• Elastomers and Composites
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• 제47권4호
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• pp.310-317
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• 2012

계면접착력 향상을 위해 실린더형 RF 플라즈마 발생기를 이용하여 Jute fiber의 표면을 아르곤가스로 처리하였고 최적 처리조건을 설정하였다. 플라즈마 강도, 가스압력, 및 처리시간을 변경한 후 이러한 인자들이 황마섬유 표면모폴로지, 섬유 인장강도, 및 폴리프로필렌과의 모델복합체에서 계면접착강도에 미치는 영향을 조사하였다. 플라즈마 처리인자에 따라 황마섬유의 표면은 거칠어졌다. 가스압력의 영향은 처리시간 및 플라즈마 강도의 영향보다 다소 낮게 나타났다. 플라즈마 강도와 시간에 따라 황마섬유의 강도는 약 25% 감소한 반면, 가스압력의 영향은 크게 나타나지 않았다. 계면전단강도 (IFSS)를 기준으로 결정된 최적 플라즈마 처리조건은 처리시간 30 s, 전력 40 W, 가스압력 30 mTorr로 나타났다.

• 한국건설순환자원학회논문집
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• 제2권2호
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• pp.115-127
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• 2014

Addition of fibers in cement or cement concrete may be of current interest, but this is not a new idea or concept. Fibers of any material and shape play an important role in improving the strength and deformation characteristics of the cement matrix in which they are incorporated. The new concept and technology reveal that the engineering advantages of adding fibers in concrete may improve the fracture toughness, fatigue resistance, impact resistance, flexural strength, compressive strength, thermal crack resistance, rebound loss, and so on. The magnitude of the improvement depends upon both the amount and the type of fibers used. In this paper, locally available waste fibers such as coir fibers, sisal fibers and polypropylene fibers have incorporated in concrete with varying percentages and l/d ratio and their effect on compressive, split, flexural, bond and impact resistance have been reported.

• Journal of the Korean Wood Science and Technology
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• 제25권2호
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• pp.33-44
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• 1997

This study was executed to examine the effects of polypropylene fiber length and process variables of the composites made from wood fiber and nonwood fiber mixed formulations. As a nonwood fiber the polypropylene with 3 denier thickness of tow condition was selected and cut into each length of 0.5, 1.0, 1.5, 2.0 and 2.5cm to mix with wood fiber. And also western hemlock wood fiber for medium density fiberboard was prepared. First, to decide an adequate polypropylene mixing fiber length, the composites of 1.0g/$cm^3$ density were made from 10% polypropylene fiber by each of five lengths and 90% western hemlock fiber mixed formulations. Thereafter as the experiments of process variable, the composites applied with adequate polypropylene fiber length(1.5cm) were made from 4 density levels (0.6, 0.8, 1.0, 1.2g/$cm^3$). 3 mixed formulations of wood fiber to polypropylene fiber(95 : 5, 90 : 10, 85 : 15), and 3 mat moisture contents(5, 10, 20%). According to the results and discussions it was concluded as follows ; The physical and mechanical properties were shown improved tendency. as polypropylene fiber length was increased in the range from 0.5 to 1.5cm, but shown decreasing tendency from 2.0 to 2.5 cm. Accordingly, it was shown that polypropylene fiber length is limited to 1.5cm or less length in mixing wood fiber and polypropylene fiber by turbulent air mixing process. As the densities of wood fiber-polypropylene fiber composites were increased, the physical and mechanical properties were clearly improved. Also they were shown significantly increasement statistically between densities respectively. In the mixed formulations, physical and mechanical properties were shown only slightly improvement, as they changed from 95 : 5 to 85 : 15 in wood fiber to polypropylene fiber. Despite of increasement of mat moisture content, mechanical properties were not improved significantly but physical properties were improved somewhat in wood fiber-polypropylene fiber composites.

