bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Finite Element Model for Progressive Damage Analysis of Composite Laminates Subjected to Low Velocity Impact
Authors: Wang Yuequan , Zhu Shuhua , Qi Junwei , Xiao Jun
Published: September 2018

Fiber reinforced polymer laminates are susceptible to transverse low velocity impact which can cause significant damages, such as matrix cracks, delamination and fiber breakage. A 3-Dimensional (3-D) finite element model (FEM) is presented for the progressive damage analysis of fiber reinforced laminates subjected to low velocity impact. The constitutive equations of material used in the FEM are based on the continuum damage mechanics (CDM). The modified HASHIN failure criterions are used in the material model to detect the initiation of all the failure modes of laminates. A simplified material stiffness degradation scheme is used to characterize the material degradation due to damages. The failure criterions and material degradation scheme have been incorporated in the software ABAQUS/Explicit through the user defined material subroutine VUMAT. The available experiments of thin carbon fiber reinforced epoxy laminates subjected to low velocity impact were used to validate the developed FEM. The good agreement of the impact contact force history and damage area between the analysis results and the experimental data shows the validation of the developed FEM.
Experimental Study on the Behavior of a New Multilayer Shield against Hypervelocity Debris Impact
Authors: Changqing Miao , Bo Liu
Published: September 2018

To protect the spacecraft from hypervelocity impact of the space debris, a new kind of multilayer shield laminated of aluminum layers and CFRP layers was designed and investigated. Three different shields with the same area density were manufactured, including single aluminum alloy layer, single CFRP layer, and multilayer of aluminum/CFRP. The hypervelocity impact experiment was carried, in which the hypervelocity projectile was launched by a two-stage light gas gun. To compare the hypervelocity impact behavior and evaluate the protection ability of the different shields, the area and depth of the projectile pits were analyzed. The experiments results show that the protection effect of the multilayer shield laminated of aluminum/CFRP layers is better than the single aluminum layer or the single CFRP layer, though they are in the same area density.
The Effects of Particle Size on the Morphology and Properties of Polyimide/Nano-Al2O3 Composite Films
Authors: Liu Lizhu , Shi Hui , Weng Ling , Ding Jun , Cui Weiwei
Published: September 2018

Polyimide/nano-sized Al2O3 composite films based on pyromellitic dianhydride(PMDA) and 4,4'-oxydianiline(ODA) were synthesized by incorporation with different particle sizes of nano-Al2O3 via in situ polymerization. The morphology and structure of composite films were studied by scanning electronic microscopy (SEM). The properties including the tensile strength, corona resistance, electric breakdown strength and dielectric properties were investigated. Results indicated that the size of Al2O3 nano-particles had a great effect on the microstructures of composite films. The smaller size of the Al2O3 particles, the more regularity of composite films were obtained. Properties testing results indicated that by increasing the Al2O3 particles' dimension would decrease the mechanical properties and electric breakdown strength of composite films, while the dielectric constant remain nearly stable. Results also showed that after Al2O3 addition, the corona resistance of composite films was improved, compared with that of pure PI films. The longest corona resistance time was obtained when the smallest Al2O3 particles was used, which had a three times longer than PI composite film with largest Al2O3 addition.
Preparation, Morphology and Dielectric Properties of Nano-Tic/Polyimide Composite Films
Authors: Ling Weng , Xa Qianshan , Yan Liwen , Wang Cheng , Cao Maochang , Liu Lizhu
Published: September 2018

A series of nano-titanium carbide doped polyimide (nano-TiC/PI) composite films were successfully prepared via in situ polymerization. The microstructure of the obtained composite films was characterized by the scanning electron microscopy (SEM). The effects of different TiC contents on the mechanical and thermal properties of composite films were investigated. Dielectric properties of the nano-TiC/PI composite films were analyzed in detail with respect to different experimental parameters including frequency and filler concentration. Results indicated that the TiC particles dispersed homogeneously in PI matrix when its' content was below 15 vol.%. The addition of TiC particles could effectively improved the thermal stability of composite films. In comparison with pure polyimide film, the dielectric constant of the composite films with 5 vol.% TiC was significantly increased by thirteen times while the loss tangent only increased a little. Moreover, the composite films exhibited good dielectric stability over a wide range of frequency. The development of these novel polyimide composite films with favorable dielectric properties are potential for embedded capacitor applications.
Engineering Method for the Thermal Mechanical Erosion of C/C Composite with the Mesoscale Ablation Model
Authors: Daiying Deng , Jijun Yu , Xiangqiao Yan , Fei Huang , Xiaoguang Luo
Published: September 2018

A physical model to simulate the mesoscale morphology evolution of carbon fiber is established to characterize the thermal mechanical erosion behavior of C/C composite in high temperature and high pressure gas flow. The process of mechanical erosion of single carbon fiber is calculated by the DSMC method. The fracture criteria and mesoscale mechanical erosion model of carbon fiber are developed by theory of mechanics of materials. Finally, an engineering method for prediction of mesoscale mechanical erosion is formulated, and the predictions agree well with the experiment results.
Comparison of the Mechanical Properties between 2D and 3D Orthogonal Woven Ramie Fiber Reinforced Polypropylene Composites
Authors: Zhang Qian , Fang Xiaomeng , Sun Xiaojuan , Sun Baozhong , Qiu Yiping
Published: September 2018

