Correlation of Tensile Strength with Brittle Points of Vulcanized Diene Polymers

1947 ◽  
Vol 20 (2) ◽  
pp. 515-524
Author(s):  
A. M. Borders ◽  
R. D. Juve
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Practical Importance ◽  
Testing Temperature ◽  
Crack Growth Resistance ◽  
Polymer Composition ◽  
Copolymer Composition ◽  
General Observation ◽  
Brittle Point

Abstract For several years work has been carried on here to evaluate a large number of diene polymers and copolymers as rubberlike materials. The writers have observed that changes in polymer composition which result in improved tensile strength and crack-growth resistance of the vulcanizate cause an increase in low temperature stiffness and a rise in brittle point. This generalization seems to apply to tensile values measured at elevated temperatures as well as to those at room temperature. For example, a butadiene copolymer of dichlorostyrene can be made which, as a tread type of vulcanizate, exhibits a tensile strength of over 1500 pounds per square inch at 93° C, in comparison with 800 to 1000 pounds per square inch for GR-S in the same test tread formula at the same temperature. The brittle point of the butadiene-dichlorostyrene rubber, however, is −35° C or higher. GR-S treads in the same test have brittle points between − 55° and −60° C. Probably of greater practical importance is the fact that the vulcanizate with the higher brittle point is stiffer at temperatures well above the brittle point. The purpose of this investigation was to determine to what extent the maximum tensile strength of tread stocks of several synthetic rubbers varies with the temperature difference between the brittle point and the tensile testing temperature of each rubber. These data can then be used to judge the validity and extent of the general observation that changes in copolymer composition which increase strength also raise the brittle point.

Tribological Properties of Hot-Pressed SrSO4 Ceramic at Elevated Temperatures in Dry Sliding Against Alumina Ball

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Chong-Chong Mao ◽  
Yu-Feng Li
Keyword(s):  
Tribological Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Testing Temperature ◽  
Dry Sliding ◽  
Potential Candidate ◽  
Friction Behavior ◽  
Wear Rates ◽  
Brittle To Ductile Transition ◽  
Lubricating Film

SrSO4 ceramic was prepared by hot-pressed sintering and its friction behavior was investigated against the Al2O3 ball under the dry sliding condition from room temperature to 800 °C. From room temperature to 400 °C, the tribological properties of SrSO4 ceramic are quite poor with the friction coefficients of 0.65–0.83 and the wear rates of about 10−3 mm3/Nm. With the testing temperature increasing to 600 °C and 800 °C, a brittle to ductile transition of SrSO4 takes place because of the activated slip systems. The friction coefficient and wear rate of SrSO4 ceramic also obviously decrease to 0.37 and about 10−4 mm3/Nm at 800 °C. The significant improvement of the tribological properties is ascribed to the formation of a smooth and continuous SrSO4 lubricating film with excellent ductility and low shear strength at elevated temperature. SrSO4 is considered to be a potential candidate for high-temperature solid lubricant with excellent lubricity.

Mechanical Properties and Fracture Study of Alumina Dispersion Hardened Copper-Based Nano-Composite at Elevated Temperatures

2013 ◽  
Vol 829 ◽  
pp. 583-588 ◽  
Author(s):  
Ali Dalirbod ◽  
Yahya A. Sorkhe ◽  
Hossein Aghajani
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Fracture Surface ◽  
Yield Strength ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Testing Temperature ◽  
Optical Microscope ◽  
Tensile Fracture ◽  
Different Temperatures

Alumina dispersion hardened copper-base composite was fabricated by internal oxidation method. The high temperature tensile fracture of Cu-Al2O3 composite was studied and tensile strengths were determined at different temperatures of 600, 680 and 780 °C. Microstructure was investigated by means of optical microscope and field emission scanning electron microscope (FESEM) with energy dispersive spectroscopy (EDS). Results show that, ultimate tensile strength and yield strength of copper alumina nanocomposite decrease slowly with increasing temperature. The yield strength reaches 119 MPa and ultimate tensile strength reaches 132 MPa at 780 °C. Surface fractography shows a dimple-type fracture on the fracture surface of the tensile tests where dimple size increases with increasing testing temperature and in some regions brittle fracture characteristics could be observed in the fracture surface.

scholarly journals Mechanical and Dielectric Properties of Two Types of Si3N4 Fibers Annealed at Elevated Temperatures

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1498 ◽  
Author(s):  
Jie Zhou ◽  
Fang Ye ◽  
Xuefeng Cui ◽  
Laifei Cheng ◽  
Jianping Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Tensile Strength ◽  
Dielectric Properties ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Fiber Bundles ◽  
Lower Content ◽  
Amorphous Silicon Nitride ◽  
Waveguide Method

The mechanical and dielectric properties of two types of amorphous silicon nitride (Si3N4) fibers prior to and following annealing at 800 °C were studied. The tensile strengths of the Si3N4 fiber bundles were measured using unidirectional tensile experimentation at room temperature, whereas the permittivity values were measured at 8.2–12.4 GHz using the waveguide method. The results demonstrated that the tensile strength and dielectric properties of Si3N4 fibers were correlated to the corresponding composition, microstructure, and intrinsic performance of electrical resistance. The Si3N4 fibers with a lower content of amorphous SiNxOy presented an improved thermal stability, a higher tensile strength, a higher conductivity, and a significantly stable wave-transparent property. These were mainly attributed to the highly pure composition and decomposition of less amorphous SiNxOy.

