Showing papers on "Styrene-butadiene published in 1998"

The Effect of Bis(3-Triethoxysilylpropyl) Tetrasulfide on Silica Reinforcement of Styrene-Butadiene Rubber

Abstract: Bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) was found to affect the curing characteristics and the physical properties of styrene-butadiene (SBR) gum rubber and xin situ silica-filled SBR vulcanizates. Silica incorporated by the in situ sol-gel reaction of tetraethoxysilane with TESPT showed a much higher reinforcing efficiency than did conventional mechanical mixing and the in situ method without TESPT. The higher reinforcing efficiency is attributed to the formation of a silica-rubber network, which also changed the dynamic mechanical behavior of the SBR vulcanizates. Transmission electron microscopy observations showed in situ silica incorporation of very fine particles in comparison to the sol-gel process without TESPT.

Living Anionic Polymerization of 1,3-Cyclohexadiene with the n-Butyllithium/N,N,N‘,N‘-Tetramethylethylenediamine System. Copolymerization and Block Copolymerization with Styrene, Butadiene, and Isoprene

Abstract: The n-butyllithium/N,N,N‘,N‘-tetramethylethylenediamine system has been found to polymerize 1,3-cyclohexadiene to produce a “living” polymer having a narrow molecular weight distribution. Ternary block copolymers with narrow molecular weight distribution could be synthesized from 1,3-cyclohexadiene, styrene, and butadiene with very high efficiency. The relative reactivity of 1,3-cyclohexadiene, styrene, and isoprene in the copolymerization was found to be in the order styrene, isoprene, and 1,3-cyclohexadiene. In contrast, the relative reactivity of the propagating species of living poly(1,3-cyclohexadiene) was higher than that of the propagating species of living polystyrene.

Electrical and mechanical properties of polyethylene–rubber blends

Abstract: A systematic electrical and mechanical study was carried out on styrene butadiene rubber (SBR), as a nonpolar rubber, and nitrile rubber (NBR), as a polar one blended with pure and waste polyethylene (PE), low and high density. The compatibility investigations, which were carried out by the dielectric method and confirmed by the calculated heat of mixing, indicate that SBR–PE blends (either low or high density) are compatible, while NBR–PE blends are incompatible. From the electrical and mechanical results, it is found that the addition of waste PE to either polar or nonpolar rubber leads to better electrical and mechanical properties when compared with those for the blends having pure PE. The values of permittivity e′ are found to increase pronouncely, while the values of dielectric loss e′ slightly decrease. Shore hardness was also measured for all the investigated systems and found to vary linearly with the permittivity e′. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 69: 775–783, 1998

Glove made from a blend of chloroprene rubber and a carboxylated synthetic butadiene rubber

Abstract: A glove comprising an elastomeric blend of chloroprene rubber and a carboxylated synthetic butadiene rubber. A preferred glove of the invention is a medical glove comprising an elastomeric blend of chloroprene rubber and one of carboxylated nitrile butadiene rubber or carboxylated styrene butadiene rubber. The glove not only reduces the risk associated with natural rubber gloves of causing allergenic reaction and shock to the wearer, but also better approximates the feel and stretch of natural rubber gloves than do other elastomeric gloves.

Effect of blend ratio on Mooney scorch time of rubber blends

Abstract: The Mooney scorch times of three rubber blends [epoxidized natural rubber (ENR) 50/SMR L, ENR 50/styrene butadiene rubber (SBR), and Standard Malaysian Rubber SMR L/SBR] were studied in the temperature range of 120-160°C using an automatic Mooney viscometer. N-Cyclohexyl-2-benzothiazyl sulfenamide was used as the accelerator, and the rubber formulation was based on the conventional vulcanization system. Results for the blends investigated indicate that a negative deviation of scorch time from the interpolated value was observed, especially for temperatures lower than 130°C. This observation was attributed to the induction effect of the ENR 50 in the ENR 50/SMR L and ENR 50/SBR blends to produce more activated precursors to crosslinks, thus enhancing interphase crosslinking. To a lesser extent, SMR L also exhibited such an induction effect in the SMR L/SBR blend. At 120°C, maximum induction effect occurred at around a 40% blend ratio of ENR 50 and SMR L in the respective blends. For the filled stock at 140°C, carbon black exhibited less effect on the scorch property of the blends compared to silica.

Film/substrate composite material

Abstract: A composite useful for making trays for the packaging of food and the like is formed from foamed polystyrene and a film bonded to the polystyrene, the film including a bonding layer of a styrene butadiene copolymer, the bonding layer including at least about 25% by weight of butadiene. The composite may be thermoformed into articles such as trays for use in the packaging of food products, especially meat products.

