Showing papers on "Styrene-butadiene published in 1996"

Percolation Concept: Polymer-Filler Gel Formation, Electrical Conductivity and Dynamic Electrical Properties of Carbon-Black-Filled Rubbers

Abstract: This paper reports results on comparison of polymer-filler gel formation measurements and electrical properties of carbon black filled styrene butadiene rubber (SBR) composites. Electrical conductivity (σ) of compounds with different filler concentration has been measured, and dielectric constant (e′), dielectric loss (e″) and dissipation factor (tanδ) have been investigated at frequency range from 1 kHz to 13 MHz. It has been found that these systems follow percolation type model. Different electrical percolation thresholds of the composites have been found for different types of carbon black. Carbon blacks with the highest specific surface area reach the percolation threshold with the least fraction of carbon black loading. The electrical percolation threshold was found to be in a very good agreement with the filler concentration which is necessary for the coherent rubber-filler gel formation.

Rheological properties of styrene-butadiene copolymer–reinforced asphalt

Abstract: Rheological properties of styrene-butadiene copolymer-reinforced asphalt were investigated. A percolation-like model was used to fit dynamical experimental data, and a comparison with the Kerner-Takayanagi model is presented. In addition, a frequency-composition-temperature correspondence principle is proposed. This correspondence principle allows the prediction of the rheological behavior of an asphalt-based composite within a wide range of compositions, provided a narrow composition range at different frequencies and temperatures is previously known. © 1996 John Wiley & Sons, Inc.

Use of natural rubber prophylactics waste as a potential filler in styrene-butadiene rubber compounds

Abstract: Owing to the unstable nature of the latex compound and the strict specifications in the quality of latex products such as condoms and examination gloves, the rejection in the latex industry comes to about 10 to 15% of the rubber consumed. These latex rejects contain about 95% rubber hydrocarbon of very high quality. A cost-effective technique has been developed for the reuse of natural rubber (NR) prophylacties waste in styrene–butadiene rubber (SBR). The influence of powdered latex rejects on the curing characteristics, mechanical properties, and failure behavior of SBR has been investigated. More emphasis is placed on the effect of both particle size and the loading of latex waste filler. Swelling studies were carried out to establish the degree of crosslinking of SBR and to assess the extent of interaction between the matrix and latex waste filler of varying particle sizes. A three layer model has been set up to study the diffusion of sulfur from the matrix phase to the filler phase. Scanning electron microscopy has been used to analyze the particle morphology, filler dispersion, and filler-matrix interface adhesion. The results of the study revealed that NR prophylactics rejects can be used effectively as a potential filler in SBR up to about 40 phr loading. © 1996 John Wiley & Sons, Inc.

A Study of the Thermal Degradation Products of Styrene-Butadiene Type Rubber by Pyrolysis/GC/MS

Abstract: Pyrolysis coupled with GC/MS was used to study thermal degradation products of styrene—butadiene rubber (SBR). Introduction of samples, using the pyrolysis carrier gas through the split injection port, followed by sub-ambient focusing of pyrolysis products gave reproducible chromatograms. The styrene content of styrene—butadiene copolymer was determined by plotting the GC areas of styrene and butadiene dimer (4-vinlycyclohexene) vs the percent bound styrene measured by refractive index and infrared spectroscopy. The accuracy and ease of use of the technique in determining the styrene content of styrene—butadiene copolymer is also compared to that of the refractive index and infrared spectroscopy methods. Finally, the effects of carbon black and other fillers on the thermal degradation products of the styrene—butadiene copolymer are also discussed.

