Some New Compositions Based on Condensation Rubbers

1950 ◽  
Vol 23 (3) ◽  
pp. 608-614
Author(s):  
D. A. Harper ◽  
W. F. Smith ◽  
H. G. White
Keyword(s):  
Cellulose Acetate ◽  
Dibasic Acid ◽  
Linear Polymers ◽  
Rubber Industry ◽  
Polyvinyl Formal ◽  
Major Interest ◽  
Acetate Mixture ◽  
Important Branch ◽  
Polymeric Plasticizer ◽  
High Polymers

Abstract By the condensation of a dibasic acid and direactive alcohol or amine, linear polymers are produced. Under certain conditions rubbery polymers are obtained, and a number of condensation rubbers with outstanding physical properties have been described. One of these, a diisocyanate-modified polyester amide (Vulcaprene-A) has been found to be compatible with nitrocellulose, polyvinyl formal, cellulose acetate, degraded vegetable tanned leather, gelatin, and glue. These mixtures can be vulcanized by formaldehyde-liberating agents used to cure Vulcaprene, and in most cases the curing reaction appears to take place not only with the Vulcaprene but with other high polymers. Combinations of Vulcaprene and cellulose acetate and of Vulcaprene and degraded leather are of great interest to the leather cloth industry, as they can be spread on to cloth to give coatings with outstanding flex and abrasion resistance. The Vulcaprene-cellulose acetate mixture is of value also as an abrasion-and flex-resisting coating for rubber proofings to give products which, while cheap to produce, are likely to give superior service to prewar leather cloths. This type of coating can be applied also to paper. The diisocyanate modified polyester amide behaves not only as a novel vulcanizable polymeric plasticizer, but, in combination with these high polymers, gives new products of major interest to an important branch of the rubber industry.

Infra-Red Spectra of Rubber and High Polymers

1941 ◽  
Vol 14 (3) ◽  
pp. 572-579
Author(s):  
W. C. Sears
Keyword(s):  
Methyl Methacrylate ◽  
Fair Agreement ◽  
Chain Molecules ◽  
Rubber Industry ◽  
Vulcanized Rubber ◽  
Gutta Percha ◽  
Infra Red ◽  
Related Compounds ◽  
Long Chain ◽  
High Polymers

Abstract The rubber industry is interested in all methods for studying the structure of highly polymerized substances. Infra-red spectroscopy has been recognized by recent workers as a possible means for determining the valence forces in long chain molecules. Accordingly, the infra-red spectra of rubber and related compounds have been measured by several workers. An investigation of rubber, gutta percha, indene, polyindene, styrene, polystyrene, polyvinylacetate and polyvinylchloracetate has been carried out by Stair and Coblentz. Later Williams measured natural and vulcanized rubber, rubber hydrochloride, isoprene, styrene and polymerized butadiene in the region between 2.5µ and 9µ, but his spectra of rubber did not agree with that of Stair and Coblentz. Williams and Taschek reported that the bands in rubber become broader with increasing stretch. Recently a rough survey of the infra-red transmission of rubber, Pliofilm, Vinylite XYSG, Shawinigan V-15, polystyrene, methyl methacrylate polymer and Cellophane has been made by Wells. The Raman data of rubber obtained by Gehman and Osterhof are in fair agreement with the infra-red results of Stair and Coblentz.

A standard for transmission electron spectroscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 530-531 ◽  
Author(s):  
Dennis Maher ◽  
David Joy ◽  
Peggy Mochel
Keyword(s):  
Thin Films ◽  
Electron Spectroscopy ◽  
Host Lattice ◽  
Single Element ◽  
Multicomponent Systems ◽  
Transmission Electron ◽  
Major Interest ◽  
Standard Specimens ◽  
Forms Of Carbon ◽  
Electron Energy Loss

A variety of standard specimens is needed in order to systematically investigate the instrumentation, specimen, data reduction and quantitation variables in electron energy-loss spectroscopy (EELS). Pure single element specimens (e.g. various forms of carbon) have received considerable attention to date but certain elements of interest cannot be prepared directly as thin films. Since studies of the first and second row elements in two- or multicomponent systems will be of considerable importance in microanalysis using EELS, there is a need for convenient standards containing these species. For many investigations a standard should contain the desired element, or elements, homogeneously dispersed through a suitable matrix and at an accurately known concentration. These conditions may be met by the technique of implantation.Silicon was chosen as the host lattice since its principal ionization energies, EL23 = 98 eV and Ek = 1843 eV, are well removed from the K-edges of most elements of major interest such as boron (Ek = 188 eV), carbon (Ek = 283 eV), nitrogen (Ek = 400 eV) and oxygen (Ek = 532 eV).

Cellulose Acetate Reverse Osmosis Membrane Structure

1972 ◽  
Vol 30 ◽  
pp. 528-529
Author(s):  
H. K. Plummer ◽  
E. Eichen ◽  
C. D. Melvin
Keyword(s):  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Membrane Structure ◽  
Freeze Drying ◽  
Dense Layer ◽  
Water Removal ◽  
Reverse Osmosis Membrane ◽  
Correct Interpretation ◽  
Electron Image ◽  
Scanning Electron

Much of the work reported in the literature on cellulose acetate reverse osmosis membranes has raised new and important questions with regard to the dense or “active” layer of these membranes. Several thickness values and structures have been attributed to the dense layer. To ensure the correct interpretation of the cellulose acetate structure thirteen different preparative techniques have been used in this investigation. These thirteen methods included various combinations of water substitution, freeze drying, freeze sectioning, fracturing, embedding, and microtomy techniques with both transmission and scanning electron microscope observations.It was observed that several factors can cause a distortion of the structure during sample preparation. The most obvious problem of water removal can cause swelling, shrinking, and folds. Improper removal of embedding materials, when used, can cause a loss of electron image contrast and, or structure which could hinder interpretation.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Bayesian removal of noise for increased sensitivity in vector pattern recognition lattice imaging of interfaces

1993 ◽  
Vol 51 ◽  
pp. 994-995
Author(s):  
L. Fei ◽  
P. Fraundorf
Keyword(s):  
Pattern Recognition ◽  
Perfect Crystal ◽  
Unit Cell ◽  
Ion Milling ◽  
Beam Radiation ◽  
Major Interest ◽  
Unit Cells ◽  
Mapping Process ◽  
Increased Sensitivity ◽  
Electron Microscopes

Interface structure is of major interest in microscopy. With high resolution transmission electron microscopes (TEMs) and scanning probe microscopes, it is possible to reveal structure of interfaces in unit cells, in some cases with atomic resolution. A. Ourmazd et al. proposed quantifying such observations by using vector pattern recognition to map chemical composition changes across the interface in TEM images with unit cell resolution. The sensitivity of the mapping process, however, is limited by the repeatability of unit cell images of perfect crystal, and hence by the amount of delocalized noise, e.g. due to ion milling or beam radiation damage. Bayesian removal of noise, based on statistical inference, can be used to reduce the amount of non-periodic noise in images after acquisition. The basic principle of Bayesian phase-model background subtraction, according to our previous study, is that the optimum (rms error minimizing strategy) Fourier phases of the noise can be obtained provided the amplitudes of the noise is given, while the noise amplitude can often be estimated from the image itself.

On the surface tension of directed linear polymers

1989 ◽  
Vol 50 (6) ◽  
pp. 599-608 ◽  
Author(s):  
V.B. Priezzhev ◽  
S.A. Terletsky
Keyword(s):  
Surface Tension ◽  
Linear Polymers
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