Showing papers on "Styrene-butadiene published in 1970"

In situ polymerization of surface-active agents on latex particles II. The mechanical stability of styrene/butadiene latexes

Abstract: The polymerization of sodium 9-(and 10)-acrylamidostearate (NaAAS) which was adsorbed in varied amounts on the surface of a relatively unstable styrene/butadiene (60/40) copolymer latex resulted in latexes the mechanical stability of which was slightly lower at low coverages but definitely higher at intermediate and high coverages than that of latexes with equivalent amounts of adsorbed monomeric NaAAS.

Dynamic Properties of a Model Reinforced Elastomer. Styrene-Butadiene Reinforced with Polystyrene

Abstract: The dynamic storage and loss moduli of SBR 1503 reinforced with 400 A˚ polystyrene particles were measured at 110 cps over a 200° temperature range. The effect of the polystyrene filler on the rubber was to raise the storage modulus dramatically in the rubbery zone, but only slightly in the glassy region of viscoelastic response. As a result the transition zone appeared broadened and shifted toward higher temperature. Corresponding changes were observed in the loss maximum with a shift of 4° at the highest filler content (46%) investigated. The height of the loss maximum was nearly unaffected. The loss tangent of the filled and unfilled polymers showed no systematic shift with temperature and the dilatometric glass transition was raised only 2° C at the highest filler content. All the essential features of the dynamic behavior could be described in terms of the properties of the component polymers by the phenomenological equivalent mechanical model treatment of Takayanagi. It is concluded that th...

Structure and properties of a styrene–butadiene–styrene block copolymer

Abstract: Electron-microscopic texture and physical properties of a styrene–butadiene–styrene (SBS) block copolymer obtained by casting from toluene, carbon tetrachloride, ethyl acetate, and methyl ethyl ketone are discussed. Two peaks are observed in the mechanical loss (tan delta;) curve at −70 and 100°C which are attributed to segmental motion of polybutadiene and polystyrene, respectively. The polybutadiene peak heights are in the order of solubility in the solvent used; the polystyrene peak heights are in converse order. In addition to these peaks, a third peak is observed at 10°C for specimens cast from ethyl acetate or methyl ethyl ketone. A transition corresponding to this peak is also noticed in thermal analysis. It is proposed that aggregation of styrene blocks is relatively incomplete in specimens cast from solution in poor solvents.

Gasket-forming solvent-based compositions containing styrene-butadiene block copolymers

Abstract: Gasket-forming compositions based on styrene-butadiene block copolymers blended with a minor portion of random styrene-butadiene copolymer and polyisobutylene are prepared by conventional rubber compounding techniques in the presence of low molecular weight polyethyethylene Fillers and solvents are used to complete the formula

Process for preparing styrene polymers having a high impact strength

Abstract: Process for the production of high impact polystyrenic polymers comprising dissolving 3-10 parts by weight of a polybutadiene rubber and/or a styrene butadiene rubber in 100 parts of a styrenic monomer, polymerizing the solution under conditions of bulk polymerization in the absence of a catalyst or initiator until the solid content in the solution becomes from about 15 to 45 percent by weight, dispersing the polymerization product in water to provide an aqueous suspension, and polymerizing the aqueous suspension under the conditions of suspension polymerization in the presence of from 0.1 to 1 part by weight of t-butyl per-iso-butyrate and from 0.01 to 0.5 parts by weight of t-butyl peracetate.

Rubber blends containing an hydrogenated styrene butadiene random copolymer

Abstract: A RUBBER VULCANIZABLE COMPOSITION HAVING AN INCRESASED GREEN STRENGTH, WHICH COMPRISES A BLEND OF (A) AT LEAST ONE POLYMER SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER, POLYISOPRENE, STYRENE-BUTADIENE COPOLYMER, POLYBUTADIENE, BUTYL RUBBER AND ETHYLENE-PROPYLENE TERPOLYMER AND (B) FROM 5 TO 95 PARTS BY WEIGHT OF SAID BLEND, GENATED COPOLYMER PER 100 PARTS BY WEIGHT OF SAID BLEND, SAID HYDROGENATED COPOLYMER HAVING POLYMERIC MONOMER UNITS WHICH CONSIST OF (1) STYRENIC UNITS, (2) CONJUGATED DIOLEFINIC UNITS, AND (3) HYDROGENATED CONJUGATED DIOLEFINIC UNITS, WHEREIN THE STYRENIC UNITS ARE RANDOMLY DISTRIBUTED IN THE POLYMERIC MONOMER UNITS.

