bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Dynamic FE Simulation of Smart Piezolaminated Structures Based on First- and Third-Order Transverse Shear Deformation Theory
Authors: Schmidt Ruediger , Vu Thang Duy
Published: September 2009

This paper deals with nonlinear finite element analysis of smart structures with integrated piezoelectric layers. Two geometrically nonlinear finite plate elements incorporating piezoelectric layers are applied based either on first- or third-order transverse shear deformation theory. Nonlinear strain-displacement relations are used that are valid for small strains and moderate rotations. Numerical tests are performed for the time histories of the tip displacement and sensor output voltage of a thin beam with a piezoelectric patch bonded to the surface.
Crack Crazing Patterns Interaction Based on Damage Criteria
Authors: Seddiki H. , Chabaat M.
Published: September 2009

The present paper deals with the interactions between a main crack and a surrounding layer of crazing patterns. Analysis of the stress field distribution as well as the energy induced during these interactions is based on damage criteria through the resolution of some differential equations conditions and the use of a numerical approach. The effect of amplification and shielding on the resulting stress field is shown through a study of mode I. It is proven, herein, that crazes closer to the main crack dominate the resulting interaction effect and reflect an anti-shielding of the damage while a reduction constitutes a material toughness.
Studies on Synthesis, Morphology and Theoretical Analysis of Schiff Base Derived From p-Aminobenzoic Acid and p-Hydroxybenzaldehyde by Solvent-Free Reaction Using Jet Milling
Authors: Cai Yan Hua
Published: September 2009

A novel synthesis method on solvent-free reaction using improved jet milling was described. Synthesis of a schiff base derived from p-hydroxybenzaldehyde and p-aminobenzoic acid had been achieved by solvent-free reaction using improved jet milling, and the structure of the compound have been characterized by Fourier transform infrared spectrometer, 1H nuclear magnetic resonance techniques and mass spectrometry. Differential thermal analysis of reaction process shown that the reaction was complete within 6 min. The scanning electron microscopy shown that the particles of the schiff base were regular and the size of the most particles was 0.5~1 μm. At the same time, the theoretical analysis about reaction process of solvent-free reaction using improved jet milling was preliminary studied. This solvent-free reaction using improved jet milling not only involves mild conditions, a simple operation and short reaction time, but also gives quantitative yield without waste producing work-up procedures. Simultaneously, the investigation also showed this reaction method was feasible, and of benefit to environment.
Performance Deterioration Behavior of Existing Reinforced Concrete Bridges
Authors: An Xin Zheng , Yi Cheng , Du Rui Xue
Published: September 2009

The analyses of concrete from a bridge in Handan district shows that most bridges concrete should have cracked. The study of the technical measures against the performance deterioration of existing reinforced concrete bridges will undoubtedly become an imperative issue. In recent years, lots of bridges have been built in Handan. We choose a reinforced concrete bridge to investigate the effect of the effective member stiffness degradation and durability degradation induced by vehicle overload, vehicle overflow, rebar corrosion, and concrete deterioration on highway reinforced concrete bridges. And Static loading test was conducted at its middle span. Based on the test data in different circumstances, the seriousness of vehicle overload is discussed. In consequence, the performance of highway reinforced concrete bridges on stiffness degradation and durability degradation is more serious compared with the bridge under the condition of non-overloading. The results show that the process of rebar corrosion in highway reinforced concrete bridges is sped up under the condition of vehicle overload and vehicle overflow on the highway reinforced concrete bridges, which decreases the durability of the bridge structure, and the speed of the durability degradation increases as time goes on. The paper conclusion is instructive for the construction and maintenance of bridge.
Infrared Heating Applied in Titanium Brazing
Authors: Wu Z.Y. , Yeh T.Y. , Shiue R.K.
Published: September 2009

Infrared heating is featured with a high heating rate up to 50oC/s. It is a very powerful tool applied in brazing application, so infrared heating has been used to study the kinetics of brazing process in recent years. The importance of brazing Ti alloys has been increased in past twenty years due to the strong demand from chemical and aerospace industry. Based on the previous studies, the use of Ti-based brazes alloyed with Cu and Ni contents is considered as one of the best alloys in brazing Ti and its alloys due to their high bonding strength. However, the presence of Ti-Cu-Ni intermetallics in the brazed joint has a strong effect on the joint strength, and the reaction kinetics of the joint is still unclear. The purpose of this investigation is concentrated on transmission electron microscopy (TEM) study of the infrared brazed CP-Ti using Ti-15Cu-15Ni filler, and microstructural evolution of the infrared brazed joint is unveiled. It is helpful for industrial applications of Ti-based alloys.
Flexural Strength of Phenol Formaldehyde Composites Post-Cured in Microwaves: Preliminary Results
Authors: Trada Mohan , Ku Harry , Vedhar Jayant
Published: September 2009

A commercial phenol formaldehyde based resole thermosetting resin supplied by Borden Chemical Australia Pty. was filled with ceramic-based fillers (Envirospheres or SLG) to increase its flexural strength. By performing flexural tests at a range of filler addition levels, the optimal addition level of SLG was able to be determined in terms of workability, cost and performance. The composites obtained were post-cured in conventional oven and in microwaves respectively. It was found that the maximum flexural strength of the microwave cured composites were only 5% lower than those cured in conventional oven when the percentage by weight of SLG was 24%. However, the time required for post-curing was also reduced from 10 hours (in conventional oven) to 40 minutes (in microwaves).
Effect of Mn and Cu on Spheroidized Process of Mg-Zn-Y-Based Icosahedral Quasicrystal Phase
Authors: Wang Zhi Feng , Zhao Wei Min , Lin Xiao Ping , Hur Bo Young
Published: September 2009

