흡습에 의한 FRP의 내구성에 관한 연구

문창권(Chang-Kwon Moon),구자삼(Ja-Sam Goo) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.2

This work has been investigated in order to study the influence of the moisture absorption on the mechanical properties of the glass fiber/epoxy resin composites and the carbon fiber/epoxy resin composites. The types of glass fiber used in the glass fiber/epoxy resin composites were randomly oriented fiber and plain fabric fiber. And carbon fiber/epoxy resin composites was laminated with fabric prepreg which was formed with carbon fiber and epoxy resin. Both composites were immersed up to 100 days in distilled water at 80℃, and then dried up to 3 days in an oven at 80℃. Both composites were measured for the weight gain of water(wt.%) and tensile strength through immersion and dry time.<br/> Consequently, it was found that the tensile strength of the glass fiber/epoxy resin composites and the carbon fiber/epoxy resin composites were reduced proportionally to the moisture absorption rate. Also, the tensile strength of glass fiber composites was decreased more than that of the carbon fiber composites. Additionally. it was found that the tensile strength of all composites which decreased by moisture absorption were partly recovered by drying in an oven at 80℃.

CFRP 일방향 45도 배향각 프리프레그의 회전수 변화에 따른 HSS, TiAIN 드릴 절삭에 관한 연구

김선범 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.5

Prepreg is an abbreviation of Preimpregnated Materials. It is a sheet-type product in which a matrix is ​​impregnated with reinforced fiber. The prepreg has very different properties depending on the orientation of the fibers and the weaving method, and the orientation of the fibers plays an important role in determining the mechanical strength of CFRP. Short and randomly oriented reinforcing fibers show isotropy, while long, unidirectional reinforcing fibers exhibit anisotropic behavior and are strongest when the applied load is parallel to the reinforcing fibers. Classification by the direction of the fiber is divided into unidirectional, orthogonal, multiaxial, and the like. Uni-directional refers to a state in which almost all fibers in the fabric are aligned in one direction. When the fibers used as reinforcing materials are aligned in one direction, the fibers are used in a straight line without twisting during the fabric production process, and there is an advantage in that the amount of fibers used as a whole can be minimized. A uni-directional prepreg exhibits different cutting forces depending on the stacking orientation angle. In this experiment, the optimal cutting conditions for a uni-directional prepreg 45 degree orientation angle specimen are presented.

Mechanical Properties of Tow Prepreg Applied to AFP using Surface-tackiness

JaeHyeon Lim,Ki-Young Kim,Joonmyung Choi,Jae-Chul Lee 한국섬유공학회 2022 Fibers and polymers Vol.23 No.6

This study presents the production of a carbon-fiber composite material using a thermosetting epoxy resin andPolyether Sulfone (PESU), a thermoplastic toughening agent. A tow prepreg was fabricated using the proposed hightoughnessresin, and it was applied to the automated fiber placement (AFP) process. To obtain resin with different viscosities,different ratios of solid epoxy YD-011 were mixed with the high-toughness resin, which contained liquid epoxy YD-128 and10 phr of PESU, at certain ratios. The surface-tackiness of each mix of resin was then compared by applying the tow prepregthat was produced to the AFP process. The results indicate that the resin mix that contained 10 % of solid epoxy was the mostsuitable for the AFP process. Subsequently, the mechanical and thermal properties of the resin and tow prepregs using onlythe liquid epoxy containing the PESU were compared with the resin and tow prepregs that contained 10 % solid epoxy. Theresin produced by adding 10 % solid epoxy to the liquid epoxy exhibited improvements of 3 % in tensile strength, 16% intensile modulus, and 27 % in impact strength when compared to the resin that used only the liquid epoxy. Furthermore, thefracture toughness test results using single-edge notched bending and compact tension methods showed a decrease of 10 %and 16% , respectively, and the glass transition temperature decreased by 5 %. In the case of the tow prepreg specimenproduced by adding 10 % solid epoxy to the liquid epoxy, it exhibited a decrease of 0.6% in the 0 ° tensile strength, adecrease of 1.6% in tensile modulus, and an increase of 4 % in the 90 ° tensile strength when compared to the tow prepregthat applied only the liquid epoxy. In addition, the ILSS interfacial strength increased by 1 %, while the double cantileverbeam fracture toughness decreased by 8 %. A comparison of the results showed that the tow prepreg prepared by adding10 % solid epoxy to the liquid epoxy had excellent mechanical properties, and the tow prepregs were laminated mostappropriately in the AFP process, thus verifying its applicability as a resin in tow prepregs for the AFP process. Keywords: Carbon fiber reinforced plastic (CFRP), Automated fiber placement (AFP), Tow prepreg, Toughened

