Electrostatic and Tensile Properties of Rubber and GR-S at Elevated Temperatures

1946 ◽  
Vol 19 (2) ◽  
pp. 428-443
Author(s):  
R. S. Havenhill ◽  
H. C. O'Brien ◽  
J. J. Rankin
Keyword(s):  
Tensile Strength ◽  
Zinc Oxide ◽  
Test Specimen ◽  
Elevated Temperatures ◽  
Electrostatic Charge ◽  
Inclined Plane ◽  
Contact Potential ◽  
New Apparatus ◽  
Highly Loaded ◽  
Positive Materials

Abstract A new apparatus has been described for measuring contact potentials of rubber and GR-S compounds at elevated temperatures. In this apparatus, the electrostatic charge, acquired by rolling a steel ball down the surface of a rubber test-specimen on a heated inclined plane, is measured when the ball drops into the cup of an electrostatic modulator. This potential, although not the actual contact potential, is nevertheless, proportional to it. With this apparatus, the contact potential of GR-S at elevated temperatures was found to increase much more (become more negative) than that of rubber. The release of electrons (increase in negative contact-potential) and consequent disruption of electrostatic attractive forces within the material at elevated temperature probably partly accounts for the much greater decrease in tensile strength of GR-S over rubber, and is further confirmation of the electrostatic contact potential theory of reinforcement. By the further application of this theory, highly positive materials, such as certain proteins, finely divided silica, and sodium silicate, which retain their positive charges at elevated temperatures and make the stocks more positive, have been found to more than double the hot tensile strengths of compounds made from GR-S latex and highly loaded with zinc oxide.

Pigment Contact Potentials and Reinforcement

1963 ◽  
Vol 36 (1) ◽  
pp. 176-193
Author(s):  
R. S. Havenhill ◽  
L. E. Carlson
Keyword(s):  
Particle Size ◽  
Zinc Oxide ◽  
Calcium Carbonate ◽  
Contact Potential ◽  
Zinc Oxides ◽  
Polybutadiene Rubber ◽  
New Apparatus ◽  
Mohs Hardness ◽  
Processing Properties ◽  
Cut Surface

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.

Electrostatic Properties of Rubber and GR-S

1945 ◽  
Vol 18 (2) ◽  
pp. 337-352
Author(s):  
R. S. Havenhill ◽  
H. C. O'Brien ◽  
J. J. Rankin
Keyword(s):  
Tensile Strength ◽  
Condensation Product ◽  
Electrostatic Charge ◽  
Contact Potential ◽  
Electrostatic Charges ◽  
Audio Amplifier ◽  
Synthetic Rubber ◽  
Current Voltage ◽  
High Zinc ◽  
Stationary Electrode

Abstract A new electrostatic modulator has been described for measuring the electrostatic charges on rubber, synthetic rubber, and various materials. In this apparatus the electrostatic lines of force established between the charged specimen and a stationary electrode plate connected to the grid of an audiofrequency amplifier are cut or modulated at audiofrequency by a small four-bladed, motor-driven fan. This produces in effect an alternating current voltage which can be readily amplified by the audio amplifier and quantitatively measured on a meter in the output circuit. This device, in conjunction with a mirror-surfaced metal plunger system for contacting the rubber samples, has been used to measure the contact potential of various rubber and GR-S compounds. Electrostatic contact potential data are shown for both rubber and GR-S compounds with and without organic and inorganic reinforcing agents, and these data bear out the formulation of an electrostatic contact potential theory of reinforcement in which the reinforcement of rubber and GR-S is explained on the basis of contact potentials and resultant electrostatic attractive forces which exist between the rubber and the reinforcing agents. By the application of this theory, organic materials which have a highly positive electrostatic charge, such as polymerized trimethyldihydroquinoline and Flectol-H (an acetone-aniline condensation product), have been found to increase the tensile strength of the pure-gum type of GR-S compounds as much as fivefold and nearly to double the tensile strength of high zinc oxide loaded GR-S compounds.

The Dispersion of Gas Black and the Physical Properties of Rubber Mixtures

1931 ◽  
Vol 4 (1) ◽  
pp. 29-38 ◽  
Author(s):  
E. A. Grenquist
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Good Method ◽  
Theoretical Possibility ◽  
Homogeneous Surface ◽  
Degree Of Dispersion ◽  
Highly Loaded

Abstract Many rubber technologists have already shown the importance of the dispersion of pigments in order to obtain the maxima physical properties of rubber mixtures. In a recent publication on the physical properties of gas black Carson and Sebrell state that they do not know of any article based on tests which deals with the relations between the dispersion of gas black and the properties of corresponding mixtures. Wiegand has already shown, in discussing mixtures highly loaded with gas black, that an incomplete dispersion of the pigments is no longer possible if the consistency of rubber falls below a definite value. He states that the lustre on the surface of a sample such as is used to determine tensile strength is a good method of estimating the degree of dispersion. Hauser upholds the idea that certain pigments attain a maximum dispersion during milling. In two preceding communications I studied the distribution of gas black in vulcanized and unvulcanized mixtures. I showed that changes in dispersion occur during milling as well as during vulcanization, and I discussed the theoretical possibility of obtaining the maximum dispersion and reënforcement. On the contrary, I am not concerned in these articles with the actual physical properties of the mixtures examined. In the present work, I wish to attempt to establish the relations between the dispersion of gas black and certain physical properties of rubber mixtures, whether vulcanized or not. The dispersion was determined by means of the microscope on freshly cut surfaces of mixtures vulcanized and unvulcanized, using a Leitz vertical illuminator and a Zeiss arc lamp as the source of light. Magnified about 300 times, the aggregates of gas black appear like a non-homogeneous black mass, while on the smoother and more homogeneous surface of the rubber the reflection is so increased that the field remains lighted.

