Preparation, Vulcanization, and Characterization of Syndiotactic Trans-1,2-Polypentadiene

1970 ◽  
Vol 43 (4) ◽  
pp. 771-777
Author(s):  
G. S. Fielding-Russell ◽  
G. H. Smith
Keyword(s):  
Physical Properties ◽  
Spectroscopic Analysis ◽  
Crosslinking Agent ◽  
Catalyst System ◽  
Published Data ◽  
Monomer Mixture ◽  
Physical Measurements ◽  
Structural Differences ◽  
Reported Data

Abstract The polymerization, vulcanization, and some physical properties of two syndiotactic trans-1,2 polypentadienes (polypiperylenes) are described. Spectroscopic analysis indicated a significant (≈22%) cis-1,4 structure in the polymer prepared with the Et2AlCl/Co (AcAc)3 catalyst system which, although not in agreement with previously published data, is complementary to recently reported data. It is thought that the presence of water in the catalyst solvent or monomer mixture is responsible for the cis-1,4 content. Water appeared not to influence the Et2AlCl/Co(Octoate)2 polymerization in the same way: a greater than 95% trans-1,2 structure was obtained. Physical measurements on the vulcanizates reflected the structural differences. The copolymer vulcanizate, ≈22% cis-1,4 and ≈78% trans-1,2 structure, was more highly crosslinked than the polymer vulcanizate containing no detectable 1,4 structure. The relative levels and temperature location of the rubbery modulus and the Tg's and loss processes, respectively, are related to the 1,4 content: the vulcanizate containing 1,4 structure shows a higher Tg and rubbery modulus than the vulcanizate containing no detectable 1,4 structure. The inference is that the open copolymer presents a less sterically hindered path to the unsaturation for the bulky crosslinking agent and is therefore more susceptible to vulcanization, giving a tougher rubber that may also be reinforced by crystallization of the cis-1,4 units.

Preparation and Characterization of Crosslinked Latex Nanoparticles by Differential Microemulsion Polymerization

2013 ◽  
Vol 832 ◽  
pp. 759-762
Author(s):  
N.F. Hassmoro ◽  
Mohamad Rusop ◽  
Saifollah Abdullah
Keyword(s):  
Spin Coating ◽  
Crosslinking Agent ◽  
Butyl Methacrylate ◽  
Particle Sizes ◽  
Microemulsion Polymerization ◽  
Monomer Mixture ◽  
Spherical Image ◽  
Glycol Dimethacrylate ◽  
Coating Method

The differential microemulsion polymerization was used to synthesize crosslinked latex nanoparticles. In this paper, 1, 3-butylene glycol dimethacrylate (1, 3-BGDMA) was used as a crosslinking agent respectively 0-6 weight% of monomer total. The polymerization was carried out using butyl methacrylate (BMA), butyl acrylate (BA) and methacrylic acid (MAA) as the monomer mixture. The thin film of latex nanoparticles were prepared by using spin coating method and have been dried at 100°C for 5 minutes. The amount of the crosslinking agent added in the polymerization was optimized and we found that the particle sizes fall in the range of 30-60 nm. Field Emission Scanning Electrons Microscope (FESEM) was demonstrated that the spherical image of uncrosslinked latex change to a wooden-like image when the crosslinking agent added in the polymerization.

Characterization of Chemical Impurities in Glutaraldehyde

1975 ◽  
Vol 33 ◽  
pp. 620-621
Author(s):  
B. J. Grenon ◽  
A. J. Tousimis
Keyword(s):  
Glutaric Acid ◽  
Spectroscopic Analysis ◽  
Aldol Condensation ◽  
Condensation Product ◽  
Amorphous Solid ◽  
Water Soluble ◽  
Impurity Component ◽  
Chemical Impurities ◽  
Soluble Liquid

