element and conventional shell element. The delamination propagation and the failure of stiffened composite plates are predicted by strength-based and energy-based criteria. The bucking control effect for the different buckling of piezoelectric stiffened composite plates with applied voltage was investigated, and the delamination propagation behavior of stiffened composite plates with piezoelectric actuators was studied. The results obtained by numerical analysis indicate that the appropriate control by piezoelectric actuators can retard local buckling of delaminated sub-laminates and prevent delamination growth effectively.
Off-Axis Ratcheting Behavior of a Unidirectional Carbon/Epoxy Laminate at High Temperature
Authors: Kawai Masamichi , Kigure Takashi , Suzuki Takafumi , Pecqueur Simon , Pierron Fabrice
Published: September 2018

The ratcheting behavior of a unidirectional carbon/epoxy laminate under off-axis cyclic loading conditions at high temperature has been studied with emphasis on its dependence on load waveform and fiber orientation. Development of an engineering model for describing the off-axis ratcheting deformation in the unidirectional CFRP laminate has also been attempted. First, off-axis ratcheting tests with different levels of maximum and non-zero mean stresses were performed on coupon specimens with different fiber orientations. The experimental results showed that the accumulation of ratcheting strain occurs in the unidirectional CFRP laminate, regardless of the fiber orientation, and the off-axis ratcheting behavior is similar to the off-axis transient creep behavior in all aspects of its stress, time and fiber orientation dependence. It is shown that the proposed model allows adequately predicting the off-axis ratcheting behavior of the unidirectional CFRP laminate for different stress ratios as well as for different fiber orientations.
Integral Design for Filament-Wound Composite Pressure Vessels
Authors: Zu Lei , Koussios Sotiris , Beukers Adriaan
Published: September 2018

The most important issues for the integral design of a filament-wound pressure vessel reflect on the determination of the dome shape and applied winding patterns. The goal of this paper is to determine the meridian profiles of continuum-based domes for pressure vessels, and to demonstrate that the utilization of non-geodesic trajectories forms a favorable alternative to the dome design. An integral methodology for the design of such dome structures is outlined, with emphasis on the application of the non-geodesic winding law and the classical lamination theory. Based on the condition of equal shell strains, the governing equation for the shape of the dome meridian and the differential equation describing non-geodesic trajectories on the dome surface are derived. The meridian profiles of non-geodesics-based carbon-epoxy domes are obtained for various slippage coefficients; the structural efficiency of geodesics and non-geodesics-based domes for various polar radii are then calculated and compared to each other. The results concluded that filament-wound domes of pressure vessels designed using the non-geodesics provide better performance than geodesics-based ones.
Study on Delamination Problems of Composite Hull Structures under Slamming Loads
Authors: Zhaohui Hu , Xiaodong He , Jun Shi , Rongguo Wang , Hongjun and Liu
Published: September 2018

The finite element method is used to study delamination problem of composite hull structure. Stress analysis and delamination analysis of the hull are based on laminated plate theory and exponential forms of cohesive models respectively. By using commercial finite element software ANSYS, a two-dimensional model of the hull structure is established. Interface element based on cohesive model is inserted into potential delamination field and contact element is used in the model to avoid adjacent mesh embedded, and slamming loads is imposed as a bending moment in structure stress analysis. The calculated results show that this method can be well predicted delamination initiation and growth of the hull. Under a certain given slamming bending loads, delamination first occurs near middle layer of the hull structure, and delamination location in the vicinity of the stiffeners. The results may provide favorable references to prevent delamination of composite hull in the structure work.
SAXS Studies on the Structure Behaviors of Crosslinked PTFE Irradiated by Gamma Ray
Authors: Feng Tian , Zhongfeng Tang , Hongjie Xu , Jie Wang , Guozhong Wu , Xiuhong Li
Published: September 2018

The structural changes of crosslinked polytetrafluoroethylene (XPTFE) by gamma ray irradiation in air at room temperature were studied by thermal analysis and SAXS techniques. The chain scission of irradiated XPTFE was predominant in room temperature and increased with an increase of dose. The crystallization is enhanced by chain scission during irradiation. The melting temperature and melting heat of XPTFE irradiated by gamma ray increased with the adsorbed dose. The scattering intensity of samples decreased with increasing dose. The fractal dimension of sample decreased but the thickness of transition layer parameter becomed smaller before 100 kGy gamma ray dose, and then it increased with dose above 100 kGy Irradiated XPTFE samples exhibited self-similarity structure. Chain scission of XPTFE is responsible for its structural change after XPTFE irradiated by gamma ray in air.
A Novel Light-emitting Conjugated Copolymer Based on 1,4-diethoxybenzene and 3-Methylthiophene via Electrochemical Polymerization
Authors: Zhang Yujian , Yu Chunhui , Ouyang Mi , Wang Nachuan , Zhang Cheng
Published: September 2018

