열처리에 따른 누에품종별 누에고치의 황변 정도와 결정성 변화

이혜경,임채민,엄인철,김성완,김기영 한국섬유공학회 2023 한국섬유공학회지 Vol.60 No.3

Silk has been extensively studied as a promising material for biomedical and cosmeticapplications due to its excellent biocompatibility, cytocompatibility, biodegradability,among other unique properties. In addition to these properties, the natural silknonwoven fabric has attracted attention from researchers in bio-related fields due to itsease of fabrication. The natural silk nonwoven fabric is prepared by reeling silkwormcocoons and subjecting them to heat treatment. In this study, various silkworm varietycocoons were wet- and heat-treated and then, their whiteness index and crystallinity indexwere measured to gain a better understanding of structural characteristics of cocoons. Thewhiteness index was significantly reduced above 200 °C and the extent of reduction variedslightly depending on the silkworm variety. Wet treatment of the silkworm cocoons preventedslightly the decrease in the whiteness index of cocoons. The crystallinity index ofcocoon was different depending on the silkworm variety and Baekokjam cocoon showedthe highest crystallinity index. Outside of cocoon showed a remarkable decrease of crystallinityindex above a treatment temperature of 200 °C. However, the crystallinity index ofoutside of cocoon did not decrease when the wet treatment was conducted prior to heattreatment. On the other hand, the crystallinity index of inside of cocoon increased above200 °C regardless of wet treatment.

Structure and Properties of Polyimide (BTDA-TDI/MDI co-polyimide) Fibers Obtained by Wet-Spinning

Hong Bing Xiang,Zhong Huang,Li Qi Liu,Lei Chen,Jing Zhu,Zu Ming Hu,Jun Rong Yu 한국고분자학회 2011 Macromolecular Research Vol.19 No.7

BTDA-TDI/MDI (P84, synthesized by the condensation of 2,4-diisocyanato-1-methylbenzene and 1,1' -methylenebis(4-isocyanatobenzene) with 5,5'-carbonylbis(l,3-isobenzofurandione)) co-polyimide fibers were prepared by wet-spinning. The basic spinning conditions were found from the studies of dope viscosity, ternary phase diagrams, coagulation value, and precipitation value. The effect of the coagulation bath composition on the morphology of as-spun fibers was investigated and a theoretical approach was used to understand the coagulation phenomena. Scanning electron microscopy (SEM) showed that the cross-sectional shape of the fiber deviated more from an ellipse shape with the increasement of N-methyl-2-pyrrdidinone (NMP) content. The surface and cross section morphology of the as-spun fibers was also analyzed by the rate of diffusion and phase separation. The as-spun fibers were treated in heating tubes without drawing at different temperatures. The gravimetric analysis spectra showed that the BTDA-TDI/MDI co-polyimide fibers, which had been heat treated at 350 and 400 ℃, possessed better thermal properties than the as-spun fibers, a large weight loss was observed only above 550 ℃. Heat treatment of the fibers resulted in relatively high tensile strength and modulus. The fibers spun in Bath C (70/30, NMP/water, wt/wt)and Bath D (80/20, NMP/water, wt/wt) showed better thermal properties and higher tensile strength.