Polypropylene (PP) composites reinforced with ramie 2D plain fabric is widely developed recently. In this paper, PP composites reinforced by using 3D orthogonal woven ramie fabric under hot-press molding process were made. The tensile and flexural strength of reinforced composites were tested and discussed. The results showed that the normalized tensile strength and the normalized tensile Young's modulus of 3D composite were significantly improved compared with that of 2D composites. The normalized flexural strength and the normalized flexural Young's modulus of 3D composite were also greatly improved. Overall results indicating that compared with 2D composite the 3D orthogonal woven ramie fabric could significantly improve the mechanical property of PP composites.
Enhancement of Tensile Properties of Flax Filaments through Mercerization under Sustained Tension
Authors: Xia Yuanyuan , Xian Guijun , Li Hui
Published: September 2018

In the present paper, the tensile properties of flax filaments were modified through mercerization under sustained tension forces. The tensile stress-strain curves of the treated filaments exhibit two stages. The slope of the first stage is much higher than the second one. The mercerization under sustained forces leads the two-stage characteristic to be more obvious. The effect of the sustained tension force on the tensile properties of filaments is dependent on the alkaline concentration. The tensile properties were only remarkably enhanced with high concentration of alkaline (e.g., > 10%) and sustained forces. Compared to the untreated filaments, the maximum tensile strength and modulus with optimum treatment conditions are improved by about 36% and 64% respectively. SEM and X-ray diffraction (XRD) analysis suggested that the enhancement of the tensile properties of the treated flax filaments comes from the orientation of amorphous cellulose molecular chains of micro fibrils and remove of the defects of the filament surfaces.
Fabrication and Characterization of Polyimide/Aln Nanocomposite Films
Authors: Minghua Chen , Jinghua Yin , Dajun Song , Xiaoxu Liu , Yu Feng , Bo Su
Published: September 2018

Polyimide/AlN (PI/AlN) nanocomposite films were prepared by in-situ polymerization method with different doping concentrations and their microstructures were investigated by small angle X-ray scattering (SAXS) technique. Analyzed SAXS results indicate the average diameters of the nanoparticles in hybrid films distribute from 55 nm to 60 nm, which are consistent with the observation from Scanning Electron Microscope (SEM). The Fourier Transform Infrared Spectroscopy (FTIR) results confirm the formation of AlN particles in the PI matrix. The effects of content on the dielectric constant, loss tangent, breakdown strength and corona ageing were studied. The corona resistant time of PI/AlN with 20 wt.% doping concentration is 58.5 hours, which is twenty times more than that of pure PI. The results show that the corona resistance of PI/AlN has been improved significantly.
Hemp Reinforced Composites with Alkalization and Acetylation Fibre Treatments
Authors: Wang H. , Kabir M.M. , Lau K.T.
Published: September 2018

The increasing ecological and environmental concerns have led to the development of natural fibre composites. Chemical treatments are usually used to modify the surface of fibre to improve the bonding between fibre and resin. Alkalization and acetylation were used in this study to treat the hemp fibre. It was found that the chemical treatments remove the impurity and lignin, increasing the cellulose content of the hemp fibre. Removal of the surface lignin and hemicelluloses also exposes more active hydroxyl groups from cellulose to react with matrix. All theses lead to the increase of mechanical properties. It is also noticed that excessive treatment is detrimental to the fibre internal structure itself and weaken the fibre.
Structural Design and Multi-Objective Evaluation of Composite Bladed Propeller
Authors: Hong Y. , Hao L.F. , Wang P.C. , Liu W.B. , Zhang H.M. , Wang R.G.
Published: September 2018

This paper describes the work to design a composite bladed marine propeller. The hydrodynamic load and the nonlinear structural responses are predicted by the coupled FEM/CFD method. A pre-twist strategy is used to determine a new geometry of the composite bladed propeller for improving the hydrodynamic performance. Different material schemes and symmetric stacking sequences are considered as the design parameters. An evaluation method of multi-objective function is presented for optimizing the strength, deflection and mass at design conditions. Numerical results are obtained and the optimal design scheme of the composite bladed propeller is obtained.
Effect of Fiber Surface on the Interfacial Properties for Carbon Fiber Reinforced Polymer Composites
Authors: Liu Wenbo , Zhang Shu , Hao Lifeng , Zhao Xueying , Jiao Weicheng , Yang Fan , Wang Rongguo
Published: September 2018

We studied the effect of carbon-fiber surface on interfacial properties of carbon fiber reinforced plastic composites. Surface morphology and chemical composition of T-Series carbon fibers made in Japan were analyzed by scanning electron microscope and X-Ray photoelectron spectra. The wettability between carbon fibers and epoxy resin was characterized by dynamic contact angle testing. The interfacial shear strength was obtained by microbond testing, and the destruction morphology of the interface observed that was used to determine the failure mechanism.
Healing Carbon Fiber/Polymer Interface by Resistive Heating
Authors: Wang Rongguo , Cao Zhenxing , Hao Lifeng , Jiao Weicheng , Yang Fan , Liu Wenbo
Published: September 2018

Interface is the key region which determines, to a great extent, the set of properties of all heterogeneous systems, including composite materials. We reported interface healing of carbon fiber reinforced thermoplastic composite material via resistive heating. The carbon fiber, T700 carbon fiber, with a resistivity of 1.66 × 103 Ω·cm was used as the heating element while the matrix is polyarylether sulfone with cardo. Micro-droplet experiment was used to study the interface strength before and after heating to determine the healing efficiency. The measurement shows (experimental results show) that resistive heating is an efficient way to heal cracks near interface.
Study on Mechanical Behaviors of Variable-Stiffness Composite Laminates
Authors: Zhonghai Xu , Zhe Liu , Xiaojing Lv , Hongtao Ma , Lifeng Hao , Weicheng Jiao , Fan Yang , Rongguo Wang
Published: September 2018

