Showing papers on "Styrene-butadiene published in 1997"

Toxicology and epidemiology of 1,3-butadiene.

Abstract: 1,3-Butadiene is a colorless, volatile gas that has high-volume usage in the synthesis of polybutadiene, styrene-butadiene, and other polymers. Due to its volatile nature, uptake of butadiene occur...

Compatibility and Storage Stability of Styrene-Butadiene-Styrene Copolymer Modified Bitumens

Abstract: The compatibility and storage stability of styrene-butadiene-styrene copolymer (SBS) modified bitumens were studied using fluorescence microscopy and dynamic mechanical analysis. Chemical characteristics of base bitumens and SBS polymers were determined by means of thin layer and gel permeation chromatography, respectively. The results showed that the morphology and phase separation of the modified binders varied with the characteristics of bitumens and polymers and were influenced by polymer content. At a given polymer content, the modified binders produced from bitumens with a higher content of aromatics exhibited better compatibility and higher storage stability. An increase in asphaltenes was observed to adversely affect storage stability. When mixing a small amount of polymer with bitumen, the modified binder showed dispersed polymer particles. At relatively high polymer content, depending on the base bitumens used, a continuous SBS phase was observed. On the other hand, the storage stability of modified binders decreased with increasing SBS content. Compared with branched SBS polymer, linear SBS displayed a finer dispersion in modified binder, and consequently, a lower phase separation was observed during hot storage. The degree of SBS dispersion in bitumen influenced storage stability and the rheological properties of modified binders; however, no definite relationships among them could be established.

Oil gel formulations containing high vinyl content hydrogenated styrene-butadiene-styrene block copolymers

Abstract: This invention provides oil gel compositions which comprise a hydrogenated styrene-butadiene-styrene (SEBS) block copolymer (although other vinyl aromatic hydrocarbons may be used) which has an overall weight average molecular weight of from 30,000 to 300,000, a styrene block weight average molecular weight of from 4000 to 35,000, and a vinyl content of at least 45% by weight (% wt), preferably 45 to 90%, and an oil and, optionally, a polyolefin wax and/or an extender liquid. For every 100 parts by weight of copolymer, there should be at least 900 parts of oil or a mixture of oil and polyolefin wax and/or an extender liquid.

Reinforcement of styrene–butadiene rubber vulcanizatebyin situsilica prepared by the sol–gel reaction oftetraethoxysilane

Abstract: In situ silica reinforcement of styrene–butadiene rubber (SBR) has been achieved by a sol–gel process using tetraethoxysilane (TEOS). SBR was sulfur-cured and the sol–gel reaction of TEOS was carried out in TEOS or in a TEOS–tetrahydrofuran (THF) mixture. The in situ silica was filled homogeneously in the rubber matrix and the size of the in situ silica was influenced by the cross-linking density of the SBR vulcanizate. n-Butylamine was effective for the method using TEOS only, whereas both hydrochloric acid and n-butylamine worked as catalysts under the experimental conditions using THF for the in situ polymerization of TEOS in the SBR vulcanizate. From the viewpoint of the reinforcement of in situ silica and the size stability of the SBR vulcanizate, the method using only TEOS was found to be better than the mixture system. This conclusion was based on the results of tensile tests, dynamic mechanical measurements, optical and transmission electron microscopies.

Fracture Morphology and Fracture Toughness Measurement of Polymer-Modified Asphalt Concrete

Abstract: Pavement distress occurs through a variety of mechanisms, but it is always controlled by the adhesive and cohesive performance of the asphalt binder. Although the causes of pavement failures are known, the precise mechanisms by which they occur remain to be understood. Observation of the fracture morphology of asphalt concrete can provide some information in this respect. The fracture morphology of asphalt concrete is dependent on the morphology of the binder. A network structure was observed in thin asphalt binder films and the fracture morphology and engineering properties of asphalt concrete were found to be dependent on the network morphology of the asphalt binder. Addition of polymers to asphalt binders causes changes in the nature of the network structure, and its effect can be qualitatively determined by characterizing the fracture morphology. Styrene butadiene styrene (SBS), styrene ethylene butylene styrene (SEBS), styrene butadiene rubber (SBR) latex and an epoxy-terminated reacting polyolefin (...

