• 대한화학회지
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• 제7권2호
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• pp.96-105
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• 1963

The weight decrease curves of 18 kinds of polymers have been measured by thermobalance at the same condition where temperature is increased $1^{\circ}C$ per minutes under nitrogen or air atmosphere. The curves are further differentiated to obtain rate curve of weight decrease. Those curve offer a method to compare relative thermal stability, effects of oxygen or modes of thermal degradation of polymers qualitatively. The curves could be classified into following four types: Polystyrene, polymethylmethacrylate and acetal polymer belong to the first type. Those polymers depolymerize mainly into corresponding monomers, weight decrease curves are steepy up to perfect vaporization of polymers and rate curves show a relatively sharp peak. (Type I) Polyvinyl chloride represents the second type. This polymer decomposes with splitting off of hydrogen chloride. The thermogravimetric curve rises rapidly at first, then level off at the moderate weight decrease and gradually rises. Polyvinyl acetate also belongs to this class. (Type II) The modification of the second type is represented by polyester. The curve at the early stage is less steep, the leveling off at the next stage is less clear and the final rising of the curve is steeper than the normal second type. Polyamide, polyurethane, and polycarbonate belong to this type. (Type II') The thermal decomposition of the third type polymers is more complex than that of others. Various irregular chain scissions including side chain splitting and depolymerization to monomers occur simultaneously. The weight of the polymer decreases gradually and the rate curve does not show sharp peaks. Polyvinyl alcohol and diene polymers belong to this type. (Type III) Generally, polycondensation polymers are more stable toward heat than addition polymers and polymers having aromatic nucleus show good thermal stability. Polymers having tertiary carbon atoms such as polystyrene or polypropylene and acetal resin start decomposition under airatmosphere at the temprature below $50^{\circ}C$ or more of the temperature where the polymers start decomposition under nitrogen atmosphere.

• 한국식품위생안전성학회지
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• 제24권3호
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• pp.211-216
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• 2009

4,4'-diaminodiphenylmethane (4,4'-MDA)는 일차방향족아민 (primary aromatic amino, PAA)류의 일종으로, 최근 유럽에서는 RASFF를 통하여 나일론 재질의 주방용 국자, 주걱 등에서 4,4'-MDA 이행 사례를 보고하고 있어 국내 유통 합성수지제 조리기구 중 4,4'-MDA 이행량 실태를 조사하였다. 4,4'-MDA의 분석을 위하여 0.3 ppb의 정량한계 및 87.6% 이상의 우수한 회수율을 나타내는 LCMS/MS를 이용한 분석방법을 확립하였다. 식품유사용매 물, 4% 초산, 20% 에탄을 및 n-헵탄에 대하여 4,4'-MDA 이행여부를 조사한 결과, 4% 초산 및 20% 에탄올인 경우에는 분석대상 100 품목 중 나일론 재질 14 품목에서, 물인 경우에는 나일론 재질 11 품목에서 식품유사용매로 4,4'-MDA가 이행되는 것으로 나타났으나, n-헵탄을 사용한 경우에는 1개 품목에서만 미량의 4,4'-MDA가 이행되었다. 이중 유럽연합 기준인 0.01 ppm을 초과하는 제품은 2품목이었다.

• 대한조선학회논문집
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• 제54권2호
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• pp.151-160
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• 2017

Growing demand and rapid development of the synthetic fiber rope in mooring system have taken place since it has been used in deep water platform lately. Unlike a chain mooring, synthetic fiber rope composed of lightweight materials such as Polyester(polyethylene terephthalate), HMPE(high modulus polyethylene) and Aramid(aromatic polyamide). Non-linear stiffness and another failure mode are distinct characteristics of synthetic fiber rope when compared to mooring chain. When these ropes are exposed to environmental load for a long time, the length of rope will be increased permanently. This is called 'the creep phenomenon'. Due to the phenomenon, The initial characteristics of mooring systems would be changed because the length and stiffness of the rope have been changed as time goes on. The changed characteristics of fiber rope cause different mooring tension and vessel offset compared to the initial design condition. Commercial mooring analysis software that widely used in industries is unable to take into account this phenomenon automatically. Even though the American Petroleum Institute (API) or other classification rules present some standard or criteria with respect to length and stiffness of a mooring line, simulation guide considers the mechanical properties that is not mentioned in such rules. In this paper, the effect of creep phenomenon in the fiber rope mooring system under specific environment condition is investigated. Desiged mooring system for a Mobile Offshore Drilling Unit(MODU) with HMPE rope which has the highest creep is analyzed in a time domain in order to investigate the effects creep phenomenon to vessel offset and mooring tension. We have developed a new procedure to an analysis of mooring system reflecting the creep phenomenon and it is validated through a time domain simulation using non-linear mooring analysis software, OrcaFlex. The result shows that the creep phenomenon should be considered in analysis procedure because it affects the length and stiffness of synthetic fiber rope in case of high water temperature and permanent mooring system.