Styrene-butadiene Rubber Latex Research Articles

Hydrogenation of styrene-butadiene rubber (SBR) latexes

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

Hydrogenation of styrene‐butadiene rubber (SBR) latexes

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

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

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 (Elvaloy AM) were used in this study. A quantitative method to determine the effect of polymer modification on the fracture properties of asphalt concrete is the J-contour integral fracture toughness measurement. An experimental protocol to measure the critical J-integral fracture toughness ( J1 c) was developed and the low temperature (-10°C) J1 c values were determined for SEBS and Elvaloy AM-modified asphalt concrete at three different concentrations.

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

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.

Particle Size Distribution of SBR and NBR Latexes by UV-VIS Turbidimetry near the Rayleigh Region

Abstract This paper deals with data treatment problems that arise when turbidimetry is employed to estimate the particle size distribution (PSD) of soft polymer latexes with low diameter limits around 40 nm. Scanning electron microscopy and dynamic light scattering were used as comparison techniques. Industrial latexes of styrene-butadiene rubber (SBR) and of acrylonitrile-butadiene rubber (NBR) were investigated. The data treatment involved the use of Mie's Model to obtain an average diameter and/or the complete PSD. For estimating the complete PSD, a least squares optimization (with an imposed distribution shape) and a numerical deconvolution procedure (without assumptions on the distribution shape) were attempted. A synthetic example was solved to investigate the limits of the applied numerical methods. For the polymer refractive index functions, Cauchy's Law was used — and its adequate adjustment proved essential for good turbidimetric estimations. A reasonable agreement between the turbidity measurements and the other independent estimations was verified. For the SEM observations, the soft latexes were hardened by irradiation before observation, but negligible diameter variations were detected.

ラテックスにおけるゾル‐ゲル法を利用したスチレン‐ブタジエンゴムの補強

Rubber reinforcement using in situ prepared silica by sol-gel method using tetraethoxysilane (TEOS) was carried out on styrene-butadiene rubber (SBR) latex. SBR latex, TEOS, water and catalyst were mixed at room temperature. After keeping the temperature of the mixture at 40°C for 24hr to proceed sol-gel reaction, the system was held at 80°C for 8hr under vacuum to remove TEOS, water and alcohol which were formed by the sol-gel reaction. Vulcanization of the SBR/silica stock was conducted at 150°C by hot-press. Silica content of composite was determined by thermogravimetry (TG). Tensile strength, 300% tensile modulus and elongation of vulcanizates were measured by a tensile tester. Silica particles dispersed in SBR matrix were observed by transmission electron microscope (TEM). Silica content of composite could be controlled by amounts of added TEOS to SBR latex. Mechanical properties were improved by in situ prepared silica, compared with the gum stock of SBR. In addition, in situ prepared silica showed high reinforcement effect than white carbon that was compounded by the conventional method. Particle size of in situ prepared silica dispersed in the SBR matrix was 0.1-0.5μm. Molar ratio of TEOS to water added to SBR latex influenced to mechanical properties of the composite.

New concept for polymer electrolyte: Dual-phase polymer electrolyte

Two types of dual-phase polymer electrolytes (DPE), mixed latex DPE and core-shell latex DPE, were fabricated from styrene-butadiene rubber (SBR) and acrylonitrile-butadiene rubber (NBR) latex mixture, and from polybutadiene (PB)/ poly (vinyl pyrrolidone) (PVP) core-shell latex. Polar phases of films made from these latices were selectively impregnated with lithium salt solution, constituting dual-phase structures. TEM images verified the dual-phase structures. The ionic conductivity vs. NBR conductive-phase content relationship showed a profile characteristic of percolation effect, which also endorsed the dual-phase structure of mixed latex DPE. For both types of DPEs, ionic conductivity on the order of 10 −3S/cm was obtained. However, the PVP conductive phase of the core-shell latex DPE was partially leached out in the preparation process. The modulus of mixed latex DPE was 6 × 10 6dyn/ cm 2 at room temperature, even with a lithium salt solution content of 61 wt%, suggesting that the SBR supporting phase is little affected by the lithium salt solution.