In-situ spherical icosahedral quasicrystal phase (I-phase) was fabricated in Mg-Zn-Y-based alloys by metal mold casting route. The effects of Mn and/or Cu on spheroidized process, morphology and microhardness of primary I-phase were studied in this paper. The results showed that the solidified morphology of I-phase depended on the stability of spherical I-phase during the subsequent growth and critical radius Rr of the spherical I-phase. Only when actual radius smaller than critical radius Rr can spherical IQC be formed. The effects of the fourth component and degree of undercooling on Rr were studied for the first time. Amazing spherical minisize IQC had been produced by improving cooling rate using a water-cooled copper mold. Multicomponent spherical IQC is hopeful of being strengthening phase to novel metal composites.
Design and Analysis of a Ring Type Traveling Wave Ultrasonic Motor Using Cantilever Type Composite Transducer
Authors: Liu Ying Xiang , Liu Jun Kao , Chen Wei Shan , Shi Sheng Jun
Published: September 2009

To take advantage of merits of higher output-power and efficiency of bolt-clamped transducer, a ring type traveling wave ultrasonic motor using cantilever type composite transducer is proposed in this paper. In this new design, two cantilevers are set for the coupling between ring and transducer. Two standing bending waves (with phase difference of π/2 on time and space, respectively) are generated in the ring by the bending-longitudinal vibrations of transducer. Thus, a flexural traveling wave can be excited. The working principle of proposed motor is analyzed. The stator is designed and analyzed with FEM, and the motion trajectories of nodes on the teeth are analyzed. The results of transient analysis verify the theoretical feasibility of proposed design. The results of this paper could guide the development of this new type of motor.
Release of Aspirin from Biodegradable Polyesterurethane Networks
Authors: Feng Ya Kai , Zhang Shi Feng , Zhang Li , Guo Jin Tang , Xu Yong Shen
Published: September 2009

In this paper, the release of model drug aspirin (ASP) from biodegradable polyesterurethane networks was studied. Poly(D,L-lactide-co-glycolide)urethane (PULG) networks were prepared from hydroxyl telechelic star-shaped oligo(D,L-lactide-co-glycolide) coupled with 1,6-diisocyanate-2,2,4-trimethylhexane and 1,6-diisocyanate-2,4,4-trimethylhexane or isophorone diisocyanate. PULG networks turned from transparent to opaque after ASP loading. PULG networks with lower crosslinking density always resulted in higher drug loaded content. The results of differential scanning calorimetry (DSC) and scanning electron microscope (SEM) measurements demonstrated that ASP was uniformly distributed in the networks. The drug release courses of ASP from PULG networks in phosphate buffered saline pH = 7.0 at 37 °C could be divided into three stages. Firstly, ASP release was at approximately uniform rate from PULG networks; Secondly, the release rate obviously increased for the degradation of the PULG networks; Thirdly, the release rate decreased gradually because most of the ASP had diffused out of the PULG networks. The crosslinking density of polyesterurethane networks also affected drug release rate. The in vitro release test revealed that ASP accelerated the degradation process of PULG, which exhibited a typical erosion-controlled release mechanism.
Characterization of Hot Deformation of Nb-V-Ti Microalloyed Steel Using Processing Map
Authors: Xiang Song , Liu Guo Quan
Published: September 2009

The hot deformation behavior of Nb-V-Ti microalloyed steel in the temperature range of 850°C～1100°C and the strain rate range of 0.001s-1～30s-1 was investigated by establishing the processing maps. The strain rate sensitivity (m), power dissipation efficiency (η) and instability parameter were calculated based on the experimental compression data and are plotted in the temperature–strain rate plane to obtain power dissipation and instability maps. The processing maps exhibit that the deformation at 1000°C and 2s-1 is one peak efficiency of power dissipation of 21%, the deformation at 1050°C and 0.01~0.001 s-1 is another peak efficiency of power dissipation of 45%. The optical microstructure observations show that they represent two dynamic recrystallization domains. Based on the above processing maps, the hot working parameters were optimized.
Influences of Fe2O3 Doping on the Crystallization of SiO2-Al2O3-MgO-K2O-ZrO2-F Glass-Ceramics
Authors: Tian Qing Bo , Xu Li Na , Yang Li , Yin Yan Sheng
Published: September 2009

The influences of Fe2O3 doping on crystallization characteristics and microstructural morphology in the SiO2-Al2O3-MgO-K2O-ZrO2-F glass were investigated by using differential scanning calorimeter, X-ray diffraction and scanning electron microscopy techniques. The results indicate that the addtions of Fe2O3 shift the crystallization peaks to higher temperatures and the crystallization peaks increases in magnitude and the gap values between two crystallization peak temperatures boarden with the increment of Fe2O3 contents.The star-shaped crystals of cordietite by dendritic-manner growths are homogeneously precipitated in the rusidual glass. The mica phases, which are precipitated at interdendritic cordietite phases and formed the plate shapes at the elevated temperatures. The mica crystals grow at the expense of cordietite phases and finally form the composites of mica/cordietite uniformly distributed.
Structural and Optical Properties of SnO2 Films Grown on 6H-SiC by MOCVD
Authors: Zhu Zhen , Ma Jin , Luan Cai Na , Yang Fan , Kong Ling Yi
Published: September 2009

