The Chromatography of Rubber Solutions

1939 ◽  
Vol 12 (4) ◽  
pp. 762-773 ◽  
Author(s):  
Giampietro Cajelli
Keyword(s):  
Elastic Properties ◽  
Potassium Hydroxide ◽  
The Other ◽  
Precipitation Method ◽  
Insoluble Residue ◽  
Fractional Precipitation ◽  
Micellar Structure ◽  
X Ray ◽  
Colored Product ◽  
Considerable Doubt

Abstract In the opinion of Pummerer, there is considerable doubt about the homogeneity of the fractions obtained by fractional precipitation of rubber from dilute benzene solutions, both with respect to the size of the molecules and to the state of aggregation. Based on the results of x-ray measurements of fibrous substances, to which type stretched rubber belongs, Meyer and Mark have advanced the hypothesis of the existence of chains of primary valences and of a micellar structure. PURIFICATION OF RUBBER There are four important and at the same time essentially different ways of carrying out the difficult process of purifying rubber. According to Harries, acetone extraction gives a colored product and leads to profound changes in the elastic properties. Staudinger adopted the method described by Wildmann in 1911, which involves the use of a mixture of acetone and chloroform. On the other hand, Pummerer and Koch used the method of fractional precipitation; the rubber after severe mastication was extracted with acetone, was dissolved in benzene, the liquid was allowed to stand for several weeks, the solution was decanted from the insoluble residue and was fractionally precipitated by alcohol and acetone. More recently this same method has been perfected by Pummerer and Meidel, and by this means a fraction of crystallized rubber was isolated from the mother liquors of the fractional precipitation. Finally Pummerer and Koch have purified rubber by treatment with an alkali, combining the precipitation method with the use of a solution of potassium hydroxide in methanol. Later this method was modified by Pummerer and Pahl. The use of latex in place of crude rubber is the most important development in obtaining a satisfactory product. De Vries and Beumée-Nieuwland have described in detail some results obtained with fresh latex. The total-rubber obtained by the methods just described contains, according to the quality and the age of the sample of latex, from 0.1 to 0.4 per cent of nitrogen which cannot be removed by washing, even when this is exhaustive.

Catalytic Decomposition of Energetic Liquid Solution Over Various Types of Hexaaluminate Catalysts

2020 ◽  
Vol 20 (11) ◽  
pp. 7114-7118
Author(s):  
Youngmin Choi ◽  
Sujeong Heo ◽  
Munjeong Kim ◽  
Jeongsub Lee ◽  
Young Chul Park ◽  
...  
Keyword(s):  
Catalytic Decomposition ◽  
Liquid Solution ◽  
The Other ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Heat Treated ◽  
Powdered Catalyst ◽  
Co Precipitation

A hexaaluminate support was prepared by a co-precipitation method, and a metal (Cu, Pt, or Ir) was impregnated on the support to prepare a powdered catalyst. After that, organic and inorganic binders were added to the powdery catalyst and then pellets were formed. The so-formed catalysts were heat-treated at 1200°C, and their physicochemical properties were analyzed by N2-adsorption, X-ray diffraction (XRD), X-ray fluorenscence (XRF), and scanning electron microscopy (SEM). The decomposition activity of the catalysts on an ammonium dinitramide (ADN)-based liquid propellant was evaluated repeatedly, and the effects of catalyst composition and morphology on low temperature decomposition activity and durability were investigated. It was confirmed that the Cu-hexa-pellet, Pt-hexa-pellet, and Ir-hexa-pellet catalysts could be recovered and reused as a catalyst for decomposition of an ADN-based liquid monopropellant. The initial activity and the thermal stability of the Cu-hexa-pellet catalyst for the decomposition of ADN-based liquid monopropellants were better than for the other catalysts. The better activity of the Cu-hexa-pellet catalyst seems to be because the dispersion of the copper was higher than the metal dispersion in the other two catalysts.

