Showing papers on "Styrene-butadiene published in 1977"

Styrene-butadiene interpolymer latex based cement additives containing a silane

Abstract: Cement compositions having improved strength and enhanced adhesion to siliceous substrates are obtained by admixing Portland cement with a cement additive comprising (1) a styrene-butadiene interpolymeric latex containing up to about 60 parts by weight of interpolymer solids, said latex being present in an amount sufficient to provide from about 5 to about 25 parts by weight of latex polymer solids based on the weight of cement and (2) from about 0.05 to about 3 parts by weight of latex solids of a silane of the formula ZSi(OR') 3 wherein Z is a member selected from the group consisting of hydrocarbon groups and substituted hydrocarbon groups in which the substituent is bonded to the silicon atom through at least one carbon atom, and R' is selected from the group consisting of alkyl radicals of from 1 to 3 carbon atoms, --CH 2 CH 2 OR" and --CH 2 CHOH where R" is an aliphatic hydrocarbon radical of 1 to 3 inclusive carbon atoms.

Diffusion and solution of gases and vapors in styrene-butadiene block copolymers

Abstract: The diffusion, solution, and permeation behavior of a series of inert gases (helium, argon, nitrogen, krypton, and xenon) in S-B block copolymer films was studied by transient permeability measurements and by the equilibrium desorption method. The morphologies of most of the samples used in the measurements were (a) polystyrene rods dispersed in a polybutadiene matrix and (b) alternating lamellae of styrene and butadiene components. It was indicated, as far as the kinetic nature at lower temperatures is concerned, that the diffusion and permeation processes of gases, except for helium, are governed primarily by behavior in the polybutadiene matrix. At lower temperatures, it was shown that the transient method counts only the mobile penetrant in the polybutadiene matrix, while the equilibrium method counts less diffusive species in the polystyrene domains as well. The diffusion behavior in the copolymer films was compared with that in homopolybutadiene and discussed in terms of two impedance factors: the tortuosity and the chain immobilization factors. From the homopolymer-block copolymer comparison along with results obtained from diffusion experiments using n-hexane as the penetrant, it was indicated that segmental motions in the polybutadiene phase in the copolymers are restricted relative to motions in homopolybutadiene. Also, from data on gas sorption in samples of various styrene contents, involving both S-B block copolymers and binary mixtures with homopolystyrene, it was suggested that the partial mixing of component block chains occurs at the interface between the domains, resulting in rather diffuse domain boundaries.

Styrene-butadiene interpolymer latex based cement additives

Abstract: of the Disclosure This invention is a cement additive comprising (1) a styrene-butadiene interpolymer latex, (2) a non-ionic surfactant, (3) a polyelectrolyte comprising the product obtained by copolymerizing methylmethacrylate and a sulfoester of .alpha.-methylene carboxylic acid or its salt, and (4) a polyorganosiloxane foam depressant, which additives provide portland cement compositions having improved strength properties, workability and adhesion to cementitious substrates.

Spread-coating compositions for paper comprising an aqueous dispersion of styrene/butadiene polymer and polyethylene oxide

Abstract: Spread-coating compositions for improving the surface properties of paper comprising an aqueous dispersion of a styrene/butadiene-polymer, and from about 2% to about 30% by weight of total polymeric solids of polyethylene oxides of a molecular weight of from about 6,000 to about 50,000.

Structure of styrene-butadiene-styrene block copolymers by diffusion analysis

Abstract: In this study, solvent sorption was used to investigate the morphology of a styrene–butadiene–styrene (SBS) triblock copolymer. The sorption process was found to deviate from the normal Fickian character, usually found in conventional elastomer–solvent systems, because of the presence of an interfacial region for both polybutadiene and polystyrene. This interphase absorbed solvent at a temperature below its glass transition and contributed to the resulting non-Fickian time-dependent diffusion process. The equilibrium diffusion coefficient was estimated to be 3.2 × 10−7 cm2/sec regardless of the casting surface. Nevertheless, according to the sorption measurements, the casting surface did have an effect on the approach to equilibrium. The results indicated a denser packing of the molecules and hence a decreased diffusion coefficient for Teflon and glass cast films, because of internal stresses left within the films during casting.

Thermo‐optical analysis of poly(2,6‐dimethyl‐1,4‐phenylene oxide)/triblock styrene–butadiene–styrene copolymer blends

Abstract: Blending of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO resin) with a triblock butadiene–styrene–butadiene copolymer (Kraton 101) monotonically increases the softening temperature of the latter as measured by TOA. The TOA transition temperatures of the styrene/PPO resin phases closely approximate those of polystyrene/PPO resin blends having the same styrene/aromatic ether unit compositions. Uniform mixtures of the styrene blocks with the poly(2,6-dimethyl-1,4-phenylene oxide) molecules is inferred.

