LMPM/PP复合材料中PP的晶体形态与晶胞结构

本文用偏光显微镜观察了聚丙烯(PP)晶体的形态,用X射线衍射(WAXD)分析了低熔点金属(LMPM)与PP的复合材料(LMPM/PP)中PP的晶胞结构,用DSC测试研究了LMPM/PP复合材料中PP晶体的熔融过程.结果表明,LMPM的引入,使PP的晶粒变小,并能诱发β-晶体产生,但形态结构仍是球晶.随着LMPM用量增加,PP晶粒尺寸下降,β-晶型含量提高,PP的熔点升高,熔限变宽,晶体更不完善.     

X-ray Investigations of Shape Memory Alloys

The investigation aims to analyse the influence of different kinds of thermal treating on the structure of martensite. Maxima of the X-value are observed at 60–70 minutes for the sample aged at 200°C and 90 minutes for that aged at 375 °C and minima for Y after almost the same time. We consider that with these results the discussion on the processes occurring during short ageing times will be activated, because in the literature there is lack of such a results.     

The Structure of a Lyotropic Liquid Crystalline Phase that Orients in a Magnetic Field

Abstract

The structure of a lyotropic liquid crystalline phase with positive diamagnetic anisotropy (type I), that spontaneously orients in a magnetic field has been studied by means of water NMR quadrupole splittings, NMR diffusion and polarized absorption spectroscopy. It is concluded that this phase is built up of long rodlike aggregates. A preliminary study of a sample with negative diamagnetic anisotropy (type II) shows that this phase probably consists of lamellar aggregates. It is suggested that these phases are suitable as orientation matrices for studies of chromophores with polarized light spectroscopy.     

Self-Assembly and Phase Behavior of Short Chain Phosphonic Acid-Water Systems in a Wide Concentration Range Microscopic,NMR, and X-ray Diffraction Studies

The phase behavior of n-octane and n-hexane phosphonic acid-D₂O systems was studied in the concentration range from 0.1 to 90 wt.% and in a temperature range from 10° to 130°C by polarizing and dark field microscopy and by ¹H, ²D and, ³¹P NMR. Further, electron microscopy, X-ray diffraction and surface tension measurements were performed. For the first time, a widely spaced lamellar phase was observed over large concentration and temperature ranges in an essentially two-component system. By using the sonication or injection methods, unilamellar liposomes were obtained below 1 wt.%. At high temperatures, the clouding phenomenon was observed. The importance of hydrogen bond formation between polar groups for building up stable lamellae even at high dilution is stressed. The results are discussed with respect to some existing points of view concerning the possibility of lamellar structure formation from single short chain amphiphilic compounds including lipids.     

Quantitative Phase Analysis of Fine Crystalline Substances

The present paper contents the Alexander's and Klug's equation arranged for quantitative phase analysis of fine crystalline substances.     

NMR Investigations on Di- and Tri-Azanaphthalenes Oriented in Liquid Crystals

Proton NMR spectra of 1,3-diazanaphthalene and 1,2,4-triazanaphthalene have been investigated in the nematic phase of three liquid crystals. The spectral analysis provided direct dipole-dipole couplings which have been used to derive the molecular structure. Geometry of the phenyl ring in both the molecules deviates from the regular hexagonal structure. Signs of the order parameter of the largest magnitude are opposite in liquid crystals with positive diamagetic anisotropies.     

Investigations of the energy flow of X-ray wavefields in crystals

The energy flow of the X-ray wavefields in the Laue case of diffraction and its importance for X-ray topography and interferometry are discussed.     

X-ray structure and NMR assignment of 3,4-dimethylthioquinoline

The title compound (C₁₁H₁₁NS₂) is monoclinic:P2₁/c,a=15.200(4),b=14.644(4),c=10.098(3),Z=8. The structure was solved by direct methods, and refined to anR value of 0.047 with 2886 independent reflections. There are two nonequivalent molecules in the unit cell. BothS-methyl groups have different spatial orientation: the-methyl group side-chain is approximately coplanar with the pyridine ring and turned to the ortho-position, but -methyl group side-chain is turned over this ring. Both¹H and¹³C NMR spectra were assigned using 1D and 2D experiments. The NOE measurements are consistent with inter-proton distances from X-ray data.Part XV in the series of Azinyl sulfides.     

Electrooptic behaviour of a nematic MBBA layer with a thick interfacial surfactant layer

The electro-optic behaviour of MBBA nematic layers with various surfactants added of anionic, cationic, zwitterionic and non-ionic character and a considerable amount (2wt% to 8 wt%) was studied. The formation of surface-induced flexoelectric domains in all cases clearly showed that the anchoring of the liquid crystal layers has been weak. Such a weak anchoring can be explained with the formation of a perioidc (in the most simple case sinusoidal) MBBA-surfactant interface boundary with a mutual penetration of the liquid crystal and surfactant molecules with some gradient.     