Anionic bituminous emulsions with improved adhesion

Abstract: This invention relates to rapid set, medium set, and slow set anionic emulsions prepared from straight bitumen or bitumen modified by the incorporation of polymers such as styrene butadiene rubbers (SBR), styrene block copolymers (SBS), ethylene vinyl acetate copolymers (EVA), and other suitable modifiers. The invention also relates to emulsions modified by the incorporation of solvents (such as diesel oil or kerosene) or by the addition of polymer latices (such as SBR-latex or natural rubber latex). More particularly, the invention relates to improved methods for enhancing adhesion between asphalt and aggregate in anionic solventless and solvent-containing bituminous emulsions wherein the emulsifiers are alkali earth salts of tall oil fatty acids, fortified tall oil fatty acids, tall oil rosins, and fortified rosins as well as combinations of kraft lignins and nonionic emulsifiers. The adhesion promoting compositions utilized in these improved methods are produced by reacting tall oil fatty acid and/or modified tall oil fatty acid to yield a polyalkylene amine, then blending the polyamidoamine with Bis-hexamethylenetriamine to produce the adhesion promoter.

Effect of catalyst onin situ silica reinforcement of styrene–butadiene rubber vulcanizate by the sol–gel reaction of tetraethoxysilane

Abstract: In situ silica reinforcement of styrene–butadiene rubber (SBR) vulcanizate has been achieved by the sol–gel reaction of tetraethoxysilane (TEOS) using n-butylamine as a catalyst. SBR was vulcanized with sulfur and soaked in TEOS and in an aqueous solution of the catalyst. When hydrochloric acid was used as a catalyst for the sol–gel reaction, silica particles were not introduced into the SBR matrix in this study. The increase of the dynamic modulus and tensile strength at break was considered to be due to the interaction between the rubber and the in situ silica filler in the SBR vulcanizate.

Relationships between rheological properties, morphological characteristics, and composition of bitumen-styrene butadiene styrene copolymers mixes. I. A three-phase system

Abstract: The variation, with temperature, of the dynamic mechanical properties (at 5 Hz) of bitumen–SBS mixes has been established. Typical features of the storage modulus, the loss modulus, and the loss angle variations with temperature could be attributed to the different phases that compose the mix. Finally, relationships between viscoelastic measurements and morphological characteristics (number of phases, phase composition, and phase content in the blend) have been proposed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1595–16, 1997

Thermoplastic elastomeric hydrogenated styrene-butadiene elastomer: Optimization of reaction conditions, thermodynamics, and kinetics

Abstract: Thermoplastic elastomeric hydrogenated styrene—butadiene (HSBR) elastomer was prepared by diimide reduction of styrene-butadiene rubber in the latex stage. The products were characterized by infrared, 1H-NMR, 13C-NMR spectroscopy, and differential scanning calorimetry (DSC). The standard free energy change, ΔG0 at 298°K is −44.7 × 104 kJ/mol, indicating that the formation of HSBR is thermodynamically feasible. The value of heat change of the reaction at constant volume, ΔUT is −41.6 × 104 kJ/mol. The effect of different reaction parameters on the level of hydrogenation, calculated from nuclear magnetic resonance spectroscopy, was also investigated. The degree of hydrogenation increases with the increase in reaction time, temperature, the concentration of reactants and catalyst. A maximum of 94% hydrogenation was obtained under the following conditions: time, 4 h; temperature, 45 ± 2°C; pH, 9.36; cupric sulphate (CuSO4 · 5H2O) catalyst concentration, 0.0064 mmol; hydrazine concentration, 0.20 mol; and hydrogen peroxide concentration, 0.26 mol. The diimide reduction of SBR is first-order with respect to olefinic substrate, and the apparent activation energy is 9.5 kJ/mol. The glass transition temperature increases with the increase in saturation level due to development of crystalline segments. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1151–1162, 1997

Degradation of Hydrogenated Styrene—Butadiene Rubber at High Temperature

Abstract: Degradation of hydrogenated styrene—butadiene rubber (HSBR) having different levels of unsaturation has been studied over a wide range of temperatures under anaerobic and aerobic conditions using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), IR and NMR spectroscopy. TGA data indicate higher thermal stability of hydrogenated rubber as compared to SBR in nitrogen, although an anomalous behavior is observed in air due to crosslinking and oxidation of styrene—butadiene rubber (SBR). Isothermal data confirm the above observations. IR and NMR results reveal thermal isomerization, cyclization, oxidation, depolymerization, and chain scission processes. The nature and amount of products formed depend on the time and temperature of degradation and also on the level of hydrogenation of SBR.

