Showing papers on "Styrene-butadiene published in 1993"

Catenoid-lamellar phase in blends of styrene-butadiene diblock copolymer and homopolymer

Abstract: A new morphology is observed in a blend of a symmetrical (lamellar) styrene-butadiene diblock copolymer and a styrene homopolymer, in which the two blocks and the homopolymer all have approximately the same molecular weight of 25000. This morphology is associated to the catenoid-lamellar (CL) structure recently discussed in the literature. The CL phase contains lamellae where the layers of component A are penetrated by channels of component B, and the shape of the interphase dividing-surface resembles a minimal surface based on revolution of a catenary about the central axis of the channel

Adhesion of flame-treated polyolefins to styrene butadiene rubber

Abstract: Samples of polyethylene and polypropylene have been submitted to repeated short duration (75 ms) flame treatments, at optimum flaming conditions. Surface energies of untreated and flamed specimens were determined by liquid contact angle measurements. It appears that the surface energy of polyethylene increases much more than that of polypropylene after flame treatment. The flamed polymer surfaces were further examined by electron spectroscopy, Fourier Transform IR spectroscopy and secondary ions mass spectrometry. The adhesion properties of modified polymer surfaces were studied by testing in peel the bonded Styrene Butadiene Rubber/polyolefins assemblies. Scanning electron microscopy (SEM) and water contact angle measurements have been used to observe the locus of failure. Good correlations were obtained between surface energy and adhesion strength, the increase in adhesion strength being particularly important for flamed PE/SBR assemblies. In addition, the peeling in a liquid medium allowed the determin...

Effect of styrene-butadiene-styrene block copolymer on fatigue crack propagation behavior of asphalt concrete mixtures

Abstract: The effect of styrene-butadiene-styrene (SBS) additive percentage on the fatigue crack propagation behavior of AC-5 asphalt concrete mixture was studied. Beams were prepared from AC-5 asphalt binder containing 6, 10, and 15% SBS by weight. Flexural fatigue tests were conducted on three identical specimens at each additive percentage. Parameters controlling the crack propagation process were evaluated--namely, the energy release rate and the change in work expended on damage formation and history-dependent viscous dissipation processes. The modified crack layer model was used to extract the specific energy of damage characteristic of the mixture's resistance to crack propagation and the dissipative coefficient. It has been found that the 15% SBS mixture displayed superior fracture toughness as reflected in the specific energy of damage and the dissipative coefficient. As the additive percentage was increased, the fracture toughness of the mixture increased. Also, the ultimate strength and modulus increased. Within the range of additive percentage tested it appears that both the polystyrene endblocks and butadiene rubbery midblocks are working together to improve the ultimate strength and fracture toughness of the asphalt concrete mixture. Scanning electron microscope examination revealed an obvious change in the morphology of the fracture surface as the percentage of additive in the binder increased. This change is manifested in ridge formation in the binder-rich areas of the mixture. This change is also indicative of better adhesion between the binder and the aggregate as well as better cohesion within the binder, which in turn contributes to the increased toughness of the asphalt concrete mixture.

Sorption and diffusion of aldehydes and ketones into elastomers

Abstract: The results of the sorption and diffusion of aldehydes and ketones into structurally different elastomers such as ethylene propylene diene terpolymer, styrene butadiene rubber, nitrile butadiene rubber, neoprene and natural rubber are described in the temperature interval of 25-60°C. From these data, the Arrhenius parameters for the processes of diffusion and permeation are determined. The activation parameters for the diffusion of ketones range from 10.29 to 49.62 kJ/mol and for aldehydes, from 13.18 to 50.42 kJ/mol; these values fall in the range expected for rubbery polymers well above their glass transition temperatures. Transport data are affected by the nature of the interacting solvent molecule rather than its size and also by the structural variations of the elastomers. For all the solvents, the polymers remained intact; however, natural rubber in the presence of benzaldehyde showed degradative reactions at higher temperatures. Volumetric expansions of the elastomers have been measured from the dimensional response in the presence of aggressive solvents.

