LABORATORY STUDY OF GERMAN BUNA S-3 CHEMICAL RUBBER

1949 ◽  
Vol 27f (3) ◽  
pp. 119-142
Author(s):  
J. W. L. Fordham ◽  
A. N. O'Neill ◽  
H. Leverne Williams
Keyword(s):  
Molecular Weight ◽  
Laboratory Study ◽  
Reaction Rate ◽  
General Purpose ◽  
Solution Viscosity ◽  
Dilute Solution ◽  
Tire Rubber ◽  
Methods Of Analysis

The German general purpose tire rubber, Buna S-3, differed from the chemical rubber produced in Canada. The study of the polymerization recipe used for this polymer centered around the role of the regulator in the system. The German technique resulted in a system in which the dilute solution viscosity of the polymer remained relatively constant during the reaction. It was found that this system could be duplicated in the laboratory using the equivalents of the German materials. Methods of analysis for diproxid in solution and in latex were investigated. It was observed that the diproxid disappeared very rapidly from the system and the regulating index was found to be similar to that of tertiary amyl mercaptan and to lie between that of n-dodecyl and n-tetradecyl mercaptan when all were used in the Buna S-3 system. The polymers produced compared favorably with the German polymer as to molecular weight homogeneity, response to heat softening, and other data. Substitution of tertiary amyl mercaptan in the Buna S-3 system resulted in a polymer very similar to that produced using diproxid, and the reaction rate was increased nearly fivefold. The polymer prepared with diproxid and other regulators in this system seemed to be more homogeneous than those prepared by the Mutual formula.

THE ROLE OF ADSORPTION IN CONTROLLING THE RATE OF REACTION OF CHLORAMBUCIL WITH PROTEIN

1963 ◽  
Vol 41 (4) ◽  
pp. 931-939 ◽  
Author(s):  
J. H. Linford
Keyword(s):  
Molecular Weight ◽  
Carboxylic Acid ◽  
Bovine Serum Albumin ◽  
Inverse Relationship ◽  
Reaction Rate ◽  
The Other ◽  
Alkylation Reaction ◽  
Rate Of Reaction

Two proteins, haemoglobin and bovine serum albumin, have been studied with respect to their rates of alkylation by chlorambucil in vitro at 37 °C and pH 8.4. The proteins are of nearly the same molecular weight and free carboxylic acid content, but the alkylation reaction is 30 times faster with haemoglobin. On the other hand, the adsorption of chlorambucil by albumin is 20 times greater than that exhibited by haemoglobin. This inverse relationship between extent of adsorption and reaction rate suggests that adsorption protects the chlorambucil from activation in the solvent.

THE VISCOSITY – MOLECULAR WEIGHT RELATION FOR POLY-levo-2,3-BUTANEDIYL o-PHTHALATE

1948 ◽  
Vol 26b (12) ◽  
pp. 783-797
Author(s):  
R. W. Watson ◽  
N. H. Grace
Keyword(s):  
Molecular Weight ◽  
High Purity ◽  
Molecular Orientation ◽  
Degree Of Polymerization ◽  
Solution Viscosity ◽  
Dilute Solution ◽  
Molecular Weights ◽  
Complex Relation ◽  
End Group ◽  
Long Chain

The inherent viscosities of dilute solutions of acidic polyesters of high purity have been compared with number average molecular weights accurately determined by end-group titration. For unfractionated resins with a degree of polymerization from 2 to 11 [Formula: see text] the viscosity – molecular weight relation is linear in chloroform at 25 °C. Where [Formula: see text], K = 1.923 × 10−5 and β = 0.0176. For fractionated polyesters from DP 5 to 8, K = 1.959 × 10−6 and β = 0.0161. For unfractionated resins with a DP > 11, molecular weights increase more rapidly than inherent viscosities. Above [Formula: see text] for fractionated resins linearity is resumed, and the slope increases. Several attempts have been made to explain this complex relation. Apparently the short chains remain linear, and the formation of anisotropic fibers at a DP close to 100 establishes a degree of molecular orientation in the long-chain superpolyesters. Isomerization of levo-diol to the diastereoisomer during polycondensation is without effect on the dilute solution viscosity of the resulting resin. Preferential degradation of the longer chains is assumed to be partially responsible for the decreasing slope from DP 11 to 65. As yet it has not been possible to assess the roles played by changes in size distribution, and variation in solvation with increasing chain length, but the data point to a curved viscosity – molecular weight relation in chloroform at 25 °C.

