bluuebunny/crossref_metadata_2025_split huggingface dataset:
Apparatus to Measure Thermal Conductivity in Filled Rubber Stocks
Authors: Atkins J. H. , Sullivan J. E. 
Published: February 2011

Abstract
An instrument to measure thermal conductivity of cured rubber stocks is described. The apparatus can be used with readily available equipment or additional equipment may be purchased. The results obtained are as accurate and precise as those obtained using other instruments and can be done at a rate of three samples per hour. The apparatus is designed around a calibrated heat flux probe which measures the sample's heat flux. The heat flux, the temperature drop across the sample, and the sample thickness values permit conversion of the above data into a thermal conductivity value. Thirteen samples of Butyl rubber in a curing bladder formulation with 40-part loadings of various carbon blacks were prepared and tested. The thermal conductivity values obtained varied from 0.096 to 0.117 (Btu)/(ft2) (hr)(°F/ft) over a range of 95° F to 212° F with an overall relative standard deviation of 1.2%. The thermal conductivity of the above samples were also measured on a modified apparatus over a temperature range of 95° F to 350° F and there was no change in the thermal conductivity values. To check the above measurements, five of the samples were tested on two commercial instruments. The results agreed within 4 per cent. For reasons explained in the paper, we believe our results to be the most accurate.
The Effect of Oil and Black on the Injection Molding of EPDM Compounds. I.
Authors: DePierri William G. , Hopper J. R. 
Published: February 2011

Abstract
Factors affecting the flow properties of EPDM compounds have been studied and the findings of the study applied to the injection molding of these compounds. The level of oil and of black were found to change the flow properties of EPDM compounds. Higher levels of oil decreased the compound viscosity while higher levels of black increased the compound viscosity. The viscosity of the oil influenced compound viscosities. Compounds made with the more viscous (at 210° F) oil had slightly higher viscosities. However, changing from an aromatic to a naphthenic oil of similar viscosity had little effect on the compound viscosity. Compounds made from two different polymers of similar Mooney viscosity were found to have widely divergent flow behavior at high shear rates. Injection molding of EPDM compounds was studied with a molding assembly which had a capillary rheometer as barrel and plunger. Injection pressure data from the molding experiments was found to parallel closely the rheological data. An analysis of the pressure drops in passing through different parts of the mold assembly was made. The total calculated pressure drop agreed closely with the measured pressure drop. The viscous generation of heat was found to be proportional to pressure drop, and an equation is presented which relates the temperature increase to the pressure drop.
Research for a Uniform Quality Grading System for Tires. II. Wheel Speed Capability Test
Authors: Brenner F. C. , Mandel J. , Simson B. G. 
Published: February 2011

Abstract
The wheel speed capability of a tire is defined by a test method which determines the speed at which the tire fails on a laboratory test wheel. Data is reported on over 100 different passenger car tires of all grades and types over a range of sizes. A scaling system is devised for this property. It is found that the system produces consistent results for tires of given manufacturer's nominal grade across the size range tested and for samples produced several months apart.
Pigment Contact Potentials and Reinforcement
Authors: Havenhill R. S. , Carlson L. E. 
Published: February 2011

Abstract
1. A new apparatus has been described for measuring the contact potential of powdered reinforcing pigments. 2. With this apparatus, contact potentials on MPC and FT blacks, fine and coarse particle size zinc oxides, whiting, and barytes show correlation with their reinforcing properties in natural rubber and cis-1 ,4-polybutadiene rubber. 3. Contact potentials of Hi-Sil, Suprex clay, coated zinc oxides and coated calcium carbonate pigments showed no correlation with their reinforcing properties in rubber. 4. Contact potentials on the minerals, diamond, quartz, zinc oxide, calcite and barite correlated with the reinforcing properties of their pigment counterparts. 5. Contact potentials of the minerals also correlated with Mohs hardness. 6. Contact potentials on coated zinc oxide pigments correlated with their improved processing properties in rubber. 7. A new apparatus has been described for measuring the contact potentials of cured stocks in which cut surfaces, rather than molded surfaces, are used. Greater accuracy is possible due to the elimination of surface bloom and other surface contamination. 8. Contact potentials measured on the cut surface of cis-1,4-polybutadiene stocks containing various pigments showed good correlation with their reinforcing properties, thus confirming, with this new rubber, the Electrostatic Contact Potential Theory of Reinforcement.
Reaction of Deuterio Polyisoprene and Deuterio Polybutadiene with Sulfur
Authors: Shipman J. J. , Golub M. A. 
Published: February 2011