Styrene-butadiene rubber for truck tires

Abstract: The subject invention discloses a styrene-butadiene rubber (SBR) which is particularly valuable for use in making truck tire treads, said rubber being comprised of repeat units which are derived from about 10 weight percent to about 20 weight percent styrene and from about 80 weight percent to about 90 weight percent 1,3-butadiene, wherein the repeat units derived from styrene and 1,3-butadiene have a sequence distribution wherein at least about 55% of the styrene repeat units are in blocks of only one styrene repeat unit, wherein at least about 75% of the styrene repeat units are in blocks of 1 or 2 repeat units, and wherein at least about 5% of the styrene repeat units are in blocks of more than 8 repeat units, wherein from about 32% to about 40% of the repeat units derived from the 1,3-butadiene are of the cis-microstructure, wherein from about 50% to about 60% of the repeat units derived from the 1,3-butadiene are of the trans-microstructure, wherein from about 6% to about 15% of the repeat units derived from the 1,3-butadiene are of the vinyl-microstructure, wherein the rubber has a glass transition temperature which is within the range of about -85° C. to about -70° C., wherein the rubber has a number average molecular weight which is within the range of about 150,000 to about 400,000, wherein the rubber has a weight average molecular weight of about 300,000 to about 800,000, and wherein the rubber has an inhomogeneity which is within the range of about 0.5 to about 1.5.

Charge-mosaic membrane from gamma-irradiated poly(styrene-butadiene-4-vinylpyridine) triblock copolymer

Abstract: Poly(styrene-butadiene-4-vinylpyridine) triblock copolymers were prepared from styrene (S), butadiene (B), and 4-vinylpyridine (P) by sequential anionic polymerization with n-butyllithium as initiator and benzene as solvent. The triblock copolymer was characterizated by gel-permeation chromatography (GPC), transmission electron microscopy (TEM), and viscoelastic spectrometry. Films of the triblock copolymer cast from solution in mixtures of chloroform and n-butyraldehyde were subjected to gamma-ray irradiation to form cross-linked networks, Cationic and anionic groups were introduced by sulfonation and quater-nization to obtain charge-mosaic membranes. The resulting membrane had substantial cation-exchange and anion-exchange capacities. The membranes were very permeable to electrolyte (JKCI = 2.10×10−8 mol/cm2 s). © 1993 John Wiley & Sons, Inc.

In-situ direct polycondensation in polymer matrices. II. In-situ direct polycondensation in styrene-butadiene block copolymers

Abstract: Direct polycondensation of 3-substituted-4-hydroxybenzoic acid was carried out in solutions of styrene-butadiene block copolymers (SBS) at room temperature in the presence of triphenylphosphine and hexachloroethane as an initiator for the direct polycondensation of these monomers. Solution casting after the direct polycondensation provided opaque films in which the aromatic polyester was finely dispersed within the matrix of SBS. Mechanical properties of these films were examined by tensile tests. A great improvement of tensile strength was achieved by the incorporation of phenyl substituent in the resulting polyester. In-situ direct polycondensation leads to the formation of new composites of rigid polymers and flexible polymers. © 1993 John Wiley & Sons, Inc.

New solid polymer electrolytes prepared from styrene–butadiene copolymer latices

Abstract: A new dual-phase polymer electrolyte solid system was proposed in which the low polarity host polymer matrix contains a network of dispersed polar domains. The host styrenebutadiene copolymer supports mechanical stability of the electrolyte while the high polarity domains retain plasticizer and salt, forming ion conduction pathways. The electrolyte has an ionic conductivity range of 1x10 -9 -3.1x10 -5 S/cm depending on the solvent plasticizer content

Epoxidized linseed oil-free fatty acids modified with substituted anilines as antioxidants and antirads for SBR vulcanizates

Abstract: Epoxidized linseed oil-free fatty acids were reacted with aniline and three isomers of toluidine, anisidine, and chloroaniline in such a manner that the carboxylic groups remained free. The prepared adducts were evaluated as antioxidants and antirads for styrene butadiene rubber (SBR) vulcanizates. It was found that 2 phr of orthotoluidine, paraanisidine, orthochloroaniline, and aniline adducts were the best antioxidants and/or antirads. © 1993 John Wiley & Sons, Inc.

Preparation method of styrene-butadiene block copolymer

Abstract: Atactic block is generated after non-elastic block is formed during anionic polymerization of styrene-butadiene that is triggered by organolithium and elastic structural-regulated block is finally formed. By use of lithium-base polymer chain with active end, which is created by coupling of alkoxysilicon compound, at this time, a styrene-butadiene atactic block copolymer with star structure is generated.