• Journal of the Korean Wood Science and Technology
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• 제24권3호
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• pp.101-109
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• 1996

Effects of process variables were evaluated in physical properties of the wood fiber-thermoplastic fiber composites using nonwoven web method. Turbulent air mixer using compressed air was employed to mix wood fiber with two types of thermoplastic polypropylene and nylon 6 fibers. The optimal hot press temperature and time were found to be $190^{\circ}C$ and 9 minutes in wood fiber-polypropylene fiber composite and to be $220^{\circ}C$ and 9 minutes in wood fiber-nylon 6 fiber composite. As the density of wood fiber-polypropylene fiber composite and wood fiber-nylon 6 fiber composite increased, the physical properties were improved The density appeared to be the most significant factor on physical properties in the statistical analysis. The composition ratio of polypropylene or nylon 6 fiber to wood fiber was considered not to be statistically significant factor. The thickness swelling decreased somewhat in wood fiber-polypropylene fiber composite and wood fiber-nylon 6 fiber composite as the content of synthetic fiber increased. As the increase of mat moisture content, dimensional stability was improved in wood fiber-polypropylene fiber composite but not in wood fiber-nylon 6 fiber composite.

• Computers and Concrete
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• 제25권6호
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• pp.509-516
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• 2020

Adding fibers improves concrete performance in respect of strength and plasticity. There are numerous fibers for use in concrete that have different mechanical properties, and their combination in concrete changes its behavior. So, to investigate the behavior of the fiber reinforced concrete, an in vitro study was conducted on concrete with different fiber compositions including different ratios of steel, polypropylene and glass fibers with the volume of 1%. Two forms of fibers including single-stranded and aggregated fibers have been used for testing, and the specimens were tested for compressive strength and dividable tensile strength (splitting tensile) to determine the optimal ratio of the composition of fibers in the concrete reinforced by hybrid fibers. The results show that the concrete with a composition of steel fibers has a better performance than other compounds. In addition, by adding glass and propylene fibers to the composition of steel fibers, the strength of the samples is reduced. Also, if using the combination of fibers is required, the use of a combination of glass fibers with steel fibers will provide a better compressive strength and tensile strength than the combination of steel fibers with propylene.

• 한국안전학회지
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• 제12권4호
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• pp.230-240
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• 1997

본 연구에서는 폴리프로필렌 섬유보강 콘크리트의 파괴특성을 알아보기 위해 Monofilament 섬유와 Fibrillated 섬유의 두 종류 폴리프로필렌 섬유를 선택하여 10$\times$10$\times$50 cm 보 시편을 만들었는데, 이때 사용된 두 종류의 섬유 길이는 19 mm이고, 섬유 혼입량은 0%, 1%, 2%, 3%로 하였으며, 초기균열 깊이의 영향을 알아보기 위해 초기 균열길이를 각 섬유 혼입량에 따라 1.5cm, 3.0cm, 4.5cm로 하여 실험을 수행하였다. 또한, 본 연구에서는 폴리프로필렌 섬유보강 콘크리트의 파괴특성을 규명하기 위해 보 시편에 대한 4 점 하중 휨시험을 통해 하중-하중점 변위 곡선을 각 시편에 대해 측정하였고, 이때 COD 게이지를 이용하여 하중-CMOD 곡선도 측정할 수 있었다. 이러한 실험결과를 통해, 섬유혼입량과 초기 균열 깊이에 따른 압축강도, 휨강도 및 휨인성, 응력확대계수, 파괴에너지 등이 규명되었다. 이러한 결과에 대한 분석으로부터 Fibrillated 폴리프로필렌 섬유가 Monofilament 섬유보다 연성 효과가 큰 것을 알 수 있었으며, 특히 하중-CMOD 곡선으로부터 계산되는 파괴에너지인 Jc가 믿을만한 파괴특성 인자임을 알 수 있었다.

