Applied Mechanics and Materials Vols. 670-671

Abstract: A novel polyacrylic acid /xanthan gum/bentonite superabsorbent polymer (SAP) was prepared through chemical crosslinking by a polymerization technique in a complete aqueous environment. This SAP was fabricated effectively by dispersing xanthan gum (XG) and bentonite in a monomeric solution, using N,N’-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. Fourier transform infrared (FTIR) spectral analysis showed that graft copolymerization reaction took place between acrylic acid (AA), XG and bentonite. The optimal process conditions of preparing SAP were investigated. Results showed that the relevant SAP had maximal salt-water absorption (98g/g) when mass ratio of m (bentonite):m (AA) was 5:1, m (ammonium persulfate):m (AA) was 1.75×10^-4, m (N,N’-methylenebisacrylamide):m (AA) was 3×10^-4, m (XG) :m (AA) was 1:5, the neutralization degree of AA was 75%. Bentonite can not only effectively increase water absorbency, but also improve water retention ability.

Abstract: The article considers the one-dimensional problem of the destruction of the simplest model of adhesively engage consisting generally of the many plates, which are substrates (what are glued) and adhesives (glues). The ability of the model to resist to thermal impact without fracturing here conventionally called the thermal strength. The problem is solved in the elastic formulation.

Abstract: To describe vibration characteristic of composite laminated plates with various fiber orientations, a composite laminated finite element, which follows classical lamination theory, was constructed. In each ply of rectangular composite laminated plates, the fiber orientation changes with respect to the horizontal coordinate. Natural frequencies and mode shapes of composite laminated plates were studied. The first six natural frequencies and mode shapes of composite laminated plates with various fiber orientations are obtained. The accuracy of this composite laminated element is verified by comparing numerical and theoretical results. The results show that the changes of fiber orientation bring a greater degree of flexibility for structure design of composite laminated plates, which can be used to adjust frequencies and mode shapes of composite laminated plates according to practical engineering need.

Abstract: Using 663-tin bronze, Ni, W, nanoAl₂O₃, MoS₂, graphite, CaF₂, and Ni coated graphite as the matrix alloy powder, in which copper-coated carbon fiber of 5%, 7%, 9%, 11% and 13% in volume fraction were added as the reinforcing phase, a novel type carbon fiber/copper-matrix self-lubricating composite materials was prepared by means of powder metallurgy. The results indicate that the mechanical properties of the composite materials are improved after adding copper-coated carbon fibers. The composite materials reach optimal overall mechanical performance under testing when the volume fraction of the added copper-coated carbon fibers is 11%.: with a hardness of 57.8 HV and a compressive strength of 222 MPa. The addition of carbon fiber also improved the friction and wear properties of the composite materials. Increasing the volume fraction of fiber, was found to increase the wear resistance and improve self-lubricating performance. A volume fraction of 11% gave a friction coefficient of 0.09 and abrasion loss of 4mg.

Abstract: Semi-rigid polyurethane foam to soften the instrument panel has a lightweight, impact and energy absorption performance, while improving the texture of the surface of the instrument panel. This article was prepared by one-step car instrument panel with semi-rigid polyurethane foam, through the design of the four factors and three levels orthogonal test program, using Fourier infrared spectroscopy to characterize its structure, measuring its apparent density and hardness properties of transformation, the combination of research influence of the proportion of polyether foam system.

Abstract: In order to solve the problem of the face/core bonding performance of the sandwich structure, this paper proposed a M - pattern folded sandwich structure. Structural performance in direct (pure) shear was investigated for sandwich structure. FE-Analytical of sandwich structure strength under shear loading condition was presented for possible failure modes. Panels with core of different thickness were tested for different failure modes and the mechanical properties. In general, the measured failure loads showed good agreement with the FE-analytical predictions.The results shown that failure modes of the sandwich structure with low relative density were shear buckling and fracture of thin-walled of cores, respectively. For the sandwich structure with high relative density, the dominant failure mode was interfacial debonding of face/cores, and the initiating failure along the ends of the specimens.

Abstract: In this paper, In this paper, polypropylene / mica composites were prepared by blending, using polypropylene (PP) as matrix, mica as filler. In order to study the anti-aging properties of polypropylene / mica composite materials, the above polypropylene / mica composite materials were placed outside to study the influence of natural aging time on the anti-aging properties and to explore the natural aging mechanism of polypropylene / mica composites. Natural aging research results show that:with the extension of the natural aging time the surface of materials will appear cracks and sheddings. The trends of tensile strength reduce at first, then increase and then decrease; the notched impact toughness values show fluctuating in the early aging, then an increase following and then decreasing.The increase of mica content are good for maintaining the mechanical properties of PP / mica composite, PP-g-MAH helps to maintain the tensile strength, while toughening POE-g-MAH will weaken the anti-aging properties of polypropylene / mica composite materials.

Abstract: The opportunity of application of natural aluminosilicate – perlite – as reactive mineral admixture and as individual binding component when production of construction materials.

Abstract: Silica sand is the main material in glass production. It can also be used for water purification. In this work, two types of silica sand used for the glass production were directly applied in the removal of Cr⁶⁺ from aqueous solutions. The chemical composition, loss-on-ignition, acid solubility and surface area of the two sands are compared. The results indicate that both sands are quite similar in chemical and mineral compositions. However, sand B has a higher organic content, a smaller crystalline grain size, a larger surface area and acid solubility. As a result, sand B shows a larger absorption of Cr⁶⁺ than sand A. In addition, both sands exhibit declined absorption of Cr⁶⁺ with increasing the pH of the solution from 1 to 3. No absorption occurred when the pH was higher than 3.

Abstract: Miscanthus is a high yielding bioenergy crop which has been tested as substrate for the bioprocess. In this study, we selected four typical pairs of Miscanthus samples which present different cell wall compositions. The sample shows significant difference in saccharine production with different concentration pretreatment of H₂SO₄ (0.5%, 1.0%, and 4.0%). Much more pentose (about 15.0% -30.0%) was extracted in the supernatant solution; and no significant difference between four species. The hexose yield of all samples is disciplinary and not in order. Direct enzymatic hydrolysis of the H₂SO₄ presoaked biomass was found to give higher hexose yields of 6.0%–13.0%, but low pentose yields of 1.5%–3.0%.Higher H₂SO₄ concentration resulted in more hexose, but less pentose in enzymatic hydrolysis, while they exhibit good tendency in saccharin yields between four typical pairs.