SnO2 thin films have been deposited on 6H-SiC(0001) substrates by metalorganic chemical vapor deposition (MOCVD) system. The structural and optical properties of SnO2 films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and spectrophotometry. The XRD analysis revealed that the prepared samples were SnO2 epitaxial films of rutile structure with a clear relationship of SnO2(100)// 6H-SiC(0001). The average transmittance for the deposited SnO2 samples in the visible range was about 60%.
Synthesis and Characterization of Polyaniline/Montmorillonite/La3+ Nanocomposites
Authors: Wu Ying Bing , Mo Zun Li , Chen Hong , Niu Gui Ping
Published: September 2009

A new nanocomposite consisting of polyaniline (PANI), montmorillonite (MMT) and La3+ was developed via in-situ polymerization of aniline in the presence of MMT and La3+ through emulsion polymerization, and also a novel network structure consisting of nanowires had been shaped. The morphology and the chemical structure of the product were studied by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The thermal property was exmined by mean of gravimetric analysis (TGA). The results indicated that PANI/MMT/ La3+ namocomposite has formed nanowires with diameter about 5 nm. The novel network structure consisting of nanowires has been shaped and overlapped towards certain direction. The formation of this network structure reveals that PANI molecules have been successfully inserted into the interlayer of MMT. Meanwhile, this conductivity network is believed to lead to the great improvement of the electrical conductivity for the nanocomposites. The FT-IR spectra reveal that PANI is obtained via in situ polymerization of the aniline monomer and there is a strong interaction between PANI and MMT. From XRD analysis, it can be also seen that the PANI molecules had been successfully intercalated into the galleries of the MMT. Moreover, the arrangement of PANI is more ordered in PANI/MMT/La3+ nanocomposite than that of pure PANI. From TGA curves, it is apparent that the introduction of MMT and rare-earth ions (La3+) exhibited a beneficial effect on the thermal stability of pure PANI. This markedly enhanced thermal stability of the nanocomposites can be ascribed to the MMT nanolayers acting as barriers for the degradation of PANI in the interlayer spacings and the inorganic nanoparticles trammeled the movement of the PANI molecule chains. They make the thermal decomposition of the nanocomposites at a disadvantage. As a consequence, the needed energy of the thermal decomposition increased, the thermal stability of nanocomposite increased. The paper offers a novel PANI/MMT/La3+ nanowire composites.
Rolling Processes and Performance of Cu-Fe In Situ Composites
Authors: Guo Jun Qing , Yang He , Liu Ping , Jia Shu Guo , Bi Li Ming , Huang Hua
Published: September 2009

The deformation processed Cu-based in-situ composite was a kind of structural function materials with high physical and mechanical performance and used widely in large scale integrated circuit. Especially, the sheet material of Cu-Fe in-situ composites was interested to researchers because the Fe was cheaper and the use of sheets was more widely in electron industry. In this study, the sheets of Cu-10Fe-1Ag in-situ composite were achieved by cold rolling which the thickness was from 6mm to 2.56mm, 1.28mm, 0.64mm and 0.32mm. Corresponding, the rolling ratio was 4.9, 5.3, 5.9 and 6.6. The maximum strength was 722Mpa at the rolling ratio 4.9. The conductivity was measured also with maximum 59.5% IACS. The experimental results show that the tensile strength and electrical resistance increase with the increasing of rolling strain. Although the conductivity of Cu-Fe in-situ composites was not very high, the matching of strength and conductivity was favorable. It is feasible that the high performance Cu-based in-situ composite can be obtained by cold rolling with merits of materials cheaper, melting simple and usage wide
Crystal Structure and Optical Spectra of Er:NaLaxYb9-x(SiO4)6O2 (x=0,3,5,7,9) Crystals Prepared through a Hydrothermal Routine
Authors: Zhang Wen Yan , Lu Chun Hua , Ni Ya Ru , Zhang Yan , Xu Zhong Zi , Song Jian Bin
Published: September 2009

For the first time, nano-scale rods of NaLaxYb9-x(SiO4)6O2 (x=1,3,5,7,9) crystals (NLS) activated with Er3+ have been synthesized through a mild hydrothermal conditions with subsequent calcination. The as-obtained products were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicate that the compound has an apatite structure and crystallizes in the hexagonal system, space group P63/m. The excitation spectrum and emission spectrum were also emplyed to investigate the optical properties of the nano-rods. The Er3+ doped NLS exhibit green/red up-conversion luminescence under excitation with a diode laser at 980 nm.
Preparation and Properties of Novel Bonded Perovskite Manganite Oxides
Authors: Yang Xin Sheng , Yang Li Qin , Lv Li , Zhao Yong
Published: September 2009

The two-phase perovskite manganese composites have potential application in the field of spintronics, as the observed enhanced low-field magnetoresistance in this kind of composite. To prepare the real manganite-based two-phase composition, the concept of bonded perovskite manganese was put forward recently. In this article we review main research results in these bonded perovskite manganite oxide composites and give some expectation.
Effectiveness of Steel Slag Powder on Suppressing Alkali Aggregate Reaction of Concrete
Authors: Li Yun Feng , Liu Shu Ai , Du Rong Qiang , Kong Fan Ying
Published: September 2009

