用低能电子衍射研究Ag（001）表面吸附硒的表面结构

用低能电子衍射研究Ａｇ（００１）表面吸附硒的表面结构熊泽珍，刘秀文，白荣（电子科技大学材料科学与工程系成都６１００５４）关键词银吸附硒，表面结构，ＬＥＥＤ谱，能带理论引言Ｉｇｎａｔｉｅｖ等￣［１．２］已观测和计算了清洁Ａｇ（００１）表面吸附硒的ＬＥＥ...     

CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS I.POLY(P-PHENYLENE TEREPHTHALATE)

The morphology and crystal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin film melt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electron microscopy, electron diffraction and molecular modeling. The unit cell is monoclinic (P21/a space group) with parameters a =7.89, b = 5.49, c =12.65 A α= γ= 90°,β= 100.33°, density = 1.48 g/cm3, the a, b andβ values differing slightly from those reported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted [001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence was found for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220°C (up to 370°C) and CTFSP crystals polymerized at 300°C consisted of lamellae 100-200 A thick.     

EFFECT OF DRAWING ON MORPHOLOGY,STRUCTURE AND MECHANICAL PROPERTIES OF BLENDS OF A LIQUID CRYSTALLINE POLYMER AND MODIFIED POLY(PHENYLENE OXIDE)

Polymer strands with various draw ratios of a thermotropic liquid crystalline polymer(LCP) and modified poly(phenylene oxide) were prepared by drawing the melts leaving aslit die in open air. The morphology, structure and mechanical properties of the resultingstrands were studied as a function of LCP content and draw ratio. It was found that thethermal and mechanical properties of the matrix phase did not change dramatically withthe amount of LCP and draw ratio, but the orientation of LCP phase could be increasedwith draw ratio. The mechanical properties of the strands could be improved by moderatelydrawing the melts. Wide angle X-ray diffraction suggested that the improvement in tensilestrength of the strands was due to the resultant fibrillation of LCP phase and enhancedmolecular orientation. Morphological observation indicated that excessive drawing of thestrands could lead to the break down of the microfibrils of LCP and thus resulted in thedecrease of mechanical strength.     

EFFECTS OF SOLVENT TREATMENT ON SURFACE MORPHOLOGY AND COMPOSITION OF POLY(METHYL METHACRYLATE)-g-POLY(ETHYLENE OXIDE)

Surface morphology and composition of solution-cast films of poly(methyl methacrylate)-g-poly(ethylene oxide)(PMMA-g-PEO) were investigated by using XPS, DSC, SEM and contact angle measurement. The microphase separatedstructure of the copolymers was studied by TEM. Generally, for the same graft copolymer, the surface content of PEO orhydrophilicity can be as follows: Surface treated with petroleum ether or cyclohexane>surface untreated with solvent>surface treated with water or ethyl alcohol. Graft copolymer having longer PEO side chains and higher PEO content shows aseparated PEO phase with even a certain degree of crystallinity on the surface. PEO crystallinity was destroyed by water orethyl alcohol treatment, however, surface treatment with petroleum ether or cyclohexane favors the growth of PEO crystal.TEM shows that graft copolymers with longer PEO side chains (M_n of PEO, 3200) may readily undergo microphase separation and the shape and size of domains depend on the copolymer's composition.     

纳米二氧化硅粒子对聚氯乙烯膜的表面结构及浸润性能的调控作用

报道了一种简便的调控聚合物材料表面结构及浸润性能的方法.利用流延成膜和纳米二氧化硅粒子的印迹修饰作用,制备出3种具有不同表面结构的聚氯乙烯(PVC)膜,膜的浸润性能表现为与水的接触角从103°的疏水性变为65°的亲水性,再改变至130°的疏水性.扫描电镜结果表明印迹修饰后的PVC膜具有纳米和微米尺寸的凹凸表面结构.通过对比实验证实了溶剂氯仿和NaOH溶液并不影响膜表面的疏水性能.     

SURFACE STRUCTURE AND BULK PROPERTIES OF FLUORINATED POLY(ETHER URETHANE)S AND POLY(ETHER URETHANE) BLENDS

INTRODUCTIONPolyurethanes (PU) have been widely used for manufacturing medical devices because of their excellentmechanical properties and moderate biocompatibility[1]. Although polyurethanes used in applications requiringall of the above properties have been successful for short-term use, the problems of long-term thromboresistanceand biostability in a biological environment still remain unsolved[2,3]. A legitimate approach to improving theproperties of polyurethanes is introduction of f…     

制备方法对MoO_3／ZrO_2结构的影响及MoO_3／ZrO_2固体超强酸的结构特征 Ⅰ．ZrO_2的形态与样品比表面的研究

ＸＲＤ，ＤＴＡ，比表面测定等结果表明，制备方法对ＭｏＯ３／ＺｒＯ２结构有决定性影响．仲钼酸铵浸渍仅经干燥的Ｚｒ（ＯＨ）４再经高温焙烧所得团体超强酸ＭｏＯ３／ＺｒＯ２（Ⅰ）与浸渍晶态ＺｒＯ２所得部分氧化催化剂ＭｏＯ３／ＺｒＯ２（Ⅱ）的载体形态有明显不同．（１）ＭｏＯ３／ＺｒＯ２（Ⅰ）的比表面数倍于ＭｏＯ３／ＺｒＯ２（Ⅱ）；（２）ＭｏＯ３含量增加时，ＭｏＯ３／ＺｒＯ２（Ⅰ）的比表面逐步增大至一极大值再缓缓下降，而ＭｏＯ３／ＺｒＯ２（Ⅱ）的比表面随ＭｏＯ３含量增加而单调下降；（３）在ＭｏＯ３／ＺｒＯ２（Ⅰ）中，ＺｒＯ２以介稳四方相存在，而在ＭｏＯ３／ＺｒＯ２（Ⅱ）中则是稳定的单斜相．在此基础上研究了事先引入的活性组分在载体织构形成过程中的作用，包括延迟ＺｒＯ２晶化，阻碍晶粒长大及与之相关的相变等，并讨论了ＭｏＯ３／ＺｒＯ２（Ⅰ）中ＭｏＯ３最佳含量的科学含义．     

非溶剂添加剂对共聚砜铸膜液体系及膜性能与结构的影响

以含二氮杂萘酮结构的新型共聚砜为膜材料 ,通过浊点滴定法和特性粘数的测定研究了几种非溶剂添加剂对铸膜液体系的影响 .并由共聚砜 NMP 添加剂三组分相分离曲线数据计算了共聚砜的Θ溶剂中NMP与添加剂的比例 ,考察了添加剂EGME用量对共聚砜超滤膜结构和性能的影响 .发现当EGME NMP接近Θ组成时膜性能发生突变 ,在EGME NMP低于Θ组成时 ,膜的水通量随添加剂用量的增大而增大 ,截留率基本不变 .