A novel light-emitting conjugated copolymer based on 1, 4-diethoxybenzene (DEB) and 3-methylthiophene (MTh) is polymerized electrochemically in acetonitrile containing tetrabutylammonium perchlorate by the direct oxidation of DEB/MTh mixtures. The structure, morphology and electrochemical properties of the obtained copolymer are investigated by Fourier transform infrared spectroscopy, 1H NMR spectrometer, scanning electron microscopy and cyclic voltammetry. The results confirm the achievement of DEB/MTh copolymerization. UV-vis spectra show that the absorption peak of the copolymer red shifts gradually with the decrease of DEB/MTh monomer feed ratio and the applied potential. Moreover, photoluminescence spectra of the copolymer exhibit great change in emission color from pale blue to pale green with the variety of ratio of two monomers. Therefore, monomer feed ratio and polymerization potential play important roles in the optical properties of copolymers.
An AE Investigation on Bending Failure Process of Concrete Filled CFRP-Steel Tube
Authors: Zhang Liwei , Zhao Yinghua , Jiang Alan , Hou Yilie
Published: September 2018

A four-point bending test is performed for concrete filled square steel tubular beams strengthened by CFRP in longitudinal and circumferential directions. The mechanical parameters and acoustic emission (AE) signals are acquired for investigating the failure process. Test results indicate that the failure process could be divided into four stages including elastic, elastic-plastic, descending and softening stages, and AE parameters and waveforms are found to characterize this process properly. In addition, damage sources of the specimen are localized and position concentration degree (PCD) of AE events is defined which can quantitatively reflect the distributing regularity of damage sources along the axial direction under different loading conditions. The research suggests that, acoustic emission sensing technique can be used as an effective tool for on-line monitoring of damage degree and failure process of concrete filled CFRP- steel tube under bending load.
Crystallizable Polyisoprene under Strain Obtained by Nd-based Catalyst
Authors: Li Guilian , Yin Weidong
Published: September 2018

The conventional Ziegler-Natta catalyst composed of neodymium versatate (Nd(vers)3), alkylaluminum (Al( i-Bu)2H or Al( i-Bu)3) and diisobutylaluminum chloride (Al( i-Bu)2Cl) was examined in isoprene polymerization. The polymer with narrow molecular weight distribution ( Mw/ Mn < 3) can be obtained by controlling Al( i-Bu)2H amounts and component addition order. While, polyisoprene with high cis-1,4 content (> 96%), high molecular weight (> 100×104) and narrow molecular weight distribution (Mw/Mn < 2.2) is synthesized by using Al( i-Bu)3 as cocatalyst. In the meantime, the obtained polymer has crystallization behavior under strain.
Simulation of Non-isothermal Crystallization Kinetics of Thermoplastics during Fiber Placement Process
Authors: Li Yuehua , Fu Hongya , Han Zhenyu
Published: September 2018

Currently more and more thermoplastic composites are applied in aircraft structures. During automated fiber placement process, thermoplastic composites, which adopted “ in-situ consolidation” technology, can be formed and consolidated in several minutes. Therefore, using “ in-situ consolidation” technology instead of autoclave technology is more economically. However, some technical indicators of laminates using “in site consolidation” technology are below the autoclave laminates. In order to eliminate the most significant barriers, the automated fiber placement process should be studied. The crystallization rate of thermoplastic in the cooling stage of automated fiber placement is one of the most important factors. In order to obtain the special crystallization, the cooling temperature and cooling time should be strict controlled. According to the coupling phenomena between the non-isothermal crystallization kinetics and the heat transfer in thermoplastic during the cooling stage, a mathematical model has been established. By solving above model, the relationship among cooling temperature, cooling time and relative crystallization rate has been obtained. Above simulated data can guide the cooling stage of automated fiber placement process.
Preparation and Properties of Transparent SEBS/Titania Nanocomposite Films via Functionalization of SEBS and Sol–Gel Process
Authors: Guo Huanwang , Li Xue
Published: September 2018