Styrene-butadiene copolymer and rubber composition comprising the copolymer

Abstract: A styrene-butadiene copolymer having excellent low hysteresis loss characteristic, wet skid resistance, fracture characteristics, and abrasion resistance and a rubber composition comprising the copolymer are disclosed. The styrene-butadiene copolymer has a total styrene content in the range of 33 to 42% by weight of the styrene-butadiene copolymer; a content of styrene sequences having 4 to 20 styrene units in the range of 40 to 65% by weight of the total styrene content, as obtained by measurements by NMR and GPC; a content of styrene sequences having more than 20 styrene units in the range of 5% by weight or less of the total styrene content, as obtained by measurement by GPC; a content of vinyl unit in the range of 30% by mol or less of a butadiene part of the styrene-butadiene copolymer; a sum of the total styrene value and ½ of the content of vinyl units in the range of 46 to 52%; and an inner or end structure having, for example tin-carbon bond. The copolymer and the rubber composition are used for tire treads and the like.

Fracture mechanisms of poly(ethylene terephthalate) and blends with styrene-butadiene-styrene elastomers

Abstract: Poly(ethylene terephthalate) (PET) was blended with 5 wt % of an elastomeric block copolymer. The hydrogenated styrene-butadiene-styrene (SEBS) elastomers were functionalized with 0–4.5 wt % maleic anhydride grafted on the midblock. Notched tensile tests in the temperature range − 40–55 °C differentiated among the blends in terms of their toughness. The least effective elastomer was the unfunctionalized SEBS; all the functionalized SEBS elastomers effectively increased the toughness of PET. Fractographic analysis indicated that PET and the blend with unfunctionalized SEBS fractured through a pre-existing craze. Although adhesion of the unfunctionalized SEBS to the matrix was poor, the elastomer strengthened the craze somewhat, as indicated by an increase in length of the pre-existing craze when final separation occurred. A functionalized SEBS caused the fracture mechanism to change from crazing to ductile yielding. Graft copolymer formed by reaction of PET hydroxyl end groups with the anhydride in situ was thought to act as an emulsifier to decrease particle size and improve adhesion. These factors promoted cavitation, which relieved the triaxiality at the notch root and permitted the matrix to shear yield.

Aqueous-phase hydrogenation of polybutadiene, styrene-butadiene, and nitrile-butadiene polymer emulsions catalyzed by water-soluble rhodium complexes

Abstract: Hydrogenation of polybutadiene (PBD), styrene-butadiene (SBR), and nitrile-butadiene (NBR) polymers in aqueous/organic biphasic media catalyzed by the novel water-soluble complex [RhCl(HEXNa) 2 ] 2 1 , (HEXNa  Ph 2 P(CH 2 ) 5 CO 2 Na) at 100°C and 5.5 MPa H 2 was investigated. The results obtained under identical conditions with the previously known water-soluble catalyst RhCl(TPPMS) 3 2 , (TPPMS = monosulphonated-triphenylphosphine) are also presented for comparison. Both complexes showed a reasonable catalyst activity toward polymer hydrogenation. Under the conditions employed in the present work the catalyst 1 was extracted into the organic phase during the reaction. This was attributed to the phase transfer properties of the complex which was rendered by the amphiphilic HEXNa ligand. The extraction of 1 into the organic phase was dependent on the nature of the organic co-solvent. Both 1 and 2 showed enhanced selectivity for hydrogenation of the 1,2 (vinyl) addition units over the 1,4 (internal) units in all the polymers studied in the present work.

Tire puncture sealant

Abstract: A tire puncture sealant containing water in an amount of from about 6% to about 64% by weight; ethylene glycol in an amount of from about 36% to about 94%; styrene butadiene latex in an amount of about 3%; polyethylene powder and ground rubber in an amount from about 3% to about 6%; a minor effective amounts of an alkali metal carbonate, a cellulosic thickener, an alkali metal nitrite and a corrosion inhibitor. The polyethylene powder and ground rubber are preferably surface-activated and include various particle sizes.