Rheological behavior of blends of natural rubber and styrene–butadiene rubber latices

AbstractThe rheological behavior of blends of natural rubber (NR) and styrene–butadiene rubber (SBR) latices has been studied with reference to the effects of blend ratio, shear rate, surface‐active agents (casein and sodium carboxymethyl cellulose), and temperature. When the SBR content was less than 50%, the viscosities of the blends appeared to be a nonadditive function of the viscosities of the constituent homopolymers; i.e., a positive deviation was observed. This was due to the structural buildup of the SBR domains. The SBR domains underwent agglomeration and consequently so‐called microflocculation took place. The viscosities of all the blends were found to decrease with increase of temperature and shear rate. The increase in temperature and shear rate marginally weakened the structural buildup as evidenced by the lowering of viscosity. As the SBR content in the system increased, the pseudoplasticity of the blend increased. Even in the presence of surface‐active agents the blends showed composition‐dependent positive deviation. However, surface‐active agents marginally reduced the extent of structural buildup by reducing the microflocculation behavior of SBR domains. © 1995 John Wiley & Sons, Inc.

Emissions of volatile organic compounds from new carpets measured in a large-scale environmental chamber.

This study was undertaken to quantify the emissions of volatile organic compounds (VOCs) released by new carpets. Samples of four typical carpets, including two with styrene-butadiene rubber (SBR) latex adhesive and two with different backings, were collected from the finish lines at manufacturers' mills. Individual VOCs released from these samples were identified, and their concentrations, emission rates and mass emissions were measured under simulated indoor conditions in a 20 m3 environmental chamber over one week periods. Concentrations and emission rates of VOCs emitted by a new SBR carpet were also measured in a house. The carpets emitted a variety of VOCs. The two SBR carpets primarily emitted 4-phenylcyclohexene (4-PCH), the source of "new carpet" odor, and styrene. The concentrations and emission rates of 4-PCH were similar for the two carpets, while the styrene values varied significantly. The carpet with a polyvinyl chloride backing emitted formaldehyde, vinyl acetate, isooctane, 1,2-propanediol, and 2-ethyl-1-hexanol. Of these, vinyl acetate and propanediol had the highest concentrations and emission rates. The carpet with a polyurethane backing primarily emitted butylated hydroxytoluene. With the exception of formaldehyde, little is known about the health effects of these VOCs at low concentrations.

Comparative Study of Latex-Modified Concretes and Normal Concretes Subjected to Freezing and Thawing in the Presence of a Deicer Salt Solution

Freezing and thawing tests in the presence of a 2.4% NaCl solution were carried out on normal concretes and styrene butadiene (SBR) rubber latex concretes in accordance with ASTM C 672. The results indicate that SBR in concrete improves very significantly the resistance of the concrete surface to freezing and thawing in the presence of deicer salts. This improvement depends on the quantity of SBR, the air void spacing factor, and the water/cement ratio. Only 2 of the 9 standard mixtures, but 12 out of the 17 modified concrete mixtures had mass losses lower than 1 kg/sq m at 100 cycles. The results also show that a conventional concrete with a good air-void spacing factor and a low water-cement ratio can be almost as resistant to salt scaling as latex-modified concrete.

The influence of polymer latex modifiers on the properties of concrete

The influence of styrene-butadiene rubber (SBR) and acrylic latices on the properties of Portland cement concrete is investigated. Properties of modified concretes are compared with unmodified samples, on the basis of constant water/cement ratio, and on the basis of constant workability. In samples with constant water/cement ratio, reduction of compressive strength in polymer-modified concretes is statistically significant, and some improvements in flexural and tensile strengths are observed. Scanning electron microscopic examination of the SBR latex modified concrete, using a heavy element tagging technique and energy dispersive analysis of X-rays, demonstrates a non-uniform distribution of polymer modifier in the cement matrix at higher concentrations.