In this paper, we study the mechanical behaviors of variable-stiffness composite laminates by setting curvilinear fiber paths. We assume that the fiber orientation angles vary linearly with the reference axis. Based on the different fiber paths, we vary the fiber placement formats and the curvilinear fiber orientation angles of the composite laminates, and then make the simulation for the buckling loads of the three kinds of laminates: the straight fiber placement, the curvilinear fiber placement and the mixed fiber placement. By comparing and analyzing, we give the best fiber placement format and the curvilinear fiber orientation angle. The study provides references to the design of variable-stiffness composite laminates.
Synthesis of Organo-Montmorillonite/Sodium Alginate Graft Poly(Acrylic Acid -Co-2-Acrylamido-2-Methyl-1-Propane Sulfonic Acid) Superabsorbent Composite and Its Adsorption Studies
Authors: Zhu Linhui , Zhang Lili , Tang Yaoji
Published: September 2018

A new superabsorbent composite based on the natural material sodium alginate (SA) was synthesized by intercalation graft polymerization of SA, acrylic acid (AA), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and organo-montmorillonite (OMMT) using ammonium persulfate (APS) as an initiator and N,N'-methylenebisacrylamide (MBA) as a cross linker. The composite was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), and was used to remove heavy metal ions such as Pb2+, Ni2+ and Cu2+ from aqueous solutions. Maximum adsorption capacities for Pb2+, Ni2+ and Cu2+ were 1485, 303 and 294 mg/g respectively. It was found that the adsorption of Pb2+ was consistent with both the Langmuir and the Freundlich model, while that of Ni2+ and Cu2+ was in accordance with the Langmuir model. Mechanisms for the adsorption process were speculated upon. It revealed that chelation was dominant for the adsorption of Pb2+, while ion-exchange played an important role for adsorption of Ni2+ and Cu2+. The superabsorbent composite had good reuse performance in wastewater treatment.
Preparation and Thermal Conductivity of Nickel Fiber (Powder)/Silicone Rubber Composites Induced by Magnetic Field
Authors: Xie Dongsheng , Meng Xianfeng , Ma Jie , Zhu Lin , Shen Xiangqian
Published: September 2018

Silicone rubber composites filled with Ni powder (fiber) were successfully prepared, and the effect of fillers and magnetic field on the thermal conductivity of composite was investigated. The results showed that with the increasing of volume content of fillers, the thermal conductivity of composite increases. The Maxwell model and Cheng-Vachon equation were used to predict the thermal conductivity to explain the effect of Ni powder (fiber) fillers on the formation of thermal conductive networks. The SEM results indicated that aligned linetype-like structure had formed under magnetic field. Therefore, the presence of magnetic field during curing process could significantly enhance the thermal conductivity of composite.
Experimental Study of Epoxy Resin Repairing of Cracks in Fractured Rocks
Authors: Xing Huige , Yang Xingguo , Dang Yuhui , Yao Xin , Zhou Jiawen
Published: September 2018

Cracks in rock mass have always posed a big threat on the durability of fractured rocks in shear zone. Cracking of rock mass in shear zone is a random process, highly variable and influenced by many factors. Cracks in fractured rocks can be repaired by injection of epoxy resin in order to bond the crack and restore its structural integrity. Epoxy resins are used to repairing the shear zone at the Jinping Hydropower Station. An improved polymer grouting material is adopted and the polymerization process is determined. The polymer grouting materials is consisted of resin (component A) and hardener (component B). Polarizing microscopy (PM) tests and mechanical experiments are adopted to evaluate the filling situation of epoxy resin in rock and the mechanical properties of epoxy-repaired rock, respectively. Experimental test results show that, the cracks and pores are filled by epoxy resin, and also the crack surface are boned. The mechanical properties of epoxy-repaired rock are improved by the polymer grouting and the permeability coefficient is decreased.
Dispersion of Pristine Cnt in Uhmwpe Solution to Prepare Cnt/Uhmwpe Composite Fiber
Authors: Hao Xiangyang , Chien An-Ting , Hua Xiaoying , Lu Jian , Liu Yaodong
Published: September 2018

CNT dispersion in polymer matrices uniformly remains a challenge. Uniform dispersion of carbon nanotube (CNT) within ultra-high molecular polyethylene (UHMWPE) solution is the first step to achieve CNT/UHMWPE fibers with excellent properties. Several approaches have been tried. Composite powder was acquired by coating CNT on UHMWPE powder, then, dissolved in decalin, through gel-spinning, higher stronger composite fiber is fabricated.
Synthesis and Properties of Phenylmethylsilicone/Organic Montmorillonite Nanocomposites by In-Situ Intercalative Polymerization
Authors: Yuan Xinhua , Guo Wenhua , Jiang Xiao , Liu Yongqiang , Pan Shulin , Hu Jie , Li Songjun
Published: September 2018

