• Title/Summary/Keyword: fiber drawing

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Fluoro-illite/polypropylene Composite Fiber Formation and Their Thermal and Mechanical Properties (불소화 일라이트/폴리프로필렌 복합섬유 형성 및 열 및 기계적 특성)

  • Jeong, Euigyung;Lee, Young-Seak
    • Applied Chemistry for Engineering
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    • v.22 no.5
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    • pp.467-472
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    • 2011
  • This study investigated illite/polypropylene (PP) composite filament formation via melt-spinning and evaluated their physical properties to prepare functional fibers using natural materials. When composite filaments were formed, the composite filaments exhibited smaller fiber diameters compared to that of neat PP filament because of the lubricant effect of illite induced by its layered structure. Moreover, fluorination effect increased interfacial affinity and dispersion in the polymer, resulting in smaller diameter of fluorinated illite/PP composite filament, which was 2/3 of the neat PP filament diameter. Addition of raw and fluorinated illite improved thermal stability of illite/PP composite filament. Raw illite/PP composite filament cannot be used for a practical application, because it broke during drawing process, whereas the fluorinated illite/PP composite filament can be used for a practical application, because it exhibited similar tensile strength of the neat PP filament and 50% increased modulus. Even with improved illite/PP interfacial affinity and illite dispersion in the polymer, illite/PP composite filament formed microcomposite, because non-expandable illite had strongly bound layers, resulting in only a little illite exfoliation and PP intercalation into illite.

Mechanical Properties of Fiber-reinforced Cement Composites according to a Multi-walled Carbon Nanotube Dispersion Method (다중벽 탄소나노튜브의 분산방법에 따른 섬유보강 시멘트복합체의 역학적 특성)

  • Kim, Moon-Kyu;Kim, Gyu-Yong;Pyeon, Su-Jeong;Choi, Byung-Cheol;Lee, Yae-Chan;Nam, Jeong-Soo
    • Journal of the Korea Institute of Building Construction
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    • v.24 no.2
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    • pp.203-213
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    • 2024
  • This study delves into the mechanical properties of fiber-reinforced cement composites(FRCC) concerning the dispersion method of multi-walled carbon nanotubes(MWCNTs). MWCNTs find utility in industrial applications, particularly in magnetic sensing and crack detection, owing to their diverse properties including heat resistance and chemical stability. However, current research endeavors are increasingly directed towards leveraging the electrical properties of MWCNTs for self-sensing and smart sensor development. Notably, achieving uniform dispersion of MWCNTs poses a challenge due to variations in researchers' skills and equipment, with excessive dispersion potentially leading to deterioration in mechanical performance. To address these challenges, this study employs ultrasonic dispersion for a defined duration along with PCE surfactant, known for its efficacy in dispersion. Test specimens of FRCC are prepared and subjected to strength, drawing, and direct tensile tests to evaluate their mechanical properties. Additionally, the influence of MWCNT dispersion efficiency on the enhancement of FRCC mechanical performance is scrutinized across different dispersion methods.

Characteristics of High Strength Polyethylene Tape Yarns and Their Composites by Solid State Processing Methods (고상공정법에 의한 고강도 폴리에틸렌 테이프사와 그 복합재료의 특성)

  • Lee, Seung-Goo;Cho, Whan;Joo, Yong-Rak;Song, Jae-Kyung;Joo, Chang-Whan
    • Composites Research
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    • v.12 no.2
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    • pp.91-100
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    • 1999
  • The manufacture of high strength polyethylene(HSPE) tape yarns has been accomplished by a solid state processing(SSP) method as the compaction of ultra-high molecular weight polyethylene(UHMWPE) powders and drawing of the compacted film under the melting point without any organic solvents. In this study, the characteristics of HSPE tape yarns produced by SSP which is desirable for production cost and environmental aspect were analyzed. As the results, tensile strengths of HSPE tape yarns increased with increasing the draw ratio and the fracture morphology of highly drawn HSPE tape yarns showed more fibrillar shape than the low drawn one. Interfacial shear strengths of HSPE tape yarns with vinylester resin increased by $O_2$ plasma treatment and maximum interfacial shear strength was obtained in the plasma treatment condition of 100W and 5min. In addition, mechanical properties of HSPE tape yarn reinforced composites were investigated and compared with those of the gel spun HSPE fiber reinforced composites.

