• Title, Summary, Keyword: kevlar fiber

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Grafi Copolymerization of $\varepsilon$-Caprolactam onto Kevlar-49 Fiber Surface (Kevlar 49 섬유 표면에 대한 $\varepsilon$-Caprolactam의 Grafi 공중합에 관한 연구)

  • 김은영;강주영
    • Textile Science and Engineering
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    • v.32 no.4
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    • pp.412-419
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    • 1995
  • The graft copolymerization of ε-caprolactam onto Kevlar 49 fiber surface was carried out by the anionic chain addition of s-caprolactam to the N-metalated Kevlar. Studies have been made on the effects of reaction conditions on the wafiing percentage(GP) and on the tensile strength of the fiber. GP significantly increased with increasing metalation time, NaH concentration, polymerization temperature and time. The tensile strength of fiber decreased with increasing metalation time, NaH concentration, polymerization temperature and time. In order to retain over 90% of tensile strength of the original Kevlar 49 fiber and to increase over 20% of GP, the optimum reaction conditions are as follows: NaH concentration; ion; 4.2mmol/l/0.5g Kevlar, metalation time; 30min, monomer concentration; 5.04mol/l/0.5g Kevlar, polymerization temperature; 70℃, polymerization time; 10sec. The Young's modulus of N-metalated Kevlar 6ber showed lower values than that of the original Kevlar fiber. However, the Young's modulus increased with increasing GP.

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Chemical Modification of Kevlar-49 Fiber(III)-Characteristics of Grafted Kevlar-49 Fiber Reinforced Composite- (케블라 섬유의 화학적 개질(III) - Grafted Kevlar-49 섬유 보강 복합재료의 특성 -)

  • 김한도;김은영
    • Textile Science and Engineering
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    • v.33 no.8
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    • pp.729-735
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    • 1996
  • The discontinuous Kevlar fiber-reinforced composites which structure was random-in-plain fiber orientation were prepared by solvent-casting/melt processing method. The interfacial interaction of Kevlar fibers [original Kevlar tribe.(O-K), ac.olein-grafted Kevlar fibers(AL-g-K), methacrylonitrile-grafted Kevlar fiber(MAN-g-K)] with matrix polymers(Phenoxy, PMMA, and SAN) was investigated by dynamic mechanical analysis, thermomechanical analysis and FT-IR spectroscopy. In the dynamic mechanical analysis at 11 Hz, the storage modulus (E') and the decline temperature of were found to increase in the order of MAN-g-K, AL-g-K, and O-K. The tan peak temperature related to glass transition increased in the same order. By ther-momechanical analysis, the trends mentioned above were also seen for T obtained from the first displacement change as a function of temperature. However, the second transition which appeared at higher temperature may be due to interfacial interaction between the fiber and the matrix. Two onset temperatures of TMA displacement change increased also in the same order of MAN-g-K, AL-g-K, and O-K. By FT-IR spectroscopy, it was found that characteristic peaks(phenoxy : C-O-C(240 cm ), PMMA : C=O(1720 cm ), and SAN : C=N(2240 cm )) of composite films shifted to the amide peak (amide I: 1650 cm & amide II : 1540 cm ) of original Kevlar fiber, however, the amide peak of original and grafted Kevlar fibers of composites moved to the characteristic peaks of matrix polymers. From these results, it may be concluded that the interfacial interaction between reinforcement fibers and the matrix polymers (phenoxy, PMMA and SAN) increased in the order of MAN-g-K, AL-g-K and O-K.

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A Study on the Failure Modes of Neat Kevlar Fabric and Kevlar Liquid Armor Impregnated with Shear Thickening Fluid (케블라 직물과 전단농화유체로 함침된 케블라 액체 방탄재의 파단모드 연구)

  • Yoon, Byung-Il;Song, Heung-Sub;Paik, Jong-Gyu
    • Composites Research
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    • v.20 no.3
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    • pp.17-24
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    • 2007
  • In this study, the failure modes by ballistic impacts were studied both for a neat Kevlar woven fabric and a Kevlar liquid armor impregnated with shear thickening fluid (STF) containing silica particles. These two materials showed quite different failure modes macroscopically in ballistic impacts tests used by Cal.22 FSP and 9mm FMJ bullet. Yarn pull-out for the neat Kevlar woven fabric and yarn fracture occurred partially through all plies from 1st ply to last one for the STF-Kevlar are an important energy absorption mechanisms. The results observed by S.E.M showed commonly fiber damage which are torn skin in the longitudinal fiber direction, fiber split axially and fiber fracture for two materials. The reasons why STF-kevlar liquid armor material exhibits excellent ballistic performance are as follow: firstly the increased friction forces between yarn-yarn and fabric-fabric covered with silica particles and secondary the evolution of shear thickening phenomenmon resulting in suppression of yarn mobility.

