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101.
The multilamellar barrier materials based on the blends of high‐density polyethylene (HDPE) and copolyester (PETG) were prepared via melt extrusion, and poly(ethylene‐co‐acrylic acid) (EAA) as a compatibilizer was incorporated into the blends. A systematic investigation was carried out, with regard to morphology and properties. Scanning electron microscopy observation displayed the laminar morphology for the blends with the whole compositions, and the thinner laminas of the PETG phase formed in the HDPE matrix by incorporating EAA into the blends. In addition, the number and the size of the laminas of the dispersed phases were also dependant on the die temperature and screw speed, respectively. Evaluation of the mechanical properties demonstrated that incorporation of the EAA resulted in an improvement of the mechanical properties. These behaviors are attributed mainly to better adhesion and compatibility between HDPE and PETG, which has been confirmed by thermal analysis and the rheological properties. On the basis of these premises, it is reasonable to suggest that the improved barrier properties of the ternary blends with increasing concentration of the EAA be attributed to both the increase in the number of the laminas of the PETG and the decrease in their thickness, which prohibits the organic solvent molecules from entering into and permeating through the amorphous regions of the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3791–3799, 2006 相似文献
102.
基于唐家山堰塞坝溃决的实测数据,使用BREACH模型及中国水科院DB-IWHR模型,对唐家山堰塞坝溃决过程进行了反演分析,并对两种模型进行参数敏感性分析。研究结果表明:使用针对唐家山的参数,两种模型均可较好地反演唐家山溃决洪水的过程,BREACH模型的下游坡比和孔隙率是对结果影响比较敏感的输入参数;DB-IWHR模型在冲刷参数和下游水深计算两方面做了改善,较好地解决了这一问题;DB-IWHR提供了一个Excel格式的计算软件,数值分析稳定性好,使用简洁客观,可供类似堰塞湖应急处置时参考。 相似文献
103.
Liang Xu Lei Su Hongjie Wang Min Niu Lei Zhuang Kang Peng Xingyu Fan Hongfei Gao De Lu 《Journal of the American Ceramic Society》2022,105(8):5490-5500
Pursuing novel thermal barrier–coating materials with lower thermal conductivity and high-temperature stability can simultaneously improve the working efficiency and service temperature of a gas turbine. In this study, a series of high-entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 (RE = La, Nd, Sm, Gd, Dy, and Er) oxides were prepared though solid-state reaction. Through tuning the rare-earth cations, an order–disorder transition occurs from certain partially ordered weberite structure (C2221) to disordered defective fluorite structure (Fm m). All the high-entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 oxides possess low thermal conductivity in the range of 0.91–1.34 W m−1 K−1 at room temperature, which can be attributed to increased lattice anharmonicity and disorder, resulting in additional phonon scattering. Herein, we proved that the incorporation of heterovalent cations at B-sites in high-entropy A2B2O7 crystals is an effective strategy to reduce the thermal conductivity without compromising the decrease of oxygen vacancy. Moreover, the high-entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 oxides show the relatively higher thermal expansion coefficients of 10.3–10.7 × 10−6°C−1 and excellent phase stability at elevated temperatures. 相似文献
104.
In the field of biomaterials and biomedical devices, surface activation has been focused on creating functional groups capable of preferential adsorption of biologically active species (proteins, enzymes, cells, drugs, etc.). In this way an interface can be created between the synthetic material and the biological medium, with the aim of increasing the compatibility of the implant with the human organism. In our experiments a dielectric barrier discharge (DBD), in helium at atmospheric pressure, was used as the source of energy capable of creating active centers that render the functionalized surface favorable to immobilization of biological molecules. Retention of immunoglobulin (IgG) and heparin biomolecules on polyamide‐6 (PA‐6) surfaces after treatment by the DBD was analyzed by atomic force microscopy, adhesion evaluation, and measurement of the contact angle titration in order to assess this incorporation on the treated surfaces. The marked adsorption of the biomolecules on the active sites created by DBD on the exposed surfaces also was related to a complex set of processes, such as enhanced roughness, increased surface wettability, and modified distribution of cationic and anionic groups on the treated surfaces. All these factors could promote interfacial interactions between the specific groups of the biomolecules existing in the biological medium and the type of cationic and/or anionic groups present on the surface. The efficiency of the DBD treatment showed that the DBD technique is useful for preactivation of the polymer surface for immobilization of other biologically active species (such as drugs and enzymes). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1985–1990, 2003 相似文献
105.
