Showing papers on "Styrene-butadiene published in 1974"
TL;DR: In this paper, the dynamic mechanical response of a styrene/butadiene/styrene (SBS) block copolymer with segment molecular weights of 16,000/78, 000/16,000 (designated as Shell 16/78/16) was determined at various temperatures between -83 and +86°C at frequencies between 0.1 and 1000 Hz.
Abstract: The dynamic mechanical response of a styrene/butadiene/styrene (SBS) block copolymer with segment molecular weights of 16,000/78,000/16,000 (designated as Shell 16/78/16) was determined at various temperatures between -83 and +86°C at frequencies between 0.1 and 1000 Hz. The data were shifted into a master curve according to a procedure developed for thermorheologically complex materials and utilizing an additive compliance model. Data on two other triblock copolymers, Kraton 102, and an SBS triblock copolymer exhibiting a continuous polystyrene phase (designated NBS 10/30/10), are also presented. A noteworthy feature of all three triblock copolymers is a long-drawn-out intertransition plateau in which the modulus changes very little for many decades of time. The modulus is high because of the presence of the polystyrene phase and trapped entanglements in the polybutadiene phase. The extent of the plateau, effectively the distance between the two glass transitions, depends on temperature because ...
35 citations
Patent•
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20 Nov 1974
TL;DR: A coated metal pipe is a pipe which comprises a pipe coated with a composition comprising 5-30 wt parts of ethylene-vinylacetate copolymer having a vinylacetate content of 15-40 wt% and a melt index of 1-1,000 g/10 min this article.
Abstract: A coated metal pipe which comprises a pipe coated with a composition comprising 5-30 wt parts of ethylene-vinylacetate copolymer having a vinylacetate content of 15-40 wt% and a melt index of 1-1,000 g/10 min; 2-20 wt parts of low molecular weight oxidized polymer of polypropylene or propylene-ethylene copolymer; 5-40 wt parts of styrene butadiene copolymer; 5-50 wt parts of a tackifier and 10-80 wt parts of asphalt.
34 citations
TL;DR: In this paper, it was shown that SBR with 50 phr of HAF carbon black has a positive temperature coefficient of resistivity close to 0.07/°C at 27°C and an activation energy of 0.56 eV at 75°C.
Abstract: Styrene–butadiene rubber (SBR) charged with 50 phr of HAF carbon black has been found to show a positive temperature coefficient of resistivity close to 0.07/°C at 27°C. Beyond a point (75°C) of minimum conductivity, however, it behaves as a normal noncrystalline semiconductor with a resistivity which decreases with rise of temperature with an activation energy of 0.56 eV. Blending the composition with poly(vinyl chloride) (PVC) shifts the minimum towards lower temperatures. The descending branch of the conductivity versus reciprocal absolute temperature characteristic is probably associated with thermal expansion of tunnelling paths separating the conducting carbon particles.
28 citations
TL;DR: In this paper, the effects after 90 days in water on both swelling and tensile properties of starch xanthide reinforced styrene-butadiene (SBR) are fully reversible by drying test specimens.
Abstract: Both conventionally reinforced and starch xanthide reinforced styrene-butadiene (SBR) rubbers swell continuously during water immersion without reaching equilibrium and eventually mechanical breakdown occurs. During 90 days of water immersion, starch xanthide-reinforced SBR swells more than conventionally reinforced SBR, but much less than would be calculated from the volume fraction of starch xanthide and its swelling ratio as measured separate from rubber. Swelling rate of vulcanized starch xanthide-SBR rubber specimens depends on their shape and is negligible for specimens with low enough surface to volume ratios. Standard tensile test specimens have low cross sections in the break area and provide a sensitive measure for the deleterious effect of prolonged water immersion. The effects after 90 days in water on both swelling and tensile properties of starch xanthide-SBR are fully reversible by drying test specimens. Starch xanthide-SBR masterbatch can be compounded either with reactive crosslinking and coupling agents or with low-cost extenders and fillers to reduce greatly the effect of prolonged water immersion.
20 citations
TL;DR: In this article, it was found that the necessary conditions for good dialytic membranes were as follows: a fairly large total exchange capacity, an exchange capacity ratio approaching unity, and a fairly small membrane potential.
15 citations
9 citations
TL;DR: The effect of sulfur, MBT, zinc oxide, and stearic acid on the DCP vulcanization of SBR has been studied in this article, showing that DCP decomposition obeys first order kinetics in all cases, but its rate constant.
Abstract: The effect of sulfur, MBT, zinc oxide, and stearic acid on the DCP vulcanization of SBR has been studied. DCP decomposition obeys first order kinetics in all cases, but its rate constant i...
7 citations
TL;DR: The tensile stress relaxation of carbon-black-filled SBR was studied in the linear viscoelasticity region as a function of temperature and volume fraction of fillers.
