• Title/Summary/Keyword: C/Glass Composites

Search Result 252, Processing Time 0.027 seconds

A study on the structural changes and the TSC characteristics of epoxy composites cured with acid-anhydride (산무수물 경화된 에폭시 복합체의 구조변화와 TSC특성에 관한 연구)

  • 왕종배;이준웅
    • Electrical & Electronic Materials
    • /
    • v.7 no.1
    • /
    • pp.32-41
    • /
    • 1994
  • In this study, the TSC spectroscopy has been applied to investigate the influence of structural change due to a process of curing reaction on the electrical properties of epoxy composites cured with acid-anhydride. Five TSC peaks appeared in -160-250[.deg.C]: in the low temperature region below glass transition temperature(T$\_$g/), three relaxation mode peaks due to action of side chains, substitution group or terminal groups have been observed, a peak associated with T$\_$g/, appeared in 110[.deg. C] and p peak due to ionic space charges located in 150[.deg.C]. Each peak was separated into elementary peaks by the partial polarization procedure, and the distribution of activation energy and relaxation time were analized to clearify the origin of each peak. Also, overaboundantly added hardener separated a .betha. peak near 10[.deg. C] into two peaks of .betha.$\_$1/(10.deg. C) and .betha.$\_$2/(20.deg. C) according to increasement of forming field, and the separated hardener was oxidated thermally with increasing surrounding temperatures. The expansion of the free volume need in molecular motion and the reduction of the structural packing density through thermal oxidation process increased TSC between .alpha. peak and .betha. peak and decreased T$\_$g/.

  • PDF

Green Composites. I. Physical Properties of Ramie Fibers for Environment-friendly Green Composites

  • Nam Sung-Hyun;Netravali Anil N.
    • Fibers and Polymers
    • /
    • v.7 no.4
    • /
    • pp.372-379
    • /
    • 2006
  • The surface topography, tensile properties, and thermal properties of ramie fibers were investigated as reinforcement for fully biodegradable and environmental-friendly 'green' composites. SEM micrographs of a longitudinal and cross sectional view of a single ramie fiber showed a fibrillar structure and rough surface with irregular cross-section, which is considered to provide good interfacial adhesion with polymer resin in composites. An average tensile strength, Young's modulus, and fracture strain of ramie fibers were measured to be 627 MPa, 31.8 GPa, and 2.7 %, respectively. The specific tensile properties of the ramie fiber calculated per unit density were found to be comparable to those of E-glass fibers. Ramie fibers exhibited good thermal stability after aging up to $160^{\circ}C$ with no decrease in tensile strength or Young's modulus. However, at temperatures higher than $160^{\circ}C$ the tensile strength decreased significantly and its fracture behavior was also affected. The moisture content of the ramie fiber was 9.9 %. These properties make ramie fibers suitable as reinforcement for 'green' composites. Also, the green composites can be fabricated at temperatures up to $160^{\circ}C$ without reducing the fiber properties.

A Viscoelastic Study of Glass Transition and Degradation Processes of Phenolic Resin/Carbon Fiber Composites (페놀수지/탄소섬유 열경화성 복합재료의 유리전이와 고온 분해과정에서 관찰되는 점탄성 특성 연구)

  • ;J. C. Seferis
    • The Korean Journal of Rheology
    • /
    • v.11 no.1
    • /
    • pp.9-17
    • /
    • 1999
  • Viscoelastic characteristics of cured phenolic resin/carbon fiber composite materials were investigated through glass transition and degradation reaction processes in the high temperature region up to $400^{\circ}C$. A typical glass transition of the cross-linked thermoset polymer was followed by irreversible degradation reactions, which were exhibited by the increasing storage modulus and loss modulus peak. A degradation master curve was constructed by using the vertical and horizontal shift factors, both of which complied well with the Arrhenius equation in light of the kinetic expression of degradation rate constants. Using an analogy to the Havriliak-Negami equation in dielectric relaxation phenomena, a viscoelastic modeling methodology was developed to characterize the frequency- and temperature-dependent complex moduli of the degrading thermoset polymer composite systems. The temperature-dependent relaxation time of the degrading composites was determined in a continuous fashion and showed a minimum relaxation time between the glass transition and degradation reaction regions. The capability of the developed modeling methodology was demonstrated by describing the complex behavior of the viscoelastic complex moduli of reacting phenolic resin composite systems.

  • PDF

Influence of Moisture Absorption on the Mechanical Properties in the Laminated Composites (적층형 복합재료의 기계적 성질에 미치는 수분의 영향)

  • Moon, Chang-Kwan;Choi, Hee-Lark;Lee, Bong
    • Journal of Ocean Engineering and Technology
    • /
    • v.14 no.3
    • /
    • pp.90-99
    • /
    • 2000
  • This study has been investigated about the influence of moisture environment properties in the unidirectional and cross laminated carbon fiber/epoxy and glass fiber/epoxy composites. As a results, it was found that the weight gain of water increased with the immersion time and the mechanical properties were decreased with the weight gain of water. And it was also shown that the mechanical properties of carbon fiber/epoxy laminates were better than those of glass fiber/epoxy laminates. And a gap of the mechanical properties between the two kinds of laminates was increasing with the immersion time in distilled water of 80$^{\circ}C $. Mechanical properties which decreased by moisture absorption in the CF and GF reinforced laminates were recovered up to some extent by drying in oven at 80$^{\circ}C $ for 10 days.