A hot-melt pressure-sensitive adhesive based on styrene-butadiene-styrene rubber. The effect of adhesive composition on the properties

Abstract: Hot-melt pressure-sensitive adhesives based on styrene-butadiene block copolymers with aliphatic and aromatic tackifying resins and plastifying oils have been analyzed. The importance of the resin structure in the compatibility with the block copolymer and the influence of the different paraffinic-naphthenic character of the oil in PSA performance have been shown. Ternary systems with a fixed polymer content (30%) and with variable resin and oil contents show a good miscibility over the whole range of compositions, and only one glass transition temperature was found in each composition. The relationship between chemical composition and bulk performance are expressed in terms of the visco-elastic behavior of the adhesives, measured by DMTA. It has been shown that at a given resin content there is a minimum on tan δ peak vs. temperature, the melt viscosities present a plateau region and the tack strength shows a maximum. An important conclusion is that phase separation is not a requirement for maximum tack; some restricted miscibility is enough, present in a few microdomains of the blend. © 1996 John Wiley & Sons, Inc.

Pyrolytic treatment of rubber waste: Pyrolysis kinetics of styrene—butadiene rubber

Abstract: The pyrolysis kinetics of commercial-grade styrene–butadiene rubber (SBR), which is one of the major constituents of tyre rubber as well as one of the principal products of the rubber industry in Taiwan, was investigated by a dynamic thermogravimetry (TG) reaction system in a nitrogen atmosphere over the temperature range of 400 to 950 K at the nominal heating rates of 3, 5 and 7 K min−1. The experimental results indicated that the pyrolysis of SBR may be attributed to three reactions, with three distinct mass change characteristics in the mass-loss curves of reactant deduced from the experiments. The corresponding activation energies, frequency factors and reaction orders of the three reactions were determined. A simplified three-reaction model based on the mass-loss curves of reactant was also proposed for engineering purposes. Satisfactory agreements between the proposed model and the experimental results were obtained. The results of this study are useful for the utilization of scrap SBR as an energy resource.

Dynamic Mechanical Study of Sodium Sulfonated Random Ionomers Based on Hydrogenated Styrene−Butadiene Copolymer

Abstract: Sodium sulfonated poly(styrene−ethylene−butylene) random ionomers [P(SEB-co-SSNa)] were obtained by hydrogenation, sulfonation, and neutralization of styrene−butadiene copolymers containing 45 wt % styrene. The dynamic mechanical properties were measured as a function of temperature for ionomers of a wide range of ion contents. Most of the ionomers showed two glass transitions, as well as a well-developed ionic plateau region in the storage modulus between the two glass transitions. The loss tangent peak of the upper Tg appeared below the decomposition temperature of the polymer, which permitted its detailed analysis as a function of ion concentration. The results of this study are explained on the basis of a recent model of morphology of ionomers in the solid state (the EHM model) and compared with those of the styrene−sodium methacrylate copolymers [P(S-co-MANa)] and sodium sulfonated polystyrene [P(S-co-SSNa)]. Considerable similarities exist in the properties of the matrix phase in the P(SEB-co-SSNa) ...

Epoxidation of partially hydrogenated styrene-butadiene block copolymers using peracetic acid in a cyclohexane/water heterogeneous system

Abstract: The preparation of partially saturated lightly functionalized styrene-butadiene block copolymers of polyA-block-polyB-block-polyA type (SBS) is described. The work involves epoxidizing partially hydrogenated SBS block copolymers using peracetic acid in a cyclohexane/water heterogeneous system. Five partially hydrogenated model polymers containing low levels of unsaturated aliphatic double bonds were used to study the epoxidation reaction and kinetics. The existence of the epoxide functional group on the product polymer was evidenced by IR and 1 H-NMR spectra and the epoxide concentration was determined by direct titration. The partially hydrogenated SBS copolymers were more difficult to epoxidize than the unhydrogenated ones. The temperature dependence of the epoxidation rate was

Surface characteristics of polystyrene latex particles and comparison with styrene-butadiene copolymer latex particles using dynamic light scattering and electrophoretic light scattering measurements

Abstract: The surface characteristics of two samples of polystyrene latex particles of uniform size, one having only sulfate and the other both sulfate and aromatic amino groups, have been examined using dynamic light scattering and electrophoretic light scattering measurements. The surface properties are compared with those of styrene–butadiene copolymer latex particles having both sulfate and carboxyl groups. The differences in the overall dimensions of the latex particles suggest that the hairy layers at the latex surfaces determine the observed dynamic behavior. The surface polymer composition and the surface charge density derived from ionizable groups strongly influence the adsorption of inorganic electrolyte ions. These properties also determine the hydration at the latex surface and lead to the temperature dependence/independence of the particle dimensions. Amination/carboxylation of the latex particles results in surface properties which are strongly dependent on the pH of the medium and thus produce complex changes in both overall dimension and mobility with changing pH.

