Effect of Eu3+-doping on morphology and fluorescent properties of neodymium vanadate nanorod-arrays

Tetragonal structural (t-NdVO₄) nanorod-arrays were fabricated by simple one-pot hydrothermal method. The phase, morphology and microstructure of NdVO₄ were characterized by X-ray diffractometer, scanning electron microscope (SEM), transmission electron microscope (TEM), dispersive X-ray spectrometer (EDS) and selected area electron diffraction (SAED) techniques. t-NdVO₄ nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm, which grow orientally along the direction of (112) crystalline plane and self-assemble to form nanorod-arrays. The results show that Eu³⁺-doping interrupts the formation of NdVO₄ nanorod-arrays, and then leads to the red-shift of the strongest luminescence emission of Nd³⁺ transition from ⁴D_3/2 state to ⁴I_11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply. The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.     

In situ compatibilization of a polyethylene,polypropylene, and polystyrene ternary blend through Friedel–Crafts alkylation

The Friedel–Crafts alkylation reaction has been applied to reactively compatibilize a ternary blend of high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). The reactions were carried out in an internal mixer using varying catalyst concentrations. The resulting compatibilizer was quantified after Soxhlet extraction. In addition, p-substitution due to the grafting of alkyl groups onto the PS benzene ring was identified via nuclear magnetic resonance spectroscopy. The size of the PS domain in the reactive compositions is decreased by 80%. Moreover, the phase in which PS droplets were dispersed varied, that is, in the nonreactive blends they were found in the PP phase and in the reactive blends they shifted toward the HDPE phase. The effect of the compatibilizing agent was to improve the mechanical properties of the blend. Even with the lowest catalyst content, the properties of elongation-at-break, tensile strength, toughness, and elastic modulus showed improvements. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48295.     

Effect of morphology on shear viscosity for binary blends of polycarbonate and polystyrene

The structure and rheological properties of binary blends of polycarbonate (PC) and polystyrene (PS) were investigated using various PS samples with different molecular weights, namely PS1k (M_w = 1,000), PS53k (M_w = 53,000), and PS240k (M_w = 240,000). The blends with PS53k and PS240k show phase-separated structures, whereas the blend with PS1k is miscible. The shear viscosity decreases greatly on addition of PS53k and PS240k, especially at high shear rates, which would be a great advantage at processing operations. Because the nonlinear response occurs in the small strain region for multilayered films of PC and PS240k, the origin of the significant viscosity drop for the phase-separated system is interfacial slippage at the phase boundary.     

水泥回转窑系统固相中硫、碱分布特性研究

采用XRF、XRD与EPMA分析方法对取自某水泥厂生产线的几种试样(入预热器生料、入窑热生料、烟室结皮、窑皮、熟料)进行测试分析,研究硫、碱在水泥回转窑系统内固相中的分布特性.结果表明:回转窑内入窑热生料、烟室结皮以及过渡带区域窑皮中,硫、碱含量较高;且不同试样中硫、碱的存在形式也不一样,其中烟室结皮最为复杂.不同粒径大小的熟料,将硫、碱带出回转窑系统的情况存在着差异,大粒径熟料带出的钾、硫含量较小粒径熟料高出许多,但是钠含量相差不大,而且后者的晶体发育程度较好.     

Tribological and corrosion behaviors of fluorocarbon coating reinforced with sodium iron titanate platelets and whiskers