Transparent nanocomposite films based on a thermoplastic elastomer, poly[styrene- b-(ethylene- co-butylene)- b-styrene] triblock copolymer (SEBS), and titania sol-gel precursors are fabricated. The SEBS grafted with maleic anhydride (SEBS-g-MAH) can enhance the dispersion of titania in the SEBS matrix. The SEBS- g-MAH/titania nanocomposite films are transparent and exhibit excellent mechanical properties, including increased modulus and tensile strength, with only a slight loss of stretchability. Moreover, the uniformly dispersed titania nanoparticles in the SEBS-g-MAH matrix can enhance thermal stability of the nanocomposites.
Experimental Study on Interlaminar Fracture Toughness of Modified Epoxy Resin Composites
Authors: Wang Xiang Ru , Wu Xiao Qing , Liu Mei Ling
Published: September 2018

The epoxy resin was modified with silica nanoparticles and reinforced by carbon fibre by means of resin transfer molding (RTM). The interlaminar fracture toughness of the laminated composites was tested and the fracture surface was observed by the microscope. The result shows that the critical energy release rate (GIC) increases by 45% and the fracture surface is tougher than the unmodified specimen. The interlaminar fracture toughness has been improved significantly.
Study on Morphology and Mechanical Properties of PVC with Ultrafine CaCO3 Surface-modified by Acrylate Macromolecular Modifiers
Authors: Zhang Ousheng , Zhang Chaocan , Wu Lili , Sun Wenbing , Hu Liang
Published: September 2018

In this paper, ultrafine CaCO3 particles were modified by four acrylate macromolecular modifiers, AC730, AC532, AC235 and AC037 with glass transition temperature from low to high, and subsequently added into PVC to investigate their influence on morphology and mechanical properties of the composites. Dispersity tests in organic solvents with different polarities show that modified CaCO3 particles can be well-dispersed in ethyl acetate and dichloromethane whose polarities are close to that of PVC, indicating good compatibility between modified CaCO3 particles and PVC. AC235 and AC037 with more content of “rigid” MMA units have better dispersing effect on CaCO3 particles than AC730 and AC532 with more content of “soft” BA units as revealed by SEM images of modified CaCO3 particles and PVC composites. Moreover, the results of tensile tests show that modified CaCO3 particles have obvious reinforcing and toughening effect on PVC, and the highest tensile strength and elongation at break were observed in the PVC sample modified by AC235. The results of tensile properties tests can be explained on the basis of the variations of interfacial cohesive strength and dispersing state of CaCO3 particles in PVC matrix.
The Evaluation of Low Profile Additives on the Shrinkage Control of Unsaturated Polyester Resin Cured at Room Temperature
Authors: Zare Leila , Beheshty Mohammad Hosain , Vafayan Mehdy
Published: September 2018

The unsaturated polyester (UP) resins have the largest consumption of thermoset resins in the composite industry. The copolymerization of alkyd oligomer with styrene monomer at low temperature condition leads to 5-10% volume shrinkage which may cause problems in the surface quality and dimensional control of produced parts. One effective way for the reduction or elimination of the shrinkage is adding a thermoplastic polymer called low profile additive (LPA). The effect of poly(vinyl toluene) (PVT) and poly(ethyl methacrylate) (PEMA), as two new LPAs have been compared to three types of poly(vinyl acetate) (PVAc) and polystyrene (PS) which are used as conventional LPAs. The phase separation results and morphology of samples containing PEMA showed that this LPA enable to reduce the volume shrinkage. It reduced the volume shrinkage of neat UP from 8.3% to 5.4%. The cure kinetics behaviour of the samples containing PVT and PVAc was completely different from that of the neat UP resin.
Study of the Mechanical and Dynamic Mechanical Properties of Polypropylene/Talc/Nanoclay Ternary Nanocomposites
Authors: Alavi S.M.B. , Esfandeh M. , Morshedian J. , Jahani Y.
Published: September 2018