Ever since the introduction of glutaraldehyde as a fixative in electron microscopy of biological specimens, the identification of impurities and consequently their effects on biologic ultrastructure have been under investigation. Several reports postulate that the impurities of glutaraldehyde, used as a fixative, are glutaric acid, glutaraldehyde polymer, acrolein and glutaraldoxime.Analysis of commercially available biological or technical grade glutaraldehyde revealed two major impurity components, none of which has been reported. The first compound is a colorless, water-soluble liquid with a boiling point of 42°C at 16 mm. Utilizing Nuclear Magnetic Resonance (NMR) spectroscopic analysis, this compound has been identified to be — dihydro-2-ethoxy 2H-pyran. This impurity component of the glutaraldehyde biological or technical grades has an UV absorption peak at 235nm. The second compound is a white amorphous solid which is insoluble in water and has a melting point of 80-82°C. Initial chemical analysis indicates that this compound is an aldol condensation product(s) of glutaraldehyde.

scholarly journals Design, growth, and characterization of Y2Mo4O15 crystals for Raman laser applications

RSC Advances ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 1164-1171
Author(s):  
Xiangmei Wang ◽  
Zeliang Gao ◽  
Chunyan Wang ◽  
Xiaojie Guo ◽  
Youxuan Sun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Physical Properties ◽  
Raman Laser ◽  
Laser Applications ◽  
Potential Use

This work reports the crystal structure and physical properties of the Y2Mo4O15 crystal and its potential use in the Raman laser.

scholarly journals Fabrication and characterization of the ternary composite catalyst system of ZnGA/RET/DMC for the terpolymerization of CO2, propylene oxide and trimellitic anhydride

RSC Advances ◽  
2021 ◽  
Vol 11 (15) ◽  
pp. 8782-8792
Author(s):  
Ningzhang Liu ◽  
Chuanhai Gu ◽  
Qinghe Wang ◽  
Linhua Zhu ◽  
Huiqiong Yan ◽  
...  
Keyword(s):  
Propylene Oxide ◽  
Ternary Complex ◽  
Catalyst System ◽  
Composite Catalyst ◽  
Trimellitic Anhydride ◽  
Ternary Composite ◽  
Metal Cyanide ◽  
Fabrication And Characterization ◽  
Poly Propylene

For poly(propylene carbonate trimellitic anhydride) with good yield, thermal stability and high molecular weight, a catalyst of zinc glutarate/rare earth ternary complex/double metal cyanide was used for terpolymerization of CO2, propylene oxide and trimellitic anhydride.

Development of a prototype for modelling soil–pipe interaction and its application for predicting uplift resistance to buried pipe movements in sand

2018 ◽  
Vol 55 (10) ◽  
pp. 1451-1474 ◽  
Author(s):  
Yousef Ansari ◽  
George Kouretzis ◽  
Scott W. Sloan
Keyword(s):  
Scale Effects ◽  
Reaction Force ◽  
Failure Surface ◽  
Relative Displacement ◽  
Published Data ◽  
Buried Pipe ◽  
Image Velocimetry ◽  
Close Range ◽  
Uplift Resistance

This paper presents a testing rig for measuring the reactions on rigid pipes buried in sand during episodes of relative displacement. Following a detailed presentation of the 1g prototype, the test preparation procedure, and the characterization of the test sand’s shear strength and dilation potential under the low confining stresses pertinent to the problem, the paper focuses on the workflow devised to obtain accurate measurements of friction and arching effects, and accordingly normalize them to account for scale (stress level) effects. Emphasis is put on demonstrating the effectiveness of the sand deposition method for accurately controlling the density of the sample, and on quantitatively assessing its uniformity. Measurements obtained during a series of uplift tests, including reaction force – pipe displacement curves and images of the developing failure surface, facilitated by particle image velocimetry and close-range photogrammetry techniques, are compared against published data and analytical methods. The results lead to the development of a new simplified formula for calculating the uplift resistance to buried pipe movements in sand: capable of accounting for scale effects, yet simple enough to be used for the analysis of pipes in practice.

scholarly journals Conjuring up a ghost: structural and functional characterization of FhuF, a ferric siderophore reductase from E. coli