Method of bonding polypropylene or a copolymer of ethylene and propylene to an elastomer

Abstract: A METHOD OF MODIFYING A POLYALKENE WHICH COMPRISES APPLYING TO THE SURFACE OF THE POLYALKENE A SOLUTION CONTAINING 0.025 TO 10 PERCENT BY WEIGHT OF A POLYALKENE WHICH IS THE SAME OR DIFFERENT FROM THE POLYALKENE TO BE TREATED. EXAMPLES OF SUITABLE POLYALKENES WHICH MAY BE MODIFIED INCLUDE POLYPROPYLENE AND PROPYLENE/ETHYLENE COPOLYMERS. SUITABLE SOLVENTS FROM FORMING THE SOLUTION OF THE POLYALKENE INCLUDE WHITE SPIRITS, PARAFFIN, HEAVY COAL TAR NAPHTHA, TOLUENE AND XYLENE. THE MODIFIED SURFACE OF THE POLYALKENE MAY BE BONDED TO AN ELASTOMER SUCH AS NATURAL RUBBER, STYRENE BUTADIENE COPOLYMER RUBBERS AND ACRYLONITRILE RUBBERS.

Characterization of sulfur-cured styrene–butadiene copolymer rubbers and their polybutadiene blends

Abstract: Dissolution of sulfur-cured, carbon black-loaded copolymers and their blends with cis-1,4-polybutadiene (PBD) are brought about by boiling with o-dichlorobenzene which contains a small amount of 2,2′-dibenzamidodiphenyl disulfide. The resulting slurries are subjected to a sequence of separations which include high-speed centrifugation to remove solids, and solvent precipitation followed by filtration to isolate the precipitates. The precipitates are washed with solvent to remove soluble organic materials followed by carbon disulfide washing to dissolve the polymers. Cast films of the polymers are obtained by evaporating the carbon disulfide washings onto sodium chloride discs. The infrared spectra of the cast films of these preparations are very similar to those of their respective polymers prior to loading and curing. Calculations for relative concentrations of bound styrene and PBD microstructures permit nominal identification of the kinds of styrene–butadiene rubber and the amounts of cis-1,4-PBD used in a cured rubber formulation. Absorption bands used are near 3.35 μ for cis-1,4-PBD, 6.65μ for bound styrene, 10.35 μ for trans-1,4-PBD; and 11.0 μ for vinyl-1,2-PBD. Efforts are being made to improve the data by using a grafting infrared instrument and also to extend the calibrations to include other rubber blends.

Ethylene/vinyl chloride/acrylamide interpolymer and styrene/butadiene/unsaturated acid terpolymer polyblend

Abstract: COMPOSITION COMPRISING A POLYBLEND OF ETHYKENE/VINYL CHLORIDE/ACRYLAMIDE INTERPOLYMER AND STYRENE/BUTADIENE UNSATURATED ACID TERPOLYMER USEFUL AS ADHESIVE BINDER IN INORGANIC PAPER-COATING COMPOSITIONS.

