The Cold-Compression sets of Natural and Synthetic Vulcanizates

1946 ◽  
Vol 19 (1) ◽  
pp. 151-162 ◽  
Author(s):  
Ross E. Morris ◽  
Joseph W. Hollister ◽  
Paul A. Mallard
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Leading Edge ◽  
Testing Procedure ◽  
Present Problem ◽  
Cold Compression ◽  
The Past ◽  
Compression Set ◽  
Synthetic Rubber ◽  
Rubber Compounds

Abstract The behavior of certain large synthetic rubber gaskets on naval vessels during the past winter points to the necessity for a cold compression-set test in the specifications for these gaskets. It has been found, for example, that Neoprene gaskets on large valves, which perform satisfactorily at temperatures of 60° F and above, are not usable at temperatures of 40° F and below. They take a cold compression-set, while the valves are closed, so that when the valves are opened and then again closed, the leading edge or surface of the valve does not seat properly. This cold compression-set is not permanent; when the gaskets which exhibit cold compression-set are removed to a warm atmosphere (about 80° F), they slowly regain their original shape. A survey of the literature dealing with the effects of low temperatures on rubber compounds yielded no information on cold compression set. The set test proposed by Morris, James, and Evans in connection with their low temperature stiffness test is not directly applicable to the present problem because it is conducted in tension. Therefore to investigate cold compression-set, it was necessary to devise a new testing procedure.

Effect of Storage and Temperature on Flexibility of Natural and Synthetic Rubbers

1948 ◽  
Vol 21 (4) ◽  
pp. 864-876
Author(s):  
John B. Gregory ◽  
Irving Pockel ◽  
John F. Stiff
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Strain Curve ◽  
Polymer Chains ◽  
Stress Strain Curve ◽  
Low Temperature Storage ◽  
Synthetic Rubber ◽  
Loading And Unloading ◽  
Temperature Storage ◽  
Natural And Synthetic

Abstract A new method for measuring the flexibility of rubber has been described. The method consists essentially in determining the stress-strain curve obtained by loading and unloading a loop formed from a one-inch by six-inch strip cut from a test slab. A coefficient of flexibility independent of the thickness of the sample and, in addition, information on per cent resilience were obtained. By the use of the method described, the behavior of various natural and synthetic rubber gas mask facepiece compounds was studied during one month to three months' exposure at various temperatures down to −20° F. Progressive stiffening probably due to crystallization was found for natural rubber, GR-I, and GR-M compounds at low temperatures. No tendency to crystallize was noted for the GR-S compound. Of the crystallizable polymers GR-I was the most resistant, and GR-M the least resistant to stiffening during low temperature storage. It is of course evident that different polymers have inherently different degrees of resistance to low temperatures. Disregarding these inherent differences the work reported indicates that the resistance of elastomer compounds to stiffening during prolonged low temperature storage is favored by the following: 1. Use of interpolymers made from monomer mixtures having a relatively large proportion of each component, thus obtaining mutual intereference with crystallization. 2. Use of a “tight” cure which probably so impedes the movement of the polymer chains as to make crystallization difficult.

Biofuel Compatibility of Sealing Materials at Low Temperatures

2017 ◽  
Vol 44 (11) ◽  
pp. 1-4
Author(s):  
H.-C. Rost
Keyword(s):  
Low Temperature ◽  
Physical Properties ◽  
Automotive Industry ◽  
Low Temperatures ◽  
Regulatory Framework ◽  
New Markets ◽  
New Developments ◽  
Compression Set ◽  
Sealing Performance ◽  
Sealing Materials

The combination of very good biofuel compatibility with excellent low-temperature properties is of major importance to the automotive industry. Changes in the regulatory framework and the tapping of new markets have increasingly led to new developments in this field. Parker has developed FKM compounds with TR10 values of −30°C, −35°C, −40°C and −45°C, which display only slight changes in physical properties upon storage in FAM B, E85 and KGS (VW first fill fuel). The sealing performance of these compounds at very low temperatures was investigated in compression set tests from −25°C down to −50°C.

Low-Temperature Behavior of Butadiene-Styrene Copolymers. Effect of Compounding Variables

1950 ◽  
Vol 23 (4) ◽  
pp. 760-769
Author(s):  
R. D. Juve ◽  
J. W. Marsh
Keyword(s):  
Low Temperature ◽  
Natural Rubber ◽  
Compression Set ◽  
Similar Work ◽  
Styrene Copolymers ◽  
Synthetic Rubber ◽  
Low Temperature Flexibility ◽  
Extended Exposure ◽  
Butadiene Styrene ◽  
Elastic Characteristics

Abstract Synthetic rubbers and natural rubber increase in stiffness at low temperatures and tend to lose their elastic characteristics. This stiffening and hardening phenomenon occurs in varying degrees with various elastomers. Natural rubber and certain synthetic rubbers crystallize during extended exposure at low temperature, whereas other synthetic rubbers such as GR-S remain amorphous. In a general review of the low temperature properties of synthetic rubber, Liska has shown that decreased styrene in butadiene-styrene copolymers improves the flexibility at low temperature. The low temperature flexibility of vulcanized articles made from any particular rubber or synthetic rubber is influenced by the compounding ingredients admixed with the elastomer. This paper shows the results of some studies of the effect of these compounding ingredients on the low temperature serviceability of butadiene-styrene copolymers. Somewhat similar work on the effect of a large number of plasticizers in GR-S has been conducted at the Rubber Laboratory, Mare Island Naval Shipyard, with particular emphasis on compression set at low temperature.