A Study on the Physical Properties of Heat resistance and Cut resistance of Coating Gloves for Work

  • Pyo, Kyeong-Deok;Jung, Eugene;Park, Cha-Cheol
    • Elastomers and Composites
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    • v.54 no.2
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    • pp.91-96
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    • 2019
  • The purpose of this study was to examine the effect of different yarn twisting methods on physical properties. Plain single jersey structured fabrics were knitted from Kevlar yarn, and from Kevlar/HPPE, and from Kevlar/Basalt fiber, and from Kevlar/Glass fiber and Kevlar/Stainless steel fiber blended and core-spun yarns. and then, The fabrics were coated NBR Latex. The physical properties, including tear strength, modulus, degree of penetration, heat resistance, and cut resistance of the knitted fabrics were investigated and compared. Kevlar/HPPE blended yarn fabrics recorded the highest heat resistance (13 Sec.). and Kevlar/HPPE blended yarn fabrics had good cut resistance (Cut Level 4).

Graft Copolymerization of Methacrylonitrile(MAN) onto Kevlar 49 Fiber Surface (Kevlar 49 섬유 표면에 대한 MAN의 Graft 공중합에 관한 연구)

  • 김은영;강주영;최재혁;김한도
    • Textile Coloration and Finishing
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    • v.7 no.1
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    • pp.43-50
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    • 1995
  • The grafting of methacrylonitrile(MAN) onto Kevlar 49 filament surface was carried out by anionic polymerization using sodium methylsulfinylcarbanion formed from sodium hydride and dimethyl sulfoxide(DMSO). The effects of reaction conditions on the grafting percentage(GP) and on the tensile strength of the fiber were investgated. GP marktedly increased with increasing metalation time, and NaH concentration, polymerization temperature and time. The tensile strength of fiber decrased with increasing metalation time, and NaH concentration, polymerization temperature and time. The optimum conditions to increase over 40% of GP with below 10% reduction rate of tensile strength of fiber : NaH concentration ; 30.6 mmol/l/0.5g Kevlar, metalation time : 10min, polymerization tempera- ture : 5$0^{\circ}C$, polymerization time: 20 sec, monomer concentration : 1.12mol/l/0.5g Kevlar.

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Nondestructive Microfailure and Interfacial Evaluation of Plasma-Treated PBO and Kevlar Fibers/Epoxy Composites using Micromechanical Test and Acoustic Emission (Micromechanical 시험법과 음향방출을 이용한 플라즈마 처리된 PBO와 Kevlar 섬유강화 Epoxy 복합재료의 비파괴적 파단특성 및 계면물성 평가)

  • 박종만;김대식;김성룡
    • Composites Research
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    • v.16 no.4
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    • pp.74-79
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    • 2003
  • Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole(PBO. Zylon) and poly(p-phenylene terephthalamide)(PPTA, Kevlar) fibers/ epoxy composites were investigated using micromechanical technique and nondestructive acoustic emission(AE). Interfacial shear strength(IFSS) and work of adhesion, Wa of PBO or Kevlar fibers/epoxy composites increased by oxygen-plasma treatment. Plasma-treated Kevlar fiber shooed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum value. Microfibril fracture pattern of plasma-treated Kevlar fiber appeared obviously. Based on the propagation of microfibril failure toward core region. the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly. The results oi nondestructive AE were consistent well with microfailure modes by optical observation in microdroplet and two-fiber composites tests.

Effect of Moisture and Thermal fatigue on the Mechanical Properties of Composites (수분과 열피로에 의한 복합재료의 물성변화에 대한 연구)

  • 최영호;강태진;이경우
    • Textile Science and Engineering
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    • v.37 no.5
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    • pp.273-279
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    • 2000
  • Changes in the mechanical properties of Kevlar/epoxy and glass/epoxy composites with increasing immerision time have been studied. Kevlar/epoxy composite showed poorer mechanical properties than glass/epoxy composite with increasing immersion time in water. This is because Kevlar/epoxy absorbed more water than glass/epoxy composite did. Effect of thermal fatigue on the mechanical properties of kevlar/Spectra hybrid composite has also been studied. Strength of hybrid composite showed a sharp decrease with increasing thermal fatigue cycle due to the decrease in interfacial strength between fiber and matrix.