Concrete properties can be greatly improved with the advanced mineral admixtures such as steel slag powder. Used in combination with Super-plasticizer admixture, steel slag powder can lead to economical high performance concrete with enhanced durability and reduced cement content. The effectiveness of steel slag powder on suppressing Alkali Aggregate Reaction is analyzed. The effectiveness of steel slag powder on suppressing AAR expansion was assessed using the method of ASTM C441 and accelerated test method. Results show that mineral admixtures with steel slag powder as partial replacement for Portland cement in concrete is an effective means for controlling expansion due to AAR. At most a 50% decrease in expansion rate of mortar bars can be found.
Preparation of High-Purity YAG Powders by Gel Solid-State Reaction
Authors: Wang Xiu Hui , Zhao Guo Quan , Lu Sheng Bo , Li Gang
Published: September 2009

YAG crystal possesses chemical stability, mechanical intension, thermal conductivity and isotropy. These properties make it widely be used as functional and structural materials. YAG powder was successfully synthesized by gel solid-state reaction. AlOOH were reacted respectively with Y2(C2O4)3•10H2O (Route YІ) and Y2O3 (Route YІІ). The XRD indicated that the main phases were from YAM to YAP, finally to YAG with the increase of temperature in both routes, and YAG began to generate at 1250°C. The single-phase YAG generated after holding for 4h at 1450°Cin the YІ, but a little bit of YAP and Al2O3 was still remained in the YІІ. It was that Y2(C2O4)3•10H2O might be decomposed into high-activity, loose-structure yttrium oxide, which promoted the diffusion of Al3+ ion. According to XRD analysis, YAG generated slowly during 1250°C~1300°C and then fast during 1300°C~1450°C. The SEM images showed that the primary particles of YІ were 2-3µm, larger than that of YІІ. Particle distribution indicated that the average diameter is 18.68μm in the YІ and 9.35μm in the YІІ.
Preparation of Nitrogen Doped ZnO Dilute Ferromagnetic Semiconductor by Magnetron Sputtering
Authors: Lin Wen Song , Wei Wang , Heng Wei
Published: September 2009

ZnO/Zn3N2 multilayer films were synthesized on slide glass substrates by radio-frequency (RF) magnetron sputtering technology with RF powers of 100 W. After annealing in oxygen atmosphere for 3 hours at the temperature changed from 473 K to 873 K, the multilayer films were changed to be single-layer films of nitrogen doped ZnO dilute ferromagnetic semiconductor. The structural, elementary constituents, carrier concentration and magnetic properties of the films were investigated with X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), hall-effect measurements and vibrating sample magnetometer (VSM) magnetization measurements, respectively. The XRD measurements revealed that the nitrogen doped ZnO films had a wurtzite structure with their crystal (002) directions oriented along the c-axis of the substrate. Hall-effect measurements indicated that nitrogen doped ZnO thin film, annealed at 673 K for 3 hour, had the best p-type properties. Carrier concentration and resistivity of the film was 3.12 × 1017 cm-3 and 93 Ωcm, respectively. A Lakeshore 7407 vibrating sample magnetometer was employed for magnetization (M) versus applied field strength (H) investigations of these thin films. A typical hysteresis loop was found in the observed M–H curve of the samples, demonstrated that the films annealed at 673 K for 3 hour were ferromagnetic at 300 K. The XPS analysis revealed the presence of Zn-N chemical bonding in the films. It suggested that nitrogen atoms are substituted at the oxygen sites of the ZnO films and mediate the ferromagnetic properties of the films.
Effects of Boron, Silicon on Structure and Properties of Fe-Based Superalloy
Authors: Wang Hai Tao , Yu Hua Shun , Wang Yu Qing
Published: September 2009

The affecting laws of boron and silicon on structure and properties of Fe-based superalloy were studied by analyses of scanning electron microscope (SEM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Proper content of boron could not only purify the matrix and restrain the polymerizing and growing of carbides effectively, but also promote the forming of secondary precipitate of borides, which dispersed in form of micro particles to strengthen grain boundaries and enhance the heat strength for Fe-based superalloy. Boron was an adverse element to high temperature oxidation resistance. Silicon could toughen the matrix by solid solution strengthening. Overfed silicon in alloys caused great dropping of strength and toughness. The component of SiO2 endowed the oxide scale with flat and compact structure, fine and even grains, and few exfoliating. The optimum contents of boron and silicon in Fe-based superalloy are 0.02wt.% and 1.5wt.% respectively by comprehensive consideration of high temperature mechanical properties and oxidation resistance.
Preparation and Properties of Nano-Inorganic Mineral Material as Lubricating Oil Additive
Authors: Wang Ping , Zheng Shao Hua , Yin Yan Sheng , Su Deng Cheng
Published: September 2009

In this paper, a 20nm inorganic mineral particles, mainly includes Mg3Si2O5(OH)4, KAlSiO4 and CaMg(CO3)2, were prepared by the ultrasonic nanometer grinder. As a lubricating oil additive, the dispersion property of the particles was characterized and the tribological properties were evaluated. The antiwear mechanism was investigated with SEM, EDS and XRD. Results show the inorganic nano-mineral material as an oil additive has excellent stable-dispersion property. The load-carrying capacity and antiwear property of the base oil were improved greatly. It can be inferred that the additive creates certain deposit on the friction surface. The physical-chemical deposition could not only bear the load but also prevent forming direct contact of two rubbing surface. 0.5wt% is the optimal additive concentration.
Preparation of Inorganic/Organic Hybrid Membrane Adsorbents for Gasoline Desulfurization: Control of the Membrane Structure
Authors: Wang Tao , Zhao Xue Ling , Zhang Yu Zhong , Li Hong
Published: September 2009