수분-열처리로 제조한 멥쌀가루의 호화 특성과 겔 강도

서혜인(Hye-In Seo),김창순(Chang-Soon Kim) 한국식품영양과학회 2011 한국식품영양과학회지 Vol.40 No.2

HMT가 아밀로오스 함량이 다른 쌀가루의 이화학적 특성과 물리적 변화에 미치는 효과를 조사하였다. 고 아밀로오스 쌀은 태국산 수입쌀 TG(29.2%)와 국내산 특수미인 고아미GM(28.9%)을 사용하였고, 중간 아밀로오스 쌀은 추청미 CC(23.6%)와 고시히카리 KSHK(21.2%)를 사용하였다. HMT쌀가루는 습식제분 쌀가루를 수분함량 21%, 24%, 27%, 30%로 조절하여 각각 100℃와 105℃에서 30, 60, 90분 처리하여 제조하였다. HMT GM, HMT, TG 쌀가루의 RVA 특성 변화는 HMT 처리시간, 수분함량 증가에 따라 PV와 BD가 낮아지면서 peak가 사라지는 경향을 보였으며, HMT KSKH 쌀가루는 처리온도와 처리시간 증가에 의해 BD의 현저한 감소와 높은 FV값을 보였고, HMT CC는 다른 쌀가루에 비하여 현저한 PV와 SB 증가와 낮은 BD로 FV가 매우크게 상승하였다. HMT GM과 HMT TG는 수분 21%, 100℃, 30분에서 HMT 효과가 크게 이루어졌으나 HMT CC와 HMT KSKH는 그보다 높은 105℃ HMT 온도나 긴 처리시간이 요구되는 것으로 나타났다. 모든 HMT 쌀가루의 BD는 수분함량, 처리온도와 처리시간이 증가함에 따라 감소하여 수분함량 30%, 105℃, 90분의 HMT 조건에서 최소값을 보였다. HMT로 모든 쌀가루의 팽윤력은 증가였으며 용해도는 CC 이외의 다른 쌀가루에서 모두 증가하였다. 무처리 쌀가루시료의 겔 강도는 TG(79.23 g)> GM(38.24 g)> CC(32.26 g)> KSHK(25.66 g) 순이었고 HMT로 모든 쌀가루의 겔 강도는 증가하였으며, HMT GM과 HMT TG가 큰 증가폭을 보였다. 겔 강도는 SB(r=0.777, p<0.01)와 강한 양의 상관관계를, BD(r=-0.713, p<0.01)와 PV(r=-0.355, p<0.05)와는 음의 상관관계를 보여 HMT에 의해 쌀가루의 전분입자 내 분자 간 결합력 강화에 의한 BD 감소와 SB 증가가 겔 강도 상승에 영향을 미친 것을 알 수 있다. Heat-moisture treatment (HMT) was applied to 4 samples of rice flours, Goami (GM), Taeguk (TG), Choochung (CC) and Koshihikari (KSHK), of which amylose contents were 31.5, 32.3, 24.3, and 23.3%, respectively. Wet-milled rice flours were dried, moisture content adjusted to 21, 24, 27 and 30%, respectively, and autoclaved at 100 and 105℃ for 30~90 min. The changes on swelling, solubility, RVA (rapid visco analyser) paste viscosities and gel strength were observed. In GM and TG, peak viscosity (PV) and breakdown (BD) decreased and no peak appeared as moisture and treatment time increased by HMT. In CC, FV increased notably with big increase of PV and setback (SB) by HMT compared to the other rice flours. BD in all the samples decreased as moisture, temperature, and time increased by HMT. RVA pasting properties of HMT GM and HMT TG were changed remarkably under conditions of moisture 21%, 100℃ and 30 min whereas for HMT CC and HMT KSHK, higher temperature or more time was required at the same mois ture levels. The swelling power, solubility and gel strength increased by HMT. Gel strength correlated positively with SB (r=0.78, p<0.01) and negatively with BD (r=-0.71, p<0.01) and PV (r=-0.36, p<0.05) resulting from strengthening the structure of starch granules in rice flours by HMT.

스판덱스 코어 나일론 커버링 two way 복합사 직물의 전단특성

李春吉 慶一大學校 2002 論文集 Vol.18 No.-

The two way fabrics woven by spandex-core nylon-covering complex yarn play a decisive role in producing the high quality textile garments. The fabrics used in this experiments, woven by polyurethane 40 denier core filament and nylon 140 denier/ 48 filaments covering yarn, were wet and dry heat treated two way fabrics. We performed the experiments to know the influence of treatment time and temperature on the shear properties of the two way fabrics. In wet treatment, the samples were made by using the two way fabric at boiling temperature through the treatment time of 2, 4, 6, 8, 10 min. respectively. In dry treatment, the samples were made at the temperature of 100, 120, 140, 160℃ for 2, 6, 10, 20 min. respectively. The shear properties of the samples were evaluated by using Kawabata Hand Evaluation System. Through the experiments the following results were obtained. The shear stiffness of the wet treated samples increased according to the treatment time and the shear stiffness of the dry treated samples decreased at the treatment temperature of 160℃ according to the treatment time. The hysteresis of shear force at the shear angle φ=0.5° of the wet treated samples decreased and the hysteresis of shear force at the shear angle φ=0.5° of the dry treated samples decreased at the treatment temperature of 160℃ according to the treatment time. The hysteresis of shear force at the shear angle φ=5°of the wet treated samples had almost the same values but the hysteresis of shear force at the shear angle φ=5°of the dry treated samples decreased over the treatment temperature of 120℃ according to treatment time.