Dichlorocarbene modification of styrene–butadiene rubber

Abstract: np!nt resulted in n product that showed good mechanical properties, excellent ilami i-esistnnce, solvent resistance, and good thermal stability. The activation energy fill- this chemical reaction calculated from the time-temperature data on the chemical re;lciton L,y the measul.cment of the percentage of chlorine indicated that the rcnctinn prr,c~,r.ded according to first-order kinetics. The molecular weight of the po1y111~1.s. d~t 1998 John

Nonaqueous solvent secondary battery

Abstract: PROBLEM TO BE SOLVED: To improve the discharge capacity and a cycle characteristic by providing a negative electrode including a graphitized mesophase corpuscle as a negative electrode material and a cellulose ether material and a synthetic rubber latex adhesive as binders, and a positive electrode including a lithium-containing metal oxide as a positive electrode active material. SOLUTION: A cellulose ether material and a synthetic rubber latex adhesive are set to 0.5-1 wt.% and to 0.5-2 wt.% to 100 wt.% of the whole negative electrode constituting material. A graphitized mesophase corpuscle, which stores a lithium ion within the crystal lattice, preferably has a spacing of lattice plan (002) of 3.45 Å or less and a size of C-axial crystal element of 300 Åor more. As the cellulose ether material, a one having an etherification degree of 0.5-2.5, an average polymerization degree of 100-200, and an average molecular weight of 25,000-400,000, for example, carboxymethyl cellulose sodium is preferably used. As the synthetic rubber latex adhesive, carboxyl-denatured styrene butadiene rubber latex is preferable.

Flame retardant polypropylene composition

Abstract: The present invention provides a new and improved flame retardant polypropylene composition that exhibits substantially no bloom and plate-out during processing and use In a preferred embodiment the composition comprises a homopolymer or copolymer of polypropylene, a styrene butadiene compatibilizer, a bromine and phosphorus containing flame retardant additive and a metallocene ethylene copolymer In addition to displaying excellent color development characteristics, the composition of the present invention displays excellent physical properties and a UL94 rating of V-2

Method for preparing modified styrene butadiene rubber powder used as toughness-increased agent for poly vinyl chloride

Abstract: The prepn method of modified styrene-butadiene rubber powder for preparing toughened polyvinyl chloride is characterized by that the rubber used by said invention is a general styrene-butadiene latex, said invented method adopts or does not adopts the precrosslinking procedure, and adds a mixed monomer to make graft copolymerization reaction, then adds a polymer covering agent in which Mn is 40-60 thousands in the graft-modified latex, and uses a multivalent water-soluble metal salt to make polycrosslinking reaction and adopts such procedures as filtering, washing, dewatering, mesh screeningand drying so as to obtain the invented product whose grain size is less than 1 mm and rubber content is up to above 60% By properly regulating dose and kind of monomer and its reaction condition the different modified SBR powders respectively for toughening rigid PVC and soft PVC can be made up

Nonaqueous electrolyte battery negative electrode and battery using it

Abstract: PROBLEM TO BE SOLVED: To produce and provide, in large quantities, batteries having a high rate discharge characteristic, in particular, having an excellent discharge characteristic at low temperatures. SOLUTION: In relation to a nonaqueous electrolyte secondary battery negative electrode 3 formed from a carbon material capable of occluding and releasing lithium as a negative electrode material and a binder, a nonaqueous electrolyte secondary battery negative electrode that has an excellent low temperature discharge characteristic, is provided with an electrode plate having large peel strength and is easy to handle can be provided by mixing and using, as the binder of the negative electrode material, one or more kinds of binders A selected from a polyacrylic acid or acrylic salt, polyacrylic methyl, polymethacrylic acid or methacrylic salt, polymethacrylic methyl, ethylene.acrylic acid or acrylic salt copolymer, ethylene.methacrylic acid or methacrylic salt copolymer, and a binder B selected from a styrene butadiene copolymer of which combined styrene quantity is not less than 80% and less than 100% or polystyrene.

Sound absorbing sheet

Abstract: PROBLEM TO BE SOLVED: To improve sound absorbing performance by including active components which increase the dipole moment quantity of a high-polymer material of a fiber sheet into the high-polymer material. SOLUTION: This sound absorbing sheet is formed by adhering the high- polymer material to the fiber sheet. The high-polymer material contains the active components which increase the dipole moment quantity in the high- polymer material. The high-polymer materials having the largest dipole moment quantity in the molecules include polar high polymers. These polar high polymers more specifically include polyvinyl chloride, chlorinated polyethylene, acryl rubber(ACR), acrylonitrile-butadiene rubber (NBR), styrene butadiene rubber(SBR), chloroprene rubber(CR), etc. The high polymer having a glass transition temp. in a service temp. region is used as the high-polymer material. The amt. of the active components to be compounded is preferably a ratio of 10 to 300 pts.wt. per 100 pts.wt. high-polymer material.

Use of peroxides to crosslink rubber compositions containing high vinyl styrene-butadiene rubber

Abstract: High vinyl styrene-butadiene rubber is cured through the use of organic peroxides. The organic peroxide may be used singly or in combination with sulfur curing ingredients to cure the high vinyl styrene-butadiene rubber wherein the organic peroxide to sulfur curing ingredient is at a molar ratio of from about 3:1 to about 1:3.