The hybrid membranes have been prepared using polyethersulfone (PES) as membrane matrix material and cerium-loaded Y-zeolites (CeY) particles as adsorptive functional group for gasoline desulfurization. The structures of hybrid membrane have a significant influence on membrane performance and adsorption desulfurization process. In this study, the effects of dope composition and membrane formation conditions including coagulation bath composition and its’ temperature on membrane structures were investigated in detail. The SEM results showed that air-side surface of the membrane were a dense layer structure, cross-section of the membrane great changes of the structure present when change the dope composition and membrane formation conditions. From the SEM photos of membrane at glass-side, it can be seen that the inorganic particles were tightly held together within the porous polymeric matrix. The appropriate structures of inorganic/organic hybrid membrane adsorbents can be got by regulating dope composition and membrane formation conditions. The maximum adsorption capacity was 21.6mg S/g membrane, which should have the potential to be used for the deep desulfurization of gasoline.
Sic Based Ceramic Foams Reinforced by In Situ Mullite Whisker
Authors: Ji Xiao Li , Xu Fei , Chen Hai Ya
Published: September 2009

Prepared silicon carbide(SiC) ceramic foams combined with mullite whiskers which synthesized by in-situ reaction. Studied on the influence of temperature on the synthesis of mullite whisker, and the influence of mullite content on the compressive strength, thermal shock resistance of SiC ceramic foams. The results indicate that the performance of mullite whiskers synthesized at 1400°Cwere best, when mullite content was 25%, SiC ceramic foams could reach the maximum compressive strength for 1.75MP, the most thermal shock resistance for14 times.
Mechanical Properties and Ablation Behavior of Machinable ZrB2-SiC-BN Ceramics
Authors: Wu Hai Tang , Zhang Wei Gang
Published: September 2009

ZrB2-SiC-BN ultrahigh-temperature ceramic (UHTC) was fabricated by hot-pressing at 1800°C under 23MPa pressure of argon. Compared to ZrB2-SiC, the flexural strength of ZrB2-SiC-BN composite material was enhanced by adding 30% BN, and the fracture toughness showed a slight decrease, while the hardness decreased sharply. The addition of 30% BN also noticeably improved the machinability of the composites. Furthermore, ablation resistance tests were carried out using an oxyacetylene torch under subsonic conditions. Results indicated that a coherent compact scale of zirconium silicate was formed, which acted as an effective barrier against the inward diffusion of oxygen.
Improvement Properties of Recycled Polypropylene by Reinforcement of Coir Fiber
Authors: Threepopnatkul Poonsub , Kulsetthanchalee Chanin , Bunmee K. , Kliaklom N. , Roddouyboon W.
Published: September 2009

This research was to study the related mechanical and thermal properties of recycled polypropylene from post consumer containers reinforced with coir fiber. Surface of coir fiber was treated with sodium hydroxide to remove lignin and hemicelluloses and likely to improve the interfacial adhesion in the composites. The composites of treated coir fiber and recycled polypropylene were prepared by varying the coir fiber contents at 5%, 10% and 20% by weight using a twin screw extruder. The thermal properties were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimeter (DSC). The results from TGA showed that thermal stability of the composites was lower than that of recycled polypropylene resin and thermal stability decreased with increasing coir fiber content. From DSC results, it indicated that the crystallinity of treated coir fiber composites increased as a function of fiber content. The mechanical properties of injection-molded samples were studied by universal testing machine. The treated coir fiber composites produced enhanced mechanical properties. The tensile strength, tensile modulus and impact strength of modified coir fiber/recycled polypropylene composites increased as a function of coir fiber content.
Functional Silica Aerogels with High Specific Surface Area: Influence of Preparation Conditions on Structure Properties
Authors: Ye Li , Han Wei Jian , Ji Zhi Hong , Hu Ji Dong , Zhao Tong
Published: September 2009

A series monolithic silica aerogels modified by amino-substituted organic groups were synthesized by sol-gel processing of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) mixtures, followed by drying of the wet gels with supercritical carbon dioxide (SCCO2). The molar ratios of EtOH/TEOS and DMF/ (TEOS+APTES) were fixed at 5 and 0.4, respectively, and APTES/TEOS ratio was varied between 1:9 and 3:7. HCl was added to obtain a narrow pore distribution, and the ratio of HCl/ (TEOS+APTES) was varied between 0 and 0.004. When APTES/TEOS ratio was kept at constant, gelling of the precursor mixtures was accelerated with an increasing ratio of HCl/ (TEOS+APTES). The physical properties of the aerogels have been investigated in detail by the bulk density, porosity, nitrogen sorption measurements and scanning electron microscopic (SEM). The results showed that adding HCl did increase the specific surface areas of the aerogels and make the aerogels have narrow pore distributions, but also resulted in some increase in bulk densities and decrease in porosities. The bulk density of the aerogels was 0.13-0.32 g/cm3, the corresponding porosity between 80% and 92%. Microscopically, the framework of the functional aerogels consists of spherical secondary nano-particles, which stack into grape-like aggregate and interconnect in different directions into a network. The specific surface area of the aerogels were in the range of 362-1044 m2/g, and uniform pore distribution aerogels were obtained when the molar ratio of APTES/ (TEOS+APTES)/HCl at 1/10/0.002 and 1/10/0.004.
Fire-Damage or Freeze-Thaw of Strengthening Concrete Using Ultra High Performance Concrete
Authors: Lee Min Gin , Huang Yi Shuo
Published: September 2009