Direct synthesis of H2O2 over Pd/C catalysts prepared by the incipient wetness impregnation method: Effect of heat treatment on catalytic activity

Vu Thi Thuy Hang,정영민 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.1

Although various Pd/C catalysts have been applied in the direct synthesis of H2O2, unsatisfactory H2O2 yields have been achieved. We systematically investigated the effect of heat treatment on the physicochemical properties of Pd/C catalyst, and thereby on the catalytic performance in the direct synthesis of H2O2. Pd/C catalysts prepared by the incipient wetness method were subjected to different heat treatments and applied in H2O2 synthesis. The calcination temperature was found to have a key role in determining the Pd nanoparticle (NP) size; calcination at 523 K yielded highly oxidized and small Pd NPs corresponding to the sub-nano domain (1.4-2.5 nm). This Pd/C catalyst is superior not only in promoting H2O2 formation, but also in suppressing the subsequent unfavorable H2O2 decomposition and hydrogenation, which explains its excellent H2O2 productivity (as high as 4,443mmol H2O2/g Pd·h) and selectivity (94.5%). On the other hand, the reaction performance of the Pd/C catalysts calcined at a higher temperature (673 K) or reduced under hydrogen was sharply reduced owing to the formation of larger Pd NPs or the enhancement of the metallic nature of Pd, respectively. The amount of residual Cl ion on Pd/C catalyst after heat treatment also had an impact on the catalytic activity as it affected the pH of reaction solution. These results clearly demonstrate that an efficient Pd/C catalyst can be realized by fine tuning the conditions of heat treatment during catalyst preparation.

Preparation of Iron Aluminate (FeAl2O4) Nanoparticles from FeAl2O4 Hollow Particles Fabricated by using a Spray Pyrolysis Process

윤재철,김양도,박대희,윤정열 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.10

Iron aluminate (FeAl2O4) hollow particles with a spinel structure were synthesized by using a spray pyrolysis process. FeAl2O4 hollow particles were formed at a reaction temperature of 900 C at a flow rate of 40 L/min as a result of the rapid solvent evaporation and decomposition gases from the droplets in the spray solution prepared from metal salts and organic reagents. FeAl2O4 hollow particles were fabricated at a reaction temperature of 900 C with a flow rate of 40 L/min. The FeAl2O4 hollow particles were heat treated for 3 hours at 600 C in a 5% H2/Ar atmosphere to form the crystal particles. Subsequently, FeAl2O4 nanoparticles were fabricated from the FeAl2O4 hollow particles by using the wet milling process. After milling for 60 minutes, transmission electron microscopy revealed the FeAl2O4 particles to have a mean size of approximately 50 nm. The FeAl2O4 nanoparticles were fabricated successfully by using a two-step process, spray pyrolysis and wet milling.

수분-열처리에 의해 제조한 멥쌀가루의 특성

이미경,신말식 한국조리과학회 2006 한국식품조리과학회지 Vol.22 No.2

분무열분해법(Spray Pyrolysis)에 의한 알루미늄 산화물과 보론 산화물이 함께 도핑된 산화아연(AZOB: Al2O3 and B2O3 Co-doped Zinc Oxide)의 분말 제조에 대한 연구

김상헌 한국유화학회 2014 한국응용과학기술학회지 Vol.31 No.4

투명 전도성 산화물로서 알루미늄과 붕소가 함께 도핑된 아연산화물(AZOB)이 900℃에서 분무 열분해법에 의해 제조되었다. 얻어진 마이크론 크기의 AZOB 분말은 알루미늄, 붕소 및 아연의 수용액으로부터 얻어진다. 분무 열분해로 얻어진 마이크론 크기의 AZOB 분말은 700℃에서 두 시간동안의 후 소성 과정과 24 시간 동안의 볼 밀링을 통해 나노 크기의 AZOB으로 변환된다. AZOB을 구성하는 일차 입자의 크기를 Debye-Scherrer 식에 의해 계산하였고 압축된 AZOB 펠렛의 표면 저항을 측정하였다. Aluminum and boron co-doped zinc-oxide(AZOB) powders as transparent conducting oxide(TCO) were prepared by spray pyrolysis at 900℃. The micron-sized AZOB particles were prepared by spray pyrolysis from aqueous precursor solutions for aluminium, boron, and zinc. The micron-sized AZOB particle after the spray pyrloysis underwent post-heat treatment at 700℃ for 2 hours and it was changed fully to nano-sized AZOB particle by ball milling for 24 hours. The size of primary AZOB particle by Debye-Scherrer Equation and surface resistance of AZOB pellet were measured.