Characterization of Sulfur-Cured Styrene-Butadiene Copolymer Rubbers and Their Polybutadiene Blends

Abstract: Dissolution of sulfur-cured, carbon black-loaded copolymers and their blends with cis-1,4-polybutadiene (PBD) are brought about by boiling with o-dichlorobenzene which contains a small amount of 2,2′-dibenzamidodiphenyl disulfide. The resulting slurries are subjected to a sequence of separations which include high-speed centrifugation to remove solids, and solvent precipitation followed by filtration to isolate the precipitates. The precipitates are washed with solvent to remove soluble organic materials followed by carbon disulfide washing to dissolve the polymers. Cast films of the polymers are obtained by evaporating the carbon disulfide washings onto sodium chloride discs. The infrared spectra of the cast films of these preparations are very similar to those of their respective polymers prior to loading and curing. Calculations for relative concentrations of bound styrene and PBD microstructures permit nominal identification of the kinds of styrene–butadiene rubber and the amounts of cis-1,4-PBD used in a cured rubber formulation. Absorption bands used are near 3.35 μ for cis-1,4-PBD, 6.65μ for bound styrene, 10.35 μ for trans-1,4-PBD; and 11.0 μ for vinyl-1,2-PBD. Efforts are being made to improve the data by using a grafting infrared instrument and also to extend the calibrations to include other rubber blends.

Characterization of styrene-butadiene block copolymers

Abstract: 市販のスチレン-ブタジエンブロックコポリマーのブロック構造について調べた. ブロックコポリマー中のポリスチレン含有量とポリブタジェンの微細構造とを赤外線吸収スペクトル法によって決定した. また, ポリブタジエン部分を過安息香酸と過よう素酸とで酸化切断してポリスチレンを得, その重量からポリスチレンの含有量を求めた. 上記2方法で得たポリスチレン含有量は一致した. ブロックコポリマーおよびポリスチレン部分の分子量は, ゲルパーミエイションクロマトグラフィー法によって求めた.ブロックコポリマーおよびポリスチレン部分の分子量とその重量パーセントによってブロック構造を推定した.

Adsorption of oleic acid soap in styrene-butadiene latex

Abstract: A study has been made of adsorption of isomers in soaps made from commercially available oleic acids to rubber by separating and analyzing the serum from styrene-butadiene (S-BR) latex. Both the cis and trans forms of potassium 9-octadecenoate (potassium oleate and elaidate) adsorb strongly to the rubber particles. The rubber phase was separated from the serum without disturbing the soap distribution by successive filtration through Millipore filters of diminishing pore size. These filters had been thoroughly washed to remove surface-active wetting and plasticizing agents and treated with methylene blue to block active sites which would otherwise adsorb emulsifier. Potassium erucate (C22−) was added as an internal standard to the rubber-free serum, which was then acidified and extracted with ethyl ether. The extraction glassware was rinsed with cyclohexane to remove adsorbed fatty acid. Methyl esters of the recovered emulsifier-erucic acid mixture were quantitatively analyzed by gas liquid chromatography. The results show selective adsorption of certain isomers on the rubber particles. In cases where only enough emulsifier was present to cover the rubber surface, the octadecenoic isomers were greatly depleted in the serum indicating preferential adsorption. Addition of emulsifier to the latex increases the quantities of selectively adsorbed isomers in the serum until with large excesses, the serum soap composition approaches that of the original emulsifier.

Stress–birefringence study of styrene–butadiene multiblock copolymer

Abstract: The styrene–butadiene block copolymers of SB, SBS, and SBSBS types were investigated by means of the stress–birefringence technique to elucidate the effects of the block multiplicity on the mechanical properties of copolymers. The SBS-type and the SBSBS-type block copolymers exhibit nonlinear stress–birefringence relations, which were classified into three regions. They are a low stress-optical coefficient region (optical creep), an increasing coefficient region, and a region of retarded increase in coefficient, as pointed out by Henderson et al.8 It was found that optical creep is associated with the polystyrene continuum. The third region, however, originates not only from the phenyl groups of the polystyrene block but also from a form-birefringence due to the orientation of the polystyrene domain. The multiblock copolymer of SBSBS type was found to be rheo-optically similar to the SBS type, both being affected solely by the details of the terminal styrene block. Pure gum vulcanizates of the SB-type and SBS-type block copolymers also exhibit optical creep. In a vulcanized block copolymer having both chemical and physical crosslinks, the latter seemed to disappear at elevated temperatures. At decreasing temperatures, the vulcanizates of block copolymers showed higher modulus of elasticity and lower stress-optical coefficients.