Pore size distribution and oxygen diffusion resistance of polymer-modified mortars

The present paper deals with the resistance of oxygen diffusion of polymer-modified mortars which are often used as low-cost promising materials for repairing work for various reinforced concrete structures. The polymer-modified mortars using three types of commercial polymer dispersions, i.e., styrene-butadiene rubber latexes, ethylene-vinyl acetate and polyacrylic ester emulsions, and tested for pore size distribution by mercury porosimetry and oxygen diffusion by a diffusion cell method. It is concluded from the test results that the oxygen diffusion resistance of the polymer-modified mortars is superior to that of unmodified mortar, and is markedly improved with an increase in the polymer-cement ratio. The use of such mortars can be recommended as effective materials for preventing the wet corrosion of reinforcing bars in the concrete structures.

The hydration of Portland and aluminous cements with added polymer dispersions

We have studied the hydration of ordinary Portland cement and “Secar 71” aluminous cement with added polyvinyl alcohol, polyvinyl acetate, acrylic, poly (vinylidene chloride-acrylic), poly (styrene-acrylic) polymers and poly (styrene-butadiene) rubber latex. We have used the techniques of conduction and differential scanning calorimetry, infrared spectroscopy and X-ray diffraction in our studies. The nature of the interactions between the polymers and the two cements is significantly different. For Portland cement all polymers were found to retard the hydration rate to some extent, with the acrylics producing the maximum affect, whereas in the case of Secar 71, polymer additions had minimal effects on the hydration of or heat evolution from the cement. Our results suggest that many polymers interact with Portland cements in a chemical way although for aluminous cements the observations are less clear except in the case of polyvinyl alcohol-acetate.

The influence of polymer latex modifiers on the properties of concrete

The influence of styrene-butadiene rubber ( sbr) and acrylic latices on the properties of Portland cement concrete is investigated. Properties of modified concretes are compared with unmodified samples, on the basis of constant water cement ratio, and on the basis of constant workability. In samples with constant water cement ratio, reduction of compressive strength in polymer-modified concretes is statistically significant, and some improvements in flexural and tensile strengths are observed. Scanning electron microscopic examination of the sbr latex modified concrete, using a heavy element tagging technique and energy dispersive analysis of X-rays, demonstrates a non-uniform distribution of polymer modifier in the cement matrix at higher concentrations.

Behaviour of Ca(OH) 2 in polymer modified mortars

This paper deals with the effect of polymer modification on the behaviour of Ca(OH) 2 in modified mortars. The polymer modified mortars were prepared using powdered emulsions and aqueous polymer dispersons at various polymer-cement ratios; they were then tested for air content, moulded into specimens and cured. The cured specimens were tested for compressive strength. The fine powder samples obtained from broken specimens were subjected to X-ray diffraction, differential thermal analysis and thermogravimetric analysis. From the test results, it is concluded that formation of Ca(OH) 2 in the polymer modified mortars is reduced possibly because of the absorption of Ca(OH) 2 on polymer films formed in the mortars. The extent of reduction in the quantity of Ca(OH) 2 depends upon the polymer-cement ratio, polymer type or both. Generally powdered poly(vinyl acetate-vinyl carboxylate), poly(ethylene-vinyl acetate) emulsions and aqueous poly(ethylene-vinyl acetate) emulsion were found to be more effective than styrene butadiene rubber latex in reducing the quantity of Ca(OH) 2 in the modified mortars. The cement modifiers did not cause any detrimental effect on the degree of hydration as indicated by their higher compressive strength. Estimation of the quantity of Ca(OH) 2 in the polymer modified mortars therefore, does not provide a proper means for predicting their degree of hydration.