Abstract
Infrared absorption spectroscopy has been employed in the past in efforts to determine the nature of the chemical changes which occur in natural rubber during vulcanization. The most prominent change in the infrared spectrum of rubber accompanying vulcanization with sulfur is the appearance of a new absorption band at 10.4 µ. In the spectra of useful soft rubber vulcanizates this band is barely detectable, while in those of hard rubber (ebonite) it is moderately intense. It has not been known whether this band is related in some way to the actual crosslinking reaction or is the result of some noncrosslinking reaction between the rubber and sulfur molecules.
Law of Friction for Surfaces in Elastic Contact
Authors: Bartenev G. M. , Lavrentev V. V. 
Published: February 2011

Abstract
In the elastic contact of two bodies, there corresponds to each value of the normal load N a definite area of actual contact S, the magnitude of which depends on the geometry of the surfaces and the stiffness of the contacting materials. In practice, friction of solid bodies in absolute elastic contact is not observed in the strict sense of the word. With metals in general there is formed a plastic contact, the magnitude of which is determined by the yield point of the softer metal of the friction couple; with plastics there is formed a nonelastic area of contact as a result of the property of plastics of developing quasi-residual deformation with loads above the limiting forced elasticity analogous to the yield point. Along with these materials there are others which give practically complete elastic contact with solid surfaces. These include rubbery network polymers (vulcanized rubbers). With the contact of vulcanized rubbers and metals, the actual area of touching is determined mainly by the properties of the rubber as a high elastic material with a modulus of elasticity about 104 times less than that of metals. There are at present a number of facts, which confirm that the law of friction, expressing the connection between the force of friction and the normal load, is determined by the load, to the extent that the load is capable of forming an actual area of contact. This postulate, formulated for pure metals and vulcanized rubbers is expressed by the formula:
Comparison of Standard and Microtests for International Rubber Hardness
Authors: Stiehler R. D. , Roth F. L. 
Published: February 2011

Abstract
1. Results obtained with an electronic microtester and the standard testers for International Rubber Hardness agree within about 1 IRHD unless there is a pronounced hardening near the surface or other nonuniformity of the compound. 2. The precision of test is not quite as good with the microtester as with the standard tester, but the precision obtained with the microtester can probably be improved by using a visual indicator in place of the audio indicator for detecting the null position. 3. The values of hardness are more dependent on thickness of the specimen at low levels of hardness than at high levels. The ratio of thicknesses to be used with the standard and microtesters appears to be 4:1, rather than 6:1, in order to obtain comparable results. 4. Some compounds exhibit a pronounced hardening near the surface or other nonhomogeneity, which causes high and erratic values of hardness, particularly with the microtester. 5. The incorporation of the microtest for rubber hardness in ASTM Method D 1415 is recommended. It is particularly useful for measuring the hardness of small rubber parts, for which there is no satisfactory test at the present time in the Book of ASTM Standards.
Nuclear Magnetic Resonance Studies of Molecular Motion in Natural Rubber
Authors: Slichter W. P. , Davis D. D. 
Published: February 2011

Abstract
Nuclear magnetic resonance measurements have been made on natural rubber to examine how frequency, temperature, and crystallinity affect the nuclear relaxation. Moecular motions were studied by observing NMR linewidths and spin-lattice relaxation times at temperatures between −100° and 100° C, and at radio frequencies between 2 and 60 Mc. The effect of crystallinity was seen in measurements on stark rubber. The relation between frequency and temperature in the spin-lattice relaxation process is examined in terms of the Arrhenius equation and the WLF expression. The importance of using frequency as a variable in NMR studies of molecular motion is stressed.
Reinforcement of Rubber by Fillers
Authors: Andrews E. H. 
Published: February 2011

