이 연구에서는 해양폐기물인 해조류에서 추출된 알긴산을 혼입하여 모르타르의 압축강도 특성을 분석하였다. 알긴산은 해양폐기물 중 해조류의 성분 중 하나로 라텍스와 비슷한 성분을 띄고 있으며, 방수성 성질이 있어 포장용 콘크리트에 활용 시 콘크리트의 수명 을 연장하고 파손 방지에 도움이 된다. 따라서 이 연구에서는 기존에 널리 사용되고 있는 라텍스 콘크리트에 알긴산을 혼입한 라텍스 콘크리트 개발의 일환으로 알긴산 혼입 라텍스 모르타르의 역학적 특성에 대한 실험적 연구를 수행하였다. 실험결과, 알긴산 혼입량 증가에 따른 응결은 빨라지는 경향을 나타내었으며, 압축강도는 저하하는 경향을 나타내었다.

Various dry actives wastes (e.g., gloves, wipers, shoes, clothes) are generated during operation and maintenance of nuclear facilities. Among those, latex gloves gets interest because they contain both organic and inorganic compounds. CaCO3 is a common filler material for production of latex rubbers. Here, latex gloves were thermally treated in a closed vessel to separate the organic and inorganic compounds. Using the closed vessel is beneficial as it can prevent escape of any species, including radioactive nuclides in a real case, generated during the treatment. It was found that thermal decomposition of latex gloves occurred above 250°C. Latex gloves were decomposed to gas, liquid, and solid compounds. The gas product is thought to be volatile organic compounds (VOCs). The liquid product seems to be a mixture of oils and water. A CaCO3 phase was identified in the solid product, as expected. The VOCs can be easily separated at room temperature by purging in vacuum or inert atmosphere. The liquid-solid mixture can be separated by distillation. It is thought that gammaemitting nuclides, such as Cs-137, Sr-90, and Co-60, dominantly remain in the solid product. In the best situation, the solid product is the only subject to be transferred to final wasteform fabrication stream and thus volume of final waste can be reduced. Surrogates of contaminated latex gloves (containing Cs, Sr, and Co) were prepared and they were treated at 350°C in the closed vessel. How these contaminants behaves in this thermal process will be discussed in the presentation.

In the United States and Europe, new environmentally friendly asphalt pavement has been researched as an alternative to traditional hot asphalt pavement. After the Paris Convention of 2015, policies should be found to reduce carbon dioxide. In the field of asphalt pavement, new methods are needed to reduce carbon dioxide from the traditional hot asphalt pavement. In Korea, waste asphalt is growing and natural aggregate is running dry. So the government is implementing policies to increase the use of waste resources. So, it created a new asphalt pavement method to reduce CO2 and use waste asphalt. It is a cold recycled asphalt pavement. Emulsified asphalt has a balance of dispersibility, stability, and adhesive between water, aggregates, and asphalt. But, the physical properties of emulsified asphalt can be degraded compared to traditional hot asphalt pavement. So there are limitations in actual use. The study compared the softening point, elastic recovery, and penetration properties of asphalt mix compounds by using latex in emulsified asphalt. In particular, cations latex was used for the emulsified asphalt, which could further improve the physical properties.

Ficus carica L. (common fig), one of the first plants cultivated by humans, originated in the Mediterranean basin and currently grows worldwide, including southwest Asia and South Korea. It has been used as a traditional medicine for treatment of metabolic, cardiovascular, and respiratory diseases as well as hemorrhoids and skin infections. Its pharmacological properties have recently been studied in detail, but research on the anti-cancer effect of its latex has been only been studied on a limited basis on several cell lines, such prostate cancer, breast cancer, and leukemia. In this study, we investigated the anti-cancer activity of the latex of Ficus carica L.and its underlying mechanism in FaDu human hypopharynx squamous carcinoma cells. (See Ed. note above) We confirmed through SDS-PAGE analysis and gelatinolytic activity analysis that the latex of Ficus carica contains cysteine protease ficin. Our data showed that the latex inhibited cell growth in a dose-dependent manner. In addition, the latex treatment markedly induced apoptosis in FaDu cells as determined by FACS analysis, elevated expression level of cleaved caspase-9, -3 and PARP (poly (ADP-ribose) polymerase), and. increased the expression of Bax (pro-apoptotic factor) while decreasing the expression of Bcl-2 (anti-apoptotic factor). Taken together, these results suggested that latex containing the ficin inhibited cell growth and induced apoptosis by caspase and the Bcl-2 family signaling pathway in FaDu human hypopharynx squamous carcinoma cells. These findings point to the potential of latex of Ficus carica to provide a novel chemotherapeutic drug due to its growth inhibition effects and induction of apoptosis in human oral cancer cells.

