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Effects of Sizing Treatment of Carbon Fibers on Mechanical Interfacial Properties of Nylon 6 Matrix Composites (탄소섬유의 사이징처리가 탄소섬유/나일론6 복합재료의 기계적 계면 특성에 미치는 영향)

  • Park, Soo-Jin;Choi, Woong-Ki;Kim, Byung-Joo;Min, Byung-Gak;Bae, Kyong-Min
    • Elastomers and Composites
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    • v.45 no.1
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    • pp.2-6
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    • 2010
  • The sizing treatments of PAN-based carbon fiber surfaces were carried out in order to improve the interfacial adhesion in the carbon fibers/nylon6 composite system. The parameter to characterize the wetting performance and surface free energy of the sized fibers were determined by a contact angle method. The mechanical interfacial properties of the composites were investigated using critical stress intensity factor ($K_{IC}$). The cross-section morphologies of sized CFs/nylon6composites were observed by SEM. As the experimental results, it was observed that silane-based sizing treated carbon fibers showed higher surface free energies than other sizing treatments. In particular, the KIC of the sizing-treated carbon fibers reinforced composites showed higher values than those of untreated carbon fibers-reinforced composites. This result indicated that the increase in the surface free energy of the fibers leads to the improvement of the mechanical interfacial properties of carbon fibers/nylon6 composites.

In vitro Degradation of β-TCP/PLGA Composites Prepared with Microwave Energy in Simulated Body Fluid (마이크로파에 의해 합성된 β-TCP/PLGA 복합체의 의사체액에서의 분해 거동)

  • Jin, Hyeong-Ho;Min, Sang-Ho;Hyun, Yong-Taek;Park, Hong-Chae;Yoon, Seog-Young
    • Korean Journal of Materials Research
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    • v.16 no.11
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    • pp.676-680
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    • 2006
  • The biodegradable $\beta$-tricalcium phosphate ($\beta$-TCP)/poly(lactide-co-glycolide) (PLGA) composites were synthesized by in situ polymerization with microwave energy. The degradation behavior of $\beta$-TCP/PLGA composite was investigated by soaking in simulated body fluid (SBF) for 4 weeks. The molecular weight of the $\beta$-TCP/PLGA composites decreased with soaking time until week 2, whereas the loss rate of molecular weight reduced after week 2. The incubation time was needed for the degradation of the $\beta$-TCP, indicating that the $\beta$-TCP should be detached from the PLGA matrix and then degraded into SBF solution. The studies of mass loss of the composites with the soaking time revealed that the degradation behavior of PLGA would be processed with the transformation from the polymer to the oligomer followed by the degradation. Morphological changes, whisker-like, due to transformation and degradation of polymer in the composites were observed after week 2. On the basis of the results, it found that the degradation behavior of $\beta$-TCP/PLGA composites was influenced by the $\beta$-TCP content in the composites and the degradation rate of the composites could be controlled by the initial molecular weight of PLGA in the composites.

Processing and Characterization of Polyamide 610/Carbon Fiber/Carbon Nanotube Composites through In-Situ Interfacial Polymerization (계면중합법을 이용한 폴리아마이드 610/탄소섬유/탄소나노튜브 복합재 제조 및 물성 평가)

  • Cho, Beom-Gon;Hwang, Sang-Ha;Park, Young-Bin
    • Composites Research
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    • v.33 no.6
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    • pp.415-420
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    • 2020
  • The interfacial properties in carbon fiber composites, which control the overall mechanical properties of the composites, are very important. Effective interface enhancement work is conducted on the modification of the carbon fiber surface with carbon nanotubes (CNTs). Nonetheless, most surface modifications methods do have their own drawbacks such as high temperatures with a range of 600~1000℃, which should be implemented for CNT growth on carbon fibers that can cause carbon fiber damages affecting deterioration of composites properties. This study includes the use of in-situ interfacial polymerization of polyamide 610/CNT to fabricate the carbon fiber composites. The process is very fast and continuous and can disperse CNTs with random orientation in the interface resulting in enhanced interfacial properties. Scanning electron microscopy was conducted to investigate the CNT dispersion and composites morphology, and the thermal stability of the composites was analyzed via thermogravimetric analysis. In addition, fiber pull-out tests were used to assess interfacial strength between fiber and matrix.

