• Journal of the Korean Wood Science and Technology
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• v.22 no.1
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• pp.85-90
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• 1994

The flow properties of binder latices for paper coating were investigated, together with dynamic viscoelastic properties of latex films and electron micrographs of latices, under various conditions. The amphoteric latex, binder pigment latex and anionic latex were used in this work. The amphoteric latex has both anionic and cationic functional group on its surface. The binder-pigment with a core-shell structure has dual functions : plastic pigment and binder. The low shear viscosity of binder latices and clay slurry were measured with Brookfield vis cometer. At low-shear rates. the viscosity decreased with increasing particle size of latex. On the amphoteric latex surface, the carboxyl groups are assumed to be fully dissociated over the region of pH 9~12, but the density of negative groups seems to be increased because of the gradual decrease in the degree of dissociation of amino groups. Since the apparent particle size of latex increases with surface charge, the electroviscous effect can be observed. On the anionic latex surface, the charge density is assumed to be nearly constant above pH 8. However, below pH 8 the coagulation of particles could be observed probably because of the decrease in the charge density.

• Elastomers and Composites
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• v.50 no.2
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• pp.81-86
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• 2015

In this study, natural rubber latex foam was prepared in order to replace commercialized polyurethane foams as a car seat material. Physical properties of the latex foam were investigated and the light stability was improved. The latex foam was mixed in an aqueous solution state, and the degree of foaming and the accelerator ratios were appropriately controlled. Tensile properties, hysteresis and dynamic mechanical properties of the latex foam were measured to compare with those of polyurethane foams. UV light absorbers and radical scavengers were added for improving light stability of the latex foam. Xenon lamp test was conducted to investigate the effects of the reagents on light stability. Our results revealed that the prepared latex foam including a light absorber with an antioxidant showed excellent light stable performances.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.301-306
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• 2001

Drying shrinkage cracking which may be caused by the relatively large specific surface is a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. Therefore, the purpose of this dissertation was to study the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), latex contents(0, 5, 10, 15, 20%), W-C ratios, and curing days at a same controlled environment of 60% of relative humidity and $20^{\circ}C$ of temperature. Test results revealed that the drying shrinkage of latex modified concrete(LMC), rapid-setting cement latex modified concrete(RSLMC) was considerably lower than that of ordinary portland cement concrete(OPC), rapid-setting cement concrete(RSC), respectively. This may be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic and colloidal properties of the latexes, resulting in reduced water evaporation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.1
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• pp.11-16
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• 2011

This study was carried out in order to elucidate the effect of latex dosage and properties on aging behavior of coated paper. The coated paper with five different coating formulations were prepared and also four different latices were used. The coated paper were thermally aged at $105^{\circ}C$ for 14 days and the optical properties were measured. Increasing latex content increased the magnitude of reduction in brightness and whiteness. In addition, the variations in CIE a$^*b^*$ were larger with increasing latex dosage. Latex which has the lower gel content and the higher Tg showed the higher reduction in brightness and whiteness and much variation in CIE a$^*b^*$. However the particle size of latex didn't affect to thermal behavior of coated paper. These results indicate that latex which has higher Tg and lower gel content is the one of the main factors affecting aging behavior of coated paper.

• Elastomers and Composites
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• v.33 no.2
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• pp.83-92
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• 1998

SBR latex, polyurethane latex and epoxy latex were mixed with polyvinyl acetate emulsion in 0~15% (wt.%). For the mixtures, the viscous properties were examined. The viscosity was influenced by the dispersed phase and the chain structures of polymer, and decreased with the rising of temperatures. The viscosity was increased with mixing of epoxy latex, but decreased with addition of SBR latex or polyurethane latex. Thixotropic index was influenced on the size of micelle and hydrogen bond. The thixotropic index was increased with mixing of epoxy latex or polyurethane latex within 5%, but keep up equality over that. The thixotropic index was decreased with mixing of SBR latex within 5%, but keep up equality over that. The relative viscosity were influenced on the activity of molecule and the interference of dispersed phases, was increased with the rising of temperatures. The relative viscosity was decreased with mixing of epoxy latex, but increased with mixing of SBR latex or polyurethane latex.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1029-1034
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• 2001