Inorganic micro and nano fillers such as talc and nanoclay are used to improve various properties of polypropylene (PP). In general, the use of inorganic fillers affects the mechanical, rheological and service temperature of the matrix. In recent years, the simultaneous use of nano and micro fillers and investigation of the effect of these hybrid systems on various properties of the composite has gained the attention of many scientists. In this work, ternary nanocomposites, PP/talc/nanoclay, were prepared via melt compounding of the ingredients in a twin-screw extruder. The dispersion status of the fillers was followed by XRD and TEM techniques. The mechanical and dynamic mechanical properties of the composites were investigated in comparison to the binary composites (PP/talc and PP/nanoclay). The results showed that in ternary nanocomposites, the nanoclay was better exfoliated than that of PP/nanoclay composite. This could be due to higher matrix viscosity as the result of the presence of talc, which provides a balance between shear stress and molecular diffusion. As a result of this better exfoliated structure, a substantial increase in modulus, yield stress and other mechanical and dynamic mechanical properties was achieved in PP/talc/nanoclay nanocomposites.
Effects of Functionalisation on Curing and Decomposition Behaviour of Epoxy-MWCNT Nanocomposites
Authors: Theodore Merlin , Hosur Mahesh , Thomas Jonathan , Jeelani Shaik
Published: September 2018

Cure kinetics and decomposition behaviour of a two part epoxy resin system, Epon 862, reinforced with 1 wt.% unmodified, oxidized (MWCNT-COOH) and fluorinated (MWCNT-F) multi-walled carbon nanotubes have been studied through dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) at different conversion levels. Functionalized MWCNTs have disturbed the curing/decomposition behaviour, crosslink density, and the interactions between individual phases in the composite systems thus altering cure kinetics parameters like degree of conversion, activation energy, rate of reaction, enthalpy change, percentage conversion, which were determined using Arrhenius theory.
Enhanced Ionic Conductivity of Composite PVA-Nafion Electrolyte Containing Ionic Liquid by Addition of Hydroxyapatite Particle
Authors: Li Zhiying , Zhang Xin , Zhou Changli , Sun Danzi
Published: September 2018

Composite electrolyte comprising hydroxyapatite (HAp) filler and 1-butyl-3-methyl-imidazolium bis-(fluoromethane sulfonyl)imide (BMImTFSI) room temperature ionic liquid (RTIL) in poly(vinyl alcohol) (PVA) combined with Nafion matrix has been prepared. The polymer matrix was composed of PVA and Nafion providing the proton conductivity, BMImTFSI was used as both ionic source and plasticizer; HAp filler enhanced the ionic conductivity and thermal stability in this system. The electrolyte with HAp at the 20 wt.% showed the highest ionic conductivity of 1.2×10-3 S cm-1 at room temperature and 96% relative humidity.
Effect of Polypropylene–Grafted–Maleic Anhydride Compatibilizer on the Physical Properties of Polypropylene/Carbon Nanotube Composites
Authors: Hemmati M. , Shariatpanahi H. , Ahangari M. Ghorbanzadeh , Fereidoon A. , Narimani A.
Published: September 2018

The mechanical, rheological, morphological and thermal properties of a polypropylene (PP) matrix reinforced with single-walled nanotubes (SWNTs) and poly(propylene-grafted-maleic acid) (PP-g-MA) content were investigated by melt processing. PP-g-MA was used as a compatibilizer to promote carbon nanotube dispersion. Compared to uncompatibilized PP/SWNT nanocomposites, the tensile modulus of the material increased considerably when nanotubes and compatibilizer were employed. Furthermore, the Izod impact strength and tensile strength improved when 0.5 wt.% SWNTs and 1 wt.% PP-g-MA were added to the PP matrix. The rheological characterization results revealed that addition of SWNTs increased the storage modulus and complex viscosity at low frequencies. When PP-g-MA was introduced, the complex viscosity and storage modulus further increased. Scanning electron microscopy revealed that the SWNTs were uniformly distributed when low concentrations of SWNTs were employed. In addition, the dispersion and adhesion between SWNTs and the PP matrix were improved when 0.5 wt.% SWNTs and 1 wt.% PP-g-MA were added. The results of differential scanning calorimetry indicated that the addition of SWNTs increased the crystallinity of PP/SWNT nanocomposites.
Mechanical Properties and Tribological Behaviour of Polyurethane Elastomer Reinforced with CaCO3 Nanoparticles
Authors: Zhao Zhengping , Guo Qiang , Qian Junzhi , Pan Guoliang
Published: September 2018

