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Polybutadiene rubber extensibility

At the same time binders were introduced which gave mechanical integrety to the grains as well as acting as fuels. The list of fuel/binders used in solid propellant rockets is extensive and has ranged from as-phalt/oil mixtures to polybutadiene rubbers. [Pg.58]

COMMERCIAL USE S5mdiotactic 1,2-polybutadiene is used in films, footwear soles, tubes, and hoses atactic 1,2-polybutadiene is extensively used in the rubber and tire industry. [Pg.318]

Polymers can be divided into two main classes on the basis of their reactivity to NO [1]. Saturated polymers such as polyethylene (PE) and polypropylene (PP) belong to the first group, but Nylon 66 does not. The second group covers elastomers. Butyl rubber (BR) undergoes scissions of the main chain, and polybutadiene is extensively cross-linked under the action of NO. These elastomers have approximately the same reactivity to NO as to ozone. All films exposed to NO become yellow, and their infrared (IR) spectra show that nitro groups enter into macromolecules. In polyvinylchloride in the presence of NO, a decrease in the amount of chlorine, along with the appearance of nitro and nitrite groups, are observed from IR spectra. [Pg.3]

Whilst, chemically, SBS triblocks are similar to SBR, for example they do not show measurable breakdown on mastication, they are seriously deficient in one respect, they show a high level of creep. This would indicate that the concept of all the styrene blocks being embedded in the domains with all of the polybutadiene blocks being in the amorphous matrix is rather too simplistic. It has also resulted in these materials not being used extensively in traditional rubber applications. One exception from this is in footwear, where blends of SBS and polystyrene have been used with noted success for crepe soles. [Pg.298]

The main conclusions of the strain induced crystallization behavior of high trans polybutadiene based rubber and natural rubber are (1) the rate of crystallization is extremely rapid compared to that of NR (2) the amount of strain induced crystallization is small compared to that of NR, especially at room temperature and (3) for the high trans SBR s relative to NR, crystallization is more sensitive to temperature at low extension ratios, and crystallization is less sensitive to strain. [Pg.96]

Figure 3. Modulus contributions from chemical cross-links (Cx, filled triangles) and from chain entangling (Gx, unfilled symbols) plotted against the extension ratio during cross-linking, A0, for 1,2-polybutadiene. Key O, GN, equibiaxial extension , G.v, pure shear A, Gx, simple extension Gx°, pseudo-equilibrium rubber plateau modulus for a polybutadiene with a similar microstructure. See Ref. 10. Figure 3. Modulus contributions from chemical cross-links (Cx, filled triangles) and from chain entangling (Gx, unfilled symbols) plotted against the extension ratio during cross-linking, A0, for 1,2-polybutadiene. Key O, GN, equibiaxial extension , G.v, pure shear A, Gx, simple extension Gx°, pseudo-equilibrium rubber plateau modulus for a polybutadiene with a similar microstructure. See Ref. 10.
The two-network method has been carefully examined. All the previous two-network results were obtained in simple extension for which the Gaussian composite network theory was found to be inadequate. Results obtained on composite networks of 1,2-polybutadiene for three different types of strain, namely equibiaxial extension, pure shear, and simple extension, are discussed in the present paper. The Gaussian composite network elastic free energy relation is found to be adequate in equibiaxial extension and possibly pure shear. Extrapolation to zero strain gives the same result for all three types of strain The contribution from chain entangling at elastic equilibrium is found to be approximately equal to the pseudo-equilibrium rubber plateau modulus and about three times larger than the contribution from chemical cross-links. [Pg.449]

The stress relaxation properties of a high molecular weight polybutadiene with a narrow molecular weight distribution are shown in Figure 1. The behavior is shown in terms of the apparent rubber elasticity stress relaxation modulus for three differrent extension ratios and the experiment is carried on until rupture in all three cases. A very wide rubber plateau extending over nearly 6 decades in time is observed for the smallest extension ratio. However, the plateau is observed to become narrower with increasing extension... [Pg.48]

Figure 1. Stress relaxation curves for three different extension ratios. Uncross-linked high-vinyl polybutadiene with a weight average molecular weight of 2 million and a reference temperature of 283 K. G is the apparent rubber elasticity modulus calculated from classical affine theory. (Solid line is data from Ref. 1). Figure 1. Stress relaxation curves for three different extension ratios. Uncross-linked high-vinyl polybutadiene with a weight average molecular weight of 2 million and a reference temperature of 283 K. G is the apparent rubber elasticity modulus calculated from classical affine theory. (Solid line is data from Ref. 1).
The 5-7% soap remaining in rubber prepared by the free-radical process results in reduced performance and reduced oil extensibility compared to organometallic-catalyzed polybutadienes. [Pg.57]

Polyisoprene (R = CH3) with a c/s-1,4 configuration is common in nature in different species of piants and is known as natural rubber. Trans-polyisoprene is found in two naturai resins known as gutta-percha and balata. Natural or synthetic polyisoprenes, as well as polybutadiene, are among the most common elastomers with many practical uses. Other elastomers with extensive practical applications are copolymers, many of them using butadiene or isoprene in the starting monomer mixture. [Pg.439]

The effects of HAF black on the stress relaxation of natural rubber vulcanizates was studied by Gent (178). In unfilled networks the relaxation rate was independent of strain up to 200% extension and then increased with the development of strain induced crystallinity. In the filled rubber the relaxation rate was greatly increased, corresponding to rates attained in the gum at much higher extensions. The results can be explained qualitatively in terms of the strain amplification effect In SBR, which does not crystallize under strain and in cis-polybutadiene, vulcanizates of which crystallize only at very high strains, the large increase in relaxation rate due to carbon black is not found (150). [Pg.205]

The crosslinking of natural rubber and polybutadiene has been extensively studied. The mechanism of radiolysis of these polymers, however, is not yet fully understood. Many discrepancies, in fact, exist between the reported results. These are most certainly due to the impurities present in the samples. A summary of the reported data has been given by Schultz [323] and by Chapiro [285]. For purified natural... [Pg.262]

The most outstanding property of butyl rubber is its very low air permeability, which has led to its extensive use in tire inner tubes and liners. A major disadvantage is its lack of compatibility with SBR, polybutadiene, and natural rubber. An ozoneresistant copolymer of isobutylene and cyclopentadiene has also been marketed. [Pg.415]


See other pages where Polybutadiene rubber extensibility is mentioned: [Pg.104]    [Pg.317]    [Pg.56]    [Pg.104]    [Pg.138]    [Pg.531]    [Pg.282]    [Pg.293]    [Pg.60]    [Pg.712]    [Pg.342]    [Pg.35]    [Pg.276]    [Pg.111]    [Pg.409]    [Pg.73]    [Pg.617]    [Pg.35]    [Pg.376]    [Pg.698]    [Pg.310]    [Pg.487]    [Pg.181]    [Pg.282]    [Pg.293]    [Pg.204]    [Pg.522]    [Pg.204]    [Pg.142]    [Pg.305]    [Pg.420]    [Pg.456]    [Pg.156]   
See also in sourсe #XX -- [ Pg.352 ]




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