• 한국주조공학회지
• /
• 제11권4호
• /
• pp.314-322
• /
• 1991

In this study, Na, Li, Sb, Sr were added as the modifiers to improve the mechanical proper ties of Al-Si alloys and their effects were compared one another Thermal analysis was carried out to measure the degree of undercooling, that is, the basic mechanism of modifying effect. The measurements of holding time and analyses of components of Al-Si alloys were carried out to compare the fading of the modifiers. Greater degree of undercooling was measured from the modified alloy than the normal alloys. In the modified alloy, the shape of Si was changed into a fine fiber phase or a lamellar phase from the coarse plate phase. There are not modifying effect of Sb below the $1.5^{\circ}C$ /sec of cooling rate. As the cooling rate increases, similar effects appears in the non-modified alloys like the modified alloys. Na and Li were faded in short time and were difficult to control on the melt, but Sb and Sr were scarcely faded for 6 hours of holding and were easy to control on the melt. Na and Sr are the good modifiers in terms of microstructure. Sb is the best modifier, but Na, Li are the inadequate modifiers in terms of fading.

• 폴리머
• /
• 제27권6호
• /
• pp.589-595
• /
• 2003

서로 다른 종류의 유기 개질제가 층간에 삽입된 세 종류의 몬모릴로나이트 (MMT)를 사용하여 불포화 폴리에스터 (UP)/MMT 나노복합체를 제조하고 유기 개질제의 화학적 구조와 각 성분들의 최종 혼합시간이 최종 나노복합체의 형태구조와 각종 물리적 특성에 미치는 영향을 조사하였다. 최종 혼합 시간은 MMT의 종류에 관계없이 나노복합체의 형태구조와 각종 물성에 별다른 영향을 미치지 못하는 것으로 확인되었으며, MMT의 유기 개질제에 두 개의 수산화기가 포함된 Cloisite 30B의 경우에는 나머지 두 종류의 MMT에 비해 형태구조나 고무 평탄 영역에서의 전단 모듈러스 및 굴곡강도 등은 우수한 것으로 나타났다 하지만 인장 강도나 열분해 거동, 유리 전이 온도 등은 별다른 차이를 보이지 않았으며, 또한 MMT의 함량에 따른 각종 특성의 선형적인 증가도 관찰되지 않았다.

• Elastomers and Composites
• /
• 제57권4호
• /
• pp.215-221
• /
• 2022

In this study, high-penetration asphalt with low greenhouse gas emissions was used in the asphalt mixing process to reduce the carbon emissions during the reaction due to its capacity to be produced even at low temperatures. In effect, cationic, anionic, and non-ionic dispersants were added and mixed in different feeding ratios, seeking an effective dispersion of the modifiers (SIS, PS, TPEE, and SEBS) into the high-penetration asphalt matrix and forming an asphalt binder with a melting point of 120 ℃. The compatibility of the modifiers and the high-penetration asphalt was examined using SEM and DSC techniques, and the role of NDP-1 as a dispersant was carefully investigated with respect to dissolution time. The analyses showed that: (1) the dispersibility of the asphalt binder is good when the non-ionic dispersant is used; (2) as the concentration of the non-ionic dispersant increases, the dissolution time decreases and the domain size contracts; (3) the ND70-PS has the shortest dissolution time, the lowest agglomeration rate, and a single Tg value.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2003년도 추계학술발표대회 논문집
• /
• pp.21-24
• /
• 2003

In general, to enhance physical properties of PET-layered silicate nanocomposites $(P_{et}LSNs)$, it has been well known that the organic modifiers should introduce into gallery regions. However, the organic modifiers in$(P_{et}LSNs)$ may result in thermal decomposition by melt processing at high temperature, and it necessarily lead to deteriorate various physical properties of final products. Therefore, in this study, $(P_{et}LSNs)$ excluding and including organic modifiers were prepared by solution method $(S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom})$ and we (focused on the effects of the organic modifiers in $P_{et}$ LSNs with exfoliation structure on the crystallization behaviors, the optical transparency, the thermal stability and the mechanical property. The absence and existence of organic modifiers in $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were investigated by EA and TGA, and nano-structure of silicate layers in $S-P_{et}LSNs$ was evaluated by using WXRD, SAXS and TEM. $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were mixed with neat PET as masterbatches by melt method $(M-P_{et}LSNs_{eom} and M-P_{et}LSNs_{iom})$, and also neat PET was mixed with organically modified layered silicates (OLS) by conventional direct melt method $(D-P_{et}LSNs) at 270^{\circ}C$. As results, it was found that $M-P_{et}LSNs_{eom}, M-P_{et}LSNs_{iom}, and D-P_{et}LSN$ showed a exfoliated structure and exhibited faster crystallization rate, better thermal stability and mechanical property than those of neat PET due to the dispersed and detaminated silicate layers in PET matrix. Whereas, considering organic modifiers effect, $M-P_{et}LSNs_{eom} and D-P_{et}LSN$ exhibited slower crystallization rate, poorer optical, thermal and mechanical properties, in comparison to $M-P_{et}LSNs_{eom}> due to the thermal decomposition of organic modifier in $D-P_{et}LSNs$ during melt method.

