• Elastomers and Composites
• /
• 제50권2호
• /
• pp.81-86
• /
• 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.

• 산업기술연구
• /
• 제22권A호
• /
• pp.177-184
• /
• 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.

• 펄프종이기술
• /
• 제33권2호
• /
• pp.41-48
• /
• 2001

This paper was made to evaluate the effect of the type of latex for coating on the printability by investigating the structure of pore such as the pore fraction, the number of pores, pore size and distribution of coated paper. The coated structure is mainly depend on the results of interaction between pigment and binder. It means that the structure of pore formed is chiefly affected by the type of latex. This physical properties of pore have a close relation with ink set-off associated with the drying rate, the speed of penetration of ink into base paper and printing gloss. Therefore it was necessary to find out the relationship between pore structure and the performance of printability by modifying the type of latex to vary the pore structure of coated paper. Acrylic latex was superior to S/B latex in the sedimentation volume, compressibility, smoothness, pore fraction and its number, the weight of transferred ink onto the coated paper and ink repellance. In contrast, water retention and ink setting were not good. in the comparison of anionic and amphoteric latex, amphoteric latex showed better performance in the thickness, smoothness, pore fraction and its number, pore size, the weight of ink transmitted and K&N ink receptivity, etc.

• 한국수학교육학회지시리즈E:수학교육논문집
• /
• 제12권
• /
• pp.509-526
• /
• 2001

이 글은 2001년 8월 24${\sim}$25일 강원대학교(춘천)에서 한국수학교육학회 주최로 개최되는 “제 27 회 전국수학교육연구대회”에서 있을 웍샵 “LATEX 의 설치 및 사용법”의 교안으로 만들었다. 이 웍샵은 LATEX을 써서 수학 교육에 관한 논문이나 순수 및 응용 수학에 관련한 논문을 작성하려는 사람을 도우려고 계획하였다. 특히 영문 LATEX(이것을 Non-local LATEX 이라 한다.)의 설치 방법, 참고 문헌의 작성과 참고 문헌을 본문에 인용하는 방법, 그리고 수식 환경에 대해서 집중적으로 다루어 보려고 한다. 시간의 여유가 있으면 한글 LATEX도 다루어 보려고 한다.

• 산업기술연구
• /
• 제21권B호
• /
• pp.301-306
• /
• 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.

• Applied Biological Chemistry
• /
• 제36권1호
• /
• pp.29-32
• /
• 1993

Latex(Hevea Brasiliensis)로부터 3종의 ${\alpha}-,\;{\gamma}-,\;{\delta}-tocotrienol$을 각각 분리하고, oil 상태의 각 성분을 얻었다. Tocotrienol을 분리하기 위하여, latex에서 추출한 조지방 성분의 비비누화분획으로 부터 semipreparative HPLC에 의한 분리방법을 사용하여 tocotrienol을 분리하였다. 이와 같은 분리방법을 이용하였을 때 latex에 함유된 tocotrienol의 함량은 약 400ppm이었으며, 순도는 ${\alpha}-,\;{\gamma}-,\;{\delta}-tocotrienol$ 각각 98.3, 99.3, 96.2%로 나타났다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1851-1852
• /
• 2005

We have created in our university material management environment, which uses database created by using LATEX-files, and LATEX2HTML translator and PHP language. In this paper we will define how these LATEX-files are transformed into our database. In this paper, we present work which we have done for providing the material used in the teaching of calculus to students at Lappeenranta University of Technology. This procedure can be divided into three separate steps: 1) creation of the LATEX-files, 2) implementation of these LATEX-files in 3) conversion of the base LATEX-files to the HTML-files. So far, we have stored hundreds of exercises with hints and solutions on our web server in addition to some theory that we felt is necessary for the students. In this paper we will also discuss the benefits and future of our functioning Web-environment [1].

• Elastomers and Composites
• /
• 제29권1호
• /
• pp.9-17
• /
• 1994

Methylmetharylate grafted latex(MGL) was prepared by emulsion graft copolymerization of methyl methacrylate onto natural rubber latex(NRL) by using t-butyl hydroperoxide and tetraethylene pentamine in an aqueous medium. Blending of MGL and NRL with different mixing ratio carried out and viscosity and particle size distribution of blend latex were determined. It was found that the optimum condition of mature time, vulcanizing temperature and time for preparation of blend latex films were investigated. latex films prepared by dipping process were meaured. As the reuslt, blend latex(NR-d-MG) films obtained from two-dipping system were more excellent than NR and MG film obtained from one-dipping system.

• 한국도로학회논문집
• /
• 제3권3호
• /
• pp.135-146
• /
• 2001

기존의 교면포장공법의 근본적인 문제점으로 인해 새로운 교면포장 공법이 점차 부각되고 있는 실정이며, 새로운 교면포장 공법으로 연구되고 있는 것이 라텍스 개질 콘크리트를 이용하는 것이다. 따라서, 본 연구에서는 신설 콘크리트 교량 교면포장으로 덧씌우기된 LMC의 강도발현 특성과 덧씌우기 될 때의 기존콘크리트와의 부착특성을 파악하고자 하였다. 이런 연구를 위해 라텍스 혼입률에 따른 라텍스 개질 콘크리트의 압축강도와 휨강도, 그리고 기존콘크리트와의 부착강도를 측정하였다. 본 연구결과 라텍스 혼입량 증가로 폴리머 입자들의 볼베어링 작용, 연행된 공기 및 라텍스 안에 있는 계면활성제의 분산작용에 의하여 LMC의 작업성과 휨강도를 증가시킨다는 사실을 파악 할 수 있었고, LMC와 기존 콘크리트 슬래브와의 부착강도는 크게 증진함을 알 수 있었다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
• /
• pp.1029-1034
• /
• 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.