Anti-abrasive flame-resistant noise-suppressant laminate

Abstract: An anti-abrasive, flame-resistant, and noise-suppressant laminate suitable for use with underground scraper conveyors or the like comprising two outer layers of ferrous material having an inner layer of styrene butadiene rubber material vulcanized therebetween The styrene butadiene rubber material has a durometer of the order of 59, a flame spread index of less than 25 according to ASTM-E162 and a thickness of the order of 1/4 inch One of the outer layers is of abrasive resistant steel and has a thickness of the order of 1/4 inch The other outer layer is of 1020 steel and has a thickness of 16 gage

Can end sealing rubber composition containing a styrene-butadiene rubbery copolymer, a tackifier and a filler

Abstract: A can end sealing rubber composition (A) consisting essentially of a styrene-butadiene rubbery copolymer, a tackifier and a filler, and (B) having (1) a creep resistance coefficient K defined by the following equation of at least 0.1 but not exceeding 0.6, K=log J.sub.90.sup.C (10)-log J.sub.90.sup.C (1) wherein J 90 C (10) is the creep compliance measured 10 minutes after exerting a load when a fabricated article of the composition as a specimen is compressed in water at 90° C. by a parallel plate plastometer, and J 90 C (1) is the creep compliance measured 1 minute after exerting a load when the specimen is compressed in water at 90° C. by a parallel plate plastomer, and (2) a creep compliance J 25 C (1) of at least 3×10 -9 cm 2 /dyne but not exceeding 1×10 -6 cm 2 /dyne, the creep compliance being measured 1 minute after exerting a load when the specimen is compressed in water at 25° C. by a parallel plate plastometer.

Diffusion of radioactively tagged penetrants through random and block styrene–butadiene copolymers and filled cis-polybutadiene

Abstract: The diffusion of radioactively tagged n-hexadecane in trace amounts has been studied in 22 random styrene–butadiene (SBR) copolymers with different styrene contents and butadiene microstructures; in several SBR block copolymers with different average block lengths (also diffusion of tagged 1,1-diphenyl ethane); in a triblock SBR copolymer cast from different solvents and also molded at elevated temperature; and in cis-polybutadiene filled to different extents with carbon black, calcium carbonate, and microglass spheres. The diffusion coefficient in random SBR copolymers decreased with increasing content of styrene and/or vinyl configuration and could be correlated with fractional free volume on the basis of linear additivity of the cis, trans, vinyl, and styrene moieties. In SBR block copolymers, the diffusion coefficient increased with increasing average block sequence length. For the triblock copolymer, the diffusion coefficient was approximately the same for samples molded or cast from solvents which are good for polybutadiene, but was far smaller for a sample cast from ethyl acetate, in which the polystyrene domains are probably lamellar. The effect of fillers on diffusion in cis-polybutadiene was compared with calculations on the basis of several theoretical models.

Influence of plasticizers on the autohesion of styrene-butadiene-styrene block copolymers☆

Abstract: A study has been made of the influence of different plasticizers on the autohesive properties of block copolymers of butadiene, isoprene and styrene. It was found that reasonably stable autohesive bonding is obtainable with a mixture of polar and apolar plasticizers. The experimental results have been analyzed, starting with the diffusion theory of adhesive bond formation.

Studies of accelerated sulfur vulcanization of styrene-butadiene rubber by N-cyclohexylbenzothiazol-2-sulfenamide in the presence and absence of dicumyl peroxide

Abstract: This study embodies the results and discussion of a comprehensive and systematic investigation of the mechanism of sulfuration of styrene–butadiene rubber accelerated by N-cyclohexylbenzothiazole-2-sulfenamide (CBS) with and without activators. Dicumyl peroxide (DCP) has been taken as a chemical aid to distinguish between free-radical and polar mechanisms of sulfuration. The rate constant for DCP decomposition in presence of CBS and the reduction in crosslink density by CBS have also been studied. With a constant amount of DCP and sulfur the crosslink density increases with increasing CBS concentration. In the presence of ZnO and stearic acid, crosslinking proceeds faster than in a similar system without these ingredients, and with DCP the crosslinks are found to be formed nearly additively as confirmed by methyl iodide treatment of the vulcanizates. In the absence of DCP, the crosslinking is characterized by an induction period, even in presence of ZnO and stearic acid. In the presence of sulfur, the 2-mercaptobenzothiazole (MSH) or amine or amine salt form crosslinkins by ionic reaction.

Flammability and degradation characteristics of styrene–butadiene rubbers

Abstract: Uncured styrene–butadiene gum, a known cured composition, and four SBR beltings used in underground coal mining were subjected to thermal oxidative degradation in static and dynamic systems. The room temperature volatiles produced under the static conditions at 370°C were identified and quantitated. Monomers and their interaction products were liberated by the raw gum; the cured composition formed together with the above products materials traceable to the curing ingredients. The four beltings gave a large spectrum of products; an attempt was made to correlate these with possible components used in belts manufacture. In the dynamic system, the occurrence of glow, the rate of smoke generation, and char yields were determined at 400°C and 500°C. None of the materials glowed at 400°C. At 500°C, the raw gum volatilized completely, and the cured rubber and two beltings glowed. One of the beltings, which failed to glow, liberated the smallest quantity of toxic products.

Relative toxicity of pyrolysis products of some elastomers

Abstract: Ten samples comprising seven generic types of elastomers were evaluated for relative toxicity using the USF/NASA toxicity screening test method. The nitrile rubber samples appeared to generally exhibit greater toxicity than the samples of polyisoprene, styrene butadiene, and chlorinated polyethylene rubber. Carbon monoxide was present in sufficient concentration in the blood of the test animals to be the principal cause of death in the case of polyisoprene and styrene butadiene rubber.

Mixing of Thermoplastic Styrene-Butadiene Elastomers

Abstract: HERMOPLASTIC ELASTOMERS have achieved a significant place in the rubber T and plastic industries in recent years. One important class of thermoplastic elastomers is the block copolymers of styrene and butadiene. These materials derive their combination of thermoplastic and elastic properties from an alternating structure of plastic and elastic segments. This paper will discuss the mixing characteristics of the radial block copolymers of styrene and butadiene. The effect of batch sizes, product form and mixing equipment on mix times and compounded physical properties will be illustrated. Mixing comparisons were made using an oil extended masterbatch in a recipe representative of current compounding practice.