Interface and Interphase in Carbon Fibre-Styrene Butadiene Rubber (SBR) Composites

Abstract: The stress transfer capacity of carbon fibre-SBR interfaces is analysed in terms of interfacial shear strength and measured by means of a fragmentation test on single fibre composites. For all the cases studied, the experimental values of the interfacial shear strength are largely higher than theoretically expected. Such a result is explained by the existence near the fibre surface of an interfacial layer in which the polymer chain mobility is greatly reduced. Such an interfacial region of low mobility is pointed out by mechanical spectrometry on unidirectional composites at different fibre contents. This interphase could exhibit a pseudo-glassy behaviour and, in particular, an elastic modulus close to that of the elastomer in its glassy state whatever the temperature.

Physical properties of styrene-butadiene rubber radiation vulcanized with functional monomers

Abstract: The efficiency of seven functional monomers toward Styrene-Butadiene rubber (SBR) were following the order, Tetramethylol methane tetraacrylate (ATMMT) = Tolyene diiaocynate (UA306T)>Trimethylol propane trimethacrylate (TMPT)>Diethylene glycol dimethacrylate (2G)>Dipentaerithrol hexaacrylate (DPE6A)>Hexamethylene diisocynate (UA101H))>Triallyl cynurat (TAC). Also it was found that low absorption of ATMMT has been overcame at low dose. The observed clear and transperant sheets indicate that the reaction was complete

Styrene-Butadiene Rubber Filled with Fluorinated Carbon Black

Abstract: A comparison is made of the properties of an SBR 1502 containing twenty volume percent of conventional furnace black, or one of three fluorinated blacks. Fluorination slows the rate at which the filler incorporates and disperses into the rubber. Final mixing torque decreases as the degree of fluorination increases, apparently due to a reduction in surface energy of the filler. Compositions with fluorinated blacks have reduced scorch times and decreased cure rates relative to compositions with normal furnace black. This is attributed to acidity of the fluorinated blacks. Scorch time increases in a linear fashion with pH of the filler. Tensile strengths of samples containing fluorinated blacks are about seven times that of a gum composition, but about 30% less than vulcanizates with regular furnace black.

Tire tread compositions of isoprene-styrene/butadiene emulsion polymers with 1,4 cis-polyisoprene rubber

Abstract: The present invention provides an emulsion polymerization synthetic isoprene-styrene/butadiene rubber for use in improved tire tread compositions is provided. The improved composition is a blend of a 1,4 cis-polyisoprene such as natural rubber and a synthetic rubber produced by emulsion polymerization which synthetic rubber includes isoprene and either styrene or butadiene or both styrene and butadiene. The tire tread composition has an excellent balance of good wear resistance and low rolling resistance as well as a low T g and good traction. These improved qualities for tire tread compositions have heretofore been unavailable in rubbers utilizing emulsion polymers, and have been achievable only with tire compositions including synthetic rubbers that are produced by solution polymerization.

Production of completely random styrene-butadiene copolymer rubber

Abstract: PURPOSE:To obtain through solution polymerization the desired copolymer rubber which has predetermined physical properties and is excellent in tensile strength, impact resilience, and other properties by copolymerizing styrene with butadiene in the presence of a catalyst and an inert diluent under specific conditions. CONSTITUTION:Styrene is copolymerized with butadiene in the presence a catalyst comprising an organic Li compound (e.g. butyllithium) and at least one Lewis base selected from among (thio)ethers, tertiary amines and phosphines (e.g. ethylene glycol dibutyl ether) and an inert diluent (e.g. hexane). This copolymerization is conducted in such a manner that the feedstock including the monomers, catalyst, and diluent is continuously introduced into a polymerization zone whose temp. is regulated to 80 deg.C or higher and which is kept being vigorously agitated at a stirring efficiency of 5X10 or higher as measured around the feedstock inlet. Thus, the objective rubber is obtained which has predetermined values of Mooney viscosity, total combined styrene content, 1,2-vinyl bond content in the butadiene units, mol.wt. distribution, free styrene content, and long styrene block chain content.