• Asian-Australasian Journal of Animal Sciences
• /
• 제3권4호
• /
• pp.337-341
• /
• 1990

An investigation was conducted to determine whether the rumen modifiers lasalocid and avoparcin, when included in molasses/urea based supplements, enhanced liveweight performance, in early weaned calves. As part of the study the broad-spectrum parasiticle Avermectin B1 was given to the calves to assess any undesirable side effects on animals of less than four months of age. There were no significant (p>0.05) liveweight responses to supplementation when the rumen modifiers lasalocid and avoparcin were included in supplement rations. Lasalocid reduced supplement intake, however, it had no adverse effect on liveweight gain. Avoparcin substantially improved growth when cottonseed meal was included in the ration. Weaners treated with Avermectin B1 tended to show a greater liveweight gain than untreated weaners during the experiment (p<0.10) and no adverse side effects were noted.

• 센서학회지
• /
• 제16권1호
• /
• pp.77-83
• /
• 2007

Nanoporous silica aerogels with various surface modifiers were prepared by ambient drying process. Tetraethylorthosilicate (TEOS) were used a raw material. Ambient drying process for various surface modifier was studied in the point of view of a crack-free monolith and thin films and low cost. Various kinds of surface modifiers like as hexamethyldisilazane (HMDSZ), trimethlychlorosilane (TMCS), methlytriethoxylsilane (MTES), and methlytrimethoxysilane (MTMS) were studied in order to enhance hydrophobicity for the silica aerogel. Surface modified aerogels were evaluated by FT-IR, TG, BET, SEM and wetting angle measurement. Homogeneous and crack-free aerogels were obtained by modifying the HMDSZ and the TMCS. However silica xerogel was obtained when modified with MTMS, MTES.

• 공업화학
• /
• 제5권1호
• /
• pp.121-126
• /
• 1994

초산의 반응추출에 미치는 영향을 규명하기 위하여 추출제로 2급과 3급 아민 및 용매화 추출제, 용매로 n-butylacetate, modifier로 4-nonylphenol, TBP 및 isodecanol을 이용하였다. 그외에 수용액상의 pH와 온도의 영향을 연구하였다. 실험결과 초산의 추출에서 3급 아민인 tril-n-octyl과 tri-n-decylamine의 50% 혼합 추출제인 MODA가 추출도 및 선택도에서 가장 좋았다. Modifier로서는 4-nonylphenol이 우수하였다. 이외에도 수용액의 pH와 추출계의 온도가 낮을수록 추출도가 높았다.

• 경영과학
• /
• 제32권3호
• /
• pp.105-118
• /
• 2015

This study examines the relationship between city slogan modifiers and slogan attitudes from the perspective of residents in other cities. To examine this relationship, the study focuses on two important characteristics of slogan modifiers : the preference for a slogan modifier and the fit of a slogan modifier. To test the hypotheses, a 2 (low vs. high city knowledge)${\times}2$ (low vs. high slogan modifier preference)${\times}2$ (low vs. high slogan modifier fit) between-subjects factorial design was adopted. A total of 254 undergraduate students at the authors' college participated in the study. Their ages ranged from 19 and 30 (average = 22.3), and 58.3% of the participants were male. According to the results, the high-preference slogan modifier had a greater positive effect on slogan attitudes than the low-preference one. Similarly, the high-fit slogan modifier had a greater positive effect on slogan attitudes than the low-fit one. Also, it was shown that the fit of the slogan modifier had a greater effect on purchase intentions than the preference for the slogan modifier when city knowledge was high. However, contrary to expectations, when city knowledge was low, the standardized coefficient of the preference for the slogan modifier was not significantly different from that of its fit.

• Computers and Concrete
• /
• 제20권2호
• /
• pp.165-176
• /
• 2017

Textile Reinforced Cementitious Composite (TRCC) became the most common construction material lately and have excellent properties. TRCC can be employed in the manufacture of thin-walled facade elements, load-bearing integrated formwork, tunnel linings or in the strengthening of existing structures. These composite materials are a combination of matrix and textile materials. There isn't much research done about the usage of polymer modified matrices in textile reinforced cementitious composites. In this study, matrix materials named as fine grained concretes ($d_{max}{\leq}1.0mm$) were investigated. Air entraining effect of polymer modifiers were analyzed and air void content of fine grained concretes were identified with different methods. Aim of this research is to study the effect of polymer modification on the air content of fine grained concretes and the role of defoamer in controlling it. Polymer modifiers caused excessive air entrainment in all mixtures and defoamer material successfully lowered down the air content in all mixtures. Latex polymer modified mixtures had higher air content than redispersible powder modified ones. Air void analysis test was performed on selected mixtures. Air void parameters were compared with the values taken from air content meter. Close results were obtained with tests and air void analysis test found to be useful and applicable to fine grained concretes. Air void content in polymer modified matrix material used in TRCC found significant because of affecting mechanical and permeability parameters directly.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권1호
• /
• pp.86-95
• /
• 2000

Animal feed additives are used worldwide for many different reasons. Some help to cover the needs of essential nutrients and others to increase growth performance, feed intake and therefore optimize feed utilization. They can positively effect technological properties and product quality. The health status of animals with a high growth performance is a predominant argument in the choice of feed additives. In many countries the use of feed additives is more and more questioned by the consumers: substances such as antibiotics and $\beta$-agonists with expected high risks are banned in animal diets. Therefore, the feed industry is highly interested in valuable alternatives which could be accepted by the consumers. Probiotics, prebiotics, enzymes and highly available minerals as well as herbs can be seen as alternatives to metabolic modifiers and antibiotics.