Diffusion and transport of aromatic solvents through prevulcanised natural rubber/styrene butadiene rubber latex blends

Abstract: Molecular transport of aromatic hydrocarbons through crosslinked NR/SBR blends prepared by latex blending has been studied in the temperature range of 28-60°C. NR/SBR blends were vulcanised by conventional and more efficient vulcanising systems. The more efficient system showed higher uptakes than the conventional system. This is due to the difference in crosslink density. The sorption behaviour of the blends was analysed in three different solvents i.e., benzene, toluene and xylene. The effects of various parameters (blend composition, vulcanising systems, temperature and penetrant size) on the sorption parameters were studied. The mechanism of diffusion showed an anomalous behaviour. The entropy, enthalpy and first order kinetic rate constant have been evaluated. Theoretical and experimental results were correlated. The molecular weight between crosslinks (M C ) was calculated from the diffusion data. The experimentally calculated Q C values were very close to the affine model. The mechanical properties of the swollen samples were evaluated and found to be lower than those for the unswollen state.

Nickel-hydrogen battery anode and manufacture thereof

Abstract: PROBLEM TO BE SOLVED: To obtain a battery anode with its superior prevention effect of battery heating due to adhesive force between a two-dimensional porous substrate and an active material composition, fine powdering of an active substance, and a prevention effect of battery heating due to oxidization of an active substance surface by containing a bonding agent consisting of a butadiene rubber or the like in the active material composition and a water repellent agent containing a fluorine resin. SOLUTION: A bonding agent is employed by selecting it from the group consisting of an acrylonitryl butadiene rubber, a styrene butadiene rubber, and acryl acid butadiene rubber, chloroprene, acryl emulsion, and their mixture. A quantity of this bonding agent used is preferably 0.2 to 3 wt.% to a hydrogen storage alloy that is an anode active material. As a water repellent agent, a fluorine resin with its low surface tensile stress and about 10 to 20 dyn/cm, an unformed fluorine resin, or a fluorine resin dispersed in a fluoride carbon solution is preferably employed.

Self-sealing tyre and method of making the same

Abstract: A self-sealing tyre comprises a toroidal main body, an inner liner (6) of a gas-impermeable rubber covering the inside of the toroidal main body, a self-sealing layer (12) disposed inside the inner liner, and a packing layer (11) covering the inside of the self-sealing layer, where the thickness of the self-sealing layer is 1.0 to 5.0 mm. The self-sealing layer (12) is made of a thermoplastic polymer having a shape retaining nature at normal temperature. The packing layer (11) is made a rubber compound such as butyl rubber or diene rubber such as styrene butadiene rubber.

Curing characteristics and mechanical properties of vinyltriethoxysilane-coupled carbon black/styrene–butadiene rubber vulcanizates

Abstract: Styrene–butadiene rubber (SBR) vulcanizates containing 0 to 2.73 parts of vinyltriethoxysilane (VTEOS) per hundred parts of rubber (phr) were prepared, keeping the other ingredients weight constant. The mixes were tested for their curing behavior by a curemeter. The vulcanizates were analyzed through a Universal tensile tester, fatigue-to-failure tester, and scanning electron microscope mainly for mechanical properties and correlation. An increase in induction time and decrease in cure time, each by 10%, was noticed by the incorporation of 2.73 phr of VTEOS. The tensile strength and elongation at break improved significantly up to 0.5 phr of VTEOS and either a small improvement or deterioration of these properties was observed beyond this concentration of VTEOS. The fatigue-to-failure cycle at four extension ratios showed a gradual and appreciable improvement. It is noteworthy to mention that the vulcanizate containing 2.73 phr VTEOS possessed about a threefold increase in the fatigue-to-failure cycle compared to its non-VTEOS vulcanizate. However, this distinction of the fatigue-to-failure cycle progressively decreased with increase in the extension ratios. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1719–1725, 1998

Dispenser for liquid or pasty material comprising pumping means

Abstract: The dispensing head (7) consists of an axially-moving pusher (26), forming a pumping chamber (22) with an intake (14) closed by an inlet valve (16) on a piston (12) which has at least one seal lip (12a, 12b) in contact with the inner walls of the chamber. The piston is able to move between upper and lower positions, first drawing in the product and then expelling it through a dispensing valve (40), while a spring (32) returns the piston to its upper position. The piston seal lips are made from a rigid or semi-rigid material, while its inlet valve (16) comprises a membrane of a supple material. The material used for the membrane is selected, for example, from the group of thermoplastic elastomers comprising propylene/ethylene copolymers, polyether blocamides, polyvinyls, ethylene propylene diene terpolymers (EPDM), sequenced styrene butadiene polymers (SBS), sequenced styrene ethylene butadiene polymers (SEBS-SIS), thermoplastic polyurethanes, or mixtures of polypropylene with SEBS-SIS, EPDM or SBS. The membrane can be made e.g. from natural or synthetic rubber, such as nitrile or polybutadiene rubber. The piston itself is made e.g. from polypropylene, high or low density polyethene, PVC, polyacetal, ethylene vinyl acetates or mixtures of these.