Elastomeric vehicle brake parts and power transmission belts

Abstract: Motor vehicle brake parts and power transmission belt based on an ethylene, alpha-olefin, vinyl norbornene elastomeric polymer are manufactured with more efficiency due to brake part compounds having lower viscosity, faster and fuller cures than ethylene, alpha-olefins, diene monomer compounds, where the diene monomer is other than vinyl norbornene. Additionally, the brake parts and the power transmission belt based on the ethylene, alpha-olefin, vinyl norbornene elastomeric polymer have improved resistance to elevated temperature properties, and good heat aging characteristics, compared to for instance ethylene, alpha-olefin, non-conjugated diene elastomers (where the diene is other than vinyl norbornene) polychloroprene, or styrene butadiene rubbers.

Early-age hydration kinetics of polymer-modified cement

Abstract: The hydration kinetics of styrene butadiene rubber latex-modified cement have been studied by isothermal conduction calorimetry. The influence of factors such as polymer concentration, polymer modi...

Oriented film with improved heat sealability

Abstract: A multilayer film is disclosed in which at least one layer thereof comprises a blend of: a first styrene butadiene copolymer having a butadiene content of 50 weight percent or more; and a second styrene butadiene copolymer having a butadiene content of 50 weight percent or less, wherein, the total butadiene content of the blend ranges from about 30 weight percent to about 50 weight percent. When used as an outer layer of an overwrap material, such blend provides an improved overlap heat seal.