A series of sodium iron titanate (NFTO)–fluorocarbon composite coatings have been prepared with the liquid-phase blending method. The effects of two types of NFTO, NFTO platelets, and NFTO whiskers, on the tribological and corrosion behaviors of the composite coatings, are systematically studied. The results show that the addition of NFTO can significantly enhance the friction-reducing and wear resistance performances of the fluorocarbon coating. Under dry sliding, the minimum specific wear rate is 1.67 × 10⁻⁴ mm³/Nm for the platelet-filled composite coatings and 1.15 × 10⁻⁴ mm³/Nm for the whisker-filled composite coatings, respectively, showing a decrease of 83.5 and 88.6% than that of pure coating. Under a simulated seawater environment, the minimum specific wear rate is 5.44 × 10⁻⁵ mm³/Nm for the platelet-filled composite coatings and 0.84 × 10⁻⁵ mm³/Nm for the whisker-filled composite coatings, respectively, showing a decrease of 90.5 and 98.5% than that of pure coating. The morphologies of worn surfaces, wear debris, and transfer films are analyzed, and the corresponding wear resistance mechanisms are discussed. The electrochemical impedance spectroscopy certifies a remarkably improved corrosion resistance of the composite coatings which have been immersed in 3.5 wt % NaCl solution for 30 days. The composite coating reinforced with 7.5 wt % platelets shows the highest resistance of 256.3 × 10⁶ Ω·cm², approximately two orders of magnitude higher than that of pure coating. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48936.     

催化裂化催化剂形貌分析方法的建立

结合显微镜观察,通过分析毫米级颗粒、微米级Duke粒子及催化裂化催化剂,研究动态数字图像分析仪CamsizerX2分析颗粒形貌的合理准确性。考察分散方式、分散压力和记录颗粒数量因素的影响,建立了催化裂化催化剂球形貌分析方法。     

硅烷偶联剂对表面微坑复合PTFE的减摩及缓释性能影响研究

目的探究硅烷偶联剂对缸套表面微坑复合PTFE微粒的减摩和缓释性能的影响。方法利用激光刻蚀机在缸套表面加工不同参数的微坑,并依据摩擦系数对表面微坑参数进行优化。选取最佳表面微坑参数,进行加工,并机械涂覆经硅烷偶联剂修饰的PTFE,制备复合润滑结构。采取往复式摩擦磨损试验机对复合润滑结构的减摩性能进行分析。利用SEM和EDS研究摩擦副的表面形貌和成分,采用三维共聚焦显微镜研究微坑内PTFE的释放情况。结果在热压复合方法下,直径为0.4 mm、深度为120μm的微坑复合PTFE具有最佳的减摩效果。硅烷偶联剂的加入会进一步改善摩擦副之间的减摩性能,其摩擦系数为0.1248。与未处理缸套试样、微坑处理缸套试样、热压复合PTFE缸套试样进行对比,其摩擦系数分别降低了24.3%、18.8%和11.2%。另外,硅烷偶联剂还可以减缓表面微坑内PTFE的释放,延长作用时效,与热压复合方法相比,微坑内PTFE颗粒的释放速率约降低96.3%。结论复合润滑结构能够改善摩擦副之间的摩擦状况,其减摩和缓释机理是固体自润滑材料、表面微坑和硅烷偶联剂协同作用的结果。     

脉冲电沉积镍-铜合金

采用脉冲电沉积技术在304不锈钢表面制备Ni-Cu合金镀层,镀液组成和工艺条件为:NiSO4ꞏ6H2O 200g/L,CuSO4ꞏ5H2O 10 g/L,十二烷基硫酸钠0.2 g/L,柠檬酸钠80 g/L,糖精0.2 g/L,pH 4.0,温度25°C,搅拌速率30 r/min,平均电流密度40~120 mA/cm2,脉冲频率0~100 Hz,占空比20%~90%,时间30 min。研究了平均电流密度、脉冲频率和占空比对Ni-Cu合金镀层的元素组成、表面形貌和显微硬度的影响,得到较优的工艺参数为:平均电流密度40 mA/cm2,脉冲频率50 Hz,占空比60%。该条件下所得Ni-Cu合金镀层由质量分数分别为56.53%和43.47%的Ni和Cu组成,呈“菜花”状形貌,结晶细致、均匀,显微硬度为614.4 HV。     

聚乙烯管材耐慢速裂纹增长性能研究进展

简要介绍了聚乙烯管材发生慢速裂纹增长(SCG)的机理,并详细介绍了影响聚乙烯管材耐SCG性能的影响因素,包括系带分子(TMs)、界面相和无定形相的活动性,以及聚乙烯管材专用料的研发和熔融加工过程中的结构与形态控制研究。