Crystallization and Mechanical Properties of Continuous Carbon Fiber Reinforced Polyether-ether-ketone Composites

Kaili Zhu,Hongsheng Tan,Yajie Wang,Changheng Liu,Xiaomin Ma,Jie Wang,Haini Xing 한국섬유공학회 2019 Fibers and polymers Vol.20 No.4

The effect of two different continuous carbon fibers (CCF1 and CCF2) with different material properties onstructure-properties of continuous carbon fibers reinforced polyether-ether-ketone prepreg tapes (CCF/PEEKPT) prepared bya wet powder impregnation process were investigated. The effects of fiber content on the tensile properties, dynamicmechanical behavior, crystallization melting behavior and fracture morphology of prepared prepreg tapes were performed bythe dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and scanning electron microscope (SEM)etc. The results showed that, the tensile strength of CCF1/PEEKPT increased with increasing of the carbon fiber contentwithin 50-75 wt%. Meanwhile, the tensile strength of 50-65 wt% CCF2/PEEKPT had the same change trend, but thendecreased when the fiber content of composites was higher than 65 wt%. The storage modulus (E′) of composites increasedwith adding content of carbon fiber. The composites still maintained high deformation resistance when the temperature roseto 290 oC. Compared with pure PEEK, the crystallinity and crystallization rate of the composites both increased with theoccurrence of fiber inducing PEEK crystallization, but the crystallization onset temperature, crystallization temperature andmelting temperature of CCF/PEEKPT moved to low temperatures with adding of fiber content. In general, these observationssuggested that CCF hindered the movement of the polymer chain segment and constrained the spherulites growth of PEEKfor CCF/PEEKPT.

Optimization of Powder Impregnation Process Parameters of Carbon Fiber Reinforced Polyether-ether-ketone Prepreg Tape by Response Surface Methodology

Tianyun Wan,Huihuang Ma,Zijian Wang,Chuanjie Fan,Xiaodong Zhou 한국섬유공학회 2022 Fibers and polymers Vol.23 No.6

Carbon fiber reinforced polyether-ether-ketone (CF/PEEK) composite materials had a wide range of applicationsin the aerospace, electronics and electrical fields, etc. The composite materials were generally prepared from prepregs. Commonly used prepreg tape preparation methods had disadvantages of uneven resin distribution and inadequate fiberimpregnation, resulting in high porosity and poor mechanical properties. In this research, a combined process of the doublepowder impregnation method and the melt homogenization method was used to prepare the CF/PEEK prepreg tape to solvethe previous problems. Using this method, the porosity of the prepreg tape was reduced by 56.30 % and the tensile strengthwas increased by 43.35 % compared with the traditional powder impregnation method. At the same time, the prepreg tapewas widened and thinned and the uniformity of resin distribution was improved. Besides, based on the single factorexperiment, the response surface method was used to construct the impregnation model of the quadratic polynomialregression equation between the process parameters (powder impregnation temperature, traction speed and melthomogenization temperature) and the porosity of the CF/PEEK prepreg tape. According to this model, the process parametersfor the porosity of the prepreg tape were calculated to reach the minimum, namely, the powder impregnation temperature was380 ℃, the traction speed was 1 m/min, and the melt homogenization temperature was 380 ℃. As a result of these processparameters, the porosity of the prepreg tape could be reduced to 7.39 %. Subsequently, the model was verified throughexperiments, which could provide a reference for the process parameters setting of the impregnation process.

