• Elastomers and Composites
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• 제57권4호
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• pp.165-174
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• 2022

The effect of fumed silica loading on the thermal stability and mechanical properties of fluorosilicone (FVMQ) rubber was investigated. The distribution of fumed silica inside FVMQ was characterized using scanning electron microscopy, and the thermal stability of composites was evaluated using thermogravimetric analysis and by the changes in mechanical performance during thermo-oxidative aging. The function mechanism of fumed silica was studied by Fourier transform infrared spectroscopy. The results show that with increasing silica content, the crosslink density of composites, the modulus at 100%, and tensile strength also increased, whereas the elongation at break decreased. Furthermore, increasing the silica content of composites increased the initial decomposition temperature (T_d) and residual weight of the composite after exposure to nitrogen. In addition, the thermal oxidative aging experiment demonstrated improved aging resistance of the FVMQ composites, including lower change in tensile strength, elongation at break, and modulus at 100%.

• 한국식품과학회지
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• 제23권4호
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• pp.465-470
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• 1991

대두유, 팜유, 쇼트닝 그리고 대두유에 팜유를 각각 50%, 70% 배합한 혼합유로 French fry용 감자를 반복 튀김 했을 때 튀김기름의 열분해 및 산화에 대한 안정성을 알아보기 위하여 10회의 반복튀김에 사용된 기름을 매회 취하여 산값, 과산화물값, TBA값, 색도, 굴절율, 비중 등의 이화학적 특성을 측정하였다. 열분해 및 산화에 대한 대두유의 불안정성은 대두유에 팜유를 배합함으로써 감소시킬 수 있었는 바, 대두유에 대한 팜유의 비율이 커질수록 그 안정성이 증가하였다. 팜유가 50% 배합된 혼합유의 경우에는 대두유를 단독 사용했을 때 보다 그 안정성이 현저히 증가하였고 팜유가 70% 배합된 혼합유의 경우에는 팜유를 단독 사용했을 경우와 거의 같았다.

• Fisheries and Aquatic Sciences
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• 제18권1호
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• pp.21-26
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• 2015

Seasoned laver Pyropia spp. is a traditional Korean seafood that has gained popularity worldwide because of its unique taste, texture, and health benefits. It is prepared by roasting a sheet of dried laver, to which vegetable oils have been applied, at an ultra-high temperature (UHT) of $300^{\circ}C$. Therefore, the oxidative stability of the oils is the most important factor in determining the shelf life of seasoned laver products. In this study, we investigated changes in the thermal oxidative stability of six major vegetable oils (sesame, perilla, sunflower, rice bran, canola, and olive) during the seasoned laver processing. The oxidation induction time of each oil from the seasoned laver products was decreased compared with the fresh oil. These results indicate that the UHT treatment ($300^{\circ}C$, 10 s) induced thermal oxidation of the oils. Among the six seasoned laver oils, the induction times of olive (OL, 8.02 h) and sesame (SE, 5.31 h) oils were significantly higher than the other oils. The acid values (AVs) of OL and SE oils from the seasoned laver were 0.49 and 0.79, respectively. On the other hand, perilla oil had the overall worst thermal oxidative properties (induction time: 0.35 h, AV: 2.82). Our results provide useful information about seasoned laver products for researchers or manufactures.

• 한국축산식품학회지
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• 제28권5호
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• pp.660-666
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• 2008

본 연구에서는 식용유지로 사용되는 돈지, 대두유 및 고추씨유를 $100^{\circ}C$에서 3일간 저장하면서 열안정성을 비교하고, 캡사이신의 첨가가 대두유 및 돈지의 산화안정성 효과에 대하여 실험하였다. 그 결과 돈지>대두유>고추씨유의 순서로 고추씨유가 가장 열에 안정적임을 밝혔다. 가장 열에 안정한 고추씨유를 돈지와 대두유에 혼합했을 때의 저장기간에 따른 산화 정도를 비교하였는데, 돈지에서는 고추씨유 30% 이상에서 산화가 억제되지만, 대두유에서는 그보다 많은 60% 이상이 혼합되어야 산화가 억제되었다. 또한 고추씨유의 주요 성분인 캡사이신을 고추씨유에 함유된 양만큼을 대두유와 돈지에 각각 첨가하여 열처리 했을 때 산화안정성에 미치는 영향도 검토하였다. 그 결과 1,200 ppm과 2,400 ppm의 캡사이신, 또는 0.3% 알파-토코페롤을 대두유에 첨가하였을 때 캡사이신은 대두유의 산화에 아무런 영향을 미치지 못하였고 알파-토코페를은 오히려 산화를 촉진시켰다. 하지만 돈지에 동량의 캡사이신이 첨가되었을 때에는 산화를 효과적으로 억제하였다. 이러한 결과로부터 고추씨유 또는 캡사이신은 돈지를 소재로 하는 튀김유나 분말유지의 가공에 이용하면 매우 좋은 산화억제 효과를 얻을 것으로 사료된다.