Shape-memorizable styrene-butadiene block copolymer. I. Thermal and mechanical behaviors and structural change with deformation

Abstract: Thermal properties in the range from room temperature to 150°C, mechanical properties from room temperature to 80°C, and structural changes by drawing and contraction at 80°C followed by crystallization have been studied in a crystalline styrene-butadiene block copolymer, which has the property of shape memory, using differential scanning calorimetry (DSC), mechanical analysis, wide-angle x-ray diffraction (WAXD), and smallangle x-ray scattering (SAXS). This copolymer has the crystal transformation temperature, the melting temperature of the trans- 1,4-polybutadiene domains, and the higher glass transition temperature of the polystyrene domains. When a high strain is adopted for the deformation at 80°C (i.e., between the melting temperature of the polybutadiene [PB] domains and the glass transition temperature of the polystyrene regions) and crystallization conditions with fixed ends are employed, a fibrillar structure with a better regularity of long spacings and a high orientation of crystals f...

Hydrogenation of styrene‐butadiene rubber (SBR) latexes

Abstract: The mechanism and the optimum conditions for the reduction of residual double bonds in styrene-butadiene rubber (SBR) latex by hydrogenating the polybutadiene in the latex form were studied. The hydrogenation involves a copper ion (II)-catalyzed procedure in which diimide hydrogenation agent is generated in situ at the surfaces of latex particles by a hydrazine/hydrogen peroxide redox system. The surface density of the copper ion in particle surfaces was found to be a crucially important parameter in controlling the degree of hydrogenation. The distribution of the double bonds in the latex particles after the hydrogenation was found to be dependent on the particle size and the extent of crosslinking in the particles. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2047–2056, 1997

Repulpable moisture vapor barrier

Abstract: The present invention provides a repulpable moisture vapor barrier. The moisture vapor barrier comprises a resin latex and a hydrophobic component having a crystalline platelet structure. Suitable resin latexes include polystyrene, styrene-acrylonitrile, styrene-acrylonitrile-butadiene, styrene acrylates, styrene-butadiene, carboxylated styrene butadiene, polyvinyl chloride, polyvinyl acetate, waterborne polyurethanes, alkyl acrylates, polyvinylidene chloride, ethyl vinyl chloride, and copolymers and terpolymers thereof. Preferably the hydrophobic component is suspended in means for suspending the component such as fully hydrolyzed polyvinyl alcohol.

Relationships between rheological properties, morphological characteristics, and composition of bitumen–styrene butadiene styrene copolymers mixes. II. A thermodynamical interpretation

Abstract: The variations of the dynamic mechanical properties (at 5 Hz) of bitumen–SBS mixes in the function of their composition (polymer content, bitumen composition) have been established. The relationships between the viscoelastic measurements and the morphological characteristics, previously determined, have been used to interprete these variations in terms of change of morphological characteristics (phase composition, phase content in the blends). Finally, a theoretical approach based on the thermodynamics of mixing is proposed to explain the relationships between the composition and the morphological characteristics. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1609–1618, 1997

High impact resistant, high gloss, and high environmental stress crack resistant polymeric compositions

Abstract: A polymeric composition is provided which exhibits a combination of high gloss and high environmental stress crack resistance, comprising: (a) high impact polystyrene having a gloss at 60 degrees of greater than 85% and an impact resistance of greater than 0.7 ft-lb/inch, (b) high density polyethylene which has a density greater than or equal to about 0.94 g/cm 3 , and which has a stress exponent less than or equal to about 1.70; and (c) a compatibilizing polymer for components (a) and (b), selected from the group consisting of diblock styrene butadiene copolymers, triblock styrene butadiene copolymers, diblock styrene isoprene copolymers, triblock styrene isoprene copolymers, and mixtures thereof, wherein the gloss at 60 degrees of the composition is greater than or equal to about 85%, and the environmental stress crack resistance measured in minutes until breakage at 1000 psi is greater than about 60.

