铁路运营重载货车后既有钢桥疲劳寿命评估

针对我国铁路对重载运输的需求,对铁路货车轴重提高至270kN时,不同年运量等级下跨度64m下承式钢桁梁的疲劳寿命进行评估。基于当前的典型疲劳列车,通过替换重载货车的办法,制订270kN轴重疲劳列车;采用大型计算软件STAAD/PRO进行建模分析,得到重载疲劳列车经过桥梁时各关键构造细节的应力历程;采用自编雨流程序,得到相应应力频谱;根据Miner线性累积损伤法则,计算得到不同年运量条件下,桥梁各关键构造细节的剩余疲劳寿命。     

改进的灰色关联模型在工程评标中的应用研究

为改进评标过程中的主观性,基于AHP法和熵值法,对灰色关联度传统权重确定方法进行了改进,即把主观权重和客观权重相结合,既能满足决策者的主观愿望,又能充分利用客观信息.将该方法用于建设工程投标方案的评价中,计算出各方案的综合评价值,从而为投标单位的合理选择提供了科学依据.     

The structure,tensile properties and water resistance of hydrolyzed feather keratin-based bioplastics☆

Feather,as a by-product of the poultry industry,has long been treated as a solid waste,which causes environmental and economic problems.In this work,the hydrolyzed feather keratin(HFK)was extracted from the chicken feather using a cost-effective method of alkali-extraction and acid-precipitation by applying urea and sodium sulfide.The aim was development and characterization of the eco-friendly films based on the HFK with variable glycerol contents by a thermoplastic process.The thermal analysis showed that high temperature and high pressure improved the compatibility between the glycerol and the HFK molecules.Also it was shown that the addition of water is necessary in the hot-pressing process of films.The FT-IR analysis indicated that the formation of the new hydrogen bonds between HFK and glycerol.By increasing the glycerol content,the film tensile strength(σ_b)decreases from 10.5 MPa to 5.7 MPa and the solubility increases from 15.3% to 20.9%,while the elongation at break(εb)achieves the maximum value of 63.8% for the film with 35% glycerol.The swelling was just below 16.9%at 25 °C for 24 h,suggesting a good stability of the films in water.The water vapor permeability(WVP)varied between 3.02 × 10~(-10)g · m~(-2)· s~(-1)· Pa~(-1)and 4.11 × 10~(-10)g · m~(-2)· s~(-1)· Pa~(-1)for the films with 20% and40% glycerol,respectively.The HFK film was uniform,translucent and tough,which could be used in packaging and agricultural field.     

Aqueous PUA emulsion prepared by dispersing polyurethane prepolymer in polyacrylate emulsion

Waterborne polyurethane/polyacrylate (PUA) emulsions were prepared by dispersing polyurethane (PU) prepolymer in polyacrylate (PA) emulsion; therefore, the PU particles formed in the presence of PA nanoparticles. The particle size and its distribution of the composite PUA emulsion were determined by dynamic light scattering. The result shows that the average particle size increases initially and then decreases with increasing PA content, which is confirmed by transmission electron microscope characterization. The surface properties of PUA films were analyzed by water contact angle and atomic force microscope topography. It indicates that the water contact angle and the average roughness of the composite PUA films are larger than those of the PU film. Meanwhile, mechanical properties test, scanning electron microscopy, and thermogravimetric analyses disclose that the PUA films are characterized by enhanced tensile strength, rough fractured surface, and good thermal stability. The preparation method proposed in this article is an effective and convenient way to manufacture composite PUA emulsion. The composite PUA emulsion can be potentially used in coatings. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43203.     

Characterization of 3D elastic porous polydimethylsiloxane (PDMS) cell scaffolds fabricated by VARTM and particle leaching

In this study, elastic porous polydimethylsiloxane (PDMS) cell scaffolds were fabricated by vacuum‐assisted resin transfer moulding (VARTM) and particle leaching technologies. To control the porous morphology and porosity, different processing parameters, such as compression load, compression time, and NaCl particle size for preparing NaCl preform, were studied. The porous structures of PDMS cell scaffolds were characterized by scanning electron microscopy (SEM). The properties of PDMS cell scaffolds, including porosity, water absorption, interconnectivity, compression modulus, and compression strength were also investigated. The results showed that after the porogen–NaCl particles had been leached, the remaining pores had the sizes of 150–300, 300–450, and 450–600 μm, which matched the sizes of the NaCl particles. The interconnectivity of PDMS cell scaffolds increases with an increase in the size of NaCl particles. It was also found that the smaller the size of the NaCl particles, the higher the porosity and water absorption of PDMS cell scaffolds. The content of residual NaCl in PDMS/NaCl scaffolds reduces under ultrasonic treatment. In addition, PDMS scaffolds with a pore size of 300–450 μm have better mechanical properties compared to those with pore sizes of 150–300 and 450–600 μm. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42909.     