There are some reinforced concrete structures exposed to severe environmental conditions might require maintenance or strengthening. Many of these severe circumstances are the result of extreme climate conditions such as low temperature, freeze–thaw action, fire attack, and exposure to deicing salts. Because of this, the environmental durability of both the repair materials and methods used in rehabilitation applications are of utmost importance. A small fire can reach 250°C, while a common blaze can easily produce temperatures of around 800°C. In major conflagrations the temperature can even reach 1100°C. At this level, the heat affects most materials, provoking the spontaneous combustion of some of them and affecting the resistance of others. However, very little research has been performed in evaluating the environmental durability of strengthening materials for concrete members. Very little work has been done on the effects of freeze–thaw cycling on bonding and repair materials.
In this study, ultra high performance concrete (UHPC) was used to investigate the effect of strengthening concrete members by fire-damage test or freeze-thaw test. The results show that the mechanical properties of UHPC possess high strength, toughness, and freeze-thaw resistance. The CFRP (carbon fiber reinforced plates) wrapping specimens exposed at 300 °C showed totally failure with the deterioration of the adhesive. The UHPC with bonding 10 mm thickness specimens exposed at 400 °C and duration of 1 hour still in good shape. The UHPC with 1-cm or 2-cm thickness on strengthening concrete members could be obtained specific retrofit effects. The performance of UHPC specimens is better than those of CFRP wrapping specimens during high temperature exposure. The results of slant shear tests show that the bond strength of PC/PC, UHPC/PC and UHPC/UHPC decreased significantly after 600 freeze–thaw cycles or high temperature exposure.
Preparation and Biological Activity of Chitosan Fibers Reinforced PLLA/HA-CaSiO3 Composites
Authors: Wang Jing , Li Hong Bo , Gao Jing , Meng Xiang Cai
Published: September 2009

Chitosan fibers(CSf) andCaSiO3 were incorporated into a poly (L-lactic acid)/hydroxyapatite (PLLA/HA) matrix as reinforcements to prepare scaffold composites with adequate strength and high porosity for bone tissue engineering combined with emulsion freeze drying technique. The structural morphology of the composites was observed by scanning electron microscope (SEM). The porosity was tested by liquid substitute method. The mechanical property was measured. The effects of addition of CSf and CaSiO3 on composites were also discussed. Simulated body fluid (SBF) experiments were conducted to assess the bioactivity of the composites. The chemical components of resultants on surfaces after the immersion in SBF were analyzed by fourier transform infrared spectroscopy (FTIR). The results show that the composites with high connectivity have pore sizes of 100~250μm, a porosity of 60%~80%, compressive strength of 3.5~8.0MPa. In the SBF tests, Chitosan fiber reinforced PLLA/HA-CaSiO3 composite degraded stably, meanwhile, the formation of a layer of bone-like apatite on the surfaces of the samples indicated a good bioactivity. Studies suggest the feasibility of using CSf reinforced PLLA /HA-CaSiO3 composite for bone tissue engineering.
Synthesis and the Characterizations of Structure and Function of Gallic Acid Microcrystalline Cellulose Ester
Authors: Liu Ning , Fang Gui Zhen , Su Shuang
Published: September 2009

In order to solve the toxicity problem of gallic acid and its esters as food antioxidant,using the advantages of microcrystalline cellulose security and not to be absorbed by the body, a new type of polymeric anti-oxidants was exploited. Gallic acid microcrystalline cellulose ester was prepared by indirect esterification method ,which gallic acid and microcrystalline cellulose were used as raw materials. The structures of reaction materials and products were characterized and its oxidation resistance, stability, acute toxicology were studied by infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy .The results showed that: gallic acid microcrystalline cellulose ester was successfully synthesized ; its ability to remove all kinds of free radicals was higher than or approximate equal to gallic acid; suitable for room temperature storage, high temperature sterilization, ultraviolet sterilizer, pH3.0~9.0,under these conditions it was stability;it was non-toxic substance, the safety was higher than gallic acid and gallic acid propyl. This study established the technical foundation for the further development of a new type of functional macromolecular compound which could be used for antioxidation.
Preparation of Core/Shell Composite Latex Particles and Toughening Modification for Polyamide 6
Authors: Liu Xi Jun , Li Hai Ping , Li Feng , Tian Rui Xia , Li Qing
Published: September 2009

In this paper, a novel poly(butyl methacry1ate)/poly(methyl methacrylate-itaconic acid)(PBA/P(MMA-ITA)) latex particles with core/shell structure (CSR) was synthesized by the method of pre-emulsion semi-continuous seeded emulsion polymerization. The core/shell structure of CSR was characterized by TEM and confirmed that the average size of CSR particles was about 330 nm and that of PBA core was about 290 nm. The polyamide 6 (PA 6)/CSR blends (N/CSR) were prepared by the melt-blending technique, and its impact strength reached 40kJ•m-2 (more than 7 times higher than neat PA 6) when the ITA dosage was in the range of 4%~10%. The results of SEM showed that the high toughness of N/CSR blends was the result of the shear deformation of PA 6 matrix induced by cavitation of dispersed phase CSR.
A Facile Method of Surface Modification Based on the Adhesive Behavior of Poly(dopamine) on Copper
Authors: Chen Yan , Zhu Hai Ying , Lei Yan Hua , Sun Wei Wei , Liu Yun Ping , Chen Shou Gang
Published: September 2009

A 3, 4-dihydroxyphenethylamine (dopamine) polymer film has been prepared on copper surface from 2.0g/L dopamine solution in tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffer solution at pH 8.5 by a simple solution-immersion method. The dopamine self-polymerized and adhered to the copper surface firmly in aqueous environment. The film surface was evaluated through SEM, EDS, XPS and contact angle measurement. The results have shown that the film was indeed formed on copper surface. And this research offers a versatile approach for the surface modification.
Influence of Curing Process on the Performance of Epoxy Thermosets
Authors: Zhang Bao Hua , Ye Jun Dan , Chen Bin , Weng Yan Qing
Published: September 2009