Thermoplastics: Directory and Databook

Abstract: One: Review of Thermoplastics.- Thermoplastic Groups.- Further Sources of Information.- Two: Directory Section.- Manufacturers and Compounders: Thermoplastic Products.- Thermoplastic Products: Manufacturers and Compounders.- Manufacturers and Compounders with Agents, Suppliers and Distributors.- Multisource Distributors and Suppliers.- Contact Details.- Companies by Country.- Useful Names and Addresses.- Three: Databook Section.- List of Test Method Standards.- Key to Data Sheets and Properties.- Polyolefins.- Low Density Polyethylene (LDPE).- Linear Low Density Polyethylene (LLDPE).- Medium Density Polyethylene (MDPE).- High Density Polyethylene (HDPE).- Ultra High Molecular Weight Polyethylene (UHMW PE).- Crosslinkable Polyethylene (XLPE).- Chlorinated Polyethylene (CPE).- Ethylene Vinyl Acetate (EVA).- Ionomers.- Polypropylenes (PP).- Polybutylene (PB).- Polymethylpentene (PMP).- Highly Crystalline Polyolefin (HCPO).- Styrenics.- Polystyrenes (PS).- Styrene Acrylonitrile (SAN).- Acrylonitrile Butadiene Styrene (ABS).- Acrylonitrile Styrene Acrylic (ASA).- Styrene Maleic Anhydride (SMA).- Styrene Butadiene Styrene (SBS).- Styrene Ethylene Butylene Styrene (SEBS).- Vinyl Chlorides.- Polyvinyl Chloride (PVC).- Chlorinated Polyvinyl Chloride (CPVC).- Poly Vinylidene Chloride (PVDC).- Fluoropolymers.- Polytetrafluoroethylene (PTFE).- Fluorinated Ethylene Propylene (FEP).- Perfluoro-alkoxy copolymers (PFA).- Tetrafluoroethylene and Perfluoromethylvinylether copolymer (MFA).- Ethylene-tetrafluoroethylene copolymers (ETFE).- Polyvinylidene Fluoride (PVDF).- Ethylene-chlorotrifluoroethylene copolymers (ECTFE).- Polychlorotrifluoroethylene (PCTFE).- Acrylics.- Polymethylmethacrylates (PMMA).- Polyacetals.- Polyoxymethylene Polyacetals (POM).- Polyamides (Nylons).- Polyamide 6 (PA6).- Polyamide 11 (PA11).- Polyamide 12 (PA12).- Polyamide 46 (PA46).- Polyamide 63 (PA63).- Polyamide 66 (PA66).- Polyamide 610 (PA610).- Polyamide 612 (PA612).- Polyamide Copolymers (CoPA).- Polyarylamide (PAA).- Polyamide PA6-6-T.- Amorphous Polyamide (PA6-3-T).- Polyurethanes.- Polyurethanes (PUR).- Thermoplastic Elastomers (TPE).- All TPE products, irrespective of type, are listed alphabetically by manufacturer's name with the first appearing on the following pages: Polyurethane based (PUR or TPU and Polyether or Polyester chemistry).- Polyester based.- Polyamide based: Polyether Block Amides (PEBA).- Styrenic based.- Olefinic based.- Polymer Alloys.- Blends.- Polyphthalamides.- Polyphthalamides (PPA).- Aromatic Polyesters.- Polycarbonates (PC).- Polyethylene Terephthalates (PET).- Polybutylene Terephthalates (PBT).- Copolyesters.- Polycyclohexylene Dimethylene Terephthalate (PCT).- Liquid Crystal Polymers.- Aliphatic Polyketones.- Aliphatic Polyketones (APK).- Polyarylene Ethers.- Polyphenylene Oxides (PPO).- Polyphenylene Ethers (PPE).- Aromatic Polyketones.- Polyketones.- Polyaryletherketone (PAEK).- Polyetheretherketone (PEEK).- Polyetherketoneetherketoneketone(PEKEKK).- Sulphides/Sulphones.- Polyphenylenesulphide (PPS).- Polysulphones (PSU).- Polyethersulphones (PES).- Polyarylsulphone (PAS).- Polyimides.- Polyamideimides (PAI).- Polyetherimides (PEI).- Thermoplastic Polyimide (TPI).- Four: Appendices and Indexes.- Appendix A - Multilingual Vocabulary.- Appendix B - Conversion Factors and Units.- Index of Trade Names.- Index of Thermoplastics with Abbreviations.

Tire tread composition

Abstract: Tire tread compositions comprising: a) a first rubber component comprising about 60-90 parts of styrene butadiene rubber (SBR) comprising less than 20 percent by weight of styrene, per hundred parts of rubber (phr); b) a second rubber component comprising about 10-40 phr of nitrile-butadiene rubber (NBR); c) 30-80 phr of carbon black; d) 10-20 phr of silica; e) 1-3 phr of a silane coupling agent; and, optionally, f) a third rubber component comprising about 10-30 phr of a high cis polybutadiene rubber (cis BR) The tire tread compositions provide tires with excellent wet traction and low rolling resistance

Study on the Polypropylene/High Density Polyethylene/Styrene-Butadiene-Styrene Block Copolymer Ternary Blends: I-Composition, Morphology and Properties of Polypropylene/High Density Polyethylene/Styrene-Butadiene-Styrene Block Copolymer Blends:

Abstract: Thermoplastic elastomers, e.g., EPR, EPDM etc., are commonly used as modifiers of the ductility of PP, PE, HDPE or other general purpose thermoplastics. The objective of this study is to develop a high performance PP/HDPE/SBS polymer blend which possesses excellent toughness and strength equivalent to those of more expensive high-grade engineering plastics and to investigate the change of ratio of PP, HDPE and SBS with morphology and mechanical properties of the blend. It was found that the introduction of HDPE into the mixture of PP/SBS gives rise ternary blends possessing not only super high ductility and impact strength (over 700 J/m), but also balanced mechanical properties (high tensile strength and flexural strength), as well as excellent thermal resistance and processing properties. It was also found that the morphology of the PP/HDPE/SBS ternary blends is a multiphase system. It appears that the resulted complex morphology renders the high performance of the ternary blends.