2021 ◽  
Author(s):  
I. B. Trindade ◽  
G. Hernandez ◽  
E. Lebègue ◽  
F. Barrière ◽  
T. Cordeiro ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Paramagnetic Nmr ◽  
E Coli ◽  
The Past ◽  
Internal Cavities ◽  
Structural Differences ◽  
Bond Strengths ◽  
Redox Bohr Effect ◽  
Micromolar Range

AbstractIron is a fundamental element for virtually all forms of life. Despite its abundance, its bioavailability is limited, and thus, microbes developed siderophores, small molecules, which are synthesized inside the cell and then released outside for iron scavenging. Once inside the cell, iron removal does not occur spontaneously, instead this process is mediated by siderophore-interacting proteins (SIP) and/or by ferric-siderophore reductases (FSR). In the past two decades, representatives of the SIP subfamily have been structurally and biochemically characterized; however, the same was not achieved for the FSR subfamily. Here, we initiate the structural and functional characterization of FhuF, the first and only FSR ever isolated. FhuF is a globular monomeric protein mainly composed by α-helices sheltering internal cavities in a fold resembling the “palm” domain found in siderophore biosynthetic enzymes. Paramagnetic NMR spectroscopy revealed that the core of the cluster has electronic properties in line with those of previously characterized 2Fe–2S ferredoxins and differences appear to be confined to the coordination of Fe(III) in the reduced protein. In particular, the two cysteines coordinating this iron appear to have substantially different bond strengths. In similarity with the proteins from the SIP subfamily, FhuF binds both the iron-loaded and the apo forms of ferrichrome in the micromolar range and cyclic voltammetry reveals the presence of redox-Bohr effect, which broadens the range of ferric-siderophore substrates that can be thermodynamically accessible for reduction. This study suggests that despite the structural differences between FSR and SIP proteins, mechanistic similarities exist between the two classes of proteins. Graphic abstract

scholarly journals Structural differences and the presence of unsubstituted amino groups in heparan sulphates from different tissues and species

1997 ◽  
Vol 322 (2) ◽  
pp. 499-506 ◽  
Author(s):  
Toshihiko TOIDA ◽  
Hisao YOSHIDA ◽  
Hidenao TOYODA ◽  
Ichiro KOSHIISHI ◽  
Toshio IMANARI ◽  
...  
Keyword(s):  
Acid Content ◽  
Heparan Sulphate ◽  
Kidney Medulla ◽  
Isolation And Characterization ◽  
Iduronic Acid ◽  
Structural Differences ◽  
Liver And Kidney ◽  
High Degree ◽  
Different Tissues

This study presents a comparison of heparan sulphate chains isolated from various porcine and bovine tissues. 1H-NMR spectroscopy (500 MHz) was applied for structural and compositional studies on intact heparan sulphate chains. After enzymic digestion of heparan sulphate using heparin lyase I (EC 4.2.2.7) II and III (EC 4.2.2.8), the compositions of unsaturated disaccharides obtained were determined by analytical capillary electrophoresis. Correlations between the N-sulphated glucosamine residues and O-sulphation and between iduronic acid content and total sulphation were discovered using the data obtained by NMR and disaccharide analysis. Heparan sulphate chains could be classified into two groups based on the sulphation degree and the iduronic acid content. Heparan sulphate chains with a high degree of sulphation possessed also a significant number of iduronic acid residues and were isolated exclusively from porcine brain, liver and kidney medulla. The presence and amount of N-unsubstituted glucosamine residues (GlcNp) was established in all of the heparan sulphates examined. The structural context in which this residue occurs was demonstrated to be: high sulphation domain → 4)-β-d-GlcAp-(1 → 4)-α-d-GlcNp-(1 → 4)-β-d-GlcAp-(1 → low sulphation domain (where GlcNp is 2-amino-2-deoxyglucopyranose, and GlcAp is glucopyranosyluronic acid), based on the isolation and characterization of a novel, heparin lyase III-derived, GlcNp containing tetrasaccharide and hexasaccharide. The results presented suggest that structural differences may play a role in important biological events controlled by heparan sulphate in different tissues.

Sign in / Sign up

Export Citation Format

Share Document