  • PDF

A study on abrasive wear characteristics of side plate of FRP ship (FRP 선박 외판재의 연삭마모 특성에 관한 연구)

  • Kim, Byung-Tak;Koh, Sung-Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.44 no.3
    • /
    • pp.250-256
    • /
    • 2008
  • Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

Formation of $Al_2O_3$-Ceramics by Reactive Infiltration of Al-alloy into Insulation Fiber Board (Al-합금의 단열섬유판 반응침투에 의한 $Al_2O_3$-세라믹스의 형성)

  • 김일수
    • Journal of the Korean Ceramic Society
    • /
    • v.34 no.5
    • /
    • pp.483-490
    • /
    • 1997
  • Al2O3/metal composites were fabricated by oxidation and reaction of molten Al-alloy into two types of commercial Al2O3-SiO2 fibrous insulation board. The growth rate, composition and microstructure of these materials were described. An AlZnMg(7075) alloy was selected as a parent alloy. Mixed polycrystalline fiber and glass phase fiber were used as a filler. The growth surface of an alloy was covered with and without SiO2. SiO2 powder was employed as a surface dopant to aid initial oxidation of Al-alloy. Al-alloy, SiO2, fiber block and growth inhibitor CaSiO3 were packed sequentially in a alumina crucible and oxidized in air at temperature range 90$0^{\circ}C$ to 120$0^{\circ}C$. The growth rate of composite layer was calculated by measuring the mass increasement(g) per unit surface($\textrm{cm}^2$). XRD and optical microscope were used to investigate the composition and phase of composites. The composite grown at 120$0^{\circ}C$ and with SiO2 dopant showed rapid growth rate. The growth behavior differed a little depending on the types of fiber used. The composites consist of $\alpha$-Al2O3, Al, Si and pore. The composite grown at 100$0^{\circ}C$ exhibited better microstructure compared to that grown at 120$0^{\circ}C$.

  • PDF

A Study on the Dielectric Properties of Epoxy Composites with Frequency Variation (주파수 변화에 따른 에폭시 복합체의 유전특성에 관한 연구)

  • 김상걸;이동규;안준호;이상극;오현석;박건호;박우현;이기식;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2001.07a
    • /
    • pp.813-816
    • /
    • 2001
  • In this paper, the dielectric properties of epoxy composites used for transformers are studied. The dielectric permittivity and loss of specimen are measured at the frequency range of 30[Hz]∼1[MHz] about temperature 20[$^{\circ}C$],100[$^{\circ}C$] and 140[$^{\circ}C$] respectively from a series of experiments. When the filler is added, between epoxy and silica is formed interface. Therefore, observed higher values of dielectric permittivity and loss in filled epoxy are attributed to MWS polarization effect. Also, glass transition temperature was shifted to higher temperature and value of dielectric permittivity and loss were decreased due to 2nd curing. Deformation of interfacial state is improved and value of dielectric permittivity and loss were decreased at low frequency region by the surface treatment of fillers with silane coupling agents.

  • PDF

Effect of Additive Composition on Fracture Toughness of In Situ-Toughened SiC−Si3N4 Composites

  • Lee, Young-Il;Kim, Young-Wook
    • Journal of the Korean Ceramic Society
    • /
    • v.44 no.4 s.299
    • /
    • pp.189-193
    • /
    • 2007
  • Effect of additive composition on fracture toughness of in situ-toughened $SiC-Si_3N_4$ composites was investigated for five different additive compositions. The highest toughness $(6.4MPa{\cdot}m^{1/2})\;in\;SiC-Si_3N_4$ composites investigated herein was obtained when an Y-Mg-Si-Al-O-N oxynitride glass was used as a sintering additive. The improvement in fracture toughness was produced by enhanced bridging and deflection by $Si_3N_4$ grains.

Surface properties of epoxy/glass Eber composites by environmental conditions (사용 환경조건에 따른 Epoxy/Glass Fiber 복합재료의 표면특성)

  • 임경범;이백수;황명환;김윤선;유도현;이덕출
    • Journal of the Korean Vacuum Society
    • /
    • v.9 no.3
    • /
    • pp.279-284
    • /
    • 2000
  • In order to analysis the degradation process of epoxy/glass fiber for outdoor condition, FRP laminate was exposed to high temperature and water. Then the degradation process was evaluated by comparing contact angle, surface potential decay, and surface resistivity. For the change of wettability, the contact angle of thermal-treated specimen with the high temperature of $200^{\circ}C$ increased. But that of water-treated specimen decreased. The characteristic of surface potential decay shows the tendency of the remarkable decrease on water-treated specimens, but increase on thermal-treated specimen compared with untreated one. Also, for the surface resistivity, it shows the same trend compared with the change of contact angle.

  • PDF

SALS Study on Transcrystallization and Fiber Orientation in Glass Fiber/Polypropylene Composites

  • Na, Kun;Park, Han-Soo;Won, Hong-Youn;Lee, Jong-Kwan;Lee, Kwang-Hee;Nam, Joo-Young;Jin, Byung-Suk
    • Macromolecular Research
    • /
    • v.14 no.5
    • /
    • pp.499-503
    • /
    • 2006
  • This report presents a new technical approach for evaluating the fiber orientation of composites using small-angle light scattering (SALS). Glass fiber (GF)/polypropylene (PP) composites with different fiber orientations were prepared by drawing compression-molded specimens. The drawn samples were remelted and then annealed at $150^{\circ}C$ in order to induce a crystalline structure on the fiber surface, and then underwent SALS analysis. The samples showed a combination of circular and streak patterns. The model calculations demonstrated that the number of nuclei on the fiber surface and the thickness of the transcrystalline layer affected the sharpness and intensity of the streak pattern. In addition, the azimuthal angle of the streak pattern was found to be dependent on the direction of the transcrystalline layer, which correlated with the fiber direction. This correlation suggests that the fiber orientation in the composites can be easily evaluated using SALS.