The performance of epoxy thermosets was greatly influenced by the curing agent and curing temperature. It was known that epoxy thermosets cured under high temperature would have high normal forces which could cause fracture of the structure and then decrease the mechanical properties of the material. It was accepted that epoxy curing system should be cured under low temperature with the thermosets had the same properties as those cured under high temperature. It was important to choose proper curing agent to reach the above goal. Latent epoxy curing agent whose main component was the hyperbranched polyester (HBP) with tertiary amine as the end group was prepared and was used to diglycidyl ether of bisphenol A (DGEBA) in this work. The properties such as tensile intensity, bending intensity, impact resistance and dynamic mechanic properties of the resulting epoxy thermosets were evaluated. It was found that the resulting epoxy thermosets cured under low temperature had better mechanical properties than those cured under high temperature. The latent epoxy curing agent whose main component was the hyperbranched polyester with tertiary amine as the end group was adaptive to be used in the epoxy base of composite.
The Effect of Second Filler on Cure Characteristic and Mechanical Properties of Si-69 Treated Precipitate Silica/NR Composite
Authors: Thongpin Chanchai , Sripetdee C. , Papaka N. , Pongsathornviwa N. , Sombatsompop Narongrit
Published: September 2009

Silica has been widely used as non-black reinforcing filler, however, the filler-filler interaction has been an important issue. Cure characteristic and mechanical properties of the rubber compound and rubber vulcanizate were affected both by filler-rubber interaction and filler-filler interaction. There have been, presently, a number of natural fillers which are also used as fillers for the rubber, i.e. fly ash, sawdust and zeolite. This work therefore will study the effect of second filler added into the 13% Si-69 treated precipitate silica (PSi) filled natural rubber compounds. It was revealed that the scorch and cure time of the rubber compound increased with the content of treated PSi. This was the effect of excess of the silane treated onto PSi which would agglomerate and form the cluster of polysiloxane and would then be able to absorb vulcanizing accelerator resulting in extending the scorch and cure time of the rubber compounds. However, this effect was over ruled with the reinforcing effect as could be seen by the increasing, with the contents of PSi, of maximum torque and mechanical properties of the vulcanizates. The NR compounded with treated PSi content of 20 phr selected to study the effect of excess silane on the cure characteristic of hybrid fillers NR composite. The addition of sawdust led to longer scorch time and cure time but not much change of the maximum torque. As expected, the modulus of the rubber vulcanizate increased with the sawdust content whereas the tensile strength and elongation at break decreased with the sawdust content. The incorporation of zeolite could accelerate the cure reaction therefore both scorch time and cure time decreased. The maximum torque also increased with the content of zeolite. Both modulus and tensile strength increased with the content of the zeolite whereas elongation at break tended to be unchanged. In the case of using fly ash as the second filler, the cure time tended to be unchanged. However, the maximum torque tended to be increased with the content of fly ash. It was found that the modulus, tensile strength increased but elongation at break decreased. Interestingly, the excess of Si-69 used effect pronouncedly for the addition of zeolite and fly ash cases as the excess silane could promote the interaction between fillers surface and rubber molecule accept for sawdust
Preparation and Blood Compatibility of Epoxidized Castor Oil-Based Polyurethane/Chitosan Biomedical Materials
Authors: Li Guo Ming , He Ya Xin , Liu Xing , Su Juan , Qu Gao Fei
Published: September 2009

Epoxidized castor oil-based polyurethane were synthesized with epoxidized castor oil (ECO) and isophorone diisocyanate (IPDI) as the main raw materials. Epoxidized castor oil-based polyurethane (ECOPU) films were impregnated in different concentrations of chitosan (CS) solution containing acetic acid to prepare CS/ECOPU composite film. The structure and morphologies of the film have been characterized by means of mass change test, infrared spectroscopy, and optical polarization microscope. The recalcification time and dynamic blood-clotting tests were used to characterize the blood compatibility of CS/ECOPU composition film. The result showed that CS has been grafted onto the surface of ECOPU film. The material had good blood compatibility, and can be used as biomedical materials.
Synthesis of Crosslinkable Core-Shell Emulsion and Rheology of the Core-Shell/Amine Crosslinking Process
Authors: Lu Jia , Easteal Allan J. , Bhattacharyya Debes , Bolt Clive J. , Edmonds Neil R.
Published: September 2009

Starve feed and semi-continuous seed emulsion polymerization were used to control the morphology of core shell latex particles with a vinyl acetate (VAc)/vinyl ester of versatic acid 10(VeoVa10) copolymer core surrounded by a poly(glycidyl methacrylate) (PGMA) shell. Pure core and core-shell structures were confirmed by TEM. The results suggest that core-shell morphology of the two stage emulsion was favoured by higher concentration of emulsifier in the seed latex: the particle size distribution of core-shell latex was broader than that of the core latex, and the average particle size of core-shell latex was larger than that of the core latex. The core-shell structure was not produced using seed emulsion with emulsifier concentration at or below the critical micelle concentration. The core shell emulsion containing epoxy functional group with added ethylene diamine showed an abrupt increase in dynamic shear moduli, G' and G'' and complex viscosity η* (several orders of magnitude) at about 35oC, during temperature ramps, over a wide range of angular frequencies. The time ramps showed that the crosslinking reaction did not occur at 15oC for the core-shell emulsion/amine system. The time for gel formation decreased with increase in temperature.
Reactive Adsorption of Sulfur Compounds from FCC Gasoline on NiO/γ-Al2O3
Authors: Yin Hai Yan , Li Chun Hu , Wang Lin Xue , Yu Ying Min
Published: September 2009