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An analytical model for PVC-FRP confined reinforced concrete columns under low cyclic loading

  • Fang, Yuan;Yu, Feng;Chen, Anchun;Wang, Shilong;Xu, Guoshi
    • Structural Engineering and Mechanics
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    • v.77 no.2
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    • pp.179-196
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    • 2021
  • Experimental investigations on the seismic behaviors of the PVC-FRP Confined Reinforced Concrete (PFCRC) columns under low cyclic loading are carried out and two variable parameters including CFRP strips spacing and axial compression ratio are considered. The PFCRC column finally fails by bending and is characterized by the crushing of concrete and yielding of the longitudinal reinforcement, and the column with a high axial compression ratio is also accompanied by the cracking of the PVC tube and the fracture of CFRP strips. The hysteretic curves and skeleton curves of the columns are obtained from the experimental data. With the increase of axial compression ratio, the stiffness degradation rate accelerates and the ductility decreases. With the decrease of CFRP strips spacing, the unloading sections of the skeleton curves become steep and the ductility reduces significantly. On the basis of fiber model method, a numerical analysis approach for predicting the skeleton curves of the PFCRC columns is developed. Additionally, a simplified skeleton curve including the elastic stage, strengthening stage and unloading stage is suggested depending on the geometric drawing method. Moreover, the loading and unloading rules of the PFCRC columns are revealed by analyzing the features of the skeleton curves. The quantitative expressions that are used to predict the unloading stiffness of the specimens in each stage are proposed. Eventually, an analytical model for the PFCRC columns under low cyclic loading is established and it agrees well with test data.

Low-cost Fiber Bragg Grating Interrogator Design for Unmanned Aircraft (무인 항공기를 위한 저가형 FBG 인터로게이터 설계)

  • Hong, Jae-Beom;Hong, Gyo-Young
    • Journal of Advanced Navigation Technology
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    • v.24 no.6
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    • pp.465-470
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    • 2020
  • Complex materials are widely used in aviation industries where lightweighting is essential because they have lighter properties than metals. However, composite materials can cause defects such as internal void formation, poor adhesive mixing, and non-adhesive parts during the production process, and there is a risk of micro-cracking and interlayer separation due to low energy impact. Therefore, a structural damage test is essential. As a result, structural integrity monitoring using FBG is drawing attention. Compared to conventional electrical sensors, FBG has the advantage of being more corrosion-resistant and multiplexed without being affected by electrical noise. However, interloggers measuring FBG are expensive and have a large disadvantage because they are made on the premise of measuring large structures. In this paper, low-cost interloggers were designed for use in unmanned or small aircraft using optical switche, WDM filter, and LTFs, and compared to conventional high-priced interrogator.

Effect of Processing Factors on the Properties of Melt-blown PP/Ba-ferrite Composite Fabrics (Melt-blown 방사에 의한 PP/Ba-ferrite 복합 부직포 제조시의 공정인자가 부직포의 특성에 미치는 영향)

  • Han, Jong-Hun;Lee, Dong-Jin;Lim, Hyung Mi;Lee, Seung-Ho;Oh, Sung Geoun
    • Applied Chemistry for Engineering
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    • v.17 no.3
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    • pp.267-273
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    • 2006
  • We have prepared PP/Ba-ferrite composite fabrics by a melt-blown spinning method and investigated the relationship between the properties of PP/Ba-ferrite composite fabrics and melt-blown processing factors. A PP composite containing Ba-ferrite as a magnetic particulate filler was prepared in the form of pellet from PP resin and Ba-ferrite powder by melt compounding using a single extruder. Screw turning force (rpm), DCD (die-to-collector distance), and Ba-ferrite content were changed. We measured diameters of fiber, mechanical, thermal, and magnetic properties for the composited PP fabrics. The elongation was increased and a fiber diameter and tensile strength were decreased as the spinning distance increased or screw turning force decreased. The crystallinity was increased with increasing spinning distance according to XRD. It was assumed that the orientation of crystalline domain in the neat PP without ferrite was increased by drawing in mechanical direction, however, the orientation in the PP composite was decreased according to XRD analysis. We measured a magnetic property of PP nonwoven fabric containing Ba-ferrite powder. A coercive force, maximum magnetization, and residual magnetization are reduced with the spinning distance. According to the result of TGA measurement, the heat resistance was increased with the Ba-ferrite powder content and with decreasing the spinning distance.

