• 한국구조물진단유지관리공학회 논문집
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• 제16권4호
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• pp.69-78
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• 2012

본 연구는 콘크리트 지하구조물 외부에 적용하는 방수공법으로 120일 후 가황되도록 가황제, 가황조제 등을 첨가하여 배합제조된 합성고무시트 방수재로써 약 85일의 delay time과 약 35일의 curing time을 가지며, 이때 인장강도는 약 692%가 증가하고, 신장률은 약 10% 감소하여, 일반시트의 시공시 단점을 미가황상태로 시공되어 보완하고, 상온에서 가황하여 내구성능을 확보할 수 있는 것으로 나타났다. 또한 가황직후 및 가황 1년 후의 각종 열화요인에 대한 내구성능을 평가한 결과 관련 품질기준을 만족하며, 미가황 상태에서의 합성고무 시트에 보호모르타르를 시공하여 접착성능을 평가한 결과 첨가된 실리케이트에 의하여 보호모르타르와 수화반응에 의한 양호한 부착성능이 확보되는 것으로 나타났다.

• 한국염색가공학회지
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• 제32권3호
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• pp.176-183
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• 2020

In order to study wearable air cushion materials capable of responding to massive impact in high-altitude fall situation, high tenacity woven fabrics were bonded by heat only depending on various type of thermoplastic films and then mechanical properties were measured. Tensile strength, elongation, and 100% modulus measurement results for 4 types of films show that TPU-2 has higher impact resistance and easier expansion than PET-1. After thermal bonding, the combination with the highest tensile strength was a material with a TPU-2 film for nylon and a PET-2 film for PET, so there was a difference by type of fabric. The tear strength of the bonded materials were increased compared to the fabric alone, which shows that durability against damage such as tearing can be obtained through film adhesion. All of the peel strengths exceeded the values required by automobile airbags by about 5 times, and the TPU-2 bonded fabric showed the highest value. The air permeability was 0 L/dm2 /min. For both the film and the bonded material, which means tightness between the fabric and the film through thermal bonding. It is expected to be applied as a wearable air cushion material by achieving a level of mechanical properties similar to or superior to that of automobile airbags through the method of bonding film and fabric by thermal bonding.

• 펄프종이기술
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• 제45권6호
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• pp.30-35
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• 2013

To conserve wood resources for papermaking, chemical compositions of the hemp (Cannabis sativa L.) bast fiber cultivated in Korea such as holocellulose, ${\alpha}$-cellulose, lignin, alcohol-benzene extractives, hot and cold water extractives, and ash contents were investigated to manufacture the specialty packaging paper effectively. Significantly very low klason lignin content of 3.3% was accomplished by removing of the outer shell of bark. Laboratory soda pulping method which is very useful for the nonwood fiber was adapted, and it was found that there was no significant difference in both kappa number and H-factor between 25% and 30% NaOH charge. Hemp pulp cooked with the laboratory digester in 25% NaOH at $170^{\circ}C$ were mixed together with the wood pulp(NBKP:LBKP=1:1) in order to find the optimum mixture ratio which exhibited acceptable paper strength properties such as tensile index, burst index, and tear strength. When 10% of hemp soda pulps was mixed with 90% of wood pulps comprised of SwBKP and HwBKP (1:1), all physical strength increased significantly. The physical strength decreased as the amount of hemp pulp increased because the cell wall of bast fiber is very thick which causes low conformability and low fiber-fiber bonding. These results showed that paper made of hemp-wood pulp can be used for the specialty packaging paper which requires both the characteristic surface properties and the high physical strength of hemp fiber.

• 펄프종이기술
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• 제41권1호
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• pp.1-8
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• 2009

Mountain Pine Beetle (MPB) attacked pine was evaluated for pulp quality, chemical and physical properties, and bleachability. Chemical analyses showed that the dehydroabietic acid and total acetone extractives content were higher in the year 3 (grey) attacked MPB chips and lower in the year 5 (grey) attacked MPB chips as compared to a typical SPF (spruce/pine/fir) reference. Lignin and carbohydrate content of the MPB wood chips were comparable to the SPF. Similarly, there was little difference in kappa number, pulp yield and liquor consumption between the 3 and 5 year MPB attacked wood. Likewise there was no significant difference in the resulting tear strength, burst, or tensile strength. There appeared to be an improved bleaching response in the MPB attacked pulp as compared to the SPF reference, but this was accompanied by a slightly lower bleached pulp yield and higher bleach filtrate COD and solids content.

• 펄프종이기술
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• 제45권5호
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• pp.44-48
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• 2013

Ultrasonic treatment of KOCC was tried to explore the possibility for improvement of KOCC quality as a raw material for making industrial packaging paper and paperboard. The effect of pH, stock consistencies and treatment times on the ultrasonic response of KOCC were investigated. WRV, apparent density, tensile index and burst index were improved as pH of KOCC slurry is increased. However highest tear index and stiffness were obtained at pH 8. It was also found that the highest WRV and strength properties could be obtained at 0.5% of KOCC consistency during ultrasonic treatment. WRV and most strength properties were improved with ultrasonic treatment time. It was found that ultrasonic treatment can be used as a useful mean for KOCC modificaton.

