POLYMERIZATION,MORPHOLOGY, AND CRYSTAL STRUCTURE OF POLY(p-BENZAMIDE)*

Isothermal polymerization of acetaminobenzoic acid at various temperatures in bulk and solution was monitored by acetic acid evolution. The polymerization took place initially in a homogeneous phase, but it soon changed to heterogeneous as the polymer precipitated from the melt or solution. The reaction course consisted of a short induction period, followed by a fast second-order reaction and a third slow, also second-order, reaction. The different polymerization rates in the second and third stage were due to polymer precipitation. The degree of polymerization of the resulting polymer was generally low, usually less than 5. The polymer was highly crystalline and prone to decarboxylation at temperatures above 300°C. Sample structure and morphology were characterized by various lamellar formations similar to those seen previously in many aromatic polyesters. Epitaxial solution polymerization/crystallization on mica resulted in three different morphologies, the most unique being shish kebab–type structures. Polybenzamide [poly(p-aminobenzoate)] is polymorphic; the most frequently seen hk0 electron diffraction patterns were similar to those from phase I of aromatic polyesters. Phase II of polybenzamide was seen only rarely. Simulation, using Cerius², suggested equal agreement with [001], [100], and fiber electron diffraction (ED) patterns and X-ray powder patterns for two different orthorhombic unit cells (a = 7.71, b = 5.35, c = 12.94 Å, ρ = 1.55 g/cm³); both have a parallel packing of adjacent molecules, but in one, successive phenyl rings along a given chain are parallel, while in the other they are twisted at ±30°. For both unit cells, neighboring molecules were displaced by ±0.14 Å along c to obtain better agreement with the observed patterns. The [010] patterns could distinguish between the two cells, but were not obtainable.

     

半导体激光对钝顶螺旋藻形态和生长的影响

采用半导体激光(波长650nm,功率40mW,功率密度13mW/cm²)辐照钝顶螺旋藻,辐照时间为30min、15min、8min.通过测定藻丝形态参量、叶绿素a、β胡萝卜素,研究半导体激光对藻生长的影响.结果表明:三个辐照时间都对藻丝形态产生影响,使藻丝长、螺旋数、螺旋长发生变化;30min辐照组抑制藻体叶绿素a、β胡萝卜素的合成,8min和15min辐照组促进藻体叶绿素a和β胡萝卜素的合成,β胡萝卜素增幅最高达17.9%.8min促长作用最明显,使比生长速率提高10.9%,15min略有促长作用,而30min则起抑制生长作用.     

利用扫描电镜和原子力显微镜测量纳米微孔阳极氧化铝膜

利用多孔型阳极氧化铝膜（PAA）制备纳米材料是近年来研究的热点之,对PAA的形貌进行准确的表征具有重要的意义,文章首先分析了传统扫描电镜（SEM）观测方法中镀膜工艺对样品和测量结果的影响,并提出了对镀膜过渡区进行观测的方案,然后着重研究了利用原子力显微镜（AFM）对PAA进行无损测量的方法,比较了不同测量模式下的测量结果,并利用Reiss模型对“针尖-样品卷积效应”进行了有效的修正,文章的研究结果不仅适用于多孔型阳极氧化铝膜这一研究领域,对于纳米多孔材料的测量也有普遍的参考价值。     

TC4钛合金及40Cr钢破片中绝热剪切带的TEM分析

 对含有约热剪切带（ASB）的TC4钛合金及40Cr钢破片作了扫描电镜（SEM）和透射电镜（TEM）分析。结果表明，TC4钛合40Cr钢中的ASB是由平均直径不到0.3 μm的微晶组成，微晶列有一定择优取向，电子衍射花样表现为不连续的环状。ASB内位错密度均很低，其邻近基体区含有高密度位错，ASB内没有察到相变发生。     

CORRELATION BETWEEN MORPHOLOGY AND MECHANICAL PROPERTIES OF DIFFERENT STYRENE/BUTADIENE TRIBLOCK COPOLYMERS: A SCANNING FORCE MICROSCOPY STUDY*

The morphology of different styrene/butadiene (SB) block copolymers with triblock architectures was investigated using tapping mode scanning force microscopy (SFM). Comparative analysis of the morphology of the samples at the polymer/substrate interface of solution-cast films and in bulk was performed. It was found that, besides the total phase volume ratio, the interfacial structure between the incompatible chains determines the phase morphology and mechanical properties of the investigated block copolymers. The asymmetric SBS triblock copolymer (φ_ps( 74 vol%) forms, as expected, a cylindrical morphology with hexagonally packed polybutadiene (PB) cylinders in the polystyrene (PS) matrix. Depending on the interfacial structure, block configuration, and the hard/soft phase ratio, other triblock copolymers (φ_ps( 74 vol% and 65 vol%) show lamellae and randomly distributed PS cylinders in a random styrene/butadiene copolymer S/B matrix, respectively.

