Molecular Theory for the Tensile Strength of Gum Elastomers

1964 ◽  
Vol 37 (4) ◽  
pp. 808-817 ◽  
Author(s):  
F. Bueche ◽  
J. C. Halpin
Keyword(s):  
Tensile Strength ◽  
Creep Curve ◽  
Viscoelastic Properties ◽  
Butyl Rubber ◽  
Molecular Theory ◽  
Creep Response ◽  
Failure Curve ◽  
Ultimate Elongation ◽  
Propagating Crack ◽  
Ultimate Properties

Abstract The tensile strength and ultimate elongation properties of any given amorphous elastomer can be described by a characteristic failure curve. It is shown in this paper that the failure curve can be predicted from a knowledge of the creep curve of the elastomer together with the data from a Mooney-Rivlin plot. The theory relating the ultimate properties to the viscoelastic properties of the elastomer is based upon the idea of a propagating crack, the rate of propagation being limited by viscoelastic mechanisms. Data for the failure curves and creep response for EPR and SBR elastomers are presented and shown to support the theory. Literature data for butyl rubber are also shown to confirm the theory.

Time and Temperature Dependence of the Ultimate Properties of an SBR Rubber at Constant Elongations

1961 ◽  
Vol 34 (3) ◽  
pp. 897-909
Author(s):  
Thor L. Smith ◽  
Paul J. Stedry
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Temperature Dependence ◽  
Rate Dependence ◽  
Strain Rates ◽  
Type Specimens ◽  
Stress Strain ◽  
Ultimate Elongation ◽  
Tensile Tester ◽  
Ultimate Properties

Abstract A study was made previously of the temperature and strain rate dependence of the stress at break (tensile strength) and the ultimate elongation of an unfilled SBR rubber. In that study, stress-strain curves to the point of rupture were measured with an Instron tensile tester on ring type specimens at 14 temperatures between −67.8° and 93.3° C, and at 11 strain rates between 0.158×10−3 and 0.158 sec−1 at most temperatures. The tensile strength was found to increase with both increasing strain rate and decreasing temperature. At all temperatures above −34.4° C, the ultimate elongation was likewise found to increase with increasing strain rate and decreasing temperature but at lower temperatures the opposite dependence on rate was observed; at −34.4° C, the ultimate elongation passed through a maximum with increasing rate.

The Ultimate Properties of Simple Elastomers

1958 ◽  
Vol 31 (1) ◽  
pp. 19-26 ◽  
Author(s):  
A. M. Bueche
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Theoretical Approach ◽  
Major Part ◽  
Large Mass ◽  
University Of Wyoming ◽  
Ultimate Elongation ◽  
Ultimate Properties ◽  
Similar Theory

Abstract The ultimate properties of polymers are very poorly understood. A large mass of practical data is available but at present there seem to be no molecular theories for its correlation or for use as a guide in obtaining new data. In the following pages a theoretical approach to the ultimate properties of simple crosslinked elastomers will be described. The treatment will be limited to the tensile strength and ultimate elongation at temperatures high enough so that crystallinity and the viscous work during extension are negligible. The theory can be extended to cover compressive or shear strength with relatively little effort. The incorporation of the effects of viscosity and crystallinity will require somewhat more work. (After the completion of the major part of this work I learned that Prof. F. Bueche, University of Wyoming, has developed a somewhat similar theory for the tensile strength of viscous elastomers.)

Diisocyanate-Linked Polymers. III. Relationships between the Composition and Ultimate Tensile Properties of Some Polyurethane Elastomers

1962 ◽  
Vol 35 (3) ◽  
pp. 753-775 ◽  
Author(s):  
Thor L. Smith ◽  
Alan B. Magnusson
Keyword(s):  
Tensile Strength ◽  
Chemical Nature ◽  
Average Molecular Weight ◽  
Extension Rate ◽  
Glass Temperature ◽  
Experimental Conditions ◽  
Polyurethane Elastomers ◽  
Ultimate Elongation ◽  
Rate Of Increase ◽  
Ultimate Properties

Abstract The tensile strength and elongation at rupture of elastomers vary markedly with the experimental conditions used in measurement. For example, when measured at a fixed rate of extension, the tensile strength may increase by a factor of 100 or more as the temperature is decreased, and the ultimate elongation may increase concomitantly by a factor of 10 or more and then decrease to a few per cent. The ultimate properties also depend on the chemical nature of the network chains, the degree of crosslinking, and on the regularity of spacing of the crosslinking sites. In addition, those elastomers which crystallize during extension (e.g., vulcanized natural rubber) normally exhibit higher tensile strengths and ultimate elongations than those which do not crystallize (e.g., SBR rubbers). In seeking relationships between the structure and the ultimate properties of elastomers, these various factors which affect ultimate properties must be carefully considered. Previously a study was made of the tensile strength and ultimate elongation of several series of polyether-polyurethan elastomers prepared from polyoxypropylene glycol 2025 (PPG), trimethylolpropane (TMP), and either toluene 2,4-diisocyanate (TDI) or hexamethylene 1,6-diisocyanate (HDI). The structure of these elastomers was characterized by (1) the number of network chains per unit volume ν and (2) the concentration of urethan groups [U]. These parameters could be varied independently over certain ranges by making appropriate changes in the average molecular weight of PPG 2025 through blending it with dipropylene glycol (DPG). The glass temperature Tg of the elastomers increased linearly with [U], the rate of increase being considerably greater for the TDI-linked than for the HDI-linked elastomers. These elastomers apparently did not crystallize upon extension, and their ultimate properties, measured at a fixed extension rate, were found to depend on both [U] and ν. However, when compared in corresponding temperature states, i.e., at equal values of T−Tg, the ultimate properties over a wide temperature range were found to be independent of [U], or approximately so, when [U] was less than about 1.85 moles/kg. Also, the ultimate elongation was observed to be inversely proportional to ν, although the proportionality constant was temperature-dependent. It thus appears that certain elastomers which do not crystallize have ultimate properties which depend not only on ν and Tg but also on the chemical nature of the network chains.

