Advanced Materials Research Vols. 11-12

Abstract: In this paper, we present the experimental results of microwave absorbing materials with a frequency-selective surface (FSS) embedded in the multilayer structural composites. Microwave absorbing materials with the FSS pattern embedded in multilayer structural epoxy resin matrix composites were fabricated. The effects of the FSS on multilayer structural composites for microwave absorbing material design have been investigated. Comparisons were made with the microwave absorptions of the multilayer composites with FSSs of different positions in composites. The microwave absorption properties of the multiplayer composites samples with FSSs are higher than those of the samples without FSSs. The experiment results show that the incorporation of a FSS can effectively change the reflection property of the composite.

Abstract: The electrochemical corrosion behavior of carbon fiber/vinyl ester resin composite (CF/VE), which has been used for sucker rods in the oil field, was studied under an immersion condition of 3% NaCl aqueous solution at 65°C. Galvanic corrosion experiment between the CF/VE composite and the alloy used as joints linking the composite sucker rods and metal suckers was performed. The results show that in a polarization system, there are a cathode reaction of oxygen absorption on the surface of the composite and an anode reaction, which is mainly depended on the concentration of the hydroxyl (OH¯). A slight acceleration of the absorption behavior and the decrease in the mechanical properties of the CF/VE composite are caused by the galvanic corrosion.

Abstract: Lithium ion was introduced into high purity aluminum (99.999%) by hydrotalcite precursor method, and Li/Al composite anodic film was obtained by anodizing. The methods of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the properties of the anodic film. The electrochemistry behaviors of composite anodic film were studied by means of potentiodynamic method and electrochemical impedance spectroscopy (EIS). The results showed that the composite anodic film was produced by hydrotalcite precursor method and which is amorphous to X-ray diffraction. The passivation current density of the anodic film in NaCl solution (1mol/L, pH=3, 7, 11) decreased obviously, while impedance value increased sharply. Corrosion resistance of the composite anodic film in NaCl solution was improved by the introduction of Li+ ion.

Abstract: The reinforcing mechanism of novel aramid pulp (AP) short fibre in CR matrix has been discussed in this paper, and it has been shown that the reinforcing effects of AP depend mainly on the dispersing uniformity and openness of those ultra-fine short fibres of AP in CR matrix.By proper pretreating method, the dispersing uniformity and openness of ultra-fine AP short fibres with high specific area can be improved markedly, so the large reinforcing potential can bring into play adequately.

Abstract: The carbon nanotubes (CNTs) were prepared by catalytic decompose of benzene using floating transition method at 1100-1200°C. Benzene was used as carbon source and ferrocene as catalyst with thiophene. The carbon nanotubes are straight with diameter 20-50 nm, internal diameter 10-30 nm and length 50-1000 μm. The carbon nanotube and continuous carbon fiber (T300) reinforced unidirectional epoxy resin matrix composites was fabricated. The volune fraction of continuous carbon fiber (first filler) in the composites without second filler (carbon nanotube) was 60%. The mechanical properties of the composites were investigated under bending, shear, and impact loading. The flexural strength and modulus of the composites increased firstly and then decreased with the increasing of carbon nanotube contents in epoxy resin matrix. The flexural strength of the composites reached the maximum value of 1780 MPa when the weight percent of carbon nanotube in epoxy resin matrix was 3%.

Abstract: Non-woven hemp fiber mat has been used to reinforce unsaturated polyester to make natural fiber composites. Thermal properties of the hemp fiber mat were investigated to discover the range of heat treatment temperatures suitable for the hemp fiber mat. Loss of weight during heat treatment and absorption of moisture from the environment during storage of the hemp fiber mat were also studied. Both hand lay-up technique and compression molding were used to make hemp mat composites. Due to the low fiber fraction, no significant reinforcing effect was found in the composite made by the hand lay-up technique. The effects of heat treatment of fibers, water content in the fibers, fiber fraction, and manufacture methods on tensile properties of the resulted composites were investigated. Hemp mat composites with tensile strength and modulus comparable to those of [±45°]4 glass fiber reinforced polyester were achieved by compression molding at a molding pressure of 2MPa.

Abstract: Since rubber was applied in people’s normal life, researchers have started to exploit the rubber reinforcing techniques and the relative mechanism. Developing high-effective, simple and economical reinforcing methods and fillers are the emphasis of rubber industry, technology and science. In this paper a rubber ideal filler (IF) is shown. This IF is a kind of composite with core-shell structure which was synthesized by seeded emulsion polymerization. It used styrene (St), polybutadiene oligomer (PBD) as monomers and divinyl benzene (DVB) as cross-linking agent. The effect of the amount of cross-linking agent, concentration of emulsifier and initiator on the stability of the emulsion was studied. The morphology of the latex particles with core-shell structure was characterized by high resolution SEM (ESEM) and DSC (Tg). The results showed that cross-linking polymeric particles exhibited strong reinforcing effect on styrene-butadiene rubber (SBR).

Abstract: this paper mainly studies the craft on how to produce viscose by using hemp fiber and affection of the process on the original property of the hemp. Meantime, the authors test and analyze the property of viscose fiber after the spinning process. The result shows that the crystallinity, and orientation degree of the culm of hemp are low. And the physical performance of hemp viscose is better than that of ordinary cotton viscose.

Abstract: Vanadium oxide nanotubes (VOX-NT) have been synthesized by using amine as structure-directing template and V2O5 as precursor under hydrothermal conditions (160°C, 7 days). The XRD, FTIR and TEM have been performed to optimize the synthesis conditions such as the amine species and the molar ratio between V2O5 and amine. The results of TEM show that the same molar ratio of V2O5 and butylamine (1.0:1.0) produce a mass of nanotubes which have intact figuration. The diameters are about 80nm for most of the nanotubes prepared by V2O5 and octadecylamine. While the obtained VOX-NT prepared by V2O5 and n-butylamine were found having diameters from 28.51nm to 97.80nm and the distance between the vanadium oxide layers is 1.84 nm comfirmed by XRD. FTIR also display that some changes of the structure have been occurred during the formation of the nanotubes compared with the staring materials.

Abstract: Titania nanotubes were successfully synthesized by a simple procedure with needle-like CaCO3 as inorganic templates at a room temperature in nonaqueous system. Through the hydrolysis of tetrabutoxytitanium (TBOT), titania crystal nucleus were deposited on the CaCO3 nanoparticles due to heterogeneous nucleation, followed by aggregation condensation on the surface of needle-like CaCO3 cores and removal of CaCO3 to produce hollow titania nanotubes. Its morphological and structural properties were characterized by TEM, SEM, and XRD, respectively. The nanotubes have a uniform tubular hollow structure with one or two big openings ends, the length of about 2.0 μm, the average inner diameters of 100-200 nm, respectively, and a wall thickness of approximately 40 nm. The phase formed was anatase after calcinations at 723 K for 2 h and nanotubes with hollow structure remained their original shapes, and the BET surface area of as-synthesized titania nanotubes was 243.45 m2/g, and decreased to 144.76 m2/g after calcinations