Improvements in or relating to the manufacture of insulated electric cables

Abstract: 1,212,255. Coating cores by extrusion. BRITISH INSULATED CALLENDER'S CABLES Ltd. 27 Feb., 1969 [28 Feb., 1968], No. 9672/68. Heading B5A. In the coating of a core 1 with rubber or a rubber-like composition the core is passed through an extruder 4 to receive a degasified rubber mix as coating, a vacuum being applied between the core and coating in the die head, and the coated core is passed substantially horizontally through a curing bath 6 open to the atmosphere such that the pressure difference across the wall of the coating is due substantially entirely to atmospheric pressure. As shown, bath 6 contains a liquid, heated by heaters 7, which preferably comprises a mixture of alkali metal nitrates and or/nitrates, e.g., a eutectic mixture of potassium and sodium nitrate and sodium nitrate and sodium nitrite. Rollers or a stainless steel belt may guide the coated wire through the bath and a detector 12 may regulate a tensioning unit 11. Also provided are a wash bath 8 and a drier 9. Instead of the liquid bath, a fluidized bed may be employed comprising small glass beads, sand or talc. The bed is preferably electrically heated with air being the preferred fluidizing gas. The extruder comprises a screw whose pitch and/or root diameter provide a precompression zone (13), Fig. 2 (not shown), a decompression zone (15) associated with a vacuum line (16) and breaker plate (14), and an output zone (17) of intermediate screw pitch to passage area ratio. Fig. 3 (not reproduced), shows a crosshead having a resilient inlet seal (23) and a vacuum port (24). The core may be a bare or previously coated wire, a group of wires, or one or more strands. The coating materials specifically mentioned are natural rubber, neoprene (poly. chloroprene), butyl rubber, silicone rubber and styrene butadiene rubber.

Relationship of Morphology to Physical Properties of Styrene-Butadiene Block Copolymers

Abstract: Block copolymers of the type polystyrene-polybutadiene-polystyrene (SBS) behave like reinforced vulcanized elastomers at room temperature.1–3 The addition of low molecular weight polystyrene adds further reinforcement. (For example, this addition to a SBS polymer of 30 wt. % styrene to give an overall composition of 40 wt. % styrene increased the modulus at an extension ratio of 5 from 23 to 44 kg. /cm.2 at a strain rate of 31.5 min.−1)

Polysis-gas chromatographic analysis of styrene-butadiene copolymers

Abstract: An analytical method for determining composition of styrene-butadiene copolymers was studied by pyrolysis-gas chromatography.Relative yield of styrene in copolymer was calculated from the corresponding peaks appearing on the pyrogram at 520°C by making correction for relative sensitivity of the flame ionization detector.The relationship between the yield (wt%) of styrene and the composition (wt%) of copolymers was linear. The composition of the copolymers was determined by using this relation within 0.6 wt% of mean absolute deviation.

Stress softening in styrene-butadiene block copolymers: Rheo-optical studies

Abstract: The stress-strain and the optical properties of styrene/butadiene block polymers indicate that at strains below those at which finite extensibility of the polybutadiene chains become Important, the mechanical properties of the polymers are determined by the combined effects of the elastic deformation of the polybutadiene phase and the degree of interaction between the polystyrene regions. The process of stress-softening in styrene/butadiene block polymers is due to the break-up of polystyrene regions, rather than to flow and rupture of weak crosslinks. Some additional softening occurs in the polybutadiene phase due to loosening-up of the polybutadiene network structure. Specimens which were softened to the same degree of internal strain of the polybutadiene phase had similar stress-strain properties when account was taken of the filler effect of the polystyrene regions. Block polymers which were prestretched to a strain below the finite extensibility of the polybutadiene chains exhibited a stable network structure. At large strains non-Gaussian behaviour of the polybutadiene chains, probably combined with a recoverable plastic deformation of the polystyrene regions, determined the stress-strain properties of the block polymers. The stress-strain and the optical studies of the original and the softened block polymers indicate that under the experimental conditions described here the physical crosslinks formed by the polystyrene regions were stable.