Characteristics of Shear Behavior of Reinforced Concrete Beams Strengthened with Near Surface Mounted CFRP Strips (CFRP 스트립 표면매립공법으로 보강된 철근콘크리트 보의 전단거동 특성)

  • Han, Sang Hoon;Hong, Ki Nam;Shin, Byoung Gil;Lim, Jin Mook;Kwak, So Shin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.5
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    • pp.178-189
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    • 2011
  • Tests and analyses were performed in this study to assess the shear strength of Reinforced Concrete(RC) members strengthened by the Near Surface Mounted(NSM) technique in shear, which is drawing attention as an alternative to the Carbon Fiber Reinforced Polymer(CFRP) bonding strengthening technique. Four-point bending tests were performed on 7 RC specimens without any shear reinforcement. The test variables such as the inclination of CFRP strip (45 degrees and 90 degrees), and the spacing of CFRP strip (250mm, 200mm, 150mm, 100mm) were considered. Through the testing scenarios, the effect of each test variable on the failure mode and the shear strength of the RC members strengthened by the NSM technique in shear were assessed. The test results show that the specimens with CFRP strips at 45 degrees go to failure as a result of the strip fracture, but the specimens with CFRP strips at 90 degrees go to failure as a result of the slip of strips. Strips at 45 degrees was the more effective than strips at 90 degrees, not only in terms of increasing beam shear resistance but also in assuring larger deformation capacity at beam failure. In addition, the RBSN analysis appropriately predicted the crack formation and the load-displacement response of the RC members strengthened by the NSM technique in shear.

An Analysis on the Effect of the Shape Features of the Textile Electrode on the Non-contact Type of Sensing of Cardiac Activity Based on the Magnetic-induced Conductivity Priciple (직물 전극의 형상 특성이 자계 유도성 전도율 기반의 비접촉식 심장활동 센싱에 미치는 효과의 분석)

  • Gi, Sun Ok;Lee, Young Jae;Koo, Hye Ran;Khang, Seon Ah;Park, Hee Jung;Kim, Kyeong Seop;Lee, Joo Hyeon;Lee, Jeong Whan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.6
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    • pp.803-810
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    • 2013
  • The purpose of this research is to analyze the effect of shape of the inductive textile electrode on the non-contact heart activity sensing, based on the magnetic-induced conductivity principle. Four types of the inductive textile electrodes were determined according to the combinations of the two shape features. A fiber-metal hybrid-typed conductive thread was developed and applied to materialization of the textile electrodes by embroidery method. The heart activity was extracted through the textile electrode sewn on a T-shirt. The experiments were implemented to constantly measure the heart activity for 20 seconds, in each case of 5 healthy male subjects. The heart activity signals acquired in each type of the inductive textile electrode were analyzed, 1)by drawing a comparison of morphology with those of ECG signal (LeadII), and 2)by calculation of the normalized mean and standard deviation of magnitude of the heart activity signals. The analysis resulted that the relatively better quality of signals were acquired in the 'square' types in the matter of whole shape, while the better results were obtained in 'donut' types in the matter of center hole. Accordingly, the relatively best quality of signals was obtained in the case of 'Square-Donut' type of the inductive textile electrode.

Current status of sweetpotato genomics research (고구마 유전체 연구현황 및 전망)

  • Yoon, Ung-Han;Jeong, Jae Cheol;Kwak, Sang-Soo;Yang, Jung-Wook;Kim, Tae-Ho;Lee, Hyeong-Un;Nam, Sang-Sik;Hahn, Jang-Ho
    • Journal of Plant Biotechnology
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    • v.42 no.3
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    • pp.161-167
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    • 2015
  • Sweetpotato [Ipomoea batatas (L.) Lam] grows well in harsh environmental conditions, and is cultivated as one of the top seven food crops in the world. Recently, sweetpotato is drawing interest from people as a healthy food because it is high in dietary fiber, vitamins, carotenoids and overall nutrition value. However, few studies have been conducted on sweetpotato genome sequencing in spite of its importance. This review is aimed at increasing the efficiency of sweetpotato genome sequencing research as well as establishing a base for gene utilization in order to control useful traits. Recently, animal and plant genome sequencing projects increased significantly. However, sweetpotato genome sequencing has not been performed due to polyploidy and heterogeneity problems in its genome. Meanwhile research on its transcriptome has been conducted actively. Recently, a draft of the diploid sweetpotato genome was reported in 2015 by Japanese researchers. In addition, the Korea-China-Japan Trilateral Research Association of Sweetpotato (TRAS) has conducted research on gene map construction and genome sequencing of the hexaploid sweetpotato Xushu 18 since 2014. The Bill & Melinda Gates Foundation launched the 'sweetpotato genomic sequencing to develop genomic tools for Sub-Sahara Africa breeding program'. The chloroplast genome sequence acquired during sweetpotato genome sequencing is used in evolutionary analyses. In this review, the trend of research in the sweetpotato genome sequencing was analyzed. Research trend analysis like this will provide researchers working toward sweetpotato productivity and nutrient improvement with information on the status of sweetpotato genome research. This will contribute to solving world food, energy and environmental problems.