Isoprene and Rubber. Part 28. The Fractionation and Cracking of Hydrorubber

1932 ◽  
Vol 5 (2) ◽  
pp. 131-135 ◽  
Author(s):  
H. Staudinger ◽  
W. Schaal
Keyword(s):  
Carbon Tetrachloride ◽  
Small Molecules ◽  
The Other ◽  
No Decomposition ◽  
Fractional Precipitation ◽  
Micellar Structure ◽  
Ethereal Solution ◽  
Carbon Tetrachloride Solution ◽  
Rubber Part ◽  
The Individual

Abstract The Fractionation of Hydrorubber According to the investigations of Geiger, treatment of rubber with hydrogen in the presence of nickel at 270° brings about a reduction with simultaneous cracking of the macromolecules of the rubber. The hemi-colloidal hydrorubber thus formed ought not to consist of uniform long molecules, but of a mixture of homologous polymers; because in other similar cases mixtures of homologous polymers were obtained when macromolecular substances are decomposed, e. g., in the acetolytic decomposition of polyoxymethylenes and of cellulose. According to the views of Pummerer, on the other hand, if rubber consists of relatively small molecules, there would be no decomposition by cracking during its reduction, but only a saturation of individual primary valence chains with breaking up of the micellar structure, with formation of a hydrorubber whose molecules are uniformly long. Pummerer and Koch believed that they had obtained such a substance. To prove whether hydrorubber consists of a mixture of homologous polymers, it was split up into five fractions by fractional precipitation with alcohol from its ethereal solution, and the viscosities of the individual fractions were determined in 0.5 molar carbon tetrachloride solution (Table I).

An X-Ray Investigation of Crystallinity in Rubber

1939 ◽  
Vol 12 (4) ◽  
pp. 706-718
Author(s):  
S. D. Gehman ◽  
J. E. Field
Keyword(s):  
Crystalline Structure ◽  
Polymeric Materials ◽  
The Other ◽  
X Ray Diffraction ◽  
Random Orientation ◽  
Chain Molecules ◽  
Micellar Structure ◽  
X Ray ◽  
Recent Developments ◽  
Long Chain

Abstract The crystalline structure which rubber exhibits under certain circumstances has come to be regarded as associated with a secondary or micellar structure of long chain molecules. The exact mechanism by which the localized ordered regions appear is a speculative subject in recent developments of the micellar theory of long chain polymeric materials. The views of various workers on this subject have been summarized by other authors. The crystalline structure of rubber displays varying degrees and types of orientation of the crystal units, depending on the conditions under which crystallization occurs. The amorphous x-ray diffraction pattern of unstretched rubber is shown in Figure 1, the unoriented crystalline diagram for frozen rubber in Figure 2. When crystallization is induced by stretching, the crystallites are aligned along the axis of stretching, giving the fiber diagrams of Figures 3 and 4. In this case there is random orientation of the other two axes of the crystallites. “Higher orientation,” in which all three axes of the crystallites are aligned, gives the diagram of Figure 15 and can be secured with suitable dimensions of the stretched piece.

Synthesis of Silica-Potassium-Nitrogen from Carbamide and Potassium Silicate by CO2 Precipitator

2019 ◽  
Vol 966 ◽  
pp. 77-82
Author(s):  
Ketut Sumada ◽  
Srie Muljani ◽  
Caecilia Pujiastuti
Keyword(s):  
Ir Spectra ◽  
Potassium Hydroxide ◽  
Potassium Hydroxide Solution ◽  
Silicate Solution ◽  
Potassium Silicate ◽  
Precipitation Method ◽  
Precipitation Process ◽  
X Ray ◽  
Hydroxide Solution ◽  
Potassium Silicate Solution

Potassium silicate is well known as a fertilizer and source of silica for plants growth. This study aims to infiltrate nitrogen from carbamide (urea) into potassium silicate solution to produced silica potassium nitrogen (Si-K-N) matrix by precipitation method using CO2 as precipitator. Potassium silicate in the range of 3-8% SiO2 was obtained by extracting silica from geothermal sludge using potassium hydroxide solution. Carbamide is added to the potassium silicate solution allowed by mixing and flowing of CO2 gas in reactor glass. The result of IR spectra indicated the presence of N-H groups, potassium and silica in the gel matrix produced from precipitation process while no N-H group appears in the gel matrix produced from precipitation in the absence of carbamide. X-ray fluorescence showed the composition of the product Si-K-N in the range of 40 to 50 %SiO2 and in the range of 50 to 60 %K2O.