Abstract: The tensile stress relaxation of carbon-black-filled SBR was studied in the linear viscoelasticity region as a function of temperature and volume fraction of fillers. Time—temperature superposition was valid, and master relaxation curves were obtained. Carbon black increases the modulus of the compound, especially in the rubbery region, and the time range over which the glass-rubber transition occurred. The shift factor is divided into three regions; an Arrhenius dependence in rubbery and glassy states, and Williams-Landel-Ferry (WLF) dependence in the transition region. The apparent activation energy in the rubbery state increases with the volume fraction of carbon black (or silica) and is unaffected by the structure of the filler. The increase in activation energy is caused by the attachment of rubber chains to the carbon surface. At 30% elongation, the activation energy for carbon-black-filled rubber has a value of 32 kcal/mole, independent of structure and concentration of the filler.
7 citations
TL;DR: Crosslinked low-amylose (0 or 28%) starch xanthates used as reinforcing materials in styrenebutadiene elastomer imparted better dry tensile properties than their highamyloses (55, 68 or 82%) analogues.
Abstract: Crosslinked low-amylose (0 or 28%) starch xanthates used as reinforcing materials in styrenebutadiene elastomer imparted better dry tensile properties than their high-amylose (55, 68 or 82%) analogues. After immersion in water for 70h the tensile strength of low-amylose starch reinforced vulcanizates deteriorated considerably while high-amylose starch reinforced vulcanizates changed little or not at all. Such variables as xanthate degree of substitution and starch loading influenced curing time and properties. Mode of crosslinking the xanthate significantly affected retention of starch in the coprecipitate, and produced significant variations in curing characteristics, and in such properties as compression set, set at break before immersion in water and tensile strength after water immersion. The method of drying affected compressions set and modulus.
7 citations
TL;DR: In this article, the 16 diads that arise from the 4 individual repeating structural units; styrene, vinyl, cis-, and trans-buta-1,4-diene; diad populations are determined from deduced relationships with peak intensites and average block lengths are calculated for each unit individually and in pairs.
Abstract: Twenty-six peaks occurring in the 13C n.m.r. spectra of styrene–butadiene copolymers are assigned to the 16 diads that arise from the 4 individual repeating structural units; styrene, vinyl, cis-, and trans-buta-1,4-diene; diad populations are determined from deduced relationships with peak intensites and average block lengths are calculated for each unit individually and in pairs.
3 citations
TL;DR: In this paper, a comparison of linear and radial styrene/butadiene-based adhesives was made, showing that the linear S-B-S polymers showed viscosity properties markedly different than the linear counterparts.
Abstract: OLUTION POLYMERIZATION of butadiene and styrene with organometal initiaStors offers a convenient and unexcelled opportunity for the synthesis of polymers with precise predetermined structures, often with unexpected properties. In the block polymerization by sequential monomer addition, the ordering of polystyrene (S) and polybutadiene (B) segments in unvulcanized rubber imparts tensile strengths that can be very low (S-B, B-S-B) or very high dependent on whether the polystyrene blocks can aggregate into the temporary crosslinks. Such temporary crosslinks occur in S-B-S polymers; properties of the linear S-B-S have been reviewed recently [1]. Monodisperse polymer lithium from which these polymers are obtained not only reacts with butadiene and styrene to give polybutadiene and polystyrene segments, but also polymer lithium can be coupled by reagents FX~ of varying functionalities to produce radial trichain (Y-shaped) and tetrachain (Xshaped) molecules. Certain differences have been observed between the coupled and linear analogs; coupled polybutadiene [2] and polystyrene [3-6] showed viscosity properties markedly different than the linear counterparts. Preliminary comparisons of linear and radial styrene/butadiene-based adhesives also showed there
TL;DR: In this article, the aging of styrene-butadiene rubber (SBR) was studied by three methods: stress relaxation, infrared spectroscopy, and swelling measurements, with the purpose of supplying information pertinent to understanding the basic mechanism of its aging.
Abstract: The aging of styrene—butadiene rubber (SBR) was studied by three methods: stress relaxation, infrared spectroscopy, and swelling measurements, with the purpose of supplying information pertinent to understanding the basic mechanism of its aging. Stress-relaxation measurements in air and nitrogen at elevated temperatures indicated that atmospheric oxygen is the principal cause of chemical stress relaxation of SBR, rather than heat. Intermittent stress-relaxation measurements showed scission and crosslinking occurring simultaneously during network breakdown, and it was concluded that random scission in the backbone is indicated to take place in preference to scission in the crosslinks. Activation energies obtained from relaxation rates at several temperatures was 28 ± 0.5 kcal, comparable to literature values of 30 ± 2 kcals. The rates of carbonyl and hydroxyl group formation in SBR in air at various temperatures were determined by ir spectroscopy, both induction and maximum rates, νm, being measur...