Applied Mechanics and Materials Vols. 457-458

Abstract: As improvement of industry and society, some potential crisis happened in working and living environment is taken into account by human people. Meanwhile, different kinds of protective appliances develop rapidly, and composite boards with cushion and puncture-resistance property are required consequently. This study aims to develop a cushion/puncture-resistance PU foam protective composites. This paper used Polyol and Isocyanate to prepare porous PU foam composite via foaming and curing process. By changing foam density and addition amount, cushion and puncture-resistance property were tested and then evaluated to seek for PU foam composite with cushion and puncture-resistance property. Result shows that, when density was 80 kg/m³, PU foaming composite board had the optimum resilience rate of 44 %, lowest impact remaining load of 638 N and best puncture-resistance force of 138.3 N.

Abstract: Freeze-drying method can create three-dimensional, porous structure bone scaffolds, the pore size of which can be changed by a cross-linking agent. This study dissolves chitosan powder in a 1 v/v % acetic acid aqueous solution to form a 2 w/v% chitosan solution. The chitosan solution and a 4 w/v % gelatin aqueous solution are blended to form Chitosan/Gelatin mixture, after which the mixture is frozen at-20 °C for 1 hour, removed, and cross-linked with a 0.5 v/v % 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) solution for different durations. The cross-linked mixture is frozen at-20 °C for 1 hour and then freeze-dried for 24 hours to form Chitosan/Gelatin composite bone scaffolds. A stereomicroscope and a scanning electron microscopes (SEM) and Image Pro Plus are used to observe the surface and pore size of the bond scaffolds, and in vitro evaluates their biocompatibility. The experiment results show that resulting bone scaffolds possess a uniform pore distribution a desirable biocompatibility.

Abstract: Soilless culture mediums are able to increase the greening areas and decrease the amount of carbon dioxide (CO₂), which reduces the global temperature and the green house effect. The aim of this study is to explore effects of the content of low melting point polyester (LPET) fibers on the physical properties of the polyester (PET)/LPET nonwoven fabrics. PET fibers and LPET fibers are blended with various ratios, and made into PET/LPET nonwoven fabrics with a nonwoven process. The air permeability, water content, water retention, and pH value tests are performed on the resulting fabrics. The experiment results show that increasing LPET fiber content increases the air permeability and water content, but decreases the water retention. The LPET content does not have an influence on the pH value.

Abstract: This study polystyrene-b-poly (ethylene-r-butylene)-b-polystyrene (SEBS) elastomer to modify recycled polypropylene (RPP). Tensile strength test, impact strength test, and a polarized light microscope are used to evaluate the mechanical properties and spherulite morphology of the resulting RPP/SEBS polyblends. The experiment results show that with an increase in SEBS, tensile strength of the polyblends decreases from 29 MPa to 13 MPa. With the distribution of SEBS in RPP, the spherulite size of RPP decreases, but the impact strength significantly increases.

Abstract: The severe global climate changes result in consecutive torrential rains in rainy season, and causes water loss and soil erosion. For an effective water and soil conservation, geotextiles are commonly used in geotechnical engineering. Geotextiles should able to isolate soil, filter water, and reinforce the soil; therefore, the material for geotextiles should be acid-resistant and alkali-resistant, such as polypropylene (PP) and polyester (PET). This study uses PP fibers as the skin and PET plied yarns as the core to form PP/PET composite tubular knits on a cord knitting machine. The PET plied yarn is fed with a specified tensile strength, and only the tooth number of the drive gear varies. Mechanical property test results show that a drive gear of 30 teeth increases the tensile strength of the resulting tubular knits; however, with a drive gear of 35 teeth, the tensile strength decreases. An optimal core coverage occurs with a drive gear of 30 teeth.

Abstract: Geotextiles made of nonwoven fabrics can be used in different fields, such as groynes, dams, seawalls, revetments, dunes, and hillsides, and the structures of nonwoven fabrics can be changed accordingly. This study explores the influence of different content of Kevlar fibers on the mechanical and physical properties of Kevlar/Polyester (PET) complex nonwoven fabrics. As specified in a nonwoven fabric manufacturing process Kevlar fibers and PET fibers are blended with various ratios to form Kevlar/PET complex nonwoven fabrics, which are then tested for tear strength, air permeability, and water permeability. The experiment results show that increasing Kevlar fibers reduces the tear strength, air permeability, and water permeability.

Abstract: The polyfunctional organic compounds 2- hydroxymethyl -1,4- butanediol (trihydric alcohol) and toluene diisocyanate -2, 4- diisocyanate (TDI) were taken as the raw materials in this study. A polyurethane dendrimer was synthesized by utilizing the difference in the reaction activity of two isocyanate groups of TDI at different temperatures. The polymerization process conditions were studied. The addition polymerization of para-position NCO groups occurred at 50 °C, and that of ortho NCO groups occurred at 90 °C. According to the structure of the dendrimer synthesized, methyl orange was used as the guest molecule. Consequently, the aqueous methyl orange showed a phase transfer. With the increase of dendrimer concentration, the transfer rate of methyl orange increased.

Abstract: The paper studies the start-up of A/O bio-filter and seeks the reasonable index for the judgment of the start-up, providing the theory basis for the start-up of A/O bio-filter with silicon-based zeolite filter material. The study makes use of the natural start-up compound with inoculum start-up. The experiment analyzed the biofilm in the start-up of A /O bio-filter with silicon-based zeolite Filter Material by measuring the changes of ammonia, COD and biological phase adhering to silicon-based zeolite surface. Compared with the hypoxia microorganisms, aerobic microbial easy to culture. The start-up time of aerobic column is about 27 days, and the start-up time of anaerobic column is about 43 days.

Abstract: Under the condition that the temperature between 20 °C ~ 27 °C, in stable operation period, the effect of the anoxic and aerobic tanks which presented in municipal wastewater treatment using orthogonal experiment, and optimum conditions of A /O Biofilm Process of Silicon-based zeolite Filter Material were studied: the gas-water ratio 1:2, and the reflux ratio of digestive juice 1:2 and hydraulic retention time (HRT) for the 2h.Under this operating conditions, the removal rate of total nitrogen, phosphorus and ammonia nitrogen are respectively up to 73.57%, 64% and 85.28%. The concentrations of total nitrogen, phosphorus and ammonia nitrogen can be respectively reduced to 18.75mg/L, 1.06mg/L and 3.94mg/L in the ultimate effluent, which meet standard B of the first class in National discharge standard of pollutants for municipal wastewater treatment plant (GB18918-2002).

Abstract: The nanometric mixed crystals of rutile and anatase TiO₂ also could be prepared by homogeneous precipitation method using both TiCl₄ and TiCl₃ as titanium source. The effects of hard point, the ratio of TiCl₄ to TiCl₃and reaction time on the ratio of nanometer TiO₂ mix-crystals and photo catalysis were studied. The prepared samples were also characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and laser diffraction particle size analyzer. The results show that nanometer TiO₂ mix-crystal with good photo catalytic activity and storage stability can be obtained under the reaction conditions: The ratio of TiCl₄ to TiCl₃ is 4 to 1, pH=0.5, normal pressure, 95°C for 6 hours. The prepared nanometer TiO₂ mix-crystal consisting of anatase of 63.9 wt.% and rutile of 36.1 wt.% is circle with an average size of 25 nm.