High-Temperature Compression Testing of Graphite

1953 ◽  
Vol 20 (2) ◽  
pp. 289-294
Author(s):  
Leon Green
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Temperature ◽  
Stress Relaxation ◽  
Temperature Control ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Limited Degree ◽  
Relaxation Curves ◽  
Short Time

Abstract Experiments on the compression of graphite cylinders at elevated temperatures are described. It is found that the short-time compressive strength increases with temperature in the range from room temperature to 2000 C, a variation which is consistent with the previously reported behavior of the tensile strength. Photographs of typical modes of deformation and their corresponding stress-strain curves are presented, but a limited degree of temperature control renders the curves semiquantitative in nature. The large, mutually opposing influences of temperature and strain rate are illustrated by photographs of typical failures, and stress-relaxation curves manifest the plasticity of graphite at high temperatures.

scholarly journals The Behavior of Graphite Under Alternating Stress

1951 ◽  
Vol 18 (4) ◽  
pp. 345-348
Author(s):  
Leon Green
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Endurance Limit ◽  
Elevated Temperatures ◽  
Fatigue Properties ◽  
Polycrystalline Graphite ◽  
Short Time

Abstract The fatigue properties of grade AUF extruded polycrystalline graphite were investigated at ambient and elevated temperatures. Specimens cut parallel to the axis of extrusion were stressed in reversed bending at room temperature and at 3550 F. The endurance limit of this graphite was found to increase from 2500 psi at room temperature to about 4400 psi at 3550 F. The increase in endurance limit is correlative with the increase in short-time tensile strength with temperature observed in earlier studies of graphite.

Effect of Bi Addition on Thermal Stability and Tensile Ductility of Mg-3%Zn-0.4%Zr Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 647-650
Author(s):  
Joong Hwan Jun ◽  
Min Ha Lee
Keyword(s):  
Thermal Stability ◽  
Tensile Strength ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Ductility ◽  
Grain Structure ◽  
Hot Rolled ◽  
Thermal Stability Of ◽  
Zr Alloy

Thermal stability of  grains and tensile ductilities at room and elevated temperatures were investigated and compared for Mg-3%Zn-0.4%Zr and Mg-3%Zn-0.4%Zr-1%Bi alloys in hot-rolled state. The Bi-added alloy showed slightly finer-grained microstructure with enhanced thermal stability, which is closely associated with fine Mg-Bi compounds acting as obstacles for the migration of grain boundaries. The Mg-3%Zn-0.4%Zr-1%Bi alloy exhibited better tensile strength at room temperature and tensile ductilities at elevated temperature. Finer and more homogeneous grain structure with higher thermal stability would be responsible for the enhanced tensile properties in the Bi-added alloy.

S.A.P.-865

Alloy Digest ◽  
1965 ◽  
Vol 14 (8) ◽  
Keyword(s):  
Tensile Strength ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Engineering Properties ◽  
Powder Metal ◽  
High Tensile Strength ◽  
Temperature Performance ◽  
Sintered Aluminum

Abstract SAP is a special Sintered Aluminum Powder characterized by high tensile strength at room temperature and at elevated temperatures. It features a range of useful engineering properties. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep and fatigue. It also includes information on high temperature performance and corrosion resistance as well as forming, machining, joining, and powder metal forms. Filing Code: Al-146. Producer or source: Aluminium Industrie Atkiengesellschaft.

Effect of Cis-Trans Ratio on the Physical Properties of 1,4 Polybutadienes

1957 ◽  
Vol 30 (4) ◽  
pp. 1118-1141 ◽  
Author(s):  
J. N. Short ◽  
V. Thornton ◽  
G. Kraus
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Physical Properties ◽  
Low Temperatures ◽  
Elevated Temperatures ◽  
Trans Content ◽  
Wide Range ◽  
Brittle Point ◽  
Low Sulfur ◽  
In Cis