크림프가 없는 탄소섬유직물/에폭시 복합재료의 동역학, 인장, 굴곡 및 충격 특성에 미치는 프리프레그 Angle-Ply의 영향

정나은(Naeun Jeong),조동환(Donghwan Cho) 한국고분자학회 2020 폴리머 Vol.44 No.1

일방향(UD) 프리프레그는 섬유방향으로 이방성을 띠고 있기 때문에 탄소섬유의 배향각은 탄소섬유/에폭시 복합재료의 기계적, 열적 특성에 중요한 역할을 한다. [0°], [0°/90°], [0°/45°/90°], [0°/30°/60°/90°] 적층 순서에 따라 서로 다른 angle-ply를 갖는 크림프가 없는 탄소섬유직물/에폭시 복합재료를 압축성형으로 제조하고, 그들의 특성에 미치는 프리프레그 angle-ply 영향을 조사하였다. [0°] 복합재료는 가장 높은 동역학적, 인장, 굴곡 및 충격 특성을 나타낸 반면, [90°] 복합재료는 가장 낮은 특성을 나타냈다. [0°/90°], [0°/45°/90°], [0°/30°/60°/90°] 복합재료는 프리프레그 angle-ply에 따라 [0°]와 [90°] 복합재료 사이의 특성을 나타내었다. 본 연구는 크림프가 없는 탄소섬유직물강화 복합재료의 특성 제어를 위해 프리프레그 angle-ply 디자인이 중요함을 가리킨다. Since unidirectional (UD) prepregs are anisotropic in the fiber alignment direction, the alignment angle of carbon fibers plays a significant role in the mechanical and thermal properties of carbon fiber/epoxy composites. Non-crimp carbon fiber fabric/epoxy composites with different angle-plies of [0°], [0°/90°], [0°/45°/90°], and [0°/30°/60°/90°] stacking sequences were prepared by compression molding. The effect of prepreg angle-ply on the properties of resulting composites was explored. The [0°] composite exhibited the highest dynamic mechanical, tensile, flexural and impact properties, whereas the [90°] composite exhibited the lowest properties. The properties of the [0°/90°], [0°/45°/90°], and [0°/30°/60°/90°] composites were intermediate between the [0°] and [90°] composites, depending on the angle-plies consisting of the composites. The present study indicates that prepreg angle-ply design should be importantly considered to manipulate their properties of non-crimp carbon fiber fabric-reinforced composites.

탄소섬유 펼침 기술을 적용한 CF/PA6 적층 복합재료의 특성

박성민,김명순,최윤성,이은수,천진성,유호욱,Park, Sung-min,Kim, Myung Soon,Choi, Yoon Sung,Lee, Eun Soo,Chon, Jin Sung,Yoo, Ho Wook 한국섬유공학회 2015 한국섬유공학회지 Vol.52 No.6

This paper reports the preparation of CF/PA6 (Polyamide 6) laminate composites using tow-spreading technology. Additionally, the effect of the spread tow on impregnation was investigated by Darcy's law. The thickness of an unspread 12K carbon fiber tow was reduced by increasing the tow width from 7 to 20 mm. The PA6 film was used to stabilize and impregnate the spread tow by covering it with a partially consolidated prepreg:12K carbon fiber spread tow/PA6 film. The laminate composites were fabricated from the prepreg and, for comparison, the other laminate composite was produced from a conventional tow prepreg of 12K carbon fiber/PA6 film. Consequently, the spread tow laminate composite exhibited a lower void content and improved mechanical properties.

Multi-scale computational fluid dynamics of impregnation die for thermoplastic carbon fiber prepreg production

Ngo, Son Ich,Lim, Young-Il,Hahn, Moon-Heui,Jung, Jaeho,Bang, Yun-Hyuk Elsevier 2017 Computers & chemical engineering Vol.103 No.-

<P><B>Abstract</B></P> <P>A multi-scale computational fluid dynamics (CFD) model of a pultrusion process was proposed for unidirectional carbon fiber (UD-CF) prepreg production. Polyamide 6 (PA6) and polyacrylonitrile-based CF were used as the thermoplastic polymer matrix and reinforcement, respectively. The non-Newtonian viscosity of PA6 was expressed by Carreau's model. A micro-scale CFD model was constructed to obtain a proper resin permeability to CF filaments, while the tow domain was treated as sliding porous media in the macro-scale CFD. The resin velocity profile showed a similar shape to the relative resin amount experimentally measured in the UD-CF prepreg. The uniformity index of the resin velocity (<I>UI</I> <SUB> <I>v</I> </SUB>) on the outlet surface was calculated for 45 case studies with several tow speeds and resin flow rates. The tow speed showing a maximum <I>UI</I> <SUB> <I>v</I> </SUB> was remarkably well expressed as a linear function of the slip velocity, which is the difference between the tow speed and resin velocity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A multi-scale CFD model was developed for a carbon fiber (CF) impregnation process. </LI> <LI> Resin permeability to CF filaments was obtained from a micro-scale CFD model. </LI> <LI> Uniformity index (<I>UI</I>) of the resin velocity was obtained from a macro-scale CFD model. </LI> <LI> Tow speed showing maximum <I>UI</I> was expressed as a linear function of the slip velocity. </LI> </UL> </P>