Using methylphenyl dichlorosilane, methyl trichlorosilane cetyltrimethylammonium bromide (CTAB) as organic treatment agent, phenylmethylsilicone/organic montmorillonite (OMMT) nanocomposites were prepared by in-situ intercalative polymerization. The internal structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Mechanical properties, high temperature resistance and barrier performance for gas and water were also studied. The results show that molecules of silicone chains insert into the layer of montmorillonite (MMT), and the interlayer distance of MMT is expanded effectively after polymerization of phenylmethylsilicone prepolymer and methyl methacrylate, even forming exfoliated nanocomposites.
Molecular Characteristics Analysis of Wood Extractives from Pinus Massoniana Trees
Authors: Zhang Zhong-feng , Huang Kai , Ye Yong-jun , Shi Jun-you , Zhang Xu
Published: September 2018

Pinus massoniana is a fast growing tree widely grown in China that is, unfortunately, difficult to process and develop due to the extractive substances. The molecular characteristics of the wood extractives from Pinus massoniana were removed by a method of petroleum ether/Benzene extraction and analyzed by gas chromatography-mass spectrometry (GC-MS) in order to provide scientific guidance for improving the processing and utilization of this plant. Twenty-eight chemical components were discovered, including: 1,2-Benzenedicarboxylic acid, butyl octyl ester (62.69%), 1,5-Hexadien-3-yne (6.00%), Squalene (3.31%), 9,12-Octadecadienoic acid (Z,Z)- (1.29%), Heptadecane (1.14%) and Eicosane (1.01%). The analysis of the GC-MS results show that the main retention time of the wood extractives is 20–30 minutes with a total content percentage of 80.18%, and the richest components are esters, which compose 80.01%.
Fabrication and Characterization of Tio2-Organic Thin Film from An Aqueous Solution
Authors: Mu W.N. , Shi S.Z.
Published: September 2018

TiO2-organic thin films were fabricated on SAMs-coated silicon substrate based on layer-by-layer self-assembly process and chemical bath deposition method by a hydrolysis of TiCl4 in acid aqueous solution. The influences of deposition time and solution pH value on structural properties and the thickness of TiO2 films were investigated. The results of UV-vis spectrum show the absorbance of aqueous solutions at 410 nm decreases gradually with increasing deposition time and solution pH value. The thickness of TiO2-organic thin film elevates as increasing deposition time and pH value. The deposition time has significant influence on the surface morphology of films, and when the time is 2 h, a continuous, density and homogeneous film is gained from SEM micrographs. The deposited films consisting of TiO2 nanoparticles are believed to be fully amorphous layers from the results of XRD. The major chemical compositions of thin films are titanium and oxygen as presented in EDS results, and O/Ti atomic ratio is close to the corresponding ratio of 2:1 for stoichiometric TiO2. The transmission infrared spectrum and UV/Vis spectrum of TiO2 film indicate excellent structure and optical properties of films.
Parametric Study on Heat Transfer for Tow Placement Process of Thermoplastic Composite
Authors: Han Zhenyu , Cao Zhongliang , Shao Zhongxi , Fu Hongya
Published: September 2018

Fiber placement process of thermoplastic material is an in situ consolidation process which can significantly reduce consolidation process time and save costs compared with autoclave consolidation. The heat and crystallization behaviours play very critical role in the quality control during the process. In this work, two dimensional model of finite element is presented to perform heat transfer analysis of fiber placement process. The relationship between heat distribution of lamination and process parameters, including roller velocity, main heating temperature, preheating temperature, preheating length and preheating location, is deeply investigated. The numerical results show that for certain heating temperature there is a safe roller velocity which should not be exceeded, and such parameters as main heating length, preheating length and preheating location could be optimized to obtain better quality of product.
Strain-Amplitude and Strain-Rate Dependent Craze Damage of Poly(Methyl Methacrylate)
Authors: Xiu Liu , Wenbo Luo , Boyuan Yin
Published: September 2018

Dynamic mechanical analysis tests and quasi-static tensile tests were conducted on polymethyl methacrylate (PMMA). Craze damage images on PMMA samples' surface were acquired by using an optical microscope. Evolution of the crazing damage was investigated. The results suggest that crazing is loading rate and strain-amplitude dependent. In dynamic mechanical tests, the craze damage becomes more and more serious with the increase in strain amplitude, resulting in the Payne effect. Under quasi-static loading, there is a critical strain over which the surface crazes become visible; the greater the loading rate, the greater the critical strain. Moreover, stretching at different rates leads to difference to the morphology of crazes. The surface crazes stressed at lower loading rate are longer and more fully developed than those at higher loading rates, which results in a faster decline in static elastic modulus.
Prediction of Elastic Constants on 3D Four-Directional Braided Composites
Authors: Zhou Liang Dao , Zhuang Zhuo
Published: September 2018

In this paper, a finite element model with a prestressed unit cell is proposed to predict the elastic constants of 3D four-directional braided composites. Firstly, a finite element unit cell model with damage constitutive for 3D four-directional braided composites is established to investigate the influence of the prestresses in the unit cell. Secondly, the elastic constants of 3D four-directional braided composites are predicted with and without the prestresses in the unit cell. Finally, the influences of the braided direction and fibre content on the elastic constants of 3D four-directional braided composites are discussed. The results will provide an important guidance for designing and evaluating the mechanical properties of 3D four-directional braided composites.
Second-Order Polarizability and Temporal Stability of Epoxy Polymers Doped with Chromophore and with Chromophore Moieties in the Main Chain
Authors: Mishurov Dmitry , Roshal Alexander , Brovko Oleksandr
Published: September 2018