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Ballistic Resistance Performance of Kevlar Fabric Impregnated with Shear Thickening Fluid (전단농화유체가 함침된 Kevlar 재료의 방탄특성)

  • Song, Heung-Sub;Yoon, Byung-Il;Kim, Chang-Yun;Park, Jong-Lyul;Kang, Tae-Tin
    • Composites Research
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    • v.20 no.3
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    • pp.1-7
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    • 2007
  • Manufacturing process of the shear thickening fluid(STF) and evaluation of the ballistic penetration resistance performance of the Kevlar-STF composites were studied. STF was made from silica and ethylene glycol, and the Kevlar-STF composite was made by impregnating the STF into the Kevlar fabric. Specimens including neat Kevlar woven fabrics and Kevlar-STF composites with two types of silica were prepared and carried out the ballistic tests. From the results STFs represented shear thickening behavior irrespective of the silica type, and Kevlar-STF composite with spherical silica showed best ballistic penetration resistance performance among them. Especially the specimens of Kevlar-STF composites with spherical silica showed radial fiber deformation by the projectile during the tests, that was somewhat different deformation behavior from those of the neat Kevlar fabrics shown fiber pull-out phenomena or fracture.

Chemical Modification of Kevlar Fiber Surface (Kevlar 섬유 표면의 화학 개질(I))

  • 최재혁;강주영
    • Textile Science and Engineering
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    • v.32 no.2
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    • pp.158-165
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    • 1995
  • To enhance interfacial adhesion between matrix polymer and Kevalr 49 fiber for composites, amino groups(-NH2) have been incorporated into Kevlar 49 fiber surface by bromination f311owe6 by amination. The number of amino groups per 100A2 fiber surface remarkably increased with increasing reaction time and temperature, and the concentration of N-bromosuccinimide(NBS) , ethylene diamine(EDA) and sodium amide. Tensile strength loss of the fiber on bromination was negligible, however, the significant strength loss of the fiber was observed in case of the high -NH2 content produced by severe reaction condition of amination, in which reaction may have occurred beneath the surface artier disruption of the structure. Pretreating the fiber with N, N-dimethylacetamide (DMAc) before bromination was effective to enhance the number of amino Voups. The optimum concentration of amination has been established to reduce down to about 10% of tensile strength loss. Grail copolymers of nylon 66 onto aminated Kevlar 49 fiber surface were prepared by the polycondensation reaction of amino Voup and acid chloride by dipping the aminated fiber into DMAc solution of adipoyl chloride and then into DMAc solution of hexamethylene diamine consecutively. The grafting percentage increased with increasing number of repeating reactions and reaction time.

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Fracture Behavior and Weibull Distribution Fitness of High Tenacity Fibers (고장도 섬유의 파단 거동과 인장 특성에 와이블 분포의 적합성)

  • Lee, Sun-Geun;Ju, Chang-Hwan;Lee, Gi-Yun
    • Textile Science and Engineering
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    • v.30 no.12
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    • pp.942-951
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    • 1993
  • The effect of strain rate and gauge length on the Weihull distribution fitness of Kevlar fibers and the influence of twist density on the fracture behavior of high tenacity fibers such as Kevlar, glass and carbon liber were studied to characterize the specialty fibers. For fitting the Weibull distribution, two experimental conditions were used. One was that strain rate was changed to 0.01. 0.04. 0.1, 0.4, 1.0 min-1 with constant gauge length(50mm) and the other was that the strain rate was kept constant at 0.1 min-1 with different gauge lengths(i.e., 10. 50. 100. 200mm). The results obtained in this study are as follows 1) The strength of Kevlar fibers increased with increasing strain rate and the trend was well fitted to Weibull distribution with various strain rates. 2) The strength of Kevlar liberal dccrcased with increasing gauge length. Especially, when gauge length Increased from 10mm to 50mm. the strength value decreased conspicuously about 12.1% and Weibull distribution was well fitted for strength values with various gauge lengths. 3) The fracture mechanism of high tenacity fibers with twist density showed that the dislocation and/or flaw took place on the fiber surface and the crack developed along fiber axis. Also, the failure shape of Kevlar fiber had long fibrils, but glass antral carbon fiber had the brittle fracture in fixed direction.

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