Modeling pharmaceutical compacts tensile strength based on viscoelastic properties

2013 ◽  
Vol 239 ◽  
pp. 441-450 ◽  
Author(s):  
Dhananjay A. Pai ◽  
Anna Alsman Hayes ◽  
Martin R. Okos
Keyword(s):  
Tensile Strength ◽  
Viscoelastic Properties ◽  
Strength Based

Promoters for the Reaction of Rubber with Carbon Black

1955 ◽  
Vol 28 (3) ◽  
pp. 895-905 ◽  
Author(s):  
Kenneth W. Doak ◽  
George H. Ganzhorn ◽  
Bernard C. Barton
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Cumene Hydroperoxide ◽  
Butyl Rubber ◽  
Nitroso Compounds ◽  
Active Centers ◽  
Alkyl Radicals ◽  
Styrene Copolymers ◽  
Aromatic Nitroso Compounds ◽  
Butadiene Styrene

Abstract Heating unvulcanized mixtures of rubber and carbon black gives increased electrical resistivity, reduced hysteresis and hardness, higher modulus, and increased abrasion resistance to the vulcanizate. This is believed to result from improved dispersion of carbon black, accompanying a chemical reaction between rubber and carbon black. Butyl rubber, with low unsaturation, reacts more slowly than Hevea rubber or butadiene-styrene copolymers (GR-S). Chemical promoters decrease the time and temperature required for the reaction. Certain quinones and aromatic nitroso compounds are effective in both Hevea and Butyl rubber. t-Butyl perbenzoate and cumene hydroperoxide are particularly effective in Hevea rubber and GR-S containing channel black, and when used in optimum amounts, do not adversely affect tensile strength. Hexachlorocyclopentadiene and hexachlorophenol are effective in both Hevea and Butyl rubber, l,3-Dichloro-5,5-dimethylhydantoin and hexachlorocyclopentadiene are effective in Butyl containing channel or furnace blacks. Chemical promoters are believed to initiate allylic or alkyl radicals on rubber chains, which react with active centers on carbon black, forming primary valence bonds.

scholarly journals Study the impact of A nanomixture of carbon black and clay on the mechanical properties of A series of irradiated natural rubber/ butyl rubber blend

2021 ◽  
Author(s):  
Dalal Alshangiti
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Carbon Black ◽  
Natural Rubber ◽  
Theoretical Models ◽  
Butyl Rubber ◽  
Nano Particles ◽  
Vinyl Silane ◽  
Link Density ◽  
The Impact

Abstract A series of natural rubber/ butyl rubber NR/IIR blend loaded with N660 carbon black CB and triethoxy vinyl silane treated clay nano particles (TCNP) were prepared using gamma irradiation in the presence of polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). The effect of incorporating different content of N660 carbon black and 5 part per hundred of rubber (phr) of treated clay on the mechanical properties of the prepared nano composites have been investigated. The additions of TCNP into CB/ rubber composites markedly increase their tensile strength due to the increase of the cross-link density. These results indicated that the TCNP may be enclosed or trapped in the occluded structure of CB. The effect of CB and TCNP content on the tensile strength (σ), elongation at break (εb %) and modulus of elasticity (E, MPa) of natural rubber/ butyl rubber NR/IIR blend have been investigated. The incorporation of 5 phr of TCNP into 30 phr carbon black loaded NR/ IIR composites results in the increased tensile strength value by about 60%. Finally, theoretical models were used to interpret the experimental results.

Abrasion Resistance and High Speed Tensile Strength of Elastomers

1966 ◽  
Vol 39 (4) ◽  
pp. 823-840 ◽  
Author(s):  
Ruprecht Ecker
Keyword(s):  
Tensile Strength ◽  
Viscoelastic Properties ◽  
High Speed ◽  
Loss Modulus ◽  
Empirical Relation ◽  
Viscoelastic Behavior ◽  
Experimental Tests ◽  
Test Results ◽  
Resonant Vibrations ◽  
Mechanical Rupture

Abstract In earlier communications, we defined abrasion, especially of tires, as a thermal-oxidative process caused at high velocity of mechanical rupture. Other authors (e.g., Schallamach, Boggs, Zapp etc.), with theoretical and experimental tests, prove the importance of viscoelastic behavior as a characteristic property for abrasion. The results of experiments on six elastomers (NR, IR, BR, SBR, IIR, and EPT) compared in tire tread compounds are communicated and discussed in the present work. Tensile strength was determined over a temperature range of 20° to 140° C at deformation speeds of 10 to 20,000 % elongation per second. Forced, non-resonant vibrations were used to determine viscoelastic properties, e.g., resilience, storage modulus, and loss modulus. As abrasion is a consequence of frictional processes, coefficients of friction, dependent on temperature, were measured on dry, wet, and frosty asphalt/fine concrete track. The apparatus is briefly described. From these test results, an empirical relation established between abrasion, friction, viscoelastic properties, tensile strength at high speed and temperature allows one to predetermine the abrasion behavior of a vulcanizate in the laboratory.

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