Abstract The physical properties of vulcanized 1,4 polybutadienes, prepared by heterogeneous catalysis and ranging from 95 per cent cis to nearly 100 per cent trans configuration, were investigated in gum and tread formulations. Comparisons were made at equal effective (physical) degree of crosslinking for both gum- and carbon black-reinforced stocks and for black stocks at equal 300 per cent modulus. In general, as polybutadienes require less sulfur for adequate vulcanization than trans polybutadienes. Vulcanizates of all 1,4 polybutadienes exceeding 15 per cent in cis content are completely rubbery at ordinary temperatures. Polybutadiene of 93 per cent trans content yields tough, leathery, crystalline vulcanizates at 80° F, which become rubbery at moderately elevated temperatures. Without exception the important physical properties change little between 25 and 80 per cent cis content. At both ends of this range the tensile strength of both gum and black stocks rises as a consequence of increasing chain regularity. However, in gum tensile strength not even the highest cis polybutadienes are equivalent to natural or synthetic cis-polyisoprenes. Black stocks of very good tensile strength with elongations ranging from 500 to 700 per cent are obtained with both cis- and trans-polybutadienes. At the crosslinking level for optimum tensile strength, modulus increases with trans content. The cis-polybutadienes have excellent resilience and low hysteresis and maintain their resilience to temperatures as low as −40° F. The latter is true even of the highest as polymers which crystallize at these temperatures. The tendency to crystallize rapidly at low temperatures disappears between 87 and 82 per cent cis content so that polymers of moderately high cis unsaturation have exceptional low-temperature characteristics. These polymers remain completely rubbery down to their brittle point (ca. −85° C). The excellent resilience of cis-polybutadiene is particularly apparent in carbon black-reinforced stocks. Because of the inherently low modulus of these stocks and their low sulfur requirement, these may be vulcanized to rather high degrees of crosslinking. This results in further improvements in resilience and heat build-up with only moderate sacrifices in tensile strength and ultimate elongation. Vulcanizates of 70 to 80 per cent trans-polybutadienes exhibit evidence of crystallinity over a wide range of temperatures and are probably not completely melted at room temperature. Although their resilience is less than that of the high cis-polybutadienes, it is still somewhat better than that of SBR, particularly at low temperatures. The 1,4 polybutadienes are more resistant to oxidative scission than emulsion polybutadiene or SBR and are greatly superior to natural rubber in this respect. The dominant effect in the aging of 1,4 polybutadienes is crosslinking. Because of their low sulfur requirements the cis polybutadienes offer a particular advantage in aging resistance. None of the polybutadienes exhibits ozone resistance comparable to Hevea.

Microstructure and Mechanical Properties of AM50+xTi Magnesium Alloys Extruded from As-Cast and Solution Treated Conditions

2005 ◽  
Vol 488-489 ◽  
pp. 629-632 ◽  
Author(s):  
Qu Dong Wang ◽  
Yongjun Chen ◽  
Jianguo Peng ◽  
Man Ping Liu ◽  
Wen Jiang Ding ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Solution Treatment ◽  
Solution Treated ◽  
Microstructure And Mechanical Properties ◽  
Mg17al12 Phase ◽  
Ti Addition

Microstructure and mechanical properties of AM50+xTi (x=0,0.01,0.1wt%) magnesium alloys extruded from as-cast and solution treated conditions have been studied. Results show that Ti element obviously refines the microstructure of AM50 magnesium alloy and Mg17Al12 phase. Only 0.01 wt% Ti addition can make the Mg17Al12 phase turn into particles and small rod-like shape. Ti addition improves tensile strength at room temperature, and obviously improves elongation at elevated temperatures up to 200°C. The AM50+xTi alloys extruded from as-cast have better tensile strength at room temperature and better elongation at 100°C, 150°C and 200°C than that of AM50+xTi alloys extruded from solution treatment; The plasticity of AM50 magnesium alloys increases with Ti content increasing and temperature increasing for the tensile fractograph.

scholarly journals The Effect of Prestressing and Temperature on Tensile Strength of Basalt Fiber-Reinforced Plywood

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4701
Author(s):  
Rynno Lohmus ◽  
Heikko Kallakas ◽  
Eero Tuhkanen ◽  
Volodymyr Gulik ◽  
Madis Kiisk ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Phenolic Resin ◽  
Elevated Temperatures ◽  
Basalt Fiber ◽  
Tensile Tests ◽  
Resin Matrix ◽  
Fiber Reinforced ◽  
Basalt Fibers ◽  
Reinforcement Effect

The reinforcement of plywood is demonstrated by laminating pretensioned basalt fibers between veneer sheets, to fabricate so-called prestressed plywood. Belt type basalt fibers bearing a specific adhesion promoting silane sizing were aligned between veneer sheets with 20 mm spacing and were pretensioned at 150 N. Three-layer plywood samples were prepared and tested for tensile strength at room temperature and at 150 °C. The room temperature tensile tests revealed a 35% increase in tensile strength for prestressed plywood compared to that of the conventional specimen. The reinforcement effect deteriorated at 150 °C but was restored upon cooling to room temperature. The deterioration is attributed to the weakening of bonding between the basalt fibers and phenolic resin matrix at elevated temperatures due to the softening of the resin.

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