Rubber, determination

Determination of the level of total sulfur in a rubber can give information on the type of cure system used, for example, elemental sulfur plus accelerator or sulfur donor system, etc. The ISO 6528-1 1992 method — Rubber — Determination of total sulfur content — Part 1 Oxygen combustion flask method is often employed. The principle of the method is oxidation by ignition in an atmosphere of oxygen in the presence of hydrogen peroxide, conversion of sulfur to sulfuric acid and determination of the sulfate by titration with barium perchlorate. The method is... 

Unreacted free sulfur can be determined to ISO 7269 1995 — Rubber — Determination of free sulfur. Three methods for the determination of free sulfur in vulcanized rubber are detailed two versions of the copper spiral method and the sodium sulfite method. The copper spiral methods are also applicable, subject to limitations, to unvulcanised rubber. The technique of DSC can detect non-reacted rubber curatives such as residual peroxides. 

BS 903-18, Physical testing of rubber. Determination of equilibrium water vapour absorption, 1973. 

ISO 4663 1986 Rubber - Determination of dynamic behaviour of vulcanizates at low frequencies - Torsion pendulum method... 

ISO 7619 2004 Rubber - Determination of indentation hardness by means of pocket hardness meters... 

ISO 6471 1994 Rubber, vulcanized - Determination of crystallization effects under compression ISO 3387 1994 Rubber - Determination of crystallization effects by hardness measurements... 

The chemical nature of the rubber determines which bonds are the weakest and are therefore more likely to be ruptured during mastication by the statistical concentration of mechanical energy about such bonds. An increase in the degree of asymmetry, an increase in the stiffness and the packing density of macromolecules facilitate mechanical scission resonance stability will influence the... 

Since the relaxation mechanisms characteristic of the constituent blocks will be associated with separate distributions of relaxation times, the simple time-temperature (or frequency-temperature) superposition applicable to most amorphous homopolymers and random copolymers cannot apply to block copolymers, even if each block separately shows thermorheologically simple behavior. Block copolymers, in contrast to the polymethacrylates studied by Ferry and co-workers, are not singlephase systems. They form, however, felicitous models for studying materials with multiple transitions because their molecular architecture can be shaped with considerable freedom. We report here on a study of time—temperature superposition in a commercially available triblock copolymer rubber determined in tensile relaxation and creep. 

ISO 5600 (conical ends) Rubber Determination of adhesion to rigid materials using conical-shaped parts... 

All these valuable characteristics of organosiloxane elastomers and or-ganosiloxane elastomer rubbers determine their wide application in vairous spheres of modem technology and economy. They help to increase the... 

Mooney viscosity is the torque of a melt of rubber determined in a Mooney rheometer. The torque is given in Mooney units (MU). It is determined on pure rubber or rubber compounds at elevated temperature (usually between 100 °C to 150 °C) after a well-defined heating procedure (usually 1 min without application of shear and subsequently 4 to 8 min with the application of shear). The method is described in detail in DIN 53523 ASTM D 1646 ISO 289... 

The rate of reaction of ozone with amine was determined during the ozonization of rubber solution, where the reaction between ozone and rubber also proceeded concurrently. The extent of the reaction of rubber with ozone was calculated from the change in unsaturation of the rubber determined by the Wijs reagent. For example, SBR (Japan Synthetic Rubber, JSR 1502), purified by precipitation with acetone from benzene solution, was dissolved in carbon tetrachloride to give a 5% rubber solution. The rubber solution (20 ml.) was added with 80 ml. of carbon tetrachloride containing 1 X 10 3 mole of amine derivatives. Oxygen, containing 0.89% ozone, was introduced into the solution at 30°C. for 3 minutes at the rate of 550-560 ml./min. Under these conditions, all... 

Pure N2 gas at 1 atin and 25°C is flowing through a lO-ni-long, 3-cm-inner diameter pipe made of 2-mm-thick rubber. Determine the rale at which N2 leaks out of the pipe if the medium surrounding the pipe is (a) a vacuum and (i>) atmospheric air at t atm and 25 C with 21 percent Oj and 79 percent Nj. 