• 한국식생활문화학회지
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• 제25권6호
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• pp.788-794
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• 2010

Camellia sinensis L. (green tea) seed oils were prepared by roasting at $213^{\circ}C$ and pressing (RP), pressing (P), and nhexane extraction (H). The physico-chemical properties of the RP, P, and H samples, including fatty acid composition, color, and sensory characteristics were analyzed. RP, P and H samples were thermally oxidized at $180^{\circ}C$, and oxidative stability was determined by DPPH, CDA, and p-AV at 0, 20, 40, 60, and 80 min. Compared to the P and H samples, RP resulted in significantly higher thermal oxidative stability according to the DPPH, CDA, and p-AV results (p<0.05). The ratio of unsaturated fatty acids to saturated fatty acids among RP, P, and H samples were significantly different (p<0.05). The oleic acid and linoleic acid contents in green tea seed oils were 58 and 23%, respectively. Hunter's color value of lightness (L) for the RP, P, and H samples was not significant. Redness (a) of RP was $3.47{\pm}0.119$ and yellowness (b) of H was $60.10{\pm}2.483$, which were significantly different. Compared to RP samples, H and P samples had the highest color and off-odor values in the sensory evaluation. RP samples showed the highest taste value and were significant overall (p<0.05). The thermal stability of RP extraction was more stable than any other method. Camellia sinensis L. seed oil extracted by RP had better sensory characteristics than other edible oils, including soybean oil, grape seed oil, and extra virgin olive oil.

• Carbon letters
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• 제25권
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• pp.60-67
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• 2018

In the present work, capability of thymolphthalein-grafted graphene oxide, which was successfully synthesized in this study, in stabilization of polypropylene against thermal oxidation were investigated and compared with that of SONGNOX 1010, a commercially used phenolic antioxidant for the polymer. The modified graphene oxide were incorporated into polypropylene via melt mixing. State of distribution of the nanoplatelets in the polymer matrix was examined using scanning electron microscopy and was shown to be homogeneous. Measurements of oxidation onset temperature and oxidative induction time revealed that thymolphthalein-grafted graphene oxide modifies thermo-oxidative stability of the polymer in the melt state remarkably. However, the efficiency of the nanoplatelets in stabilization of polypropylene against thermal oxidation in melt state was shown to be inferior to that of SONGNOX 1010. Furthermore, oven ageing experiments followed by Fourier transform infrared spectroscopy showed that the modified graphene oxide improves thermo-oxidative stability of the polymer strongly in the solid state, so that its stabilization efficiency is comparable to that of SONGNOX 1010.

• 한국응용과학기술학회지
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• 제10권2호
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• pp.1-6
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• 1993

The blended oil was prepared from cottonseed oil and palm olien. The oxidative stability of blended oil after the addition of natural tocopherol and soybean lecithin during heating was investigated and the effects of lecithin were evaluated. The result obtained were as follows: 1. When the concentration of palm olein in blended oil during heating was increased, the oxidative stability was improved. 2. By both addition of natural tocopherol and soybean lecithin during heating in blended oil, induction period was considerably increased and residual ratio of tocopherol was high. 3. The oxidative stability of potato chips prepared from blended oil was higher in the prsence of lecithin than in the absence of it.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.128-135
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• 2019

In this study, the mesoporous $SiO_2$ (5, 10, or 15 wt%) was incorporated into the polybenzimidazole matrix in order to improve the proton conduction as well as physiochemical properties of composite membrane. The chemical structure of mesoporous $SiO_2$ and crystallinity of as-prepared membranes were analyzed by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis, respectively. The thermal stability of the pristine $X_1Y_9$ and composite membranes were evaluated by thermogravimetric analyzer (TGA). On other side, the physical and chemical properties of the pristine $X_1Y_9$ and composite membranes were also determined by acid uptake and oxidative stability tests, respectively. With the incorporation of 15 wt% $SiO_2$, the composite membrane exhibits the higher proton conductivity that may be applicable for non-humidified high temperature fuel cell applications.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.73-74
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• 2002

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1097-1100
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• 2009

New types of conducting polyaniline-polymannuronate (PANI-PM) composites were synthesized by in situ deposition techniques in an aqueous media. By dissolving different weight percentage of polymannuronate (PM) (5, 10, 15, and 25%), the oxidative polymerization of aniline was carried out using ammonium per sulfate as an oxidant. The obtained composites were studied for their thermal stability and electrochemical behavior. The thermal stability of PANI-PM composites is lower than PANI, which supports a strong interaction between PANI and PM. However, the composites show an appreciable electrochemical behavior. Based on these observation the PANI-PM composites can be explored in different fields such as electric devices, sensors, functional coatings, etc.