A Possible Nanoreactor: CaFe-L(ayered)D(ouble)H(ydroxide) with Intercalated Cinnamate Derivatives

2012 ◽  
Vol 730-732 ◽  
pp. 65-70 ◽  
Author(s):  
David Srankó ◽  
Szabolcs Muráth ◽  
Monika Sipiczki ◽  
Maria Szabó ◽  
Ákos Kukovecz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Spatial Arrangement ◽  
The Other ◽  
Precipitation Method ◽  
X Ray ◽  
Host Materials ◽  
Interlayer Region ◽  
Co Precipitation ◽  
Scanning Electron

The synthesis and characterisation of various organic-inorganic nanohybrids are reported in this contribution. The host material was Ca3Fe-LDH prepared by the co-precipitation method.E-cinnamate, E-4-nitrocinnamate orE-2,5-difluorocinnamate anions were the guests. Successful intercalation occurred through the introduction of the guest anion into the interlayer region of the host materials with the dehydration-rehydration method. The obtained nanohybrids were studied by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray fluorescence (EDX) coupled to the SEM instrument and infrared spectroscopy (IR). These methods were used on one hand to prove that intercalation was successful and for the characterisation of the substances on the other. Molecular modelling was used for visualising the possible spatial arrangement of the organic anions.

Effect of pH in Morphological Properties of Brushite Microstructures Synthesized by Precipitation Method

2020 ◽  
Vol 12 (3) ◽  
pp. 400-406
Author(s):  
Néstor Méndez-Lozano ◽  
Miguel Apátiga-Castro ◽  
Eric M. Rivera-Muñoz ◽  
Alejandro Manzano-Ramírez ◽  
Miguel Ocampo-Mortera ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Trabecular Bone ◽  
Organic Phase ◽  
Potassium Hydroxide ◽  
Potassium Phosphate ◽  
The Other ◽  
Morphological Properties ◽  
Precipitation Method ◽  
Synthesis Process ◽  
Crystalline Growth

Brushite microstructures with different morphologies were synthesized by precipitation method using a mixture of calcium lactate, potassium phosphate and potassium hydroxide as precursors. Potassium hydroxide was variation factor in synthesis process. This factor has an influence on morphology of nanostructures, changing from microplates to microfibers. On the other hand, bioceramic composites were obtained with brushite microstructures, using a mixture of brushite powders and gelatin. The amount of gelatin was added in different proportions. Brushite microplates and microfibers, with lengths in the order of micrometers, were obtained; the surface of microstructures is smooth and with well-defined edges. According to studies by XRD and FTIR, microstructures show a preferential crystalline growth. For bioceramic composites an effect of brushite microstructures was observed in compression test. Compounds with a greater amount of organic phase and microfibers show a greater resistance as compared to those formed by microplates. This value is in the range of human trabecular bone. This work presents a new route of synthesis to control morphology of brushite microstructures, as well as an improvement in mechanical properties of based brushite composites.

Microchemical imaging in biomedical research

1992 ◽  
Vol 50 (2) ◽  
pp. 1118-1119
Author(s):  
P. Ingram
Keyword(s):  
Data Analysis ◽  
Electron Probe ◽  
The Other ◽  
X Ray ◽  
Cell Element ◽  
Physiological Information ◽  
Functional States ◽  
Elemental Maps ◽  
Electron Energy Loss ◽  
Secondary Ion

It is well established that unique physiological information can be obtained by rapidly freezing cells in various functional states and analyzing the cell element content and distribution by electron probe x-ray microanalysis. (The other techniques of microanalysis that are amenable to imaging, such as electron energy loss spectroscopy, secondary ion mass spectroscopy, particle induced x-ray emission etc., are not addressed in this tutorial.) However, the usual processes of data acquisition are labor intensive and lengthy, requiring that x-ray counts be collected from individually selected regions of each cell in question and that data analysis be performed subsequent to data collection. A judicious combination of quantitative elemental maps and static raster probes adds not only an additional overall perception of what is occurring during a particular biological manipulation or event, but substantially increases data productivity. Recent advances in microcomputer instrumentation and software have made readily feasible the acquisition and processing of digital quantitative x-ray maps of one to several cells.