Predicting ESP and HNT effects on the mechanical properties of eco-friendly composites subjected to micro-indentation test

  • Saeed Kamarian;Ali Khalvandi;Thanh Mai Nguyen Tran;Reza Barbaz-Isfahani;Saeed Saber-Samandari;Jung-Il Song
    • Advances in nano research
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    • v.15 no.4
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    • pp.315-328
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    • 2023
  • The main goal of the present study was to assess the effects of eggshell powder (ESP) and halloysite nanotubes (HNTs) on the mechanical properties of abaca fiber (AF)-reinforced natural composites. For this purpose, a limited number of indentation tests were first performed on the AF/polypropylene (PP) composites for different HNT and ESP loadings (0 wt.% ~ 6 wt.%), load amplitudes (150, 200, and 250 N), and two types of indenters (Vickers or conical). The Young's modulus, hardness and plasticity index of each specimen were calculated using the indentation test results and Oliver-Pharr method. The accuracy of the experimental results was confirmed by comparing the values of the Young's modulus obtained from the indentation test with the results of the conventional tensile test. Then, a feed-forward shallow artificial neural network (ANN) with high efficiency was trained based on the obtained experimental data. The trained ANN could properly predict the variations of the mentioned mechanical properties of AF/PP composites incorporated with different HNT and ESP loadings. Furthermore, the trained ANN demonstrated that HNTs increase the elastic modulus and hardness of the composite, while the incorporation of ESP reduces these properties. For instance, the Young's modulus of composites incorporated with 3 wt.% of ESP decreased by 30.7% compared with the pure composite, while increasing the weight fraction of ESP up to 6% decreased the Young's modulus by 34.8%. Moreover, the trained ANN indicated that HNTs have a more significant effect on reducing the plasticity index than ESP.

Microstructure of Squeeze Cast AC4A $Al/Al_2O_3+SiC_p$ Hybrid Metal Matrix Composite (용탕단조한 AC4A $Al/Al_2O_3+SiC_p$ 하이브리드 금속복합재료의 미세조직과 기계적 성질)

  • Kim, Min-Soo;Cho, Kyung-Mox;Park, Ik-Min
    • Journal of Korea Foundry Society
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    • v.14 no.3
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    • pp.258-266
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    • 1994
  • AC4A $Al/Al_2O_3+SiC_p$ hybrid composites were fabricated by the squeeze infiltration technique. Effect of applied pressure, volume fraction of reinforcement($Al_2O_3$ and SiC) and SiC particle size($4.5{\mu}m$, $6.5{\mu}m$ and $9.3{\mu}m$) on the solidification microstructure of the hybrid composites were examined. Mechanical properties were estimated preliminarly by fractographic observation, hardness measurement and wear test. Results show that the microstructure of the hybrid composites were quite satisfactory, namely revealing relatively uniform distribution of reinforcements and refined matrix. Some aggregation of SiC particle caused by particle pushing was observed especially in the hybrid composites containg in fine particle($4.5{\mu}m$). Refined matrix was attributed to applied pressure and increased nucleation sites with addition of reinforcements. Fractured facet also revealed finer for the hybrid composites possibly due to refined matrix. Hardness and wear resistance increased with volume fraction of reinforcements. For hybrid composites with $9.3{\mu}m$ SiC, hardness was somewhat lower and wear resistance higher than other composites.

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Constitutive Equations Based on Cell Modeling Method for 3D Circular Braided Glass Fiber Reinforced Composites

  • Lee, Wonoh;Kim, Ji Hoon;Shin, Heon-Jung;Chung, Kwansoo;Kang, Tae Jin;Youn, Jae Ryoun
    • Fibers and Polymers
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    • v.4 no.2
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    • pp.77-83
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    • 2003
  • The cell modeling homogenization method to derive the constitutive equation considering the microstructures of the fiber reinforced composites has been previously developed for composites with simple microstructures such as 2D plane composites and 3D rectangular shaped composites. Here, the method has been further extended for 3D circular braided com-posites, utilizing B-spline curves to properly describe the more complex geometry of 3D braided composites. For verification purposes, the method has been applied for orthotropic elastic properties of the 3D circular braided glass fiber reinforced com-posite, in particular for the tensile property. Prepregs of the specimen have been fabricated using the 3D braiding machine through RTM (resin transfer molding) with epoxy as a matrix. Experimentally measured uniaxial tensile properties agreed well with predicted values obtained for two volume fractions.