Low Temperature Flexing Apparatus

1943 ◽  
Vol 16 (3) ◽  
pp. 692-694
Author(s):  
S. M. Martin
Keyword(s):  
Low Temperature ◽  
Technical Committee ◽  
Careful Consideration ◽  
Short Description ◽  
The Past ◽  
Synthetic Rubber ◽  
Low Temperature Flexibility ◽  
Freeze Test ◽  
Modified Test

Abstract For the past ten months, Sub-Committee V of SAE-ASTM Technical Committee A on Automotive Rubber has been working on the standardization of synthetic rubber specifications. Insofar as possible, methods of tests have followed ASTM procedures. ASTM has no recommended procedure for measuring the low temperature flexibility of synthetic rubber. This committee, after careful consideration, has recommended the use of a modification of the Thiokol Corporation's freeze test. This method of testing for low temperature flexibility has been incorporated into a number of recent Aeronautical Material Standards Specifications covering synthetic rubber. The modified test uses the same apparatus as that used in the Thiokol Corporation's Laboratory, or slight modifications of this. Because of the interest in this apparatus, a short description of it is here given.

Retraction Test for Serviceability of Elastomers at Low Temperatures

1951 ◽  
Vol 24 (3) ◽  
pp. 684-696 ◽  
Author(s):  
O. H. Smith ◽  
W. A. Hermonat ◽  
H. E. Haxo ◽  
A. W. Meyer
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Large Deformations ◽  
Prolonged Storage ◽  
Temperature Index ◽  
Low Temperature Storage ◽  
Compression Set ◽  
Low Temperature Flexibility ◽  
Temperature Storage

Abstract Elastomer vulcanizates progressively stiffen as the temperature is lowered. Additional stiffening, due to crystallization, may occur as exposure to low temperatures is prolonged. The available methods of testing the low temperature flexibility of rubber and rubberlike materials do not reveal the losses in flexibility caused by crystallization except by using prolonged storage at low temperatures. A retraction test employing large deformations, which greatly increases the rate of crystallization, has been developed. This test rapidly gives a temperature index correlating with the stiffness of elastomer vulcanizates after storage at low temperatures, and can be used to measure the merit for low temperature applications of both crystallizable and noncrystallizable elastomers. This test in conjunction with conventional (room temperature) tests has been used successfully to study the low temperature performance of Hevea, GR-S, Paracril, and polybutadiene vulcanizates along with vulcanizates of many experimental elastomers. Correlation of results with cold compression set and hardness after low temperature storage has been excellent and substantiates the usefulness of the test.

A Method of Testing the Elasticity of Synthetic Rubbers at Low Temperatures

1943 ◽  
Vol 16 (4) ◽  
pp. 888-896
Author(s):  
George D. Kish
Keyword(s):  
Natural Rubber ◽  
Low Temperatures ◽  
New Product ◽  
Elastic Behavior ◽  
Accurate Data ◽  
Synthetic Rubber ◽  
Rubber Compounds

Abstract With the appearance of many new synthetic rubber compounds, the need has arisen for quick and practical testing to determine their comparative applicability to uses formerly filled by natural rubber compounds. One of the most important points is the elastic behavior of synthetic rubbers at low temperatures, and such information is imperative when synthetics are to be introduced into the design of a new product. To obtain accurate data, an instrument termed an Elastensometer was devised.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

INVAR M93

Alloy Digest ◽  
2008 ◽  
Vol 57 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Ni Content ◽  
Precision Alloys ◽  
Ni Alloy

Abstract Invar is an Fe-Ni alloy with 36% Ni content that exhibits the lowest expansion of known metals from very low temperatures up to approximately 230 deg C (445 deg F). Invar M93 is a cryogenic Invar with improved weldability. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear and bend strength as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as forming and joining. Filing Code: FE-143. Producer or source: Metalimphy Precision Alloys.

FEC-LiTFSI-Pyr1ATFSI Ionic Liquid Electrolyte to Improve Low Temperature Performance of Lithium-Ion Batteries

2014 ◽  
Vol 986-987 ◽  
pp. 80-83
Author(s):  
Xiao Xue Zhang ◽  
Zhen Feng Wang ◽  
Cui Hua Li ◽  
Jian Hong Liu ◽  
Qian Ling Zhang
Keyword(s):  
Low Temperature ◽  
Lithium Ion Batteries ◽  
Low Temperatures ◽  
Freezing Point ◽  
Lithium Ion ◽  
Liquid Electrolyte ◽  
Capacity Retention ◽  
Composite Electrolyte ◽  
Ionic Liquid Electrolyte ◽  
Fluoroethylene Carbonate

N-methyl-N-allylpyrrolidinium bis (trifluoromethanesulfonyl) imide (PYR1ATFSI) with substantial supercooling behavior is synthesized to develop low temperature electrolyte for lithium-ion batteries. Additive fluoroethylene carbonate (FEC) in LiTFSI/PYR1ATFSI/EC/PC/EMC is found that it can reduce the freezing point. LiFePO4/Li coin cells with the FEC-PYR1ATFSI electrolyte exhibit good capacity retention, reversible cycling behavior at low temperatures. The good performance can be attributed to the decrease in the freezing point and the polarization of the composite electrolyte.

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