Adhesion enhancers for anionic bituminous emulsions

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 rosin and fortified rosin as well as combinations of kraft lignin and nonionic emulsifiers. The novel adhesion enhancers utilized in these improved methods are the condensation reaction products of polyalkylene polyamines with a blend of polymerized linoleic acids and styrene (α-methyl styrene)-acrylic (metacrylic) acid copolymers.

Viscoelastic properties and film morphology of heterogeneous styrene–butadiene latexes

Abstract: Heterogeneous carboxylated styrene–butadiene (S/Bu) latexes were prepared by a twostage emulsion polymerization process, using three PS seeds with different molecular weights. The second-stage polymer was a copolymer with a fixed S/Bu ratio of 1 : 1 and a methacrylic acid (MAA) content of either 1 or 10 wt %. Morphological studies by transmission electron microscopy (TEM) as well as studies of the viscoelastic properties by mechanical spectroscopy have been performed on films prepared from the latexes. The studies showed that the glass transition temperature, Tg, of the second-stage polymer was considerably affected by copolymerization with MAA. An increase in the MAA content in the second-stage polymer increased the Tg of this phase significantly. Addition of DVB as a crosslinking agent in the preparation of the PS seed phase substantially increased the rubbery moduli of the films, whereas the glass transition temperature of the second-stage polymer was unaffected. On the other hand, the presence of a chain transfer agent reduced the glass transition of the second-stage copolymer containing 1 wt % MAA dramatically, whereas the rubbery modulus was unaffected. When the MAA content was increased to 10 wt % the influence of the MAA monomer had a dominating effect on Tg. Latexes containing 10 wt % MAA had Tg values close to each other, regardless of chain transfer agent present in the second-stage polymerization. It was found that the morphology of the latex particles influenced the rubbery modulus of the films. The presence of irregularly shaped seed particles in samples prepared from a crosslinked PS seed had a considerable reinforcing effect on the films, whereas spherical seed particles originating from core–shell particles had a less reinforcing effect. © 1996 John Wiley & Sons, Inc.

Thermoplastic elastomeric block copolymers and process for the preparation thereof

Abstract: This invention relates to thermoplastic elastomeric block copolymers and process for the preparation thereof. According to this invention, the block copolymers obtained through block copolymerization process at higher temperature and adding butyllithium in twice during copolymerization are mixed block copolymer of A1-B-A2/B-A2 and B-A2/B-A2 (where A represents monovinyl aromatic monomer; B represents conjugated diene monomer) having different blocks, higher elongation and appropriate melt index. The process of this invention is simple and efficient. The invention copolymers are particulary useful for various applications of typical styrene butadiene block copolymer, especially plastics modifier.

Two-component polymer composition

Abstract: A pack contains components A and B wherein component A contains Ai) a solution or dispersion comprising a polymer containing units having hydroxyl groups and Aii) a polymer containing units having carboxyl groups; component B comprises Bi) a polyfunctional crosslinker capable of crosslinking with at least one carboxyl group and at least one hydroxyl group. The components A and B may provide an adhesive, especially for wood substrates. The components A and B may also be used to form protective coatings on wood substrates. Example components Ai) include solutions of polyvinyl alcohol, or dispersions of other polymers such as polyvinylacetate/ethylenevinylacetate in polyvinylalcohol. Suitable components Aii) include carboxylated styrene butadiene rubber latex. The component A may also include filler materials, for example to improve water resistance. The crosslinker may be a polyfunctional aziridine such as one of formula (I), wherein R is a polymer chain and Y is a lower alkyl group of from 1 to 4 carbon atoms.

Adhesion of Styrene-Butadiene Rubbers with Different Silica Content

Abstract: The influence of silica content of four styrene-butadiene rubbers on their adhesion to polyurethane adhesives was studied. Untreated rubber shows no adhesion due to a weak boundary layer of zinc stearate. Roughening removed zinc stearate from the rubber surface, increased the surface energy and produced surface roughness, so improved adhesion was obtained. The adhesion increased as the silica content in rubber increased, due to an improvement in intrinsic adhesion, and mechanical and physical properties of the rubbers. Chemical surface treatments (halogenation with trichloroisocyanuric acid, treatment with fumaric acid) provided higher adhesion than roughening. In general, chlorination was somewhat more effective than the treatment with fumaric acid, especially in roughened rubbers. Improved adhesion of chemically surface-treated rubbers was due to enhanced mechanical, thermodynamic and chemical adhesion, and to the improved physical, mechanical and viscoelastic properties of rubbers.