     

离子能量和沉积温度对离子束沉积碳膜表面形貌的影响

利用质量分离的低能离子束沉积技术,得到了非晶碳膜.所用离子能量为50—200eV,衬底温度从室温到800℃.在沉积的能量范围内,衬底为室温时薄膜为类金刚石,表面非常光滑;而600℃下薄膜主要是石墨成分,表面粗糙.沉积能量大于140eV,800℃时薄膜表面分立着高度取向的、垂直衬底表面、相互平行的开口碳管.用高分辨电子显微镜看到了石墨平面的垂直择优取向,离子的浅注入和应力是这种优先取向的主要机理. 关键词： 非晶碳 表面形貌 质量分离低能离子束     

活性炭对苯蒸汽吸附分离过程的实验研究

本文选用活性炭对苯蒸汽进行了动态、静态吸附性能实验,研究了苯蒸汽在不同系列活性炭上的吸附、脱附性能以及活性炭微孔结构对吸附性能的影响。结果表明:苯蒸汽在活性炭上的吸脱附性能明显与吸附剂的比表面、孔容、孔径与孔径分布直接相关。     

绕水翼片状空化流动结构的数值与实验研究

采用数值与实验相结合的方法研究了水翼片状空化流动结构.实验采用高速录像技术观察了片状卒泡形态,应用LDV测量了翼型周围的湍动能和速度分布;采用N-S方程和基于空泡动力学方程的空化模型计算了绕水翼片状空化流场.结果表明:在片状空化阶段,翼型吸力面上附着很薄的一层透明空泡,空泡彤态呈现于指状;随着空化数的减少,空泡尾部水汽交界面相互作用增强,并且空泡尾部出现大的旋涡,影响了空泡尾部区域压力和速度分布,片状空泡尾部的水汽混合区出现不稳定现象,同时存在小的空泡团脱落.数值模拟得到的水翼片状空化流动现象和实验观察到的结果基本一致,验证了计算模型和数值方法的可靠性.     

MORPHOLOGIES OF MELT-CRYSTALLIZED THIN FILMS OF NYLON-6, NYLON-6,6, AND THEIR BLENDS AS REVEALED BY TRANSMISSION ELECTRON MICROSCOPY

Thin films of nylon-6 (N6), nylon-6,6 (N66), and their blends (N6/N66 = 70/30, 50/50, and 30/70) were prepared by casting from solution (1.0 wt%) in formic acid under ambient conditions. The dried films were melted at 260°C or 280°C and then isothermally crystallized at 200°C. Morphological observations and selected-area electron diffraction (SAED) by transmission electron microscopy (TEM) of the resulting films revealed the following results: All specimen films (N6/N66 = 100/0, 70/30, 50/50, 30/70, and 0/100) had fibrillar entities that were undoubtedly crystalline judging from SAED and dark-field (DF) imaging. Some of the fibrillar entities were constituents of a spherulite or a sheaflike structure (namely, an immature spherulite). To delete the “memory” of the structures of the N66 component that were formed in as-cast films, the films have to be melted at 280°C. As to isothermal crystallization of the blends at 200°C after melting at 280°C, it is postulated that the N66 component first starts to crystallize, and then the N6 one starts to crystallize afterward.     

XAFS研究Ni-P和Ni-Ce-P超细非晶合金的退火晶化

采用原子配位分布函数为Gaussian函数Ｐ_G和指数函数P_E直积的非 对称模型进行拟合计算,XAFS定量地研究化学还原法制备的Ni-P和Ni-Ce-P超细非晶合金大 无序度体系中Ni原子的局域环境结构随退火温度升高而产生的变化.结果表明Ni-P和Ni-Ce-P 原样的Ni-Ni配位的平均键长Ｒ_j、配位数N、热无序度σ_T、结构无 序度σ_S分别为0271nm,100,00060nm,0028n 关键词： XAFS Ni-P Ni-Ce-P 超细非晶合金 局域结构     

Ba_xWO_3的微波合成、晶体结构和超导电性研究

以分析纯的BaCO3、WO3以及W粉为原料,通过混合微波方法合成了钡物青铜BaxWO3(0.14≤x≤0.25).样品的晶体结构为正交和四方两相共存,随着x的增加正交相的衍射峰逐渐减弱,而四方相的衍射峰呈现出增强的趋势.当x从0.14增加到0.25时,电阻率ρ下降了约两个数量级,且在x=0.2附近发生了从半导体到金属的转变.交流磁化率测量显示Ba0.21WO3在Tc=2.4K时发生了超导转变.     