Abstract
The mechanical failure of a material, whether tensile failure, tear, abrasion or fatigue, always occurs by a process of rupture propagation, and this paper discusses the strength properties of reinforced rubbers in terms of this process. The effect of fillers and other reinforcing systems on rupture is illustrated and the microscopic role of filler particles discussed. The high rupture resistance of reinforced rubber is attributed to a reduction of stress at the tip of the propagating crack. Model experiments on both unfilled natural rubber and carbon loaded SBR show how such a reduction in stress can result from mechanical hysteresis in the elastomer. This new understanding of the influence of hysteresis on rupture propagation provides a firm basis for the explanation of strength-type reinforcement by fillers.
An Oscillating Disk Rheometer for Measuring Dynamic Properties during Vulcanization
Authors: Decker G. E. , Wise R. W. , Guerry D. 
Published: February 2011

Abstract
A forced oscillating-disk rheometer has been developed which can measure both the low and high frequency dynamic properties of a rubber specimen throughout vulcanization. It may also be used to measure the rheological properties of unvulcanized polymers. The instrument consists of a cone-shaped disk which is embedded in the rubber specimen and oscillated through a small angle while the specimen is heated under pressure. Both stress and strain in terms of torque and displacement, respectively, are measured by appropriate transducers and recorded on an oscillograph. Provisions are made for changing both frequency and strain. At low frequency, the instrument is a convenient tool for determining all of the curing parameters of a rubber specimen. At high frequencies, the change in the dynamic properties of a rubber specimen throughout vulcanization may be continuously followed. A unique feature of the rheometer is that the loss angle may be determined which permits resolution of the measured dynamic stiffness into its elastic and viscous components.
Mechanochemical Phenomena. I. Chemical Flow in Raw and Vulcanized Rubber
Authors: Slonimskii G. L. , Reztsova E. V. 
Published: February 2011

Abstract
1. The authors demonstrate the essential role of mechanochemical phenomena in processing. Attention is paid to the necessity of taking into account the phenomenon of chemical flow. 2. From the example of various vulcanizates there is demonstrated the possibility of mechanical processing of crosslinked polymers. Attention is paid to the significance of mechanochemical phenomena in reclaiming. 3. A demonstration is given of the influence of small additions of substances which form free radicals or which interact with them, upon the kinetics of the alteration of the properties of a polymer on prolonged milling. Attention is paid to the possibility of controlling the properties of a polymer during processing. 4. The authors show the necessity of taking into account the phenomenon of chemical flow in developing objective methods of laboratory assessment of the technological properties of polymers.
Ring-Alkylated p-Phenylenediamines as Antiozonants
Authors: Tucker Harold A. , Veith Alan G. 
Published: February 2011

Abstract
As part of a larger program to correlate the antiozonant activity of rubber additives with their chemical structure, we investigated a homologous series of ring-alkylated p-phenylenediamines. It seemed to us that such investigation might possibly determine whether or not a primary diamine could be an effective antiozonant. The present commercial antiozonants of greatest activity are all secondary diamines. Very little has been published on the behavior of ring-alkylated p-phenylenediamines as protective agents against ozone, probably because of the difficulties involved in preparing them. However, Cox reported on some secondary diamines of this type and said that they are “less potent than their unsubstituted analogs,” comparing them to N,N′-dialkyl-p-phenylenediamines without ring substituents. In contrast to Cox's findings, we have found that some of our primary ring-alkylated p-phenylenediamines have activities comparable with the best of commercial antiozonants.
Suppression of the Activity of Metal Ions in the Oxidation of Rubber
Authors: Kuzminskii A. S. , Zaitsev V. D. , Lezhnev N. N. 
Published: February 2011