THE ROLE OF WATER IN THE FORMATION OF SODIUM TRIPHOSPHATE BY CALCINATION

1954 ◽  
Vol 32 (12) ◽  
pp. 1100-1111 ◽  
Author(s):  
J. D. McGilvery ◽  
A. E. Scott
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Reaction Rate ◽  
Ionic Diffusion ◽  
Fusion Point ◽  
Rapid Formation

The formation of sodium triphosphate by calcination, below the sodium triphosphate fusion point, of various phosphate mixtures of over-all composition 5Na2O.3P2O5.xH2O was investigated. Water plays an important role, decreasing the amounts of pyrophosphate and high molecular weight polyphosphate impurities and increasing the reaction rate under certain conditions. It is suggested that water catalyzes the reactions by: (1) facilitating ionic diffusion, (2) hydrolyzing —P—O—P—linkages, and (3) assisting in the crystallization of sodium triphosphate. With ortho- and pyro-phosphate mixtures temperatures of about 300 °C. and higher are necessary for the rapid formation of sodium triphosphate. With glasses of the composition 5Na2O.3P2O5 good yields may be obtained at temperatures as low as 250 °C. when water is present.

scholarly journals Synthesis, structure and thermogravimetric analysis of α,ω-telechelic polydimethylsiloxanes of low molecular weight

2017 ◽  
Vol 82 (12) ◽  
pp. 1395-1416 ◽  
Author(s):  
Aleksandra Tasic ◽  
Marija Pergal ◽  
Malisa Antic ◽  
Vesna Antic
Keyword(s):  
Molecular Weight ◽  
Thermogravimetric Analysis ◽  
Degradation Mechanism ◽  
Gel Permeation Chromatography ◽  
Polymer Chains ◽  
Low Molecular Weight ◽  
Dilute Solution ◽  
Molecular Weights ◽  
Dilute Solution Viscometry

A series of ?,?-telechelic polydimethylsiloxanes (PDMS), with predetermined molecular weights of about 2500 g mol-1, was synthesized by siloxane equilibration reaction. Syntheses were performed using octamethylcyclotetrasiloxane (D4) and various disiloxanes: hexamethyldisiloxane (HMDS), 1,1,3,3-tetramethyldisiloxane (TMDS), 1,3-divinyltetramethyldisiloxane (DVTMDS), 1,3-bis(3-carboxypropyl)tetramethyldisiloxane (DCPTMDS) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (DAPTMDS). The role of the disiloxane was to introduce terminal functional groups at the end of the polymer chains and to control the molecular weight of the polymers. Polymers with trimethyl, hydrido, vinyl, carboxypropyl and aminopropyl end-groups were obtained in this way. The structure of the ?,?-telechelic PDMSs was confirmed by NMR and IR spectroscopy. The molecular weights of the polymers were determined by 1H-NMR, gel permeation chromatography (GPC) and dilute solution viscometry. Thermogravimetric analysis (TGA) under nitrogen and air showed that the type of the terminal groups significantly influenced the thermal and thermo-oxidative stability, as well as the degradation mechanism of the ?,?-telechelic PDMSs.