탄소섬유 펼침 기술 및 이를 적용한 적층 복합재료의 기계적 특성

박성민 ( Sungmin Park ),김명순 ( Myungsoon Kim ),최윤성 ( Yoonsung Choi ),이은수 ( Eunsoo Lee ),유호욱 ( Howook Yoo ),천진성 ( Jinsung Chon ) 한국복합재료학회 2015 Composites research Vol.28 No.5

본 연구는 탄소섬유 펼침 기술을 이용한 적층 복합재료의 특성을 평가하였다. 섬유 펼침 기술이 적용되어 기존 12 K 탄소섬유 토우의 폭이 7 mm에서 20 mm로 늘어나면서 두께가 더 얇아졌다. 폴리프로필렌 필름을 spread tow에 함침시켜 프리프레그를 만들고 이를 적층 후 열압축 성형을 통해 시편을 제조하였으며 이들의 기공함유량 및 인장, 굴곡 시험을 통해 물리적, 기계적 물성을 평가하였다. 그 결과, 탄소섬유 펼침 기술이 적용된 적층 복합재료의 기공함유량이 기존의 섬유 토우를 사용한 것보다 작게 나타났고, 섬유함유량이 낮았음에도 불구하고 기계적 물성이 향상됨을 알 수 있었다. This paper reports a study on a method for achieving lightweight thermoplastic laminate composites referred to as tow spreading technology. Thickness of an unspread 12 K carbon fiber tow is reduced by increasing the tow width from 7 mm to 20 mm. The polypropylene (PP) film was used to stabilize and impregnate the spread tow, covering it into a partially consolidated prepreg: 12 K carbon fiber spread tow/PP. Laminates were fabricated from the spread tow prepreg and control laminate composites were produced from unspread tow prepreg consisting of 12 K carbon fiber and PP. The void content, tensile and flexural properties of the composite laminates were investigated. Consequently, the spread tow laminate composite exhibited lower void content and improved mechanical properties.

열중량분석기를 적용한 탄소섬유/에폭시 복합재의 구성재 함유율 측정 기법

장정근 ( Jeong Keun Jang ),차재호 ( Jae Ho Cha ),이보미 ( Bo Mi Lee ),윤성호 ( Sung Ho Yoon ) 한국복합재료학회 2020 Composites research Vol.33 No.6

열중량분석기를 적용하여 탄소섬유/에폭시 복합재의 구성재 함유량을 평가하기 위한 측정기법을 제시하였다. 시험에 사용된 시료는 탄소섬유/에폭시 토우 프리프레그로 제작된 스트랜드 시편에서 채취하였으며 시간에 따른 시료의 무게 변화를 실시간으로 측정하였다. 또한 전자현미경을 이용하여 수지 제거 여부와 탄소섬유의 열손상 상태를 관찰하였다. 연구결과에 따르면 열중량분석기를 적용하면 기존의 머플로를 적용한 경우에 비해 소량의 시료에 대해서도 시험이 가능하며, 설정 온도와 노출 시간을 제어함으로써 구성재의 함유량을 효율적이고 정량적으로 평가할 수 있음을 알 수 있었다. We propose a measurement method for evaluating constituent contents of carbon fiber/epoxy composites through a thermogravimetric analyzer (TGA). The sample used in the test was taken from a strand specimen made of carbon fiber/epoxy tow prepreg, and the change in weight of the sample over time was measured in real time. Using a field emission scanning electron microscope (FE-SEM), we examine the thermal damage condition of the carbon fiber depending on whether resin was removed or not. We find that it was possible to test even a small amount of sample when using TGA vis-a-vis using a conventional muffle furnace. In addition, TGA enables the temperature and exposure time to be controlled, allowing the constituent contents of composite materials to be efficiently and quantitatively evaluated.