Crosslinking of styrene–butadiene rubber with 1,2-bis(benzocyclobutenyl)ethane

Abstract: 1,2-Bis(benzocyclobutenyl)ethane (BBCB) was used as a thermally activated crosslinking agent in styrene-butadiene rubber (SBR), both in the raw and carbon black-filled materials. Diels-Alder crosslinking reactions occurred to a significant degree, despite the lack of substituents of opposing electronic effects. The reaction is free of toxic crosslinking promoters and evolved by-products. Various physical properties such as ultimate elongation, tensile strength, and modulus were measured and compared to those properties of a sulfur-cured sample of SBR. Linear relationships were found between the amount of BBCB present and the modulus of the materials, as well as the amount of BBCB and solvent uptake in swell tests

Bonding of Ultra High Molecular Weight Polyethylene to Styrene-Butadiene Rubber

Abstract: The adhesion between a sulfur-vulcanized SBR and polyethylenes (PE) of various molecular weights has been determined using a T-peel geometry. When the viscosity average molecular weight of the polyethylene exceeds about 700 k, bonding is sufficient to cause rubber tear during peeling. In contrast, with PE of Mv≈147k, joint strength is reduced by more than an order of magnitude and fracture proceeds between the SBR and PE. It is hypothesized that the high bond strength with the ultra high molecular weight polyethylene (UHMWPE) is due to the formation of entrapped tangles between chains of the two adherends. Consistent with this, SBR-UHMWPE bonds are not disrupted after extensive swelling in toluene.

Novel metallic materials constructed from epoxidized styrene-butadiene copolymers and cupric oxide

Abstract: The functionalization of the insulator copolymer matrix star [styrene (30 tool%) butadiene] with epoxide groups leads to the development of a novel metallic conductor after mixing with cupric oxide (CuO), a poor electrical conductor. Conducting polymer materials are attracting research interest due to their wide range of present and possible future applications [1-6]. These polymers may be useful as microelectronic elements, for the development of photovoltaic elements, as chemical sensors, as photochromic materials and for the development of rechargeable cells [1-8]. However, making composite materials may produce polymers with improved mechanical properties. We report here, for the first time, that the epoxidation of the polymer matrix copoly(styrenebutadiene) leads to the development of a composite material with CuO that not only has good mechanical properties, but is also a metal-like electrical conductor. Epoxidation was carried out with the in situ formation of performic acid in toluene solution (5wt% solids) using an excess (110%) of the epoxidizing agent, an equimolar mixture of formic acid and hydrogen peroxide. After the addition of hydrogen peroxide at 0 °C the temperature was allowed to rise and was controlled at 20 °C for the duration of the epoxidation reaction. Other details of the procedure have been described elsewhere [9]. Epoxidized polymers were characterized using ~Hnuclear magnetic resonance (1H-NMR) spectroscopy, 13C-NMR, Fourier-transform infrared spectroscopy and volumetric analysis. The absence of 1H-NMR absorptions at 3.2-3.3 and 3.8p.p.m. indicates the absence of a diol grouping and a furan ring, respectively. Similarly, no infrared absorptions were detected for the above groups, correspondingly at 3430 and 1067 cm -1. In this work more weight was given to NMR analysis, since at higher degrees of conversion neighbouring oxirane groups may vitiate chemical analysis results through side-reactions, leading to higher-membered rings. The epoxidized copolymers were precipitated in methanol, treated in a blender, suspended in distilled water and dried at 25 °C for 48 h under vacuum. The degree of copolymer epoxidation and the polymer properties are summarized in Table I. The epoxidized polymers were dissolved in 100 ml CHC13 (Merck, pro analysis) and then added to the CuO (Merck, analytical grade) powder. Solvent was removed and the composite materials were dried to constant weight at 50 °C in a vacuum-oven, forming a thick film. The conductivity and the thermopower of these epoxidized polymers-CuO blends were measured. The star copolymer 31.5 mol% epoxidized (E2), which contained the critical quantity of 80 wt% CuO, showed an increase in conductivity by a factor of 10 s. At this concentration the CuO molecules are calculated to be in "contact". The thermopower at room temperature was about 100/xVK -~. In order to explain these results, other blends using polypyrrole (PPY), copper iridium oxide (IrO2) and titanium oxide (TiO2) were obtained. Only the first two were conductive, and their properties are summarized in Table II. An increase in conductivity was observed only in the CUE23 sample containing

