Abstract: In ocean science research, it often requires the integrity of the gas content in samples of seawater. The gas-tight deep-sea water sampler (GTWS) based on pressure self-adaptive equalizer (PSAE) can satisfy the requirement very well. The PSAE is required to achieve a reliable dynamic sealing in deep sea. The general O-ring is difficult to meet this requirement. The polytetrafluoroethylene (PTFE)-coated O-ring is chosen as the sealing parts. The finite element analysis (FEA) software ANSYS is used to analyze the contact pressure of the PTFE-coated O-ring in different conditions, that is, analyze the GTWS’s gas tightness theoretically. Combine with the sea trial results, the feasibility and reliability of the PTFE-coated O-ring in deep-sea dynamic sealing in PSAE can be prove both in theory and practice.
Abstract: Amphiphilic diblock copolymers based on methoxy polyethylene glycol (MePEG), 1, 6-hexanediol and maleic anhydride with different molar composition were synthesized by solution polycondensation. Self-assemble behavior of amphiphilic diblock copolymer in different solvents by dialyzing technique was discussed. The micelle morphologhy was observed by TEM. It was found that well core-shell MePEG1900/Polyester 2162 copolymer nanoparticles can be formed by self-assemble in acetone solution. In addition, the size of nanospheres measured using dynamic light scattering exhibited a narrow monodisphere size distribution and an average diameter in the ranger of less than 200nm.
Abstract: High speed steel (HSS) with controlled micropores was prepared via vacuum sintering process, using the mixture of stearic acid, TiH2 and CaCO3 compound as pore-forming agent. A self-made vacuum high pressure infiltration furnace was used to infiltrate the preform with 60Pb40Sn40-15Ag-0.5RE solid lubricants to create self-lubrication composite where both solid lubricant phase and matrix phase were interpenetrating throughout the microstructure. Effects of pore-forming agent on micropore structure and porosity of the prepared microporous HSS preforms were investigated. The scanning electron microscope (SEM) observation was applied to the test samples and it revealed that the micropores of the microporous materials exhibited a uniform distribution and the apertures were of almost same size in principle. The friction and wear behaviors of the composite sliding against ZrO2 ceramic under a load of 50 N at 600 °C were investigated using a pin-on-disk wear tester and the results showed that this kind composite possessed excellent high temperature self-lubrication properties.
Abstract: High performance trend of plastics has become a hot spot of current research. Select bisphenol A dianhydride and bisphenol A diamine with excellent water resistance as the reactant monomers to obtain anhydride-terminated polyimide with very high molecular weight by two-step polymerization, graft the active radicals of acyl caprolactam using the activity of anhydride and obtain PI modified nylon resin by polymerization.When the system temperature is above 160 °C and the added modifiers are greater than 10%, the system viscosity increases very fast; when the system temperature reaches 140 °C and the added modifiers are at 5%, the system viscosity increases very slowly. It is proved that the reaction in each above step is successful through infrared analysis. The mechanical properties of modified PI nylon increases with the increase of consumption and molecular weight of polyimide, when the molecular weight is selected to be about 8000~10000 and the adding amount is 10wt%~15 wt%, the tensile strength reaches over 85MPa, the notch impact strength is increased to 19.6kJ.m-2 and the elongation at break reaches 18%, which are remarkably better than general engineering plastics.Through microscopic analysis, the molecules of polyimide does not enter crystallization phase of nylon resin, but forms compact lamellar crystals existing in nylon matrix.
Abstract: The structures subjected to large displacement under ground motion may be severely influenced by the structural second-order effects. This paper studied the dynamic second-order effects of the single-degree-of-freedom (SDOF) system under earthquake ground motions. The following achievements have been made: (1) the stiffness reduction coefficients considering and effects under static and dynamic analysis were deduced; (2) through numerical analysis, the accuracy of the formulas was verified.
Abstract: Based on thermodynamic analysis, the reduction and volatilization of magnesium in ludwigite were studied using carbothermal reduction-nitridation method. The experimental result show that the total mass loss rate of samples increase with temperature rising, which the maximum is 52.88 wt% in the range from 1440°C to 1470°C. Magnesia in ludwigite was reduced and volatilized as gaseous magnesium vapour in the process of carbothermal reduction, and its mass loss rate go up to 98.138%. Part of the volatilized matter formed white powder deposited at the opening of furnace tube and adhered to tube wall together with boride/silicon volatilized. It was proved that there is volatilization of MgO from ludwigite in the process of carbothermal reduction-nitridation.
Abstract: Natural rubber latex (NRL) modified by holgonated addition with trichlorobromomethane was prepared. The thermal properties of modified NRL were analyzed by thermogravimetric analysis (TG/DTG),differential scanning calorimetry (DSC) and dynamic mechanical analysis(DMA). The results showed that the thermal stability of modified NRL was lower than NRL and the thermal degradation of modified NRL was two-stage decomposition. With increasing of stress frequency, loss modulus and storage modulus of latex increased,while loss modulus and storage modulus of modified latex decreased,compared with NRL.
Abstract: This is the first time, prepared fiber-tourmaline nano powder use of Fiber-tourmaline. Vinyl acetate, fiber-tourmaline nano powder and EDTA as raw material, use micro-polymer chemistry laboratory equipment, preparation of the fiber-tourmaline/PVA spinning solution. The first time, prepared Fiber-tourmaline/PVA composite nanofibers, use of micro-polymer processing equipment—— electrospinning machine. The samples were characterized and tested the performance of its release anions. Analysis the effects of the fiber-tourmaline powder quantity on the properties of nano-fibers, and to explore the best tourmaline content.
Abstract: With the consumption of fossil fuels and their serious impact on the environment, countries in the world are looking to the development of wind resources and the selection of material and the molding process in wind turbine blade have also put higher requirements. Multi-axial warp knitted fabrics become the good carrier of wind turbine blade with its structural diversity, comprehensive performance, good formability and permeability, etc.