In this work polyurethane (PU) elastomers based on poly(propylene glycol), diisocyanate and 2,2-Bis (hydroxymethyl)propionic acid were synthesized. CaCO3 nanoparticles were modified through esterification to increase their interactions with the PU matrix. A series of nanocomposites from polyurethane incorporated with various low concentrations of calcium carbonate were obtained. The effects of nanoparticles content on mechanical properties and the tribological behaviour of the PU composites filled with CaCO3 nanoparticles were investigated. Investigations of the worn surfaces showed that the fillers of CaCO3 nanoparticles were able to enhance the adhesion of the transfer films to the surface of counterpart ring, so they significantly reduced the wear rate of the PU matrix.
Plasticising and Stabilising Effect of Novel Epoxidised Mee Oil on PVC
Authors: Gamage Padmasiri K , Farid Ahmed S
Published: September 2018

The plasticising and stabilising effects of novel epoxidised Mee oil (EMO) and its derivatives on poly (vinyl chloride) were investigated. Peroxymethanoic acid was used to epoxidise Mee oil and the product was characterised by FTIR, iodine value, and oxirane content. Solubility parameter values were also determined. Plasticising effects of PVC incorporating EMO were evaluated using tensile and mechanical properties as well as FTIR. It was found that substantial levels of 100% epoxidised oil derivatives of Mee oil (E100M) could be added to PVC; typically about 50 phr E100M with 30 phr of DOP. It was observed that increasing levels of E100M with DOP enhanced the plasticising efficiency; flexibility, percentage elongation, softness, and MFI. The stability provided by EMO in terms of changes in elastic modulus during high-temperature ageing was modelled kinetically, and it was found that the kinetic model obeyed a law of the form:

ln (log Ea – log E) = kt + C

Activation energy values for the change in elastic modulus of PVC suggest some degree of synergism between EMO and Ca/Zn stearate system. Clearly E100M may be regarded as an effective secondary plasticiser as well as a stabiliser; perhaps more so than the other oil derivatives of Mee oil.
Effect of Electron Beam Irradiation on the Mechanical, Thermal and Dynamic Mechanical Behaviour of Waste Polyethylene-Short PET Fibre Composites
Authors: Satapathy Sukanya , Nag A. , Nando Golok Bihari
Published: September 2018

Electron beam irradiation of short PET fibre-reinforced waste polyethylene, virgin high density polyethylene and blends of waste polyethylene/high density polyethylene in the ratio 50:50 was carried out to study the effects on their physico-mechanical, thermal and dynamic mechanical properties. For comparison short PET fibres alone were irradiated with electron beam, and composites were also prepared with waste polyethylene, high density polyethylene and blends of waste polyethylene with high density polyethylene. Only a single proportion of the PET fibre was used, i.e. 50% by weight, and the dosage of the electron beam was 250 kGy. The results embodied in this paper showed that the tensile strength, flexural strength, flexural modulus, hardness increased with no change in elongation at break when the composites were subjected to the electron beam. The results obtained were confirmed by scanning electron microscopy and thermogravimetric analysis. Dynamic mechanical properties were also measured for suggesting utilization of these composites for commercial applications.
Performance of Graphite Filled Composite Based on Benzoxazine Resin. II. Decreasing the Moulding Time of the Composite
Authors: Kimura Hajime , Ohtsuka Keiko , Matsumoto Akihiro
Published: September 2018

To put the fuel cell to practical use, it is necessary to reduce its cost for the production of the bipolar plate as one of the components in the cell. Decreasing the moulding (cure) time of the graphite filled composites as a bipolar plate can increase its productivity. In this study, we aimed to decrease the moulding (cure) time of graphite-filled composites based on benzoxazine resin for the bipolar plate. Therefore, phenol novolac resin was added to benzoxazine resin as a curing accelerator. Expanded graphite was used for the preparation of the graphite-filled composites. The composites were prepared by means of the compression moulding of mixtures of graphite and benzoxazine resin containing phenol novolac as a curing accelerator. The properties of the graphite filled composites based on benzoxazine resin containing phenol novolac as a curing accelerator were characterised by mechanical properties, gas permeability and electrical conductivity. As a result, the curing reaction of benzoxazine resin containing phenol novolac as a curing accelerator could proceed more rapidly than that of only benzoxazine resin, and the moulding (cure) time of the composite was decreased. It was found that phenol novolac was an effective moulding accelerator of the graphite filled composites based on benzoxazine resin, and that it could increase the productivity of the bipolar plate using the graphite filled composite based on benzoxazine resin. It was also found that graphite filled composites based on benzoxazine resin containing phenol novolac as a curing accelerator showed good gas impermeability, electrical conductivity and mechanical properties compared with those of the graphite-filled composites based on the conventional phenolic resins.