• 콘크리트학회논문집
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• 제14권1호
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• pp.76-82
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• 2002

초속경 시멘트 콘크리트는 양생 시 초기재령에서 높은 수화열과 건조수축으로 인해 균열이 발생하기 쉽다. 이러한 문제점을 해결하기 위해 각종 소재를 적극 활용하려는 노력의 일환으로 섬유보강 콘크리트를 사용하게 된다 합성섬유보강 콘크리트는 건조수축에 대한 저항성과 내구성을 증진시키는 것으로 보고되고 있는데 대부분이 일반콘크리트에 대한 연구가 수행되었을 뿐 초속경 시멘트콘크리트에 관한 건조수축의 영향에 대해 정량적 및 정성적 연구가 미미한 상태이다. 따라서, 본 연구에서는 합성섬유보강 콘크리트의 건조수축 저감효과와 초속경 시멘트 콘크리트에서 수축에 대한 구속효과를 평가하기 위하여 콘크리트종류, 섬유보강 여부, 물-시멘트비, 구속여부를 주요 실험변수로 하여 건조수축실험을 수행하였다. 그 결과 일반 콘크리트에 비해 초속경 시멘트 콘크리트의 건조수축의 진행이 상당히 작음을 알 수 있었다. 이는 속경성 콘크리트의 수화반응이 빠르게 진행되어 건조에 의한 중량감소율이 다소 작은 점과 수화생성물과의 관계에 기인되는 것으로 판단된다. 또한 1축으로 구속된 건조수축의 구속으로 인한 초속경 시멘트 콘크리트의 건조수축을 예측할 수 있었고 초속경 시멘트 콘크리트에 섬유보강으로 인한 건조수축 제어는 일반콘크리트에 비해 효과가 매우 큰 것으로 나타났다.

• 폴리머
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• 제39권1호
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• pp.99-106
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• 2015

나노케냐프 섬유가 포함된 셀룰로스 섬유를 알카리(NaOH)로 처리 후 PP 수지에 첨가하여 물성에 미치는 영향에 대하여 조사하였다. 알카리를 섬유에 처리한 효과로는 M.I., 신장율, 충격강도가 증가하는 반면 인장강도, 휨모듈러스, 열변형온도가 처리하지 않은 섬유에 비해 감소하였다. 알카리를 나노섬유에 처리하였을 때 섬유표면의 불순물과 화학물질을 제거하여 섬유표면의 특성을 변화시켜서 나노섬유와 PP 수지간의 계면간 접착력을 감소시키고 PP의 특성을 변화시키는 것으로 보인다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.125-128
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• 2005

The dispersion of carbon nanofiber (CNF) was carried out by solution blending, mechanical mixing, and sonication. CNFs at levels of 5-50% fiber weight content were mixed with polypropylene (PP) powder, and then were melt-mixed using a twin-screw extruder. For the further alignment of fibers, extruded rods were stacked uni-directionally in the mold cavity for the compression molding. For the evaluation of mechanical properties of nanocomposites, tension, in-plane shear, and flexural tests were conducted. CNF/PP composites clearly showed reinforcing effect in the longitudinal direction. The tensile modulus and strength have improved by 100% and 40%, respectively for 50 % fiber weight content, and the flexural modulus and strength have increased by 120% and 25%, respectively for the same fiber weight content. The shear modulus showed 65% increase, but the strength dropped sharply by 40%. However, the property enhancement was not significant due to the poor adhesion between fiber and matrix. In the transverse direction, the tensile, flexural, and shear strength decreased as more fibers were added.

• 한국의류산업학회지
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• 제16권3호
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• pp.456-461
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• 2014

The objective of this study is to give PP(polypropylene) fabric a good affinity for water. Oxygen plasma was treated to PP fabrics in a commercial glow discharge reactor with different RF power, discharge pressure, and reaction time. The PP fiber surfaces were characterized by the measurement of contact angle and ESCA. A JEOL scanning electron microscope was used to observe the surface morphology of fibers. The spontaneous water uptake amount of PP fabrics was determined by the demand wettability test. To determine the effect of aging on the surface properties of $O_2$ plasma treated PP, all the above measurements of the samples were carried out after 1, 7, 30, 60, and 150 days. The results are as follows. The PP fiber surfaces treated by $O_2$ plasma treatment have a chemical composition that consisted of various oxygen containing polar groups. Consequently, the contact angles of the treated PP fibers decreased, which improved the water uptake rate of PP fabrics. Surface roughness of the treated PP affected the fabric wettabiity as well. Wettability of the treated PP decreased and leveled off with aging. The $O_2$ plasma treatment is a simple and effective method to increase the water uptake rate of PP fabrics.