Second-order nonlinear optical (NLO) properties and temporary stability of epoxy polymers based on diglycidyl ether of bisphenol A (DGEBA) both doped with p-nitroaniline (p-NA) and functionalized linear polymer DGEBA with p-NA moieties (attached to the bearing main chain) in the main chain (DGEBA-p-NA) have been investigated. Second-order polarizabilities of both p-NA and functionalized linear polymer DGEBA-p-NA were determined by a solvatochromic method. It was shown that this method could be successfully applied to determine the molecular second-order polarizabilities of both low-molecular mass chromophores and polymers with chromophore moieties attached to the chains. The relaxation behaviour of the doped and functionalized poled epoxy polymers has been studied. The crosslinked functionalized polymer DGEBA-p-NA exhibits the highest second-order NLO properties and temporal stability.
Effect of Post Spinning Modification Using Potassium Permanganate on the Thermal Specifications of Acrylic Fibres
Authors: Eslami-Farsani R.
Published: September 2018

This study is focused on post spinning treatment of acrylic fibres using 5%wt. potassium permanganate (KMnO4) solution under different impregnation times. The evaluation of initial and modified acrylic fibres by differential scanning calorimetry (DSC) showed that treating acrylic fibres with KMnO4 solution can result in changes of chemical structure and thermal behaviour of fibres. The recorded DSC thermograms of modified samples indicated that with increase of impregnation time, the onset temperature of the cyclization reaction decreased. Also there was a progressive increase in the difference of onset and endset temperature (ΔT) of chemical reactions in the DSC peak.
Three–Dimensional Polyacrylamide–Poly(Ethylene Glycol)/ Phosphoric Acid for High–Temperature Proton Exchange Membranes
Authors: Li Zhenyi , Yin Yansheng , Liu Liqiang
Published: September 2018

We report the feasibility of anhydrous polyacrylamide-poly(ethylene glycol)/phosphoric acid (PAAm-PEG/H3PO4) semi-interpenetrating network frameworks as high-temperature proton exchange membranes (PEMs). The PEMs are synthesized by imbibing H3PO4 aqueous solution into three-dimensional PAAm-PEG frameworks accompanied with a dehydration process. The electrical properties are optimized by adjusting synthesis conditions such as crosslinker, initiator and PEG dosages. Results show that the H3PO4 loading and therefore the proton conductivities of the PEMs are significantly enhanced at optimal synthesis conditions. The optimal anhydrous proton conductivity is as high as 0.18 S cm−1 at 180 °C. A fuel cell using a thick membrane as a PEM shows a peak power density of 635 mW cm−2 at 150 °C with O2 and H2 as the oxidant and fuel, respectively. The high proton conductivities at high temperatures in combination with the simple preparation, low cost, scalable hosts and proton conductors demonstrate the potential use of hydrogel materials in high-temperature PEM fuel cells.
Preparation of Polyaniline/Filter-Paper Composite for Removal of Coomassie Brilliant Blue
Authors: Liu Wanwan , Li Xiaoqiang , Li Mengjuan , Li Yonggui , Ge Mingqiao
Published: September 2018

Polyaniline/filter-paper (PANI/FP) composite was prepared by in-situ polymerization of polyaniline onto filter-paper and subsequently evaluated for the removal of Coomassie brilliant blue (CBB) from aqueous solution. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared (FTIR) spectroscopy were used to investigate the morphology and physicochemical properties of PANI/FP composite. Batch experimental results showed that the pH value and temperature could affect the removal capability of the PANI/FP composite. Langmuir and Freundlich models were used to analyse the equilibrium adsorption. Pseudo-first and pseudo-second order models were used to investigate the kinetics of CBB adsorption onto PANI/FP composite.
Synthesis and Characterization of Star-Shaped Poly(Lactide-Co-Glycolide) Using Poss as An Initiator, and Its Drug-Loaded Microspheres
Authors: Zhang Xiaojing , Li Chong , Hu Yuelei , Sun Jiashu , Fang Shaoming
Published: September 2018

In this paper, a series of star-shaped poly(lactide-co-glycolide)s (sPLGA) with different block ratios were prepared by the ring-opening copolymerization of D,L-lactide (LA) and glycolide (GA) with multi-hydroxyl polyhedral oligomeric silsesquioxane core as an initiator and tin (II) 2-ethylhexanoate (Sn(Oct)2) as the catalyst. The products were characterized by NMR, FT-IR, GPC, XRD, DSC, TGA and viscosity measurements. The results show that the contents of PLA and PGA segments in sPLGA can be controlled by the feed ratios of the copolymerization. The glass transition temperature and crystallinity of sPLGA decrease and the crystalline sPLGA becomes amorphous with increasing the molar feed ratio between GA and LA from 10:90 to 50:50. The drug-loaded sPLGA microspheres were prepared by an emulsion solvent evaporation method. The morphology and the drug release property were investigated by SEM, dynamic light scattering (DLS) and ultraviolet spectrophotometry (UV). The results indicate that the sPLGA80 microsphere surface was smooth and the mean diameter was about 1.27μm. The sPLGA80 microspheres showed good drug loading and release properties.
Theoretical Models and Experimental Study on Mechanical Properties of Reinforced Polymer Matrix Using Different Kinds of Carbon Nanotubes
Authors: Kordani N. , Adibipour R. , Vanini A. Sadough , Zare A. , Gil V.
Published: September 2018