Composite film structures of common plastic polymers including polypropylene (PP) or poly(vinyl chloride) (PVC) with whey protein isolate (WPI) coatings may be obtained by a casting method. Optical and surface properties of the resulting WPI‐coated plastic films, as affected by protein concentration and plasticizer type, were investigated to examine the biopolymer coating effects on surface modification with polymeric substrates of opposite polarity. The measured properties involved specular gloss, color, contact angle, and critical surface energy. Regardless of the substrates, WPI‐coated films possessed excellent gloss and no color, as well as good adhesion between the coating and the substrate when an appropriate plasticizer was added to the coating formulations. The protein concentration did not significantly affect gloss of WPI‐coated plastic films. Among five plasticizers applied, sucrose conferred the most highly reflective and homogeneous surfaces to the coated films. The WPI coatings were very transparent and the coated films with various protein concentrations and plasticizers showed no noticeable changes in color. Experimental results suggest that WPI coatings formulated with a proper plasticizer can improve the visual characteristics of the polymeric substrate and enhance water wettability of the coated plastic films. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 335–343, 2004 相似文献
106.
用吊片法和自制改进的最大泡压法分别测定了全氟庚氧基全氟亚乙基磺酸钾(C9FK)溶液的平衡和动态表面张力,计算得出该种表面活性剂形成胶束的标准热力学函数△Hmθ、△Smθ、△Gmθ分别为16.98 kJ/mol、218.29 J/mol·K、-48.22 kJ/mol。结合Word-Tordai方程,计算得到在不同条件下的表观扩散系数Da和吸附势垒Ea。实验证明,增大表面活性剂的浓度、降低温度、以及无机盐(NaCl)的加入都会使扩散系数减小,吸附势垒增大,从而不利于吸附的进行。当表面活性剂的浓度小于等于1×10-6 mol/L时,该体系属于扩散控制模型,而浓度大于 1×10-6 mol/L时,在吸附初期(t→O)属于扩散控制,后期均属于混合控制模型。 相似文献
107.
王琼华 《上海电力学院学报》2010,(7)
为了表征狭缝光栅自由立体显示器存在的左右眼视差图像的混叠程度,提出了立体图像串扰度C的概念。根据狭缝光栅自由立体显示器的结构和工作原理,应用几何光学知识,分析得出了立体图像串扰度C的计算公式,并给出了一个具体的狭缝光栅自由立体显示器的计算结果。通过观看实验,证明了所定义的立体图像串扰度C可以定量描述观看者在立体可视区域看到的立体图像的串扰程度。 相似文献
108.
孙小燕 《上海电力学院学报》2010,(1):22-25
用磷光材料Ir(ppy)3制备了高效率顶部发射绿色有机发光二极管(OLED),器件的结构为:ITO/Ag/NPB/Ir(ppy)3(5wt%):TPBI/TPBI/LiF/Al。研究发现与传统的无微腔结构器件相比顶部发射器件的性能有大幅度提高,其最大效率为18cd/A。通过使用F-P腔,器件的电致发光(EL)寿命由7.6μs降低为7.1μs,有效地缓解了效率随电流密度增大而下降的问题。顶部发射器件EL共振的主峰位于505nm处,发射光谱半峰宽(FWHM)窄化为23nm,色纯度为(x=0.122,y=0.671),发射光随探测角度变化较小。最后,分析了其瞬态光电性能变化原因。 相似文献
109.
在线性红利下将保单到达过程推广为Poisson过程,并通过添加Brownian运动来刻画保险公司不确定的收益和付款,建立线性红利下带干扰的复合Poisson风险模型.运用鞅方法得出了破产概率满足的Lundberg不等式和一般公式,并给出了生存概率满足的积分—微分方程。 相似文献
110.