Adhesion promoters for anionic bituminous emulsions

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 rosin and fortified rosin as well as combinations of kraft lignin and nonionic emulsifiers. The novel adhesion promoters utilized in these improved methods are the polyamidoamine condensation reaction products of polyalkylene polyamines with monomeric tall oil fatty acids and polymerized linoleic acids. Further improvement in adhesion can be obtained via adding paraformaldehyde to the reaction.

Effect of prevulcanization on the rheological behavior of natural rubber/styrene butadiene rubber latex blends

Abstract: The effect of prevulcanization on the rheological behavior of natural rubber (NR), styrene butadiene rubber (SBR) latices, and their blends was studied with special reference to shear rate, blend ratio, vulcanizing systems, prevulcanization time, and accelerator systems. The NR latex showed a sharp increase in viscosity with increase in prevulcanization time due to high extent of crosslinking. However, SBR latex showed marginal effect on viscosity with prevulcanization time due to its low dry rubber content and low degree of unsaturation. Blends showed variations in viscosity according to the change in composition. The use of a single accelerator was found to have marked influence on the viscosity of the blends compared with a combination of accelerators. Swelling experiments were carried out in order to determine the crosslink density of the blends. The viscosity changes have been correlated with the crosslinking density of the latices and their blends. © 1996 John Wiley & Sons, Inc.

Styrene-butadiene copolymerization initiated by organopotassium compounds in hydrocarbon medium

Abstract: The following values of monomer reactivity ratios were found: rS = 3,3 ± 0,3; rB = 0,12 ± 0,02 (cyclohexane, 25 °C). The comparison of the kinetic parameters obtained with Li, Na and K counter-ions shows that the great difference between coordination polymerization with Li and “typically anionic” polymerization with K is mainly determined by the variation of the cross-propagation rate constant kBS with the nature of the counter-ion. No evidences for the specific role of the solvation of Li counter-ion with butadiene monomer were found.

Pneumatic tire having a tread compound derived from latex blend

Abstract: The present invention relates to a pneumatic tire having a tread containing from 50 to 100 phr of a dried rubber derived from a blend of a styrene butadiene latex and an acrylonitrile butadiene latex.

Solution polymerization process for synthesis of styrene-butadiene or styrene-isoprene rubber

Abstract: The subject invention relates to a technique for synthesizing rubbery copolymers of styrene and butadiene and/or isoprene. These rubbers exhibit an excellent combination of properties for utilization in high performance tire tread rubber compounds. The subject invention specifically discloses a process for preparing a styrene-butadiene rubber (SBR) which comprises: copolymerizing from about 30 weight percent to about 55 weight percent styrene and from about 45 weight percent to about 70 weight percent 1,3-butadiene in an alkane solvent, such as hexane, at a temperature which is within the range of about -10° C. to about 150° C. in the presence of (a) an alkali metal alkoxide, and (b) an organolithium compound, wherein the molar ratio of the alkali metal alkoxide to the organolithium compound is within the range of about 0.01:1 to about 1:1. The subject invention further discloses a process for preparing a rubbery copolymer of styrene and isoprene having an excellent combination of properties for use in making tire treads by a solution polymerization process which comprises: copolymerizing from about 30 weight percent to about 55 weight percent styrene and from about 45 weight percent to about 70 weight percent isoprene in an alkane solvent at a temperature which is within the range of about -10° C. to about 150° C. in the presence of (a) an alkali metal alkoxide, and (b) an organolithium compound, wherein the molar ratio of the alkali metal alkoxide to the organolithium compound is within the range of about 0.01:1 to about 1:1.