This paper is a study of the role of functionalized multi-walled carbon nanotubes (MWCNT-COOH) and single-walled carbon nanotubes (SWCNT) in improving the mechanical properties of epoxy resins. In nanotube-based polymeric composite it is anticipated that high elastic modulus can be achieved by taking advantage of the interfacial friction between the nanotubes and the polymer. In order to evaluate the CNT effect on polymer composites, different weight fractions of CNTs and two different kinds of CNTs were dispersed in the matrix. First, the damping characteristics of the samples with 0, 0.5, 1 and 1.5 wt.% nanotube contents were measured and then the tensile modulus was determined experimentally. The experiments showed an increase of the elastic modulus and the damping due to adding CNTs. Theoretical models were used to show the effect of added reinforcement to compare with experimental elastic modulus data. The results showed that a modified Rule of Mixtures model, incorporating the effect of fibre orientation in 3D was closest to the experimental results.
Thermal Stability of Electrical Properties and Amine Vapour Sensitivity of In-Situ Prepared Polyaniline/Graphene Nanocomposites Assisted by Sodium Dodecyl Sulfate Micelles
Authors: Anwer Tarique , Mohammad Faiz
Published: September 2018

Polyaniline (Pani)/graphene (GN) nanocomposites were prepared by in-situ oxidative polymerization of aniline with GN in presence of sodium dodecyl sulfate. The effects of polymerization and modification of the chemical structures in the nanocomposites were characterized by fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction techniques (XRD). Sodium dodecyl sulfate played the role of a surfactant, improving the dispersion of GN within the polymer matrix simultaneously. FTIR results revealed the presence of π-π interactions between Pani and GN leading to the formation of a charge-transfer complex. The thermal stabilities of the electric properties of the as-prepared nanocomposites were investigated as a function of GN content. As-prepared Pani/GN nanocomposites showed greater electrical conductivity as well as improved thermal stability in terms of DC electrical conductivity retention under isothermal and cyclic ageing conditions compared with pure Pani. They were also observed to possess better amine sensing properties in comparison to pure Pani when exposed to the vapour of methylamine.
Heterogeneous Surface Wear Models for the Prediction of the Specific Wear Rate of Woven Carbon Fibre Reinforced Epoxy Composites
Authors: Cheng B. , Kortschot M.
Published: September 2018

Heterogeneous surface wear (HSW) models have been derived to predict the specific wear rates of woven carbon fibre reinforced epoxy composite materials. The specific wear rates of unidirectional carbon fibre/epoxy composites, with fibres orientated both parallel and antiparallel to the direction of sliding, are used as input variables. The first model (EW mode) is based on an assumption of uniform thickness reduction during wear, but uneven surface pressure. The second model (EP mode) is based on an assumption of even surface pressure throughout the test. The specific wear rates of plain and 5HS woven composite panels were measured to validate the accuracy of the models. It was found that the EW model was able to accurately predict the specific wear rates of the two types of woven composites under mild abrasive conditions (120 grit sandpaper). However, under more severe abrasive conditions (36 grit sandpaper), the woven panels exhibited a new wear mechanism caused by tearing of the out-of-plane fibres at the crossover points of warp and weft fibres. This mechanism caused both models to under-predict the specific wear rates of the woven composites in severe abrasive conditions. However, the EW model can be used with confidence under less abrasive conditions, where the asperities do not have significant interactions with the out of plane fibres.
Comparative Study of Polyethylene Composites Containing Industrial Lignins
Authors: Hu Lei , Stevanovic Tatjana , Rodrigue Denis
Published: September 2018

In this work, free-radical grafting was investigated in order to enhance the compatibility between lignins and polyolefins. High density polyethylene (HDPE) was used as the matrix and two types of industrial lignins were selected as eco-friendly fillers: Kraft lignin which represents most of the global lignin production, but lacks adequate applications; and organosolv lignin which has received increasing attention for its low molecular weight, homogeneity and sulfur-free characteristics. The compounds were produced by batch mixing, and were compression molded. From these samples, morphological, tensile and thermal properties were studied. The results show that incorporation of different lignins into HDPE yielded materials of different tensile behavior, but improvement in morphological and mechanical properties through free-radical grafting was obtained. Furthermore, free-radical grafting was found to decrease the thermal oxidation resistance and the crystallinity of the composites.
Concept of Tercet Molecular Nanocomposites and Preliminary Studies on [Ppta/(Pa-6/Pa-66)] System of Miscible Blend of Polyamide-6/ Polyamide-6,6 Molecularly Reinforced at Nano Level by Poly(P-Phenylene-Terephthalamide)
Authors: Palsule Sanjay , Baijal Anuja , Bhati Sampat Singh
Published: September 2018

A tercet molecular nanocomposite is a ternary miscible polymer system in which a miscible blend of two flexible polymers is molecularly reinforced at nanometre level by a rigid-rod macromolecule and the tercet molecular nanocomposite demonstrates properties better than those of the constituent flexible polymers and their blend. A tercet molecular nanocomposite of a blend of flexible polyamide-6 (PA6) and polyamide-6,6 (PA6,6) molecularly reinforced at the nanometre level by a rigid-rod poly-p-phenylene-terephthalamide (PPTA) has been processed by coagulating a sulfuric acid solution of the components in water. This study reports miscibility, structure and properties of PPTA/[PA6/PA6,6] tercet molecular nanocomposites. Miscibility has been established by recording single intermediate glass transition temperatures by differential scanning calorimetry. Homogeneous morphology and dispersion of PPTA in [PA-6/PA-6,6] below 5 nanometre level has been established by scanning electron microscopy. Intermolecular interactions dispersing PPTA in [PA-6/PA-6,6] below the 5 nm level by imparting miscible homogeneous morphology and have been identified by Fourier transform infra red (FTIR) spectroscopy. Improved tensile mechanical properties of the tercet molecular nanocomposite, compared to those of the constituent flexible polymer blend, have been established by universal testing machine.
Synthesis of Poly (Styrene-Block-Vinyl Alcohol) by Successive Photo-Induced Charge Transfer Polymerization and Molecular Dynamics Simulation of Its Compatibility for the Blend System
Authors: Liu Fangzhuan , Wang Lingyu , Yin Qinjian , Jiang Bo
Published: September 2018