본 논문의 주된 목적은 천연 라텍스 산출량(natural latex yield) 요인을 파악하는 것이며, 중국 열대지방인 윈난(운남)성 시솽반나 지역을 대상으로 연구를 수행했다. 천연 라텍스는 고무나무의 수액을 의미하며 의료기구, 타이어 등의 원료로 사용되므로 세계적인수요가 급증하고 있다. 하지만, 고무농장을 설립하기 위해서는 토착식생을 대거 제거하는 것이 일반적이며 이러한 이유로 인해 고무농장의 확장은 환경적 부작용을 수반한다. 시솽반나의 생태계는 고무농장의 급속한 확장으로 인해 열대 원시림이 파괴되는 등 지속적인 위협을 받고 있는 상황이고 이를 저감하기 위한 환경보전이 시급하다. 시솽반나 지역에 효과적인 환경보전 및 토지이용 전략을 수립하기 위해서는 어떤 요인이 천연 라텍스 산출량에 영향을 주는지와 요인별 공간적 변이를 파악할 필요가 있다. 본 연구에서는 현지답사를통해 수집한 자료와 위성영상 자료에 지리가중회귀모델(Geographically Weighted Regression, GWR)을 적용해 천연 라텍스 산출량요인과 그 공간적 변이를 분석했다. 그 결과, 연평균 기온, 연평균 강수량, 고무나무 나이, 해발고도, 향이 99% 신뢰구간에서 천연 라텍스 산출량에 유의한 영항을 미치는 것으로 나타났으며, 이들의 공간적 변이는 요인별로 상이했다. 본 논문의 연구 결과를 활용하면, 고무나무 재배적지 혹은 고무농장의 입지를 체계적으로 파악할 수 있기 때문에 시솽반나 지역 뿐 아니라 천연 라텍스 주요산지인동남아시아 전반의 환경보전과 토지이용 전략 수립에 유용할 것으로 예상한다.

PURPOSES : The purpose of this study is to determine the optimum addition rate of SBR latex through the evaluation of durability and strength of SBR latex applied soil pavement. Formerly used materials such as fly ash and cement in soil pavement had resulted in decreased durability due to micro crack by heat of hydration and shrinkage crack in winter. However, that agglutinated polymers help adhesion to aggregate increased comes up with preventing the crack opening when the number of capillary tubes of SBR latex get decreased in the hydration process of cement. Therefore, in this study, it is suggested that the evaluation of the field applicability of soil pavement be conducted through the performance lab test in terms of strength increment, adhesion improvement, and crack resistance based on SBR latex addition rate. METHODS: In order to evaluate the field applicability of soil pavement, SBR latex was added 0 to 3% by 1% increment, with fixed cement contents of 3% and 5%. The resistance of shear failure and crack of soil pavement were evaluated by performing the uniaxial compressive strength test and indirect tensile strength test at -20 and 20℃, respectively. RESULTSCONCLUSIONS: It was found out that from both tests, resistance of shear failure and crack were improved with increment of curing time, and especially more than 2% of SBR latex addition rate and 5% cement content gave better results.

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).