Abstract
It is shown that the catalytic activity of variable valency metal ions, Cu++ and Fe+++, with respect to the oxidation of polymeric unsaturated hydrocarbons (natural and styrene-butadiene rubbers) can be completely suppressed by introducing into the polymer, materials which form strong inner complex compounds with these ions. It was established that the synthesized compounds of copper and iron with tetramethylthiuramdisulfide, diethyldithiocarbamic acid, and p-hydroxyphenyl-2-naphthylamine not only do not accelerate the oxidation of polymers, but act as inhibitors of the oxidation process. By chemical and luminescence methods the compositions of the indicated compounds were established to correspond to the following formulas: (D—deactivator) DFe and DCu (iron and copper compounds with tetramethylthiuramdisulfide); D2Fe and D2Cu (iron and copper compounds of diethyldithiocarbamic acid); DFe2 (iron compound of p-hydroxyphenyl-2-naphthylamine); DCu3 (copper compound of p-hydroxyphenyl-2-naphthylamine). These data indicate a new route for the synthesis of effective inhibitors for raw and vulcanized rubber.
Influence of Acids on Scorching and Vulcanization of Carboxylic Rubbers
Authors: Zakharov N. D. , Shadricheva T. A. 
Published: February 2011

Abstract
1. A study of the influence of a series of acids on the process of scorching and the process of vulcanization of mixes was made. 2. It is shown that some sufficiently strong monobasic acids, not having a noticeable influence on the decrease in scorch, do, at the same time, destroy the strengthening effect of metal oxides on vulcanizates. 3. Polybasic acids and their anhydrides lessen scorch, but at the same time slow down vulcanisation. Maleic anhydride is most interesting of the group studied. 4. Vulcanizates using magnesium stearate were tested. It was shown that its use lessened scorch, for all practical purposes, had little effect on vulcanization, and improved the properties of vulcanizates somewhat.
Water Absorption of Elastomers
Authors: Briggs G. J. , Edwards D. C. , Storey E. B. 
Published: February 2011

Abstract
This study considers high temperature (160° C) water absorption in the absence of oxygen. Examination of the freezing behavior of water-swollen butyl gum vulcanizates shows the water to be disposed as discrete droplets of the order of 3µ diameter, corresponding in this case with soluble residues based on zinc. Data are shown for peroxide gum vulcanizates of natural rubber, SBR, NBR, ethylene-propylene rubber, and cis-1,4 poly butadiene. Equilibrium absorption occurs, the degree being dependent on polymer impurities and state of cure. Model systems based on cis-polybutadiene show the effects of typical emulsion polymerization residues and the nature of the equilibrium balance between osmotic pressure and the retractive pressure exerted by the rubber. Classes of absorption behavior, whether low equilibrium, moderate to high equilibrium, or nonequilibrium, are discussed in terms of osmotic and rubber pressures. The temperature dependence of absorption rate is shown for the various polymers for the range 25° to 92° C. Five decades are required to accomodate the data, ranging from low rates for butyl rubber to high rates for NBR and natural rubber. Curing systems are compared, with cis-polybutadiene and butyl rubber as base polymers. Common classes of fillers and reinforcing agents are compared, particular consideration being given to the hydrophylic calcium silicate and silica fillers, which appear to facilitate leaching of electrolytes when present in sufficient loading. From the combined experience, illustrative water-resistant formulations are derived.
Solution and Diffusion in Silicone Rubber. II. Influence of Fillers
Authors: Barrer R. M. , Barrie J. A. , Raman N. K. 
Published: February 2011

Abstract
An investigation has been made of the effect of a high area silica filler upon the solubility and diffusion of some C4 and C5 paraffins in silicone rubbers. The membranes studied contained by weight 0, 10, 20, 30 and 40 parts of filler per 100 parts of polymer. The solubilities have been discussed in terms of two reference models: the first in which silica and rubber phases act independently as sorbents; and the second in which the filler is regarded as completely wetted by polymer and is thus a non-sorbent. Diffusion and permeation have also been considered in terms of the models, assuming with the first model an immobile sorbed layer on the porous silica. It has been found that, although some aspects of the behavior can be explained, the results are not fully in agreement with either model, and that the behavior of the heterogenous membrane is complex.
Solubility and Mobility of Sulfur in Ethylene-Propylene and Ethylene-Butene-1 Copolymers
Authors: Baldi L. , Zannetti R. 
Published: February 2011