In the present work, a rapid and novel route to prepare a diblock copolymer consisting of styrene and vinyl acetate (VAC) units was performed by successive photoinduced charge-transfer polymerization (CTP) under UV irradiation, and then a series of objective products PSm-b-PVAn bearing different ratios of PS and PVA was obtained by the hydrolysis of PSm-b-PVACn with sodium ethoxide as the catalyst. Additionally, the influences of the reaction time, concentration of monomer and photoinitiator and kinetics of copolymerization were investigated. Good linear relationships of ln([St] 0/[St]) and ln([VAc]0/[VAc]) with the polymerization time indicated a first-order control/‘living’ process. The copolymers were characterized in detail by means of Fourier transform infrared (IR) spectrometry, 1H NMR and gel permeation chromatography (GPC). Furthermore, the miscibility of the originally incompatible blend system was improved quite significantly, so a full atomistic molecular dynamics simulation was applied to discuss the binary and ternary systems through the Flory-Huggins parameters, enthalpy of mixing and Tg.
Modification of Poe with Eva in Melt through Statistical Approach-Formation of Double Network Hybrids
Authors: Pervin Rumiya , Goswami Luna , Vijayabaskar V. , Bandyopadhyay Abhijit
Published: September 2018

Polar monomers are often grafted onto poly(ethylene-co-octene) [POE] to expand its application spectrum. However, the process frequently involves cautious handling of reactive monomers and hazardous solvents. On the contrary, the present work deals with similar modification but using a polymer, poly(ethylene-co-vinyl acetate) [EVA] in the melt through the formation of a double network hybrid using an external crosslinker. POE is an important new generation elastomer having great balance between physical and mechanical properties but its polarity needs to be improved for furthering its uses in industrial oil resistant applications and surface adhesion with other agents. The POE (major component)-EVA (minor component) hybrid compositions were designed using Taguchi statistical technique for optimization. Physico-mechanical properties like tensile, stress relaxation, hysteresis, rheological properties like pseudoplastic index, die swell and solvent swelling kinetics were investigated. The results were found depended on the network morphology of the hybrids. One composition was finally selected which produced better balance between all physico-rheological properties.
Preparation and In-Vitro Biocompatibility of Gelatin/Sa/Hya Composite Scaffold for Tissue Engineering
Authors: Ouyang Zhenzhong , Bai Shan
Published: September 2018

Novel gelatin/sodium alginate (SA) porous scaffolds containing hyaluronic acid (HYA) were fabricated via freeze-drying technique and their in-vitro biocompatibility was investigated. It was demonstrated that the gelatin/ SA/HYA composite scaffolds had highly homogeneous and interconnected pores with average pore size ranging from 50 to 400 μm. The extracts of gelatin/SA/HYA with various contents of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) showed no toxicity due to easy removal of excess EDC. Fibroblastic cells attached to the culture plate and showed normal morphology when cultured in the extract of gelatin/SA/HYA hydrogel. The introduction of HYA into the gelatin/SA matrix facilitated the adhesion of fibroblasts in the gelatin/SA/HYA scaffolds. The haemolytic test indicated that the gelatin/SA/HYA composite hydrogel showed no haemolysis. Therefore, the gelatin/SA/HYA composite scaffolds would be suitable for cell adhesion and growth and could offer new and important options for tissue engineering applications.
The Stability of Ag/Polyamidoamine Nanocomposites in Aqueous Solutions
Authors: Peng Zheng , Zhao Junchai , Zhang Jianmin , Sun Xiuguo , Li Yanting
Published: September 2018

Dendritic polyamidoamine (PAMAM) has been used as a template to synthesize metal nanocomposites, but the retention time of the nanocomposites in aqueous solutions has rarely been reported. In this paper, using the 5.5 generation of polyamidoamine (PAMAM) with ester-terminated groups as a template, the retention time for which the Ag ions were kept in the PAMAM aqueous solution was investigated by UV-Visible spectroscopy. It was found that the Ag/polyamidoamine nanocomposites showed high stability in the G5.5 solution even over 28 weeks. The results of TEM, TGA and DSC analyses also proved that smaller and more stable nanocomposites were formed in the solution. Thus, it can be concluded that the PAMAM may act as a good stabilizing agent for synthesizing Ag nanocomposites in aqueous solution.
A Correlation between Reinforcing Effect and Antibacterial Performance of Carbon Black and Silica Filled Natural Rubber Vulcanizates Containing Hpqm-Based Neusilin
Authors: Katathikankul Chitsupree , Kanking Sirichai , Niltui Piyaporn , Wimolmala Ekachai , Sombatsompop Narongrit , Isarangkura Khokhwan
Published: September 2018

