• Journal of Adhesion and Interface
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• v.7 no.2
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• pp.1-11
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• 2006

Interfacial evaluation of the untreated and treated Jute and Hemp fibers reinforced different matrix polypropylene-maleic anhydride polypropylene copolymer (PP-MAPP) composites were investigated by micromechanical technique and dynamic contact angle measurement. For the statistical tensile strength of Jute and Hemp fibers, bimodal Weibull distribution was fitted better than the unimodal distribution. The acid-base parameter on the interfacial shear strength (IFSS) of the natural fiber composites was characterized by calculating the work adhesion, $W_a$. The effect of alkaline, silane coupling agent on natural fibers were obtained with changing MAPP content in PP-MAPP matrices. Alkaline treated fibers made the surface energy to be higher due to removing the weak boundary layers and thus increasing surface area, whereas surface energy of silane treated Jute and Hemp fibers decreased due to blocked high energy sites. MAPP in the PP-MAPP matrix caused the surface energy to increase due to introduced acid-base sites. Microfailure modes of two natural fiber composites were observed clearly differently due to different tensile strength of natural fibers.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.140-144
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• 2010

In recent years there has been a growing interest for the use of natural fibers in composite applications due to their low cost, environmental friendliness, and good mechanical properties. The purpose of this study is to determine the characteristic of bending strength on bamboo fiber reinforced polymer composites. The parameters of RTM process depend on the weight ratio of bamboo fiber and resin, the number of bamboo ply and amount of hardening agent. Besides the existence of pore in composites according to vacuum time investigated a effect on mechanical properties of reinforced polymer composites. Test result shows that compressive strength was a maximum(approximately 1,840kgf/$cm^2$) value when weight ratio of resin was 12%.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2010.04a
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• pp.163-163
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• 2010

• Composites Research
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• v.35 no.6
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• pp.456-462
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• 2022

Since natural fibers are highly flammable, it is not easy to make them flame retardant. In this study, a liquid flame retardant based on phytic acid, APTES, and Thiourea, which are flame retardant candidates derived from nature, was prepared and its performance was verified through flame retardant treatment and flame retardancy evaluation of bamboo fibers. When a liquid flame retardant is used, it is possible to treat a large amount of natural fibers with flame retardant treatment. Nine types of flame-retardant treated bamboo fibers were prepared according to the Taguchi design of experiment method. Thereafter, vertical burning test and microcalorimeter test were performed for flame retardancy evaluation, and the surface of natural fibers before and after flame-retardant treatment was compared using scanning electron microscope. The results show that phytic acid has a significant effect on improving the flame retardancy of natural fibers. Through microstructure analysis, it was assumed that the phytic acid helps flame retardant to uniformly adhere to the surface of natural fibers. If such research results are utilized, it is possible to make a large amount of natural fibers high flammability in an eco-friendly way, which is expected to be advantageous for the application of prototypes.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.5-5
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• 2011

나노섬유를 제조하는 방법 중에는 상분리 현상을 이용한 방법, 자가 조립성을 이용한 방법, 템플레이트를 이용한 방법, 전기방사법이 있으며 특히 전기방사법은 연속적으로 균일한 나노섬유를 제조할 수 있다. 또한 전기방사법은 장비가 간단하며 고분자 blend ratio와 무기재료의 함량에 따라 뛰어난 특성을 나타내는 나노복합섬유를 만들 수 있다. 최근 식물에서 추출한 단백질을 전기방사법을 이용하여 나노입자 및 나노섬유를 제조하고 이를 의료 분야 등에 적용하기 위한 연구가 활발히 진행되고 있으며 이런 식물성 단백질은 동물성 단백질에 비하여 인체 적용이 용이하고 매장량이 풍부한 장점이 있다. 본 연구에서는 전기방사법을 이용하여 옥수수에서 추출한 단백질인 zein의 나노입자 및 나노섬유를 제조하였다. 또한 천연 추출물이 혼입된 복합 나노입자 및 나노섬유를 제조하여 zein이 가진 고유 특성 이외에 천연 추출물의 특성을 추가로 부여해서 더욱 발전된 나노입자 및 나노섬유를 제조하였다. 고분자 농도, 전압, 방사거리 등 다양한 공정변수를 조절하여 최적의 조건을 확립하였으며 제조된 나노입자 및 나노섬유는 field-emission type scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV/vis), fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC)를 이용하여 특성분석을 실시하였다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2010.04a
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• pp.43-43
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• 2010