NiO/γ-Al2O3 adsorbent was prepared by wet impregnated method. XRD, SEM-EDS, nitrogen adsorption techniques were used to characterize the adsorbents and GC-FPD was utilized to analyze the composition of gasoline before and after reaction. X-ray diffraction patterns indicate that noncrystal NiO particles are supported on the surface of γ-Al2O3. The results show that NiO/γ-Al2O3 adsorbent could be used to remove sulfur compounds and is effective on removing benzothiophene (BT). The maximum desulfurization efficiency appears when NiO content reaches 16%, and the total sulfur adsorption capacity is 1.84mg/g, however for 16%Ni/γ-Al2O3 the value reaches 3.495mg/g.
Annealing Temperature Effect on Superelastic and Cyclic Response of NiTi SMA
Authors: Lan Li , Lau Alan Kin Tak , Yin Yan Sheng , Tong Liu
Published: September 2009

To characterize the thermomechanical response, especially the superelastic behavior of NiTi shape memory alloys (SMAs), the DSC and tensile cycle test of NiTi of different annealing temperature have been presented. There’s no remarkable phase transformation peak, however, the stable tensile cycle curve and maximum dissipated energy have been observed at annealing temperature of 673K.
Shape Memory Behavior of Ti-Rich Ti-Ni-Cu Melt-Spun Ribbons
Authors: He Wen Jun , Min Guang Hui , Tolochko Oleg V.
Published: September 2009

Crystal structures and shape memory properties of Ti-rich Ti52Ni23Cu25 (at.%) ribbon annealed at 450°C for 10 min and 1 h were investigated by X-ray diffraction and dynamic mechanical analyzer. As-spun ribbon was full amorphous and its crystalline peak temperature is 455.4°C. The annealed ribbon is crystallized with strong preferential (110)-B2 orientation. It shows a well-defined shape memory effect and the transformation hysteresis for the annealed ribbon under an external load in the range of 3-9 N is about 38.5°C. With annealing time increasing from 10 min to 1 h, the maximum of transformation strain under the external stress decreases from 1.93% to 1.7%. The temperature dependence of the external stress increases from 0.3 N/°C to 0.43 N/°C. The residual plastic strain is up to about 0.4% at a load of 9 N.
Structure and Electrical Properties of PSN-PMN-PZT Piezoelectric Ceramics for Underwater Acoustic Transducer
Authors: Chen Hai Yan , Dong Li Hua
Published: September 2009

Piezoelectric Pb(Sb1/2Nb1/2)O3-Pb(Mn1/3Nb2/3)O3-PbZrO3-PbTiO3 (PSN-PMN-PZT) quaternary ceramics with the various contents of Pb(Mn1/3Nb2/3)O3 from 4 to 10mol% were prepared. The phase structure of the system was delineated by X-ray diffraction analysis. The surface morphology was examined by SEM. The piezoelectric and dielectric properties were also measured. X-ray diffraction patterns showed that the PSN-PMN-PZT piezoelectric ceramics was composed of tetragonal phase with perovskite-type structure. Study on the influence of Pb(Mn1/3Nb2/3)O3 additives on dielectric and piezoelectric properties indicated that the PSN-PMN-PZT quaternary system exhibited a high mechanical quality factor and well-situated piezoelectric properties. The optimized results of d33 =332pC/N, d31= -105pC/N, Kp=0.58, K31=0.34 and Qm=1658 can be obtained at 6 mol% Pb(Mn1/3Nb2/3)O3. The obtained electrical properties make this composition a good candidate for underwater acoustic devices.
Large-Scale Synthesis of ZnO Nanorods by Different Surfactant-Assisted and Low-Temperature Process
Authors: Ma Zheng Xian , Zhang Ning , Cao Xiao Ting , Yan Ping Ke
Published: September 2009

In this work, ZnO nanorods have been successfully synthesized by employing ZnCl2, NaOH as the starting materials by using different surfactants (including CTAB, SDS and SDBS), without using template supporting and structure-directing solvent at a low temperature ( 60 up to 90 °C ). X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) were used to analyze the crystal structure and surface morphology. XRD pattern analysis showed that the ZnO clusters are single hexagonal phase of wurtzite structure with no impurity of others. Also, TEM images revealed that the size of a single ZnO nanorod is between 20 nm and 40 nm in diameter and between 200 nm and 2 μm in length. The structures, growth mechanism and the PL spectra properties of ZnO microcrystals are investigated.
Simultaneous Adsorption of Methyl Orange and Heavy Metals from Solution Using Fly Ash
Authors: Visa Maria , Enesca Alexandru , Duta Anca
Published: September 2009

In a wastewater resulted from the dyes finishing industry there are amounts of dyes (very common Methyl Orange) and heavy metals resulted mainly from the organo-metallic dyes. Heavy metals (Cd2+ and Cu2+) advanced removal is usually proposed via adsorption and the use of modified fly ash as adsorbent represents a sustainable solution. The paper presents the results obtained in investigating the effect of methyl orange adsorbed onto the fly ash with modified surface, on the removal efficiency of cadmium and copper ionic species, considering the final application: a single step treatment process applied for wastewaters containing both heavy metals and dyes. The adsorption mechanisms are discussed based on the kinetic results and on the Langmuir model.