This work pursued, for the first time, a correlation between antibacterial performance and mechanical properties of natural rubber (NR) compounds reinforced with commercial fillers, i.e. precipitated silica (PSi) and carbon black (CB), using 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate (HPQM)-based Neusilin as an antibacterial agent against Escherichia coli (E. coli) ATCC 25922 and Staphylococcus aureus (S. aureus) ATCC 25923. Antibacterial efficacy was determined by the inhibition zone from a halo test and by the percentage reduction of bacteria using the plate count agar (PCA) method. The results suggested that the optimum loadings of PSi and CB in NR compounds were 20 and 40 phr, respectively. HPQM-based Neusilin could be used simultaneously as a co-activator and antibacterial agent in the NR compounds. The overall mechanical properties of the NR vulcanizates were not affected by the addition of HPQM-based Neusilin, which was more effective for killing E. coli. It could be concluded that the antibacterial efficacy was conversely associated with the reinforcement level of the NR vulcanizates by the PSi and CB fillers: the higher the reinforcement level, the poorer the antibacterial efficacy. At the optimum loadings of PSi and CB fillers, the antibacterial efficacy of PSi-filled vulcanizates was better than that of CB-filled vulcanizates.
Synthesis and Characterization of Poly(Amideimide)S from Ab Monomers by Direct Polycondensation Using Triphenyl Phosphite
Authors: Rajasekar S. , Venkatesan D.
Published: September 2018

Poly(amideimide)s were prepared by the reaction of two new AB monomers, N-(4-aminophenyl)-4-(p-carboxyphenoxy)phthalimide and N-(3-aminophenyl)-4-(p-carboxyphenoxy)phthalimide. The monomers were synthesized by nucleophilic displacement reaction of the corresponding nitrophthalimides with p-hydroxybenzoic acid. The monomers were characterized by IR and NMR. Poly(amideimide)s were prepared from AB monomers by direct polycondensation using triphenyl phosphite. The polymers obtained had high inherent viscosities. The polymers showed high solubility in polar aprotic solvents. The polymers showed good thermal stability and had high glass transition temperatures. X-ray diffraction pattern of the polymers indicate amorphous nature of these polymers.
Full-Field Measurement at the Weave Scale in Hemp/Epoxy Composite Using Digital Image Correlation
Authors: Perrier Amélie , de Vasconcellos Davi S. , Touchard Fabienne , Chocinski-Arnault Laurence , Mellier David
Published: September 2018

This paper presents the strain field analysis of a woven hemp composite. Two different stacking sequences were tested: [0/90]7 and [±45]7. Tensile tests were coupled with a digital image correlation method in order to measure in-plane longitudinal, transverse and shear strain fields. Strong heterogeneities were observed in both stacking sequences. The obtained spatial resolution was fine enough to allow the comparison of maximum and minimum deformation areas in strain fields with the corresponding weave architecture. It was observed that strain levels were directly linked with strand positions. Results gave, for the studied woven hemp composite, a complete analysis of the local deformation mechanisms.
Tri-Block Copolymer Based on Crystallizable Amide Segments and Functionalized Polystyrene
Authors: Vakees E. , Suresh J. , Kayalvizhi M. , Karthik S. , Arun A.
Published: September 2018

This article discusses the synthesis and characterization of segmented tri-block copolymers using monofunctional hard segments (mHS) and difunctional polystyrene soft segments. The main goal of this work was to modify high Tg polystyrene to semicrystalline material, thereby increasing the solvent resistance. Three hard segments were used. The soft segment molar mass was varied from 2500 to 10000 g/mol using dimethyl terephthalate (DMT) as a chain extender. The viscosity of the copolymer linearly increased with respect to the molecular weight of the SS. The crystallization behaviour of the copolymer was studied by DSC and FT-IR. The TGA results revealed that all copolymers had single-stage decomposition centred around 427 °C, and the solvent resistance of these materials was very high even at a low amide content. All the copolymers showed low water absorption.
Preparation and Characterization of An Aromatic Imide-Functionalized Polysilsesquioxane via the Sol-Gel Route
Authors: Schramm Christian , Rinderer Beate , Tessadri Richard
Published: September 2018

Phthalic acid (benzene-1,2-dicarboxylic acid, PA) and trimesic acid (benzene-1,3,5-tricarboxylic acid, TA) have been reacted with 3-aminopropyltriethoxysilane (APTES) at 110 °C and 220 °C (molar ratios 1:1 and 1:2). The reaction at 110 °C resulted in the formation of the corresponding poly(amic acid), whereas the thermal imidization at 220 °C gives rise to the formation of a cyclic polyimide moiety as shown by means of Fourier transform infrared spectroscopy (FT-IR). X-ray powder diffraction (XRPD) measurements revealed that a specific periodic arrangement in the as-prepared materials had been formed. Thermogravimetric analysis (TGA) made evident that the organic-inorganic nanocomposite materials showed improved thermal properties. The reaction of PA with APTES (1:1) at 220 °C is assumed to yield a ladder-like polysilsesquioxane.
Non-Isothermal Moulding of Composite Products with Impregnation of the Porous Layer
Authors: Baranov A.V.
Published: September 2018

The non-isothermal filling of a flat mould cavity by a Newtonian fluid with simultaneous two-dimensional impregnation of the porous (reinforcing) layer is investigated. The flow in the cavity is described by inertialess Navier–Stokes equations, the flow in the porous layer by Darcy's law, and the flow in the region adjacent to the ‘liquid–porous layer’ boundary by the Brinkman equation. Viscosity is considered to be temperature dependent. The temperature fields in the channel region and in the permeable layer are interrelated by conjugate boundary conditions of the fourth kind.