국내에 천연가스버스가 보급된 이래 5차례의 용기파열 사고가 발생하였는데 그중 2005년 8월 전주 덕진충전소에서 발생한 용기파열사고는 CNG용기의 라이너를 감싸고 있는 복합재료가 손상되어 발생한 사고로 보고되었다. 복합재료용기의 외피손상이 원인이 되어 발생한 사고사례는 해외에서 약 13건이 보고되었다. CNG용기 외피손상은 용기룰 고정하는 스트랩과 밀접한 관련이 있다. 용기고정이 불완전하면 슬립이 발생하고 이는 복합재의 손상으로 이어진다. 본 연구에서는 ISO 19078, CGA C6.4 등 국제코드의 규정을 고려하여 국내에서 제조된 Type 2, 3, 4 용기와 외국에서 생산된 Type 3 용기를 대상으로 결함깊이, 길이, 넓이에 따른 복합재료 결함 내구성시험을 수행하여 CNG용기의 내구성능을 평가하였고, 시험과 동일한 조건으로 복합재료 손상결함 조건을 컴퓨터로 전산모사하여 시험결과의 타당성과 유효성을 비교 검증하였다. 실험결과, Type 2 용기의 경우, 11,250회의 최소반복가압 회수를 충족하였으나 외피손상부와 반복가압에 따른 실제누출부위가 일치하지 않아 실험조건을 달리한 추가실험이 요구되었다. Type 3 용기의 경우에는 복합재 결함부위와 누수부위가 일치된 시험용기의 수는 67%정도로, 복합재료 용기의 수명을 저하시키는 원인으로 라이너와 외피손상이 서로 밀접한 관련이 있음을 확인하였다. Type 4 용기는 국제기준에서 요구하는 반복횟수를 만족하였고, 손상깊이 0.75mm와 1.25mm에서 반복가압회수가 60,000회 이상이 되어도 누설이 발생되지 않았다. 이는 라이너의 재질이 폴리머로서 균일한데다 탄소섬유 복합재료층 위에 유리섬유 복합재료 층이 1.5mm 정도 추가로 적층되어 있어서 3등급의 손상결함(결함깊이 1.25mm)에서도 구조 층이 전혀 손상되지 않은 것으로 판단되며, 이는 Type 2 용기의 강재라이너나 Type 3의 알루미늄 라이너와 비교하여 Type 4 용기의 폴리에틸렌 라이너의 물성이 반복성능이 탁월함을 확인할 수 있었다.

• Elastomers and Composites
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• v.46 no.3
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• pp.204-210
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• 2011

In this study, Jute fibers reinforced polypropylene (JFRP) composites were manufactured by injection molding technique. In order to improve the affinity and adhesion between fibers and thermoplastic matrices during manufacturing, Maleic anhydride (MA) as a coupling agent have been employed. Untreated and treated surfaces of jute fibers were characterized using SEM and Fourier transform infrared (FTIR). Physical properties like water absorption rate were studied. Tensile and flexural tests were carried out to evaluate the composite mechanical properties. Tensile test and bending test indicated that JFRP composites show higher strength and modulus than pure PP. In addition, strength and modulus were found to be influenced by the variation of MAPP content (1%, 2%, and 3%). Tensile fracture surfaces were examined using scanning electron microscope. It ensures better interfacial adhesion between fibers and matrix by increasing the percentage of MAPP.

• Elastomers and Composites
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• v.46 no.3
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• pp.223-230
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• 2011

Considering of utilizing renewable resources and recycled plastics, green composites consisted of recycled polyethylene (PE) as matrix and eco-friendly natural fibers as reinforcement were processed and characterized in the present study. First, the wood flour/recycled polyethylene pellets with different wood flour contents were prepared by twin-screw extrusion processing. Using the pellets, wood flour/recycled polyethylene green composites were fabricated and the effects of wood flour loading on their flexural, tensile, impact properties, heat deflection temperature and fracture behavior were investigated. It was concluded that the flexural strength, flexural modulus, tensile modulus and heat deflection temperature of wood flour/recycled polyethylene green composites were increased with wood flour, whereas the tensile strength and impact strength were decreased. The fracture behavior observed by means of scanning electron microscopy supported qualitatively the tendency of the impact strength with wood flour loading, compared with the ductile fracture pattern of recycled polyethylene.

• Polymer Science and Technology
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• v.19 no.4
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• pp.299-306
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• 2008

• Composites Research
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• v.22 no.4
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• pp.13-19
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• 2009

Adhesive joints are widely used for structural joining applications in various fields and environmental conditions. Polyurethane adhesive is using for LNG carrier with cryogenic temperature condition. Even if similar polyurethane adhesive is used for different substrate, it shows different adhesion properties. Specially, variation of adhesion properties depending on the resin system or fiber is very important factor for selection of adhesive on industrial application. In present study, we got different peel strength according to the different test temperature when different polyurethane adhesive was used for same fiber reinforced composite. The main cause was investigated using by SEM and it was proven that the different adhesion property between glass fiber on composite surface and polyurethane adhesives at cryogenic temperature.