Ionic Crosslinking of Carboxylated SBR

1983 ◽  
Vol 56 (5) ◽  
pp. 942-958 ◽  
Author(s):  
Kyosaku Sato
Keyword(s):  
Zinc Oxide ◽  
Carbon Black ◽  
Elevated Temperatures ◽  
Ion Clusters ◽  
Ionic Crosslinking ◽  
Reinforcing Fillers ◽  
Ionic Bonds ◽  
Tan Δ ◽  
And Shifts ◽  
Ionic Crosslinks

Abstract 1. Ionic bonding of carboxylated SBR with zinc oxide is detectable by means of measurements of the temperature dependence of tan δ. There is an α peak in the region of 60°C at 3.5 Hz. The position and shape of the α peak are strongly dependent on the state of cure of the vulcanizates. Without permanent crosslinking, the α peak is a plateau; as the crosslink density increases, the α peak becomes sharper and shifts to lower temperatures. The presence of carbon black causes the α peak to shift to higher temperatures, regardless of the presence of permanent crosslinks. 2. Ionic bonds in carboxylated SBR reacted with zinc oxide are in the form of ion clusters which function as crosslinks at room temperature. The ionic crosslinks provide carboxylated SBR with high tensile strength in the absence of reinforcing fillers. The presence of carbon black causes the 300% modulus to increase. The ionic crosslinks are labile, and the strength is lost at moderately elevated temperatures. A mixed cure system consisting of both sulfur and zinc oxide provides higher heat resistance than either of the single cure systems.

Tensile strength of HPSi3N4 at room and elevated temperatures

1987 ◽  
Vol 3 (3) ◽  
pp. 256
Author(s):  
Tatsuki Ohji ◽  
Seisuke Sakai ◽  
Masaru Ito ◽  
Yukihiko Yamauchi ◽  
Wataru Kanematsu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Elevated Temperatures

Tensile Properties of Low Nickel Austenitic Stainless Steel at Elevated Temperatures

2012 ◽  
Vol 159 ◽  
pp. 346-350
Author(s):  
Shu Min Liu ◽  
Jian Bin Zhang
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Elevated Temperatures ◽  
Peak Stress ◽  
Temperature Curve ◽  
Delta Ferrite ◽  
Cross Sectional ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Reduction Percentage

The elevated temperature short-time tensile test with the sample of casting low nickel stainless steel was conducted on SHIMADZU AG-10 at ten temperatures 300, 500, 600, 700, 800, 950, 1000, 1050, 1100, and 1250°C, respectively. The stress-strain curves with the thermal deformation at the different temperatures, the peak stress intensity-temperature curve, and the reduction percentage of cross sectional area-temperature curve were obtained. Metallographic test samples were prepared and the morphology of deforming zone was observed by optical microscopy. The experimental results show that the tensile strength of the test samples decreases with increasing temperature. From 300 to 800°C, the work harding occurred and the tensile strength increases with increasing strain. The work softening occurred and the tensile strength decreases with increasing strain at temperatures of 800 to 1250°C. The minimum value of reduction percentage was measured at 800 °C. The austenite and delta-ferrite are the main phase in the tested samples. When the tensile temperatures are increased to 1200°C, the delta-ferrite became thinner and broke down to be spheroidized.

Alumina fibre FP

1980 ◽  
Vol 294 (1411) ◽  
pp. 411-417 ◽  
Keyword(s):  
Tensile Strength ◽  
Elevated Temperatures ◽  
Low Cost ◽  
Ferrous Metal ◽  
High Strength ◽  
Textile Fibre ◽  
Continuous Filament ◽  
Fibre Spinning ◽  
Metal Castings ◽  
Room Temperature Strength

A new experimental inorganic fibre currently under development at the Du Pont Company is a continuous filament, polycrystalline a-alumina yarn designated Fibre FP. This fibre is suitable for reinforcing a variety of materials, especially non-ferrous metal castings because of a combination of properties such as high strength and modulus, stability at elevated temperatures, composite castability and potentially low cost. Fibre FP, essentially > 99 % a-Al 2 O 3 , is made by a novel continuous ceramic fibre process utilizing low cost textile fibre spinning technology and is produced as a yarn containing 210 filaments. The modulus of Fibre FP is 379 GPa (55 x 10 6 lbf in -2 ) with a tensile strength of 1380 MPa (200000 lbf in -2 ). The room temperature strength and modulus of the fibre are retained to about 1000 °C. Recently, higher strength FP fibres with a tensile strength of 2070 MPa (300000 lbf in -2 ) have been demonstrated on a laboratory scale.

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