Heights of Overlapping X-ray Reflections and Phase Analysis

The influence of reflections overlapping on the heights of their maxima is investigated using the Lorentzian profile approximation. This influence should be taken into account in automatic powder diffractometer programs of phase analysis based on the peak heights.     

Pretransition Phenomena in the Vicinity of Structural Phase Transition in Crystalline Sodium Carbonate

Crystallography Reports - Molecular relaxation processes in crystalline sodium carbonate Na2CO3 have been investigated using Raman spectroscopy. It is established that the structural first-order...     

High Pressure Investigations of the Phase Transitions in Cholesteryl Pentanoate and Cholesteryl Hexanoate

At high pressures too cholesteryl n-penta-noate (CH-5) and cholesteryl n-hexanoate (CH-6) exhibit only a cholesteric liquid crystalline phase. Our light reflection measurements up t o 2600 bars yield no indication of a pressure induced smectic phase which was suggested by Tikhomirova and Ginzberg' for CH-5 at about 850 bars and 120°C. The Obtained pressure (P_t)-temperature (T_t) phase diagrams show the expected widening of the cholesteric range with P_t and T_t. In the case of CH-5 the marked crystallization curve besides a melting curve could be explained by the transformation of the cholesteric into a metastable crystalline solid phase.     

Tilt Angle Determination of a Smectic C Phase by Field-Induced Freedericksz Transition and x ray Investigations

A smectic C liquid crystal exhibiting positive dielectric anisotropy was oriented with the director parallel to the glass substrates. When an electric field was applied normal to the director direction a dielectric reorientation (Freedericksz transition) occurred. Dissolving a dichroic dye in the smectic C phase and applying an electric field, a guest host effect similar to nematic phases was observed. From the dielectric reorientation the tilt angle of the smectic C phase was determined at different temperatures. The tilt angles obtained by the electrooptical measurements agree sufficiently with the values measured by x ray investigations.     

Experimental Investigations of the Conditions for the Formation of the Liquid Crystalline State of Polymers

The diagrams of state for concentrated PBG solution in coordinates relating volume fraction-geometric asymmetry and volume fraction-temperature are investigated. The order parameter for macromolecules in the anisortropic phase is dettermined. The experimental data compare with the existing theoretical models for th formation of the liquid crystalline state in solutions of stiff polymer molecule. It is shown that experimental data are in good quantitative agreement with the Flory's lattice model.     

Crystalline quality of lysozyme crystals grown in agarose and silica gels studied by X-ray diffraction techniques

The crystalline quality of hen egg white lysozyme (HEWL) crystals grown in agarose gels and in silica gels has been characterized by measuring resolution and mosaic spread. These crystals have been compared to solution grown ones. A quasi-plane-wave X-ray topography study has also been done on some crystals. The study concerns triclinic, monoclinic, orthorhombic and tetragonal forms of HEWL. One observes that the resolution is not really changed by gelling the growth medium, even for rather high gel contents (agarose 0.5% wt/wt). On the contrary, mosaicity, characterized through reflection profile recordings allows to differentiate crystals grown by different techniques: agarose gel grown crystals are, on average, better than solution grown ones but the best crystals are obtained in silica gel. X-ray topography confirms this result.     

不同X射线管电压下CsI和CsI(Tl)晶体的X射线辐照致发光

在室温(290 K)和低温(25 K)下,测量了从11～40 kV的一系列管电压下X射线激发纯CsI和CsI (Tl)晶体的辐照致发光(RL)谱.结果表明:在固定温度下,管电压变化后, 305 nm和340 nm的本征发光带和580 nm的非本征发光带的形状结构均不发生变化,只是其强度发生变化.对所测得的各发光带强度随管电压的变化关系用抛物线模型进行了拟合分析,得到了较好的结果.同时还发现纯CsI和CsI (Tl)晶体中所有本征RL发光带强度与X射线强度基本上成正比关系,而当管电压增加时,CsI (Tl)晶体中非本征发光带强度的增加速度慢于本征发光带.分析认为,290 K时这可能与样品中另一个位于400 nm左右的发光带有关;而在25 K时则可能和H心与VK心的竞争有关.     

Investigations of curved graphite crystals for the use as X-ray monochromators

X-ray investigations on curved graphite crystals for focusing monochromators for X-ray powder diffractometers are performed. The reflection power, avertences of crystal blocks, and radius of curvature of these crystals were determined by measuring rocking curves in dependence on the crystal position. The favourable application of curved graphite crystals as monochromators is shown by comparative X-ray measurements of selected reflexes.     

Investigations on Phase Diagrams of a Coil-Polymer (PC) and a Semiflexible Thermotropic Mainchain Polymer (PET-Co-PHB) in Solution

Cloud point curves of PET-co- PHB/PC/CHCl₃ mixtures show differences from Flory's calculations on coil-rod systems. An interpretation is attempted by calculating spinodals from Flory-Huggins interaction parameters obtained by vapour pressure osmometry.