Fracture energies of styrene‐butadiene‐styrene block copolymers (I). Effects of rate, temperature, and casting solvent

Abstract: Specimens of styrene-butadiene-styrene (SBS) block copolymers, Kraton D-1102, were prepared by solution casting using three different solvents: toluene, cyclohexane, and a mixture of tetrahydrofuran and methyl ethyl ketone (THF/MEK). Measurements of fracture energies of SBS specimens were carried out at various temperatures and rates using two methods (i.e., a conventional tear test and a recently developed cutting test). Effect of casting solvent on the fracture energy was investigated as well. It was found that stick-slip tearing dominates at low temperatures ( -50 - 20°C). Tear strength increased with decreasing temperature. Eventually, a value of 180 kJ/ m 2 was reached at -70C, close to the glass transition temperature of polybutadiene phase. At temperatures higher than 20C, however, steady tearing was found and the tear strength gradually decreased with increasing temperature. Tear strength was virtually zero at 100C, above the glass transition temperature of polystyrene phase. Effect of temperature on tear strength is more pronounced than that of tearing rate. In contrast, the intrinsic strength of SBS block copolymers determined from cutting test remains unchanged, about 570 J/m 2 , over a wide range of temperatures and rates. Specimens cast from THF/MEK solution exhibit yielding phenomena when stretched. Moreover, they possess a relatively larger tear strength, compared to those cast from either toluene or cyclohexane solution. A more continuous polystyrene phase is expected to develop in THF/MEK as-cast specimens which is believed to account for the large tear strength.

Expandable polystyrene] containing a styrene-butadiene block copolymer

Abstract: An expandable styrene polymer (I) contains: (A) a polymer matrix consisting of 70-95 wt.% polystyrene or a styrene copolymer containing up to 50% comonomers and 5-30 wt.% of a styrene-butadiene block copolymer; (B) 1-15 wt.% (with respect to (A)) of a volatile blowing agent; and optionally (C) conventional additives. The block copolymer structure: S-B/S(-S)n, in which S = polystyrene block; B/S = butadiene/styrene copolymer block with a statistical distribution of monomers; and n = 0 or 1, with S blocks comprising 5-40 vol. %. Also claimed are: (i) a process for the preparation of (I) by the addition of (B) during or after mixing of (A); and (ii) an elastomeric foam having density 5-150g/cm , which is prepared from (I).

High impact resistant, high gloss, and high environmental stress crack resistant thermoplastic manufactured articles

Abstract: Thermoplastic manufactured articles are provided which exhibit an advantageous combination of high gloss and high environmental stress crack resistance, made from a polymeric composition comprising: (a) high impact polystyrene having a gloss at 60 degrees of greater than 85% and an impact resistance of greater than 0.7 ft-lb/inch; (b) high density polyethylene which has a density greater than or equal to about 0.94 g/cm 3 , and which has a stress exponent less than or equal to about 1.70; and (c) a compatibilizing polymer for components (a) and (b), selected from the group consisting of diblock styrene butadiene copolymers, triblock styrene butadiene copolymers, diblock styrene isoprene copolymers, triblock styrene isoprene copolymers, and mixtures thereof, wherein the gloss at 60 degrees of the composition is greater than or equal to about 85%, and the environmental stress crack resistance measured in minutes until breakage at 1000 psi is greater than about 60.

Synthesis and Characterization of Styrene-Butadiene Block Copolymer/Silicate Hybrid Materials via the Sol-Gel Process I. Four-Arm Star Styrene-Butadiene Block Copolymer/Silica Hybrids

Abstract: Novel hybrid materials incorporating four-arm star styrene-butadiene block copolymer (SB-4A) with tetraethoxysilane (TEOS) have been successfully prepared by a sol-gel process. The properties, microstructure, and dynamics of the hybrid materials were investigated in detail by means of dynamic mechanical analysis (DMA), thermogravimetry (TG), and NMR techniques. The results indicate that the properties of the hybrids strongly depend on the TOES content and the silica networks prefer to form in the polystyrene (PS) domains. There exists an optimum range of TEOS content, in this work 30–50% by weight, within which the properties of the hybrids obtained were well improved: storage modulus increases, thermal stability raises, and the high-temperature Tg shifts to higher temperature. 29Si NMR spectrum shows that in the hybrids with well improved properties silica networks formed with Q4 in the greatest abundance.