초속경 라텍스개질 콘크리트(VES-LMC)를 포함한 고성능 콘크리트는 낮은 물-시멘트비, 높은 결합재량 및 고성능감수제의 사용 등으로 인해 자기수축(Autogenous Shrinkage)이 1종 콘크리트(OPC)보다 크게 나타난다. 초속경 라텍스개질 콘크리트의 배합특성은 낮은 물-시멘트비(0.38), 높은 단위시멘트량(390kg/m3) 및 라텍스첨가(단위시멘트량 대비 15%)로 구성되므로, 자기수축이 크게 발생할 수 있고, 또한 콘크리트 타설 후 3시간 이내에 발생하는 급격한 수분소산(Water Dissipation)과 수분증발은 자기수축을 증가시킬 수 있다. 본 논문의 목적은 현장에서 작업시간 확보를 목적으로 사용되는 지연제 첨가량 변화에 따른 초기수축, 온도변형 및 자기수축을 평가하는 것이다. 실험결과 지연제의 첨가는 콘크리트의 최대 수화열에 영향을 미치지 않는 것으로 나타났으며, 초속경 라텍스개질 콘크리트의 초기 팽창은 일부 자기팽창의 영향이 있기는 하지만 대부분이 열팽창에 기인하는 것으로 나타났다. 지연제 첨가량이 증가함에 따라 자기수축이 감소하는 것으로 나타났지만, 지연제의 과도한 사용은 과도한 초기 팽창을 일으킬 수 있으므로 현장조건을 고려하여 신중하게 결정되어야 한다.

Kevlar was chemically surface modified with resorcinol-formaldehyde(RF) prepolymer and VP rubber latex for application to high strength tirecords. RF prepolymer was easily obtained by polymerization at room temperature in the presence of a base catalyst. The mechanical and thermal properties of Kevlar were not significantly changed during surface treated under various conditions. The change of adhesion with rubber were investigated through H-test method. Maximum increase of adhesion force between rubber and Kevlar was obtained up to 40% than that of untreated one when the fiber was soaked in RFL dipping solution and thermally treated at 170℃ for 3 - 5min.

Core-shell polymers of methyl methacrylate-styrene system were prepared by sequential emulsion polymerization in the presence of sodium dodecyl benzene sulfonate(SDBS) as an emulsifier using ammonium persulfate(APS) in an initiator and the characteristics of these core-shell polymers were evaluated. Core-shell composite latex has the both properties of core and shell components in a particle, whereas polymer blends or copolymers show a combined physical properties of two homopolymers. This unique behavior of core-shell composite latex can be used in various industrial fields. However, in preparation of core-shell composite latex, several unexpected matters are observed, for examples, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve this matters, we study the effects of surfactant concentrations, initiator concentrations, and reaction temperature on the core-shell structure of PMMA-PSt and PSt-PMMA. Particle size and particles distribution were measured by using particle size analyzer, and the morphology of the core-shell composite latex was observed by using transmission electron microscope. Glass temperature was also measured by using differential scanning calorimeter. To identify the core-shell structure, pH of the composite latex solutions was measured.

공극구조 분석 방법은 ASTM C 457의 리니어트레버스 포인트카운트법이 있으나, 이러한 방법들은 분석하는데 시간과 노력이 너무 많이 소요되어 현재에는 거의 사용되어지지 않고 있다. 근래에는 현미경과 디지털 카메라, 컴퓨터의 프로그램 발달로 화상분석법이 많은 연구자에 의해 연구되고 있다. 본 연구에서는 화상분석법을 통하여 라텍스개질 콘크리트의 공극 구조 특성을 분석하고자 시멘트 종류(보통포틀랜드시멘트, 초속경시멘트)와 라텍스 혼입율(0,15%)에 따라 실험을 수행하였다. 실험결과, 라텍스는 경화 후 콘크리트에서 AE제의 공기연행효과보다 더 우수한 연행공기 량을 갖는 것으로 나타났다. 또한, 화상분석법을 이용할 경우 경화 후 콘크리트 내부 공극 구조에 대한 다양한 정보를 분석할 수 있을 것으로 판단되었다.