Thermal stability,flame retardance,and mechanical properties of polyamide 66 modified by a nitrogen–phosphorous reacting flame retardant

Flame‐retardant polyamide 66 (PA66) was prepared by the polymerization between PA66 prepolymer and N‐benzoic acid (ethyl‐N‐benzoic acid formamide) phosphamide (NENP). Compared with the pure PA66, the flame‐retardant PA66 exhibited better thermal stability, as indicated by thermogravimetric analysis results. The limiting oxygen index was 28% and the UL‐94 test results of the flame‐retardant PA66 indicated a V‐0 rating when the content of the NENP prepolymer was 5 wt %. The flammability and flame‐retardant mechanism of PA66 were also studied with cone calorimetry and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, respectively. The mechanical properties results show that the flame‐retardant PA66 resin had favorable mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43538.     

High‐performance polymer‐supported extractants with phosphonate ligands for scandium(III) separation

As the market demand for scandium has grown, a great deal of interest has been generated in its recovery. To substantially simplify the process and provide a green alternative for scandium separation, novel polymer‐supported extractants containing di(2‐ethylhexyl) phosphonate and bis(2,4,4‐trimethylpentyl) phosphonate, [D201][DEHP] and [D201][C272] are proposed because they demonstrate improved adsorption capacity and selectivity toward scandium(III). Scandium(III) adsorption is significantly affected by the solution pH, with the maximum adsorption occurring at a pH of approximately 0.78. The batch adsorption data fit well with the Langmuir isotherm and pseudo‐second‐order kinetic models. A combination of the Fourier transform infrared and XPS spectra suggest that the complexation of oxygen atoms in phosphate groups with scandium(III) is the predominant adsorption mechanism. Additionally, the two resins were used to recover scandium from leaching liquor of nickel laterite ore. [D201][DEHP] exhibits unusual selectivity for scandium and low competitive behavior with other metals, thus increasing its market potential. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2479–2489, 2016     

Syntheses and Characterization of Three Coordination Polymers of Zinc(II) and Cadmium(II) with Dicarboxylates and Bis(thiabendazole) Ligands

Three d ¹⁰ coordination polymers formulated as [Zn(L1)₂(mip)] _n (1), [Zn(L1)(2,6-ndc)] _n (2) and [Cd(L2)_0.5(bpdc)] _n (3) (L1 = 1,1′-(1,3-propanediyl)bis(thiabendazole), L2 = 1,1′-(1,6-hexanediyl)bis(thiabendazole), H₂mip = 5-methylisophthalic acid, 2,6-H₂ndc = 2,6-naphthalenedicarboxylic acid, H₂bpdc = 4,4′-biphenyldicarboxylic acid) were hydrothermally synthesized. Complexes 1–3 were characterized by elemental analysis, IR spectroscopy, X-ray powder diffraction analysis, and single crystal X-ray diffraction. Complexes 1 and 2 present different chain structures, both of them are extended into 2D supramolecular architectures via C–H···O hydrogen bonds, while 3 is a three-fold interpenetrating three-dimensional framework with binodal 4,4-connected mog topology. The thermal stability, UV–visible spectroscopy and luminescence properties of complexes 1–3 were also examined. Furthermore, complex 3 exhibits relatively positive catalytic activity towards the degradation of methyl orange in a Fenton-like process.     

Syntheses,Crystal Structures and Properties of Two Supramolecular Coordination Polymers with 2,6-Pyridinedicarboxylic Acids and 4,4′-Bis(imidazolyl)biphenyl

Two supramolecular coordination polymers, [Cu(PDA)(4,4′-bibp)]_n (1) and [Zn(PDA)(4,4′-bibp)]_n (2) (PDA = 2,6-pyridinedicarboxylic acid and 4,4′-bibp = 4,4′-bis(imidazolyl)biphenyl), have been obtained under hydrothermal conditions. The two polymers were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction analysis. The X-ray single crystal analysis revealed that two complexes exhibit different supramolecular architectures. The photocatalytic studies indicate complex 1 is a good candidate for the photocatalytic degradation of methylene blue, rhodamine B and methylene violet. The photoluminescence behaviour of complex 2 was also discussed.     

Preparation and characterization of hydrophilicity fibers based on 2-(dimethyamino)ethyl mathacrylate grafted polypropylene by UV- irradiation for removal of Cr(VI) and as(V)

The hydrophilic fibers based on 2-(dimethylamino)ethyl methacrylate (DMAEMA) which could remove Cr(VI) ions rapidly were prepared by UV-irradiation induced grafting of DMAEMA through pre-coating photoinitiator on the fibers and modifying with bromoethane(BE). The FTIR, FESEM, XPS, TG-DTG and contact angle spectra manifested that DMAEMA was grafted onto the surface of PP fibers and subsequently was quaternized. The maximum grafting degree (22.9 %) and exchange capacity of DMAEMA (1.2 mmol g^?1) was obtained when PP fibers was immersed in BP concentration of 0.3 % for 4 h, irradiated with the DMAEMA concentration of 100 % and irradiation time of 20 min, and then was modified with BE. The modified fibers of PP-g-DMAEMA with bromoethane were proved to remove Cr(VI) and As(V) with removal rate of 97.3 % and 96.2 % within 10 min, respectively. The prepared fibers have potential application for the removal of Cr(VI) and As(V) from wastewater highly and rapidly.