The purpose of this research is to develop rapid setting cement latex modified concrete (RSLMC) which will be used to overlay bridge deck for maintaining and repairing. The main experimental variables were the types of rapid setting cement and variation of latex and antifoam agent contents were selected as admixture factor, then the properties of workability and strength development and durability properties were investigated. The results of this study show that latex content give increment of a slump due to surface tension in polymer particles and reduce unit weight of water for preservation of workability. In addition, When no and 1.6~3.2% antifoam agent were mixed, 8%, 2.0~3.8% were respectively obtained. An increasing the amount of latex produced concrete with increased flexural strength, but with slightly lower compressive strength. Rapid chloride permeability and freezing-thawing test carried out. As a results, according to increment of containing ratio antifoamer, strength of RSLMC increase, permeability showed lower value than ignorable 100 coulombs. Also, in the case of more than antifoamer 1.6%, the relativity dynamic modulus is mantained more than 90%, but in case of 0, 5%, it decrease. In consequence, with the view of strength and workability of RSLMC, it is considered that appropriate content ratio of antifoam agent and latex solid are respectively 1.6% by latex weight, 15% by cement weight.

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.240-248
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• 2010

The blending effects of surfactants on the polystyrene emulsion polymerization were studied. The blending of Triton X-100 and SDS affects to the interfacial properties of the styrene monomer and water phases, and finally, the properties of the polystyrene latex particles. As the blending ratio of SDS/Triton X-100 increases, the interfacial tension and CMC of the blended surfactants were decreased and results in a reducing the size of the latex particles. It was found that the interfacial tension was reduced when the surfactant were blended. By increasing the SDS content, the interfacial tension was reduced, and, at a certain condition, the interfacial tension was reached to an extremely low value to form micro-emulsion and the nano-sized latex particles (80~110 nm).

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.2
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• pp.25-40
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• 1997

This research was carried out to investigated the effect of base paper and latex binder on printability and obtical properties of coated paper. Especially, it examined the effect of th pH of vase paper surface and functional groups of latices on the interactions between coating color components and on the structure of coated layer. It was found that the behavior of coating color containing amphoeric latex depends on the pH in the boundary region between coating color and base paper. Thus, the coating color formulated with amphoteric latex formed bulky coating layer by inducing stronger interaction between paper surface and coating components than the coating color with anionic latex. The coated paper with amphoteric latex showed better optical properties (i.e.gloss and optical) and printability (i.e. ink receptivity, wet ink receptivity, and ink set off) than the conventional anionic latex in the acidic and alkaline paper. However, dry pick strength of the coated paper was less decreased. This result indicated that amphoteric latex could also be applied practically to the alkaline paper.

• Journal of the Korean Wood Science and Technology
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• v.25 no.4
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• pp.10-16
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• 1997

This study was carried out to improve coating structure by controlling the electrostatic interaction of coating components and by changing the coating structure of coated paper prepared with amphoteric and anionic latices. The results indicated that amphoteric latex copolymerized with carboxylic and amine groups had stronger interaction with other coating components than anionic latex with branched carboxylic group by controlling pH. These properties of amphoteric latex showed positive effects on viscosity rheology, and supernatant sediment of coating color. The coated paper using amphoteric latex had also produced more porous and smoother coverage of the coating layer than that using anionic latex. This porous and smooth coating layer showed better optical properties and printability than those of anionic latex such as opacity, porosity, ink set-off, and wet ink receptivity.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.177-184
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• 2002

Reinforced concrete(R/C) is commonly used to structures because they have many merits that compressive strength, economy and so on. However, reinforced concrete has a crack at the tensile section which is due to the relatively lower tensile strength than its compressive strength Latex modified concrete(LMC) has higher tensile and flexural strength than the ordinary portland cement, due to the interconnections of hydrated cement and aggregates by a film of latex particles. The purpose of this study was to investigate the flexural behavior of reinforced concrete beam with latex modified concrete, having the main experimental variables such as concrete types(ordinary portland cement concrete, latex modified concrete), latex contents(0%, 15%), flexural steel ratios(0.012, 0.0235), and with/without shear reinforcement. The beam of LMC showed considerably higher initial cracking loads and ductility than that of OPC, but, similar to ultimate strength and deflection. This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation. The beam with latex modified concrete could be adopted at field for controlling and reducing the tensile crack due to its higher tensile strength.