Microwave Dielectric Properties of MgTiO3, MgTa2O6/Polytetrafluoroethylene Composite

  • Jeon, Chang-Jun;Kim, Eung-Soo
    • Journal of the Korean Ceramic Society
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    • v.49 no.3
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    • pp.272-278
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    • 2012
  • Effects of ceramics on the microwave dielectric properties of polytetrafluoroethylene (PTFE) composites filled with $MgTiO_3$ (MTi) and/or $MgTa_2O_6$ (MTa) were investigated. The dielectric constant ($K$), quality factor ($Qf$), and temperature coefficient of resonant frequency ($TCF$) of the composites were dependent on the type and volume fraction ($V_f$) of the ceramics. For the composites mixed with MTa and MTi, the $K$ and $TCF$ values decreased with increasing MTi content. The $Qf$ values of the composites were affected by relative density. The measured $K$ values of the composites were compared with those predicted by several theoretical models. Good microwave dielectric properties with values of $K$=3.6, $Qf$ = 7,788 GHz, and $TCF$ = -0.19 ppm/$^{\circ}C$ were obtained for the composites with 0.1 $V_f$ ceramics (mixed 0.025MTa and 0.075MTi).

Experimental Study on Thermal and Mechanical Characteristics of Two Resin Composites Using the Co-Curing Process (동시 경화 제작기법을 적용한 이종 수지 복합재의 열적/기계적 특성에 관한 실험적 연구)

  • Yoon, Jin-Young;Choi, Jiduck;Park, Cheolyong;Kim, Younggyu
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.5
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    • pp.475-484
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    • 2020
  • Individual curing process of each layer in two resin composites can be caused the separation between two layers. In this study, co-curing process for two resin composites is suggested to improve the inter-layer bonding. Glass fiber reinforced composites with phenolic and epoxy resins were manufactured by co-curing process, and several types of glass/phenolic composites were considered to confirm the application on two resin composites. Experiments for smoke resistance, scratch resistance and flexural strength were carried out to verify requirements corresponding to thermal and mechanical environments. It was validated that two resin composites with phenolic resin impregnated prepreg exhibits good thermal and mechanical characteristics, and it can serve as highly effective composite structures in aerospace and many industry areas.

Evaluation of Carbon Fiber distribution in Unidirectional CF/Al Composites by Two-Dimensional Spatial Distribution Method

  • Lee, Moonhee;Kim, Sungwon;Lee, Jongho;Hwang, SeungKuk;Lee, Sangpill;Sugio, Kenjiro;Sasaki, Gen
    • Journal of the Korean Society of Industry Convergence
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    • v.21 no.1
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    • pp.29-36
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    • 2018
  • Low pressure casting process for unidirectional carbon fiber reinforced aluminum (UD-CF/Al) composites which is an infiltration route of molten Al into porous UD-CF preform has been a cost-effective way to obtain metal matrix composites (MMCs) but, easy to cause non-uniform fiber distribution as CF clustering. Such clustered CFs have been a problem to decrease the density and thermal conductivity (TC) of composites, due to the existence of pores in the clustered area. To obtain high thermal performance composites for heat-sink application, the relationship between fiber distribution and porosity has to be clearly investigated. In this study, the CF distribution was evaluated with quantification approach by using two-dimensional spatial distribution method as local number 2-dimension (LN2D) analysis. Note that the CFs distribution in composites sensitively changed by sizes of Cu bridging particles between the CFs added in the UD-CF preform fabrication stage, and influenced on only $LN2D_{var}$ values.

Reheating Process of Metal Matrix Composites Fabricated by Combined Stirring Process for Thixoforming (복합교반법으로 제조한 금속복합재료의 Thixoforming용 재가열공정)

  • 이동건;강충길
    • Transactions of Materials Processing
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    • v.11 no.1
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    • pp.45-53
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    • 2002
  • The forming process of metal matrix composites by die casting and squeeze casting process are limited in size and dimension In term of final parts. The melt strirring method have the problems that the homogeneous distribution of the reinforcements is difficult due to the low weldability and the density difference between the molten metal and the reinforcement. The thixoforming process for metal matrix composites has numerous advantages compacted to die casting, squeeze casting and compocasting. However, for the thixofoming process, the billet with the desired volume fraction must be heated to obtain a uniform temperature distribution over the entire cross-sectional areas. To obtain the reheating conditions of composites, the particulate reinforced metal matrix composites for thixoforming were fabricated by combined stirring process which is simultaneously performed with electro-magnetic stirring and mechanical stirring process. The matrix alloy and reinforcement are used to aluminum alloy(A357) and SiCp with diameter 14, $25{\mu}m$, respectively. The microstructure characteristics were investigated by changing the volume fraction and reinforcement size. The heating conditions to obtain the uniform temperature distribution in cross section area of fabricated metal matrix composites billet are proposed with heating time, the heating temperature and the holding time.