Behaviour of Ca(OH)2 in polymer modified mortars

This paper deals with the effect of polymer modification on the behaviour of Ca(OH)2 in modified mortars. The polymer modified mortars were prepared using powdered emulsions and aqueous polymer dispersons at various polymer-cement ratios; they were then tested for air content, moulded into specimens and cured. The cured specimens were tested for compressive strength. The fine powder samples obtained from broken specimens were subjected to X-ray diffraction, differential thermal analysis and thermogravimetric analysis. From the test results, it is concluded that formation of Ca(OH)2 in the polymer modified mortars is reduced possibly because of the absorption of Ca(OH)2 on polymer films formed in the mortars. The extent of reduction in the quantity of Ca(OH)2 depends upon the polymer-cement ratio, polymer type or both. Generally powdered poly(vinyl acetate-vinyl carboxylate), poly(ethylene-vinyl acetate) emulsions and aqueous poly(ethylene-vinyl acetate) emulsion were found to be more effective than styrene butadiene rubber latex in reducing the quantity of Ca(OH)2 in the modified mortars. The cement modifiers did not cause any detrimental effect on the degree of hydration as indicated by their higher compressive strength. Estimation of the quantity of Ca(OH)2 in the polymer modified mortars therefore, does not provide a proper means for predicting their degree of hydration.

Properties of GRC modified by styrene-butadiene rubber latex

The properties of cement composites made from alkali-resistant Cem-FIL glass fibres and Portland cement modified by styrene-butadiene rubber (SBR) latex and kept in three different environments for up to 15 years are described. It is shown that the long-term weatherability of GRC composites is improved by the addition of SBR, the embrittlement of the material taking place at a slower rate in the presence of the polymer. In air storage SBR-modified GRC has remained strong and tough up to the period of study but in continuously wet environments the polymer did not reduce the extent of long-term strength loss in GRC in any significant way. A proportion of the cement in GRC modified by SBR can be replaced by pulverized fuel ash without sacrificing the improvements in the long-term weathered strength of the composite brought about by polymer addition.

Properties of grc containing pfa

The properties of glass reinforced cement (grc) sheets made by using Cem-FIL alkali-resistant glass fibres and containing large amounts of pulverized fuel ash (pfa) kept in different environments up to 11 years are described. The trends in the changes of the properties of pfa containing grc's with time are similar to those of composites made from neat OPC. In a relatively dry condition, there is very little change with time but in wet conditions and natural weathering various strength properties show reductions from their peak values. Large (1 m × 1 m) vertically held samples have retained higher proportions of their peak strengths than horizontally placed coupons. The proportion of initial s strength retained by grc on weathering is increased if styrene butadiene rubber latex is included in the mix formulation. Encouraging results have also been obtained using a commercially blended cement/pfa mixture.

Desorption of hydrolyzed metal ions from hydrophobic interfaces: I. Latex—aluminum nitrate systems

Desorption of hydrolyzed aluminum ions from a styrene—butadiene rubber latex and a polyvinyl chloride latex was followed by electrophoresis and optical density. The latex particles were first recharged by adsorption of hydrolyzed aluminum ions at sufficiently high pH, upon which the sols were acidified in order to dehydrolyze the metal ion complexes. It was found that with the lowering of pH, the particles became less positive with time and if the sols were made sufficiently acidic the charge was eventually reversed back to negative, indicating the desorption of the dehydrolyzed aluminum ions. The rate of the desorption process was rather slow. This is possibly due to the complex formation between the stabilizing surface active agents and the hydrolyzed metal ions at the particle/solution interface requiring a long time for decomplexation upon acidification.

Colloidal properties of rubber latex

The coagulation and reversal of charge of a styrenebutadiene rubber latex (Naugatex 2740) by freshly prepared and aged aluminum nitrate solutions has been studied as a function of pH. The entire “[Al(NO3)3]-pH” and “[Al2(SO4)3]-pH” domains have been established giving the regions of uncoagulated and coagulated latex, as well as the stabilization region due to charge reversal. The results are similar to those obtained earlier with silver halide sols. Some differences are apparently due to interactions of hydrolyzed aluminum ions with the stabilizing agent, Dresinate 214. This work represents another confirmation of previous findings that the critical coagulation concentrations of a metal counterion varies as a consequence of the change in charge due to hydrolysis. It also shows that only hydrolyzed metal ions may adsorb in amounts sufficient to cause charge reversal.