ISO 845-88 Cellular Plastics and Rubbers Determination of Apparent (Bulk) Density - 1988, Second Edition, 6 pp... 

ISO 1923-81 Cellular Plastics and Rubber —Determination of Linear Dimensions, 3 pp... 

The temperature of extraction has an effect on the result of the determination (Figure 7.19). At moderate temperatures, there is very little change in the amount of bound rubber determined. At temperatures above 70 C there is substantial increase in the amount of extracted rubber. This data shows that most carbon black is adsorbed by physical forces. 

ISO 4664 1998 Rubber—Determination of dynamic properties of vulcanisates for classification purposes (by forced sinusoidal shear strain). 

Other systems investigated by this group are butyl rubber, - natural rubber sensitized with acrylates,chloroprene, chlorobutyl rubber and nitrile rubber.More recently, Perera has examined the relationship between chemical changes in radiation-grafted natural rubber, determined using MAS NMR, and mechanical properties measured using dynamic mechanical analysis. 

The thermal behavior of polymers is of considerable technological importance. Knowledge of thermal transitions is important in the selection of proper processing and fabrication conditions, the characterization of the physical and mechanical properties of a material, and hence the determination of appropriate end uses. For example, the glass transition temperature of rubber determines the lower limit of the use of rubber and the upper limit of the use of an amorphous thermoplastic. We take up discussion of these transition temperatures in succeeding sections. 

BS EN ISO 845, Cellular plastics and rubbers—Determination of apparent (bulk) density. 1995. 

BS EN ISO 1923, Cellular plastics and rubbers Determination of linear dimensions, 1995. 

ISO 8013, Rubbers Determination of creep in compres.sion and shear. 1988. 

ISO 4649. Rubber Determination of abrasion rcsi.stance using a rotating cylindrical drum device. 198.s. 

ISO 6179 (1989), Vulcanized rubber sheet, and fabrics coated with vulcanized rubber-Determination of transmission rate of volatile liquids (Gravimetric techniques),. 

Bound rubber determination is also applied to silica compounds, even if the numerous possible interactions naturally limit the interpretation of the values [127,128]. 

Kraus, C. Stacy, C.J. Molecular weight and long-chain branching distributions of some polybutadienes and styrene-butadiene rubbers. Determination by GPC and dilute solution Viscometiy. J. Polym. Sci. A-2 1972, 10 (4), 657-672. 

Angulo-Sanchez, J.L. Caballero-Mata, P. Longchain branching in natural hevea rubber Determination by gel permeation chromatography. Rubber Chem. Technol. 1981, 54, 34. 

The accelerates and sulfur were added to the elastomer, and the mixer was operated at 100°C. When the torque had achieved a steady state and the temperature increased to 150°C to vulcanize the rubber, the rotors were removed and the disposition of the rubber determined. Typical distribution for various rotors and fill factors are shown in Figure 9. On the R-L screw rotors, voids open first on the back of the flights at the same back side of the mixer. As fill factor decreases, the void gradually increases to include the entire back parts of the mixer behind the screw flights. 

Infinite-dilution partial molar volumes for CO2 in various low molecular weight hquids (Table 6) are insensitive to the type of medium and decrease only shghtly as interactions between the medium and CO2 increase. This approximation may be somewhat inappropriate for highly supercritical gases such as nitrogen or methane, but for CO2 near ambient temperature it appears valid. The average of the CO2 partial molar volumes in the organic liquids is approximately 46 cm /mol. The value for CO2 in silicone rubber determined from analysis of... 

The charged vulcanised elastomers show a higher hysteresis that the non-charged vulcanised rubbers. The introduction of black carbon particles in rubber determines the increase both of hydrodynamic and viscoelastic hystereses. The two contributions are additive. Under the conditions of the deformation rate and temperature variation, the first one remains constant, but the second one decays with the decrease of temperature. The viscoelastic contribution was ascribed to the macromolecular chains, immobilised on the black carbon surface, which modify the viscoelastic response of the elastomer network. 

ASTM D430-95, Standard test methods for rubber determination, dynamic fatigue, 2000. 

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