TBP色层分离－ICP／AES法测定锆铀铒合金中十七个微量杂质元素和铒

本法对锆铀铒合金中十七个微量杂质元素和铒的测定进行了较系统的实验研究。取样１００ｍｇ时，Ａｌ、Ｃａ、Ｃｏ、Ｃｒ、Ｃｕ、Ｆｅ、Ｍｇ、Ｍｎ、Ｍｏ、Ｎｉ、Ｐｂ、Ｓｎ、Ｔａ、Ｔｉ、Ｖ、Ｙ和Ｚｎ的测定范围为３０～３２００μｇ／ｇ，Ｅｒ为０．２～３．２％，回收率为９４～１０８％，ＲＳＤ（ｎ＝８）为０．２～２．１％。     

傅里叶变换显微红外光谱法研究羟自由基与红细胞膜脂和膜蛋白二级结构的作用机制

利用傅里叶变换显微红外光谱法和计算机辅助解析法研究了羟自由基作用于红细胞后膜蛋白二级结构的变化规律及羟自由基对红细胞膜脂损伤的作用机理。结果表明，由于羟自由基的攻击，导致表征蛋白质二级结构的α－螺旋的含量发生变化；自由基损伤３０分钟后，放置３小时其蛋白结构仍不能恢复；由于自由基的过氧化反应，膜脂磷氧双键ＯＰ（νｐ＝０）、ＯＣ双键及ＣＣ双键的含量均改变。     

固体高分辨NMR研究PPU/PMAs,AB-交联聚合物中的分子运动和相容性

本文使用固体高分辨NMR测量了PPU/PMAs,AB-交联聚合物中PPU的侧甲基的¹³C自旋-晶格弛豫时间(T₁)。使用内旋转运动的平均谱密度函数分析了PPU侧甲基的内旋转和PMA的侧基的多重内旋转运动。结果表明PMA中的侧基距主链越远,其旋转速度越快并且PPU侧甲基的内旋转速度随ABCP中PMA侧链长度增加而变快。还使用质子的T_1ρ和T₂及自旋扩散研究了体系的相容性和相行为。得到了有关相应尺度下的每相的组成和软相微区尺度的信息。     

磁场诱导Gd5Ge4体系的低温输运跳跃和相分离研究

报告了作者对Gd_5Ge_4合金样品进行了磁化和电输运测量的研究结果,实验表明,磁化强度随外磁场的增加而出现台阶式跳跃,磁转变的可逆性与温度存在有密切的关联.在由磁场导致的磁转变附近电阻率随着磁场的增加亦表现出台阶式磁电阻现象,并在不同温区表现出正负不同的磁电阻效应,4.2K时呈现正磁电阻效应,而在16和20K时呈现出负磁阻效应,即铁磁相的阻值小于反铁磁相的阻值.结果证明了在Gd_5Ge_4中存在的典型相分离特征,从而在磁场诱导下发生了反铁磁到铁磁的转变,并对这种奇异磁电阻效应的物理机制进行了讨论.     

1H NMR研究β-环糊精与环氧氯丙烷共聚物的反应机理和分子链结构

β-环糊精(cyclodcxtrin)与环氧氯丙烷(Epichlorohydrin)一个系列的共聚物获得,¹H NMR以D₂O或DMSO-d₆为溶剂的测定,其谱峰被归属.共聚合反应机理为以羟基和环氧基为活性中心的亲核取代.当环氧氯丙烷:β-环糊精=n ≤ 3时,聚合物分子链呈现以β-环糊精母体为中心的线状或低枝化状链结构;当n ≥ 5时,分子链出现交联网络结构.n越大(n ≤ 12),分子量越急剧增加,其交联度也越大.     

TIME-RESOLVED SAXS/WAXS STUDY OF PHASE BEHAVIOR AND CRYSTALLIZATION IN POLYMER BLENDS

Real-time SAXS and WAXS patterns have been simultaneously obtained during isothermal melt-crystallization of blends of low-molecular-weight poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA). The analysis of results shows that the originally homogeneous, single-phase polymer blend separates into two phases. The PMMA molecules diffuse from the blend and form completely segregated regions while PEO starts to crystallize. The first and dominating effect at the beginning of crystallization is the formation of unstable lamellae of nonintegrally folded chains (NIF). The real-time crystallinity and density of the PEO crystalline phase in absolute units were obtained from the time-resolved SAXS/WAXS results. The structure development proceeds in two steps. A very fast evolution of PEO crystals from the melt starts to crystallize in disordered NIF lamellae with thick amorphous interlayers and with a lower density of crystalline phase. The steep growth of crystallinity and crystalline density mean quick thickening of crystalline part of lamellae and improvement of their crystalline structure. In the second step, the structure of the crystalline phase gradually improves and crystallinity grows very slowly. The recrystallization of NIF lamellae into extended chain lamellae (EC) and lamellae with once folded chains (1F) proceeds during both stages of crystallization.     

非晶态Cu_(56)Zr_(44)合金的结构及其等温退火晶化过程的研究

利用X射线衍射技术、差示扫描量热分析技术和透射电子显微镜研究了非晶态Cu56 Zr4 4合金的结构及其等温退火条件下的晶化过程 .实验结果表明 ,非晶态Cu56 Zr4 4合金在室温下的短程结构类似于硬球无规密堆积分布 .在70 3K过冷液相区内等温退火时发现 ,当退火时间为 3min时 ,晶化产物主要为Cu8Zr3相 ;当退火时间为 6min时 ,Cu8Zr3相完全消失 ,而Cu1 0 Zr7相大量析出 ;当退火时间达到 3 0min以上时 ,其晶化产物转变为Cu1 0 Zr7,CuZr2 ,Cu8Zr3等多种化合物 .由此提出了非晶态Cu56 Zr4 4合金等温退火晶化过程的扩散机理 .