新型轮胎结构的现状与发展

通过回顾轮胎发展历史,分析了以斜交轮胎和子午线轮胎为代表的传统轮胎的主要结构特点和存在的缺陷,说明新型轮胎亟待发展,并且综述了国内外出现的具有代表性的新型轮胎产品,包括非充气轮胎和新型充气轮胎两类,分别讨论了它们的结构特点和相比于传统轮胎所具有的独特优势,为未来轮胎的发展方向提供参考。与传统轮胎相比,非充气轮胎普遍具有安全、节能、环保和易维护的特点,而新型充气轮胎的开发则是基于其应用场景,在传统轮胎的基础上进行的改进。     

Different variation behaviors of resistivity for high-temperature-grown and low-temperature-grown p-GaN films

Two series of p-GaN films grown at different temperatures are obtained by metal organic chemical vapor deposition(MOCVD). And the different variation behaviors of resistivity with growth condition for high- temperature(HT)-grown and low-temperature(LT)-grown p-GaN films are investigated. It is found that the resistivity of HT-grown p-GaN film is nearly unchanged when the NH_3 flow rate or reactor pressure increases. However, it decreases largely for LT-grown p-GaN film.These different variations may be attributed to the fact that carbon impurities are easy to incorporate into p-GaN film when the growth temperature is low. It results in a relatively high carbon concentration in LT-grown p-GaN film compared with HT-grown one. Therefore, carbon concentration is more sensitive to the growth condition in these samples, ultimately,leading to the different variation behaviors of resistivity for HT- and LT-grown ones.     

Output light power of InGaN-based violet laser diodes improved by using a u-InGaN/GaN/AlGaN multiple upper waveguide

The upper waveguide(UWG) has direct influences on the optical and electrical characteristics of the violet laser diode(LD) by changing the optical field distribution or barrier of the electron blocking layer(EBL). In this study, a series of In GaN-based violet LDs with different UWGs are investigated systematically with LASTIP software. It is found that the output light power(OLP) under an injecting current of 120 mA or the threshold current(Ith) is deteriorated when the UWG is u-In_(0.02)Ga_(0.98)N/GaN or u-In_(0.02)Ga_(0.98)N/Al_xGa_(1-x)N(0 ≤ x ≤ 0.1), which should be attributed to small optical confinement factor(OCF) or severe electron leakage. Therefore, a new violet LD structure with u-In_(0.02)Ga_(0.98)N/GaN/Al_(0.05)Ga_(0.95)N multiple layer UWG is proposed to reduce the optical loss and increase the barrier of EBL. Finally,the output light power under an injecting current of 120 mA is improved to 176.4 mW.     

丁二烯/苯乙烯/4-乙烯基吡啶共聚物蒙脱土嵌入混杂材料的研究

用聚合物乳液与蒙脱土的水分散体共混共凝的方法制备混杂材料.在混合过程中乳胶粒与蒙脱土晶层相互穿插,用盐酸絮凝,带正电的共聚物能够嵌入带负电的蒙脱土层间.萃取实验发现在混杂材料中蒙脱土吸附了大量的共聚物,说明蒙脱土晶层与共聚物之间存在静电吸附作用.XRD实验发现在混杂材料中蒙脱土的晶层结构发生了膨胀,并且变得混乱,而在共混物中蒙脱土晶层结构几乎不变.用TEM观察在混杂材料中蒙脱土晶层均匀分散于共聚物基体中,蒙脱土的层间距大于6nm.共聚物嵌入蒙脱土的层间,受到蒙脱土晶层的限制作用,共聚物的T_g发生了变化.交联以后的混杂材料的性能比共聚物有了较大的提高,蒙脱土晶层在共聚物基体中起到很好的补强作用.     

石墨烯/橡胶纳米复合材料

石墨烯具有极高的力学性质和导电/导热性质,在橡胶复合材料中具有广阔的应用前景.本文首先简要综述了石墨烯的制备和功能化,而后重点介绍了石墨烯/橡胶复合材料的制备方法、性能及相关的结构-性能关系研究的现状,并对石墨烯/橡胶复合材料研究的挑战和机遇进行了展望.     

橡胶材料科学研究的现状与发展趋势

正橡胶在三大高分子材料中由于具有不能被其它材料替代的独一无二的高弹性,被称为具有战略地位的材料,在国民经济和国防军工中有着十分广泛的应用。中国已连续多年在世界橡胶耗量和轮胎产量排行榜上位居第一。2012年,橡胶工业总产值已占我国GDP的1.67%,全球三分之一的轮胎制造于中国。在这样的一种形式下,应《高分子通报》的邀请,想出一期关于橡胶材料研究进展的专刊,反映一下近     

THE HOLDER CONTINUITY OF A CLASS OF 3-DIMENSION ULTRAPARABOLIC EQUATIONS

We obtained the Cα continuity for weak solutions of a class of ultraparabolic equations with measurable coeffcients of the form
δt u = δx（a（x, y, t）δx u） ＋ b0（x, y, t）δxu ＋ b（x, y, t）δyu, which generalized our recent results on KFP equations.     

STUDIES ON THE ELECTROANALYTICAL CHEMISTRY OF RARE EARTHS——THE ADSORPTIVE-COMPLEX WAVE OF THE COMPLEXES OF N, N'-DI-(2-HYDROXY-5-SULPHOPHENYL)-C-CYANFORMAZAN (DSPCF) AND LIGHT RARE EARTH ELEMENTS

The sensitive adsorptive-complex wave of the complexes formed by light rare earth elements and DSPCF is studied in this paper. The electroactivities of the complexes of light (La-Eu) and heavy rare earth elements (Gd-Lu), are quite different, so we can determine a certain light rare earth element or the total amounts of light rare earths without separating them from heavy rare earths. The mechanism of the adsorptive-complex wave and the reason why heavy rare earths could not form the electroactive complexes have been studied as well.     

关于半线性椭圆方程正解的唯一性

本文讨论方程正解的唯一性 作者证明了若f(u)=-u+u~p,则存在ε~*>0,使当10,使当|ε|<ε~*时,方程(Ⅰ)的正解是唯一的。     

GaN-based violet laser diodes grown on free-standing GaN substrate

A violet laser diode (LD) structure is grown on a free-standing c-plane GaN substrate and 4~μ m× 800~μ m ridge waveguide LDs are fabricated. The electrical and the optical characteristics of LDs under different facet-coating and chip-mounting conditions are investigated under pulse mode operation. The active region temperatures of p-side up and p-side down mounted LDs are calculated with different injection currents. The calculated thermal resistances of p-side up and p-side down mounted LDs are 4.6~K/W and 3~K/W, respectively. The threshold current of the p-side down mounted LD is much lower than that of the p-side up mounted LD. The blue shift of the emission wavelength with increasing injection current is observed only for the LD with p-side down mounting configuration, due to the more efficient heat dissipation.