Quantitative studies of the role of alkenes during the combustion of alkanes

1970 ◽  
Vol 23 (11) ◽  
pp. 2309 ◽  
Author(s):  
T Berry ◽  
CF Cullis
Keyword(s):  
Molecular Weight ◽  
Major Part ◽  
Reaction Rate ◽  
Intermediate Formation ◽  
Substantial Proportion ◽  
Lower Molecular Weight ◽  
Direct Oxidation ◽  
Quantitative Studies

Studies of the combustion of n-butane in the presence of small amounts of [1-14C]but-1-ene and [2-14C]but-2-ene have enabled the role and importance of the two alkenes in the oxidation of the alkane to be determined quantitatively. Thus at 315�, at a stage when the reaction rate has started to decline, over one-third of the n-butane which has reacted has been oxidized to butenes and nearly two-thirds of these two alkenes has reacted further to give other products. All the larger-ring oxa-heterocyclic products and the major part of the oxirans arise by a mechanism not involving the intermediate formation of C4 alkenes but a substantial proportion of the 2-ethyloxiran and 2,3-dimethyloxiran are formed by the direct oxidation of but-1-ene and but-2-ene respectively. About one-quarter of the C4 ketones and an appreciable part of the lower molecular weight aldehydes also appear to be formed by an alkenic route. The general conclusion which emerges is that at the temperature concerned butenes play an important but not overwhelming role as intermediates in the combustion of n-butane.

THE ROLE OF ADSORPTION IN CONTROLLING THE RATE OF REACTION OF CHLORAMBUCIL WITH PROTEIN

1963 ◽  
Vol 41 (1) ◽  
pp. 931-939
Author(s):  
J. H. Linford
Keyword(s):  
Molecular Weight ◽  
Carboxylic Acid ◽  
Bovine Serum Albumin ◽  
Inverse Relationship ◽  
Reaction Rate ◽  
The Other ◽  
Alkylation Reaction ◽  
Rate Of Reaction

Two proteins, haemoglobin and bovine serum albumin, have been studied with respect to their rates of alkylation by chlorambucil in vitro at 37 °C and pH 8.4. The proteins are of nearly the same molecular weight and free carboxylic acid content, but the alkylation reaction is 30 times faster with haemoglobin. On the other hand, the adsorption of chlorambucil by albumin is 20 times greater than that exhibited by haemoglobin. This inverse relationship between extent of adsorption and reaction rate suggests that adsorption protects the chlorambucil from activation in the solvent.

Monitoring Polymer-Assisted Mechanochemical Cocrystallisation Through in Situ X-Ray Powder Diffraction

2020 ◽  
Author(s):  
Luzia S. Germann ◽  
Sebastian T. Emmerling ◽  
Manuel Wilke ◽  
Robert E. Dinnebier ◽  
Mariarosa Moneghini ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Powder Diffraction ◽  
Reaction Rate ◽  
Polymer Additives ◽  
Time Resolved ◽  
X Ray

Time-resolved mechanochemical cocrystallisation studies have so-far focused solely on neat and liquid-assisted grinding. Here, we report the monitoring of polymer-assisted grinding reactions using <i>in situ</i> X-ray powder diffraction, revealing that reaction rate is almost double compared to neat grinding and independent of the molecular weight and amount of used polymer additives.<br>

scholarly journals Adiponectin: Structure, Physiological Functions, Role in Diseases, and Effects of Nutrition

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1180
Author(s):  
Kayvan Khoramipour ◽  
Karim Chamari ◽  
Amirhosein Ahmadi Hekmatikar ◽  
Amirhosein Ziyaiyan ◽  
Shima Taherkhani ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Amino Acids ◽  
Molecular Weight ◽  
Energy Regulation ◽  
Treatment Interventions ◽  
Adipose Tissues ◽  
Physiological Functions ◽  
Cellular Events ◽  
Healthy Nutrition

Adiponectin (a protein consisting of 244 amino acids and characterized by a molecular weight of 28 kDa) is a cytokine that is secreted from adipose tissues (adipokine). Available evidence suggests that adiponectin is involved in a variety of physiological functions, molecular and cellular events, including lipid metabolism, energy regulation, immune response and inflammation, and insulin sensitivity. It has a protective effect on neurons and neural stem cells. Adiponectin levels have been reported to be negatively correlated with cancer, cardiovascular disease, and diabetes, and shown to be affected (i.e., significantly increased) by proper healthy nutrition. The present review comprehensively overviews the role of adiponectin in a range of diseases, showing that it can be used as a biomarker for diagnosing these disorders as well as a target for monitoring the effectiveness of preventive and treatment interventions.

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