Properties of polyester-urethane elastomers and the chemical structure of the chains—I. Dependence of the glass temperature on the nature of the polymeric chain

Abstract It is well known that the properties of polymeric materials depend strongly upon their chemical structure. Other more specific factors that may be related to the chemical structure also determine the macroscopic behaviour of such materials, namely the relative position of the different segments of the polymeric chain, the molecular architecture (molecular weight distribution, branching, copolymer organisation, cross-linking extent, etc.), the crystalline environment and the pressure/temperature conditions. All these factors have a common impact in the material: they are strongly correlated to the mobility on the molecular level. That is why a huge amount of work has been devoted to the study of translational/rotational mobility that occurs within the polymeric chains. This review is intended to provide a brief survey on such kinds of mobilities, how they can be studied and what are their main characteristics. Examples on systems studied in our groups will be provided, obtained by dielectric and mechanical spectroscopies and differential scanning calorimetry. It will be mainly focused on molecular motions that occur in the solid phase (i.e., to temperatures up to the rubbery plateau). The dynamics in blends or copolymers will be avoided here, as they would deserve a special discussion in their own context. Special attention will be paid to the glass transition and the mobility that occurs below and above it. The dynamics that are observed in peculiar systems, such as semi-crystalline or liquid crystalline polymers, will be addressed.

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Chemical Structure Changes and Correlation Analysis of High Density Polyethylene after Natural and Xenon Aging

Materials Science Forum ◽

10.4028/www.scientific.net/msf.809-810.323 ◽

2014 ◽

Vol 809-810 ◽

pp. 323-329

Author(s):

Jun Jun Guo ◽

Hua Yan ◽

Zhi De Hu ◽

Jian Jian Yang

Keyword(s):

High Density Polyethylene ◽

Chemical Structure ◽

Natural Aging ◽

Chain Scission ◽

Attenuated Total Reflection ◽

High Density ◽

Polymeric Chain ◽

Unsaturated Compounds ◽

Leading Role ◽

Structure Changes

Elucidation of the chemical structure changes that take place of high density polyethylene (HDPE) used as rotational packaging case by attenuated total reflection infrared spectroscopy (ATR-FTIR), when natural aging of Lasa Tibet and xenon aging. The variations of carbonyl index (CI), hydroxyl index (HI), branching degree (N) and crystallinity (Xc) have been studied from qualitative and quantitative. Finally, the correlations between natural and xenon aging have been closely followed. It found that the oxidation and growth of unsaturated compounds play a leading role in the natural aging progress, but the polymeric chain scission is weak effect. However, the samples show a slower growth of unsaturated compounds and a sharp increase in polymeric chain scission after xenon aging. The CI, HI and N increased generally in a line fashion after natural and xenon aging while the Xc changes little.

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Inelastic Electron-Matter Interactions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070047 ◽

1978 ◽

Vol 36 (3) ◽

pp. 259-267

Author(s):

J. Silcox

Keyword(s):

Electron Microscope ◽

Energy Loss ◽

Chemical Structure ◽

Inelastic Electron ◽

Primary Concern ◽

Unique Probe ◽

Introductory Paper ◽

Elastic Processes ◽

Experimental Level ◽

Inelastic Processes

In this introductory paper, my primary concern will be in identifying and outlining the various types of inelastic processes resulting from the interaction of electrons with matter. Elastic processes are understood reasonably well at the present experimental level and can be regarded as giving information on spatial arrangements. We need not consider them here. Inelastic processes do contain information of considerable value which reflect the electronic and chemical structure of the sample. In combination with the spatial resolution of the electron microscope, a unique probe of materials is finally emerging (Hillier 1943, Watanabe 1955, Castaing and Henri 1962, Crewe 1966, Wittry, Ferrier and Cosslett 1969, Isaacson and Johnson 1975, Egerton, Rossouw and Whelan 1976, Kokubo and Iwatsuki 1976, Colliex, Cosslett, Leapman and Trebbia 1977). We first review some scattering terminology by way of background and to identify some of the more interesting and significant features of energy loss electrons and then go on to discuss examples of studies of the type of phenomena encountered. Finally we will comment on some of the experimental factors encountered.

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Chemical structure of diamond-like carbon thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010017668x ◽

1990 ◽

Vol 48 (4) ◽

pp. 710-711

Author(s):

N.-H. Cho ◽

K.M. Krishnan ◽

D.B. Bogy

Keyword(s):

Electrical Resistivity ◽

Chemical Structure ◽

Diamond Like Carbon ◽

Chemical Structures ◽

Sputtering Power ◽

Data Aquisition ◽

Equilibrium Phases ◽

Electron Energy Loss ◽

Power Densities ◽

Preparation Techniques

Diamond-like carbon (DLC) films have attracted much attention due to their useful properties and applications. These properties are quite variable depending on film preparation techniques and conditions, DLC is a metastable state formed from highly non-equilibrium phases during the condensation of ionized particles. The nature of the films is therefore strongly dependent on their particular chemical structures. In this study, electron energy loss spectroscopy (EELS) was used to investigate how the chemical bonding configurations of DLC films vary as a function of sputtering power densities. The electrical resistivity of the films was determined, and related to their chemical structure.DLC films with a thickness of about 300Å were prepared at 0.1, 1.1, 2.1, and 10.0 watts/cm2, respectively, on NaCl substrates by d.c. magnetron sputtering. EEL spectra were obtained from diamond, graphite, and the films using a JEOL 200 CX electron microscope operating at 200 kV. A Gatan parallel EEL spectrometer and a Kevex data aquisition system were used to analyze the energy distribution of transmitted electrons. The electrical resistivity of the films was measured by the four point probe method.

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Relationship of Chemical Structure of Chlorpromazine to its Liver-Sensitizing Action

Gastroenterology ◽

10.1016/s0016-5085(19)35576-3 ◽

1958 ◽

Vol 35 (1) ◽

pp. 16-24 ◽

Cited By ~ 9

Author(s):

Harry Shay ◽

Herman Siplet

Keyword(s):

Chemical Structure ◽

Relationship Of

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Potential Uses of Vinegar as a Medicine and Related in vivo Mechanisms

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000440 ◽

2016 ◽

Vol 86 (3-4) ◽

pp. 127-151 ◽

Cited By ~ 3

Author(s):

Zeshan Ali ◽

Zhenbin Wang ◽

Rai Muhammad Amir ◽

Shoaib Younas ◽

Asif Wali ◽

...

Keyword(s):

Chemical Structure ◽

Review Paper ◽

Heart Diseases ◽

Folk Medicine ◽

Active Role ◽

Current Review ◽

Different Types ◽

Positive Effect

While the use of vinegar to fi ght against infections and other crucial conditions dates back to Hippocrates, recent research has found that vinegar consumption has a positive effect on biomarkers for diabetes, cancer, and heart diseases. Different types of vinegar have been used in the world during different time periods. Vinegar is produced by a fermentation process. Foods with a high content of carbohydrates are a good source of vinegar. Review of the results of different studies performed on vinegar components reveals that the daily use of these components has a healthy impact on the physiological and chemical structure of the human body. During the era of Hippocrates, people used vinegar as a medicine to treat wounds, which means that vinegar is one of the ancient foods used as folk medicine. The purpose of the current review paper is to provide a detailed summary of the outcome of previous studies emphasizing the role of vinegar in treatment of different diseases both in acute and chronic conditions, its in vivo mechanism and the active role of different bacteria.

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