Composites Research

The Korean Society for Composite Materials (한국복합재료학회)
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Study on the Flow Characteristics of the Epoxy Resin w.r.t. Sizing Materials of Carbon Fibers

탄소섬유 사이징에 따른 에폭시 수지 유동 특성에 관한 연구

  • Received : 2018.07.31
  • Accepted : 2018.11.01
  • Published : 2018.12.31
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Abstract

This paper aims to study flow characteristics of epoxy resin w.r.t. the sizing agents treated on the carbon fibers which have the same surface morphologies before sizing treatment. Dynamic contact angle (DCA) was measured to evaluate wettability of a single carbon fiber. Wicking test and Vacuum Assisted Resin Transfer Molding (VARTM) were performed to find relation between DCA measurement results and impregnation characteristics. In addition, surface properties of the carbon fibers such as surface free energy and chemical compositions were measured and interfacial shear strength (IFSS) between the carbon fiber and the resin were experimentally characterized by using micro-droplet tests. According to these experimental results, the sizing agent for carbon fibers should have appropriate level of surface free energy and good chemical compatibility with the resin to reconcile resin flow characteristics and interfacial strength.

본 연구에서는 동일한 표면 형태를 가지는 탄소섬유에 다양한 사이징제를 처리함에 따라 발생하는 에폭 시 수지의 유동 특성 변화를 분석하였다. 동적 접촉각(DCA) 측정을 통해 단일 탄소섬유의 젖음성(Wettability)을 측정하였다. DCA 측정 결과와 함침 특성 간의 연관성을 살피기 위해 Wicking test와 VARTM test를 수행하였다. 추가적으로, 탄소섬유의 표면 에너지 등 다양한 표면 특성을 분석하였으며 Micro-droplet test를 통해 수지와 탄소섬유계면의 계면전단강도를 측정하였다. 이러한 실험 결과를 기반으로, 함침 속도의 증대를 위해서는 탄소섬유의 사이징제가 적정 수준의 표면 에너지를 가져야 하며, 사이징제의 화학적 조성을 조정하여 에폭시 수지의 유동 특성과 계면전단강도가 모두 개선 가능함을 확인하였다.

Keywords

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Fig. 1. DCA measurement setup

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Fig. 2. Wicking test setup

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Fig. 3. VARTM test setup

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Fig. 4. Mold configuration

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Fig. 5. Surface free energy of Neat CF

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Fig. 6. Interfacial shear strength of Neat CF

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Fig. 7. DCA measurement Experimental case 1

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Fig. 8. DCA measurement Experimental case 2 (Test liquid : Distilled water)

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Fig. 9. DCA measurement Experimental case 2 (Test liquid :Epoxy resin)

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Fig. 10. DCA measurement Experimental case 2 (Test liquid :Epoxy resin & Hardener solution)

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Fig. 11. Wicking test results; (a) A-NCF, (b) B-NCF, (c) C-NCF

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Fig. 12. VARTM test results

Table 1. Carbon fiber and fabric

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Table 2. Plasma treatment condition

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References

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