Method for forming anti-slippage sole

Abstract: PURPOSE: To improve anti-slippage and durability of a sole below 0°C by mixing rubber with an acrylic fiber having a specified length and thickness as specified to form a rubber fabric for forming a ground sole. CONSTITUTION: 5-25 pts.wt. of an acrylic fiber 12... and 12 with a length thereof of 0.1mm-5mm and a thickness thereof of 1-30 denier and other blend chemicals for rubber are added to 100 pts.wt. of rubber as mixture of natural rubber and styrene butadiene rubber in a mixing ratio of 70:30. With the hardness after vulcanization limited to 45-65 degree, the material is kneaded with a kneading role to make a sheeting with a thickness of 1mm. The work is cut in a form of the sole to prepare a unvulcanized rubber fabric 1 for forming an upper sole. With the hardness after the vulcanization set to 75-95 degree, an unvulcanized rubber fabric 2 for forming the upper sole is piled on the unvulcanized rubber fabric 1 for forming the ground sole to be set in a forming mold 3. Heating and pressurization are performed for 8min. at 160°C by a widely used method to integrate the ground sole 1 and the upper sole 2 by vulcanization. Then, the work is taken out of the forming mold and the ground surface 11 of the ground sole 1 is buffed to expose the acrylic fiber 12 to the ground surface 11. COPYRIGHT: (C)1994,JPO&Japio

Stretch cling film for food packaging - made by extrusion of a mixt. of a styrene]-butadiene]-styrene] copolymer and a sequenced styrene]-butadiene] copolymer

Abstract: Stretch cling film with good optical and mechanical properties is made by blown extrusion through an annular die or flat extrusion through a slit die of a mixt of (a) 5-50 wt % of a styrene-butadiene-styrene copolymer and (b) 50-95 wt % of a sequenced styrene-butadiene copolymer, the copolymer(s) (a) and (b) having a density of 0950-101 g/cm3 Pref the copolymer mixt contains 8-15 (esp 25-40) wt % of component (a) The film is pref 10-40 micrometres thick USE/ADVANTAGE - The films have good optical and mechanical properties, good stretch characteristics, good autoadhesive properties by way of the rubber effect, good permeability and freedom from residual deformation The prods have good machine application characteristics and are esp useful for packaging food prods currently packaged in PVC film

Microencapsulated adhesive compositions and methods of making same

Abstract: A microencapsulated adhesive is produced from a solvent-based adhesive composition such as a styrene butadiene rubber composition or an acrylic. The solvent-based adhesive composition may be encapsulated by interfacial polymerization, gelatin/gum arabic coacervation or melamine/formaldehyde encapsulation. The solvent is removed from the microcapsules by heating or reduced pressure to form an adhesive that is non-tacky, but becomes tacky upon application of external forces, such as shearing. The microencapsulated adhesive composition may be used, among other applications, as an adhesive for stamps or envelopes.

Thermoelasticity in carbon black-filled styrene-butadiene rubber

Abstract: Temperature changes resulting from application of periodic strain (deformation) with strain amplitudes up to 60% are reported for vulcanized styrene-butadiene rubber loaded with different parts of fast extrusion furnace carbon black at room temperature. The method used involves determination of the thermoelastic coefficient, change in entropy, enthalpy per unit length and Gruneisen constant. Thermal effects were found to be dependent on the strain amplitude and carbon concentration. An empirical formula is suggested to account for the obtained results.

Dual-phase solid polymer electrolytes prepared from styrene–butadiene copolymer latices

Abstract: A new dual-phase solid polymer electrolyte system has been proposed. In this system, a network of ion pathways is formed in a low-polarity, host polymer matrix. A series of electrolytes were prepared from styrene-butadiene copolymer latices with dissolved lithium salts. Polymer films were formed from these latices, and then impregnated with γ-butyrolactone (γ-BL) or γ-butyrolactone/dimethoxyethane mixture (γ-BL/DME), giving latex polymer electrolytes. The ionic conductivity of the polymer electrolyte system increased with increasing solvent content, although a distinct percolation threshold was not measured. Ionic conductivity also increased with the use of DME cosolvent, with the highest conductivity being 1.4 × 10−4S/cm. Complex impedance diagrams are discussed. The diagrams show significant deviations from the ideal. TEM/SEM observations are consistent with the desired dual-phase morphology. © 1993 John Wiley & Sons, Inc.

Styrene-butadiene block copolymer composition

Abstract: PURPOSE:To obtain the title composition which has excellent antistatic and non-fogging effects without detriment to surface properties, transparency and impact resistance. CONSTITUTION:A styrene-butadiene block copolymer is blended with a mixture of a fatty acid ester of glycerin, a fatty acid ester of sorbitan and/or an alkylene oxide adduct thereof to obtain the title composition.