Acalypha Indica mediated MgO NPs: A novel approach in greener route with its antibacterial activity against pathogens

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Kavipriya K C ◽  
Sudha A P ◽  
Sujatha K ◽  
Sowmya Lakshmi K
Keyword(s):  
Antibacterial Activity ◽  
Metal Oxides ◽  
Bacterial Species ◽  
Magnesium Nitrate ◽  
Precipitation Method ◽  
Average Crystalline Size ◽  
Face Centered Cubic ◽  
X Ray ◽  
Novel Approach ◽  
Acalypha Indica

The interest in miniaturization of particles revealed the hidden applications of metal oxides. The potential applications of the particles may vary when the size of the particle is reduced. One of the alternative routes to the conventional approach is the use of plant extract for the synthesis of metal oxides NPs. In the framework of this study, the ecofriendly MgO nanoparticles were synthesized using Acalypha Indica leaf extract,functioning as reducing and capping agent by co-precipitation method. The predecessor taken here was Magnesium Nitrate. The biologically synthesized MgO NPs were characterized by various techniques like X ray diffraction(XRD), Fourier Transform infrared spectroscopy(FTIR), Scanning electron microscope (SEM) with Energy Dispersive X-ray spectroscopy(EDX) profile and its antibacterial activity is evaluated against causative organisms. XRD studies confirmed the face centered cubic crystalline structure of MgO NPs and the average crystalline size of MgO NPs calculated using Scherer’s formula was found to be 13 nm. FTIR spectrum shows a significant Mg-O vibrational band. Purity, surface morphology and chemical composition of elements were confirmed by SEM with EDX. The SEM result shows the fine spherical morphology with the grain size range between 43nm to 62nm. Antimicrobial assay of MgO NPs was examined against gram positive and negative bacteria. Appreciated activity was observed on the Staphylococcus aureus bacterial species. In general, the renewed attempt of this facile approach gave the optimum results of multifunctional MgO NPs.

Appraisal of innovative phytosynthetic CdO NPs from leaf extract of Ocimum Sanctum and their bactericidal activity against different strains

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Aarth R ◽  
Sudha A P ◽  
Sujatha B ◽  
Sowmya Lakshmi K
Keyword(s):  
Leaf Extract ◽  
Cadmium Oxide ◽  
Morphological Properties ◽  
Precipitation Method ◽  
Ocimum Sanctum ◽  
Oxide Nanoparticles ◽  
Average Crystalline Size ◽  
Face Centered Cubic ◽  
Bacterial Strains ◽  
X Ray

The phytosynthesis of n-type Cadmium Oxide Nanoparticles reduces the toxicity of the substance and makes it Eco-friendly. This Eco-friendly biosynthesis of CdO NPs was synthesized for the first time from the Queen of herbs, Ocimum Sanctum (holy basil).The biosynthesized Cadmium oxide was prepared using Ocimum leaf extract as a reductant and Cadmium Chloride and hydroxide as cadmium and oxide source materials by Co- Precipitation method. Thus obtained Cadmium Oxide Nanoparticles were characterized by different techniques such as X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM),Energy dispersive X-ray spectroscopy(EDS) to study the structural and morphological properties. XRD pattern exhibited the formation of face centered cubic structure of CdO NPs with an average crystalline size of 11.5nm .The chemical bond formation of CdO NPs were confirmed by FTIR spectrum in the range of (400-4000cm-1). The SEM micrographs revealed the predominant formation of Cauliflower shape with a particle size in the range of 61-142nm. The high purity of the biosynthesized nanoparticles were confirmed by EDS analysis. Further it was tested against gram positive and gram negative bacterial strains and showed significant antibacterial activity. This biosynthetic research study opens an innovative window to progress our understanding of how CdO NPs shows resistance to different bacterial strains.

The Electron Effect of Aromatic Group: Control Conformation of 2-Aromatic Cyclododecanone Derivatives

2020 ◽  
Vol 24 (10) ◽  
pp. 1139-1147
Author(s):  
Yang Mingyan ◽  
Wang Daoquan ◽  
Wang Mingan
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
The Other ◽  
Repulsive Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Effect ◽  
Group Control

2-Phenylcyclododecanone and 2-cyclohexylcyclododecanone derivatives were synthesized and characterized by 1H NMR, 13C NMR, HR-ESI-MS and X-ray diffraction. Their preferred conformations were analyzed by the coupling constants in the 1H NMR spectra and X-ray diffraction, which showed the skeleton ring of these derivatives containing [3333]-2-one conformation, and the phenyl groups were located at the side-exo position of [3333]-2-one conformation due to the strong π-π repulsive interaction between the π- electron of benzene ring and π-electron of carbonyl group. The cyclohexyl groups were located at the corner-syn or the side-exo position of [3333]-2-one conformation depending on the hindrance of the other substituted groups. The π-π electron effect played a crucial role in efficiently controlling the preferred conformation of 2-aromatic cyclododecanone and the other 2-aromatic macrocyclic derivatives with the similar preferred square and rectangular conformations.

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