Abstract
Solubility and mobility of sulfur in copolymers of ethylene/propylene and ethylene/butene-1 were determined, using S 35 according to the method developed by Auerbach and Gehman for natural rubber and certain polymers and copolymers possessing elastomeric properties. We took into consideration the effect of temperature and copolymer composition, both on the solubility and on the mobility of the sulfur. Also examined was the effect of the migration of sulfur to the surface of the vulcanized product. The results are discussed in relation to the characteristics of the vulcanization process.
Nonlinear Viscoelastic Response of Amorphous Elastomers to Constant Strain Rates
Authors: Smith Thor L. 
Published: February 2011

Abstract
Tensile stress-strain curves determined at constant strain rates are nonlinear because relaxation of stress generally occurs during a test and also because of inherent nonlinear effects. To develop a method for determining the conditions under which time and nonlinear effects are separable, consideration was first given to a linear viscoelastic material. It was shown that stress-strain curves determined at different strain rates superpose to yield a single curve on a plot of log σ(ε, t)/ε vs. log t, where σ(ε, t) is the stress, a function of the strain ε and the time t; by definition t equals ε/ε where ε is the strain rate. The quantity σ(ε, t)/ε was called the constant-strain rate modulus F(t) which is related exactly to the stress-relaxation modulus E(t) by the equation E(t)=F(t)(1+m) where m=d log F(t)/d log t. For amorphous elastomers tested in tensions over a wide range of strain, it was proposed that stress-strain curves determined at constant strain rates can be represented by F(t)=g(ε)σ(ε,t)/ε where g(ε) is a function only of strain and approaches unity as the strain goes to zero. To test this equation, an analysis was made of stress-strain curves of an SBR gum vulcanizate measured to rupture at numerous strain rates at 10 temperatures between −42.8 and 93.3° C. From − 34.4 to 93.3° C, g (ε) was found to be independent of both time and temperature, but at −42.8° C for strains greater than about unity, g(ε) was found to be different. The functional form of g(ε) was compared with that predicted by three different analytical expressions for representing stress-strain data. To show further the advantages of F(t) for representing stress-strain data determined at different strain rates and temperatures, previously published data on the NBS polyisobutylene were presented on a plot of log F(t)298/T vs. log t/aT. From the composite curve, E(t) was calculated and found to be in close agreement with published data.
Changes in Polybutadiene Rubber under Various Conditions of Aging
Authors: Salimov M. A. 
Published: February 2011

Abstract
1. The systematic relations of the oxidation of SKB under the action of heat, light, and ionizing radiation are considered and it is shown that the formation of a series of oxygen-containing products takes place (hydroperoxides, alcohols, aldehydes, ketones, acids, ethers, and esters). The general tendency for formation of these compounds was clarified for each separate case. 2. The behavior of double bonds of various configurations (1,2 and cis and trans 1,4) reveals differences in reactivity, namely: in the thermal, light, and radiation reactions, a decrease of the number of double bonds in the 1,2 position takes place, in general this is due to crosslinking and formation of volatile acids, but in the radiation reaction it is also due to hydrogenation. The increased rate of the decrease of the number of cis 1,4-bonds is in all cases interpreted as evidence of isomerization to the trans-configuration. It was shown that migration of 1,4 double bonds along the chain towards the tertiary carbon atoms and formation of conjugated double bonds (band at 1595 cm−1) takes place. 3. A decrease of the number of double bonds in the backbone (cis and trans 1,4) takes place that is mainly due to the formation of oxygen-containing compounds. Therefore, the quantitative investigation of this process can give an idea of the level of oxidative degradation. 4. The increase of the total absorption in the region 1400 to 750 cm−1 is connected with crosslinking. This, together with other existing methods (investigation of equilibrium swelling and stress relaxation) can be used for the estimation of the degree of crosslinking.
Identification of Rubber Polymers by Mass Spectrometry
Authors: Phillips J. K. 
Published: February 2011

Abstract
The identity of an elastomer or elastomers in a rubber compound can be determined within a few minutes by the use of a new analytical procedure described in this article. It involves high temperature pyrolysis for two seconds, in vacuo, with an arc imaging furnace and subsequent analysis of the gaseous pyrolyzate with a mass spectrometer. Numerical values derived from the mass spectra of standards permit semi-quantitative analyses of some mixtures of elastomers in cured products. Qualitative analyses have also been made on most of the common textile polymers and a small number of miscellaneous polymers.