Applied Mechanics and Materials Vols. 217-219

Abstract: Structure and property of akund fiber were studied. Length, linear density, infrared spectrum, X-ray diffractogram, thermal property and tensile property of akund fiber were tested and contrasted to cotton and kapok. The results indicated that akund fiber length is about 31mm and linear density is about 1 dtex; its projection diameter is close to kapok. Akund fiber contains a relative large content of lignin. All of the three kinds of fibers are cellulose I crystal, the crystallinity of akund fiber is the smallest and is only 28.92%. Breaking strength and breaking elongation rate of akund fiber is smaller than that of cotton and larger than that of kapok.

Abstract: Prepared POE-g-MAH/PA6, POE-g-MAH/OMMT/PA6 blends. The morphology of the blends had been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM),and the blends had been detected by mechanical performance test. Test results showed that with the increasing of the content of POE-g-MAH’quality, PA6 / POE-g-MAH notched impact strength showed a increaing trend, but tensile strength showed a decling trend;POE-g-MAH/OMMT which is Core-shell structure could greatly increase the effective volume fraction of POE-g-MAH, paly a role of synergistic toughening for PA6 matrix.

Abstract: Void slab systems with polystyrene form and precast concrete deck have been used to reduce the construction period and the self-weight of the slab. This paper presents experimental works on the shear of the void slabs. Four specimens were tested. The main parameters of experiments were the type of polystyrene forms and the thickness of slab. Shear performances of void slabs were evaluated on the basis of failure patterns, load-displacement curves, and ultimate shear strengths. Based on the test results, the unidirectional void slabs had the best shear resistance performance when they used PF2 type of polystyrene forms. For all specimens that failed due to shear, ultimate shear strength was 52% or higher than nominal shear strength by ACI318-08. This indicates that void slabs have a sufficient shear performance in the truss bar arrangement direction

Abstract: Composite materials of POE-g-MAH，OMMT and PA6 were prepared by blending technology. Thermodynamic performances of PA6/POE-g-MAH/OMMT were determined in different temperature by SEM, TEM and XRD. The experimental results indicate that the notched impact strength of bends with the same component gradually increases as temperature increases in the range of -37 °C-23°C ,and with POE-g-MAH/OMMT content increasing, the impact strength keeps rising and stress whitening occurs; But at 50°C, higher than the glass transition temperature of PA6/POE-g-MAH/OMMT , plastic deformation begins easily and strongly. Because POE-g-MAH to a certain content, the stress state changes from plane strain to plane stress, make the ability of plastic deformation increasing .The plastic deformation absorbs many impact energy, and make the stress whitening phenomenon.

Abstract: In this paper, carbon black was activated by grafting and coupling respectively. Then the grafted carbon black, coupled carbon black, together with the unmodified carbon black were filled into polypropylene to prepare three kinds of composites respectively. The measurements of Fourier Transform Infrared Spectroscopy (FTIR), melt flow index, and alternating current (AC) impedance were performed on the composites. From the FTIR spectra, it was shown that different groups are bonded to the surface of carbon black after activating treatment For the corresponding conductive composites，it was found that the variation of fluidity with carbon black content and temperature changed after the carbon black activation. The influence of carbon black activation on the AC impedance and fluidity of the composites was analyzed. The scheme describing the interaction between carbon black and polypropylene in composites was given according to the results mentioned above.

Abstract: In this paper, Carbon black was activated using titanate-type coupling agent, and then filled into polypropylene to prepare conductive composites, whose alternating current (AC) electrical properties, including impendence Z, phase angel θ, dielectric constantε and dissipation factor tgδ that is a function of frequency and carbon black concentration were investigated by AC impedance spectroscopy. The percolation threshold of 5wt% carbon black concentration was obtained from the experimental result of volume resistivity for the conductive composites. It was found that the variation of AC electrical properties, which is a function of frequency, was dramatic and dependent on the filler concentration. It was also found that dependence of the real and the imaginary parts of impendence on frequency decreased with the increased concentration of carbon black, while the phase angle, dielectric constant and dissipation factor increased. The AC electrical properties were given based on the conductive network model and the corresponding equivalent circuit were concluded

Abstract: The zinc methacrylate copolymers with various monomer compositions were prepared for investigating the effects of zinc methacrylate, 2-methoxyethyl acrylate contents on self polishing behavior. The effect of molecular weight of the self polishing copolymer(SPC) was also investigated. The characterizations of copolymers were performed by fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, and differential scanning calorimetry. The leaching rate of SPC was determined from the reduction of dry film thickness after seawater immersion in a dynamic condition. The experimental results revealed that leaching rate and mechanical property of the film could be controlled by the hydrophilic monomer composition of zinc based copolymer.

Abstract: The waterborne polyurethane was prepared by reaction between polyester polyol and isophorone diisocyanat, different nanoparticles were filled into the system for modification. The effect of different ratio of materials, the kinds and mass of nanoparticles on the characters of waterborne polyurethane latex and film were investigated. The results showed that the stable polyurethane latex and polyurethane film with perfect characters could be prepared when the ratio of NNCO/NOH was 2.5~3.0, the DMPA with a mass fraction of 5%~6% was added into reaction as a macromolecule extender after adding small molecule chain extender BPO. Filling nanoparticles into the polyurethane latex could improve the water resistance and mechanical characters of the film. Nano-sized SiO₂ was a better modifier than TiO₂, and the appropriate mass fraction of SiO₂ was 6% of polyurethane raw materials.

Abstract: In this paper, self-healing PUF microcapsules were prepared by in situ polymerization. The test results show that: 1) the ratio of core/wall material can had a significant effect on the average particle size of microcapsules. The ratio happens to be 1.0 to 1.0, best coating, relatively dense surface can be achieved. When the ratio reaches 1.4 to 1.0, the microcapsules have worst coating, particle size, distribution of wide range, and comparatively rough surface. When the ratio is 0.8 to 1.0 or 1.2 to 1.0, preferable coating, uniform particle size and its distribution, as well as smooth and dense surface can be obtained. 2) The faster the stirring speed, the smaller the particle size of microcapsule will be. And the size becomes bigger and varied with the stirring speed decreasing.

Abstract: Nano-CuO had been successfully synthesized by using direct precipitation method. The prepared sample was characterized by XRD. The luminous intensities of pyrotechnics composite containing KClO₄, Mg and nano-CuO were measured. The catalysis of CuO nanocrystal on KClO₄ was investigated by thermal analysis instrument. The results show that the average size of nano-CuO is 19 nm and has spherical-shape. When nano-CuO is added into the pyrotechnics composites containing KClO₄ and Al, it can improve the igniting and burning performance. The luminous intensity of trinary pyrotechnics composite is also greatly increased. On the other hand, nano-CuO can make thermal decomposition temperature of KClO₄ to decrease 97.7 °C, the decalescence amount also reduced to 79.07 J/g. It is obviously that nano-CuO has strong catalysis to KClO₄ thermal decomposition. The conclusion is consistent with the measure results of luminous intensity.