• Journal of the Korean Wood Science and Technology
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• 제21권1호
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• pp.21-38
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• 1993

In order to investigate the influence of recycling, a laboratory method simulating the papermaking process was used for assessing the effects of recycling on fiber properties. Sw-BKP, Hw-BKP and BGP were disintegrated and beaten to about 42$^{\circ}$SR-44$^{\circ}$SR by a valley beater. After beating, these pulps were dewatered by centrifuge and dried at 90$^{\circ}C$ for 72hrs. This recycling process(sequence of wetting, defiberating, dewatering and drying) was repeated seven times. Physical, mechanical and optical properties of recycled pulps were evaluated by TAPPI Standards. Morphological changes occurred through recycling process was observed by SEM. Sheet density decreased with recycling. The largest drop in density occurred during the first recycling. The porosity values decreased with recycling. Mechanical properties such as tensile, burst strength and folding endurance, decreased with recycling. However tear strength of Sw-BKP and mixtured pulp increased at the first recycling. Optical properties such as brightness, opacity and light scattering coefficient, increased with recycling. However, brightness of mixtured pulp gradually decreased with recycling. Fibrillated outer layer of the fiber was gradually removed from the surface with recycling. As a result of recycling, crinkles on the fiber surface were found to be more folded.

• 펄프종이기술
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• 제42권3호
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• pp.22-27
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• 2010

Pulping properties of the imported mixed eucalyptus chips and the domestic yellow poplar chips were investigated for comparing two chips as the raw materials for the hardwood chemical pulp. Soda-AQ (anthraquinone) pulping was applied for this study. The pulp from yellow poplar showed higher pulp yield than pulp from mixed eucalyptus, which comes from the lower hot-water soluble extractives and the higher polysaccharides in yellow poplar chips than those of the mixed eucalyptus chips. The yellow poplar pulp had higher average fiber length and fiber width than those of the mixed eucalyptus pulp, which led to the better respond to beating and the higher tear strength than those of the pulp from the mixed eucalyptus chips.

• Korean Chemical Engineering Research
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• 제47권6호
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• pp.669-675
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• 2009

연질 PVC 대체를 위한 비변색 타입의 무용제형 상온 액상수지를 폴리올을 경화제로 사용하는 폴리우레탄수지 구조제어 설계를 통한 프리폴리머 합성방법을 응용하여 제조할 수 있었다. Macro-glycol, 분자량 및 반응조건의 영향 등을 고찰하여 최적의 작업성과 물성을 가지는 무용제형 상온액상수지를 제조하였으며, 우수한 기계적인 특성과 함께 유색작업을 위한 안료의 분산성 등에서도 우수하였고, Tg가 $-40^{\circ}C$의 값을 나타내었다. 또한 자외선 노출이나 질소산화물에 의한 황변특성도 개선할 수 있었다.

• Elastomers and Composites
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• 제35권4호
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• pp.261-271
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• 2000

황과 레졸로 가교된 천연고무 배합물의 가황 특성과 가교물의 물리적 특성을 연구하였다. 분자량 분포가 다른 2가지 레졸을 사용하였다. 분자량 분포도가 낮은 레졸이 포함된 배합물의 스코치 시간은 분자량 분포도가 높은 레졸이 포함된 배합물에 비해 빠르다. 레졸 함량이 높은 가교물의 가교밀도는 $95^{\circ}C$ 열노화 후 감소한 반면, 레졸이 없는 가교물의 경우에는 열노화 후 가교 밀도가 증가하였다. 레졸 함량이 높은 가교물의 가교 밀도는 노화 시간이 길어질수록 감소하지만 모듈러스는 증가하고 인장 강도와 인열 강도는 감소한다.

• Macromolecular Research
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• 제13권2호
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• pp.81-87
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• 2005

Blends of silicone rubber (VMQ) and liquid crystalline polymer (LCP) were prepared by the melt mixing technique. Mechanical, XRD, thermal and dynamic mechanical investigations are reported for the pure silicone rubber and blends. The mechanical properties, viz. the tensile strength, tear strength and elongation at break, of the silicone rubber decreased with the addition of LCP. The SEM study on the tensile fractured surface of the blends revealed that they had a two phase structure, and that the failure was mainly due to fiber pull out, which suggests that the VMQ and LCP are incompatible in all of the proportions examined in this study. However, the FTIR study shows that there was a partial interaction between the VMQ and LCP, but which may not be sufficient to grip the fibrils under the applied load. In the XRD analysis, it was observed that the crystalline structure of the silicone rubber deteriorated in the presence of LCP. The DMA study suggested that the storage modulus of the silicone rubber was improved with the addition of LCP, due to the high modulus of the LCP phase. The thermal stability of the silicone rubber was greatly reduced by the addition of LCP, due to the latter having a thermal stability lower than that of silicone rubber.