Wettability is the property that quantifies the propensity of a solid surface (carbon fiber) to be covered by a liquid (resin). For a wettable solid, the solid-liquid contact is favoured and as a result the liquid spreads on such surface of the solid. Spreading of the liquid on the solid surface is primarily driven by the adhesive forces between the liquid and the solid, while the inter molecular cohesive forces of the liquid molecules prevent spreading and keep the liquid confined.  Wettability of the carbon fibers, namely, NX90, NX100, M55J, T700SC, CCF800H and T800HB, was determined using Wilhelmy balance method with resin test liquids, like, HY, cyanate ester, AG80, E51 and other test liquids, like, glycerol and 1-bromonapthalene.  Among all the CF-resin combinations tested for composite applications, T700SC-HY stood out with the lowest dynamic contact angle (DCA, 22.9°) and correspondingly highest wettability followed by M55J-cyanate ester and M55J-AG80.  PAN based fibers showed higher wettability (lower DCA values) compared to pitch based counter parts.  Among pitch based fibers-resin composites, NX90-HY showed the lowest DCA (55°) and so the highest wettability and this combination is recommended for the production of CFRC’s with strong interface and highest load bearing capability.  For the preparation of single filaments from the carbon fiber tows, in the course of sample preparation for the DCA measurements, it is recommended that the pitch based CFs, namely, NX90 and NX100 be wetted with a few mL of ethanol that facilitates the easy separation of CFs by making the sizing (DGEBA polymer) compound on the surface expand and thereby weakening the binding between adjacent pitch based fibers in the carbon fiber tows.  Such a measure would save time and prevent the testing of patience of the researcher.

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1. Sarkar S, Roy T, Roy A, et al. Revisiting the supplementary relationship of dynamic contact angles measured by Sessile-droplet and captive-bubble methods: Role of surface roughness. J Colloid Interface Sci. 2021; 581:690-7p.
2. Wang CY, Nair S, Wynne KJ. Wilhelmy balance characterization beyond contact angles: Differentiating leaching from nanosurface reorganization and optimizing surface modification. Polymer. 2017; 116:565-71p.
3. https://www.kibron.com/dynamic-contact-angle
4. Yang CC, Zhu DD, Sun CY, et al. Electrothermal responsive self-healing for carbon fiber/epoxy interphase based on Diels-Alder adducts. Compos Sci Technol. 2021; 208:108767.
5. Pulidindi IN. Chemical composition of oil finishing agent used in the production of carbon fibers for imparting unusual strength. IJCM. 2024; (Ahead of print).
6. Pulidindi IN. Crystallinity of Commercial Carbon Fibers from X-ray Diffraction (XRD) Studies. IJPPR. 2023; 1(1):17–27p.
7. Pulidindi IN. Raman spectroscopy for the determination of relative crystallinity of carbon fibers. IJCM. 2024; 1(1):30-7p.
8. Pulidindi IN. Three dimensional (3D) structure and morphology of carbon fibers from X-ray microscopy (XRM) analysis. IJCMM. 2024; 10 (2):23-32p.
9. Pulidindi IP. Diglycidyl ether of bisphenol A (DGEBA) based epoxy sizing agent induces surface polarity in carbon fibers. IJCM. 2024; 1 (2):24-34p.
10. Pulidindi IN. New insight into the composition and structure of sizing agent from NMR spectroscopy. IJPPR. 2024; 2 (2):6-23p.
11. Patel D, Joshi MK, Joshi YR, et al. Direct synthetic routes of MXenes and their application in carbon fiber reinforced plastics (CFRPs) as supplementary sizing layer. IJCM. 2024; 1(1):7-13p.
12. Pulidindi IN, Morphology and elemental composition of carbon fibers. IJCMM. 2024; (in press).
13. Pulidindi IN, Gedanken A. Surface Modification of Carbon Fibers. Preprints 2023; 2023082053. https://doi.org/10.20944/preprints202308.2053.v1.
14. Zhang YY, Zhang YZ, Liu Y, et al. A novel surface modification of carbon fiber for high-performance thermoplastic polyurethane composites. Appl Surf Sci. 2016; 382:144–54p.
15. Liu Y, Fang YC, Qian JH, et al.. Bio-inspired polydopamine functionalization of carbon fiber for improving the interfacial adhesion of polypropylene composite. RSC Adv., 2015; 5:107652–61p.
16. Liu Y, Zhang X, Song CC, et al. An effective surface modification of carbon fiber for improving the interfacial adhesion of polypropylene composites. Mater Design. 2015; 88:810-9p.
17. Liu Y, Fang YC, Liu XL, et al. Mussel-inspired modification of carbon fiber via polyethyleneimine/ polydopamine co-deposition for the improved interfacial adhesion, Compos Sci Technol. 2017; 151:164-73p.
18. Zou YQ, Ross N, Nawaj W, et al. A Simplified Approach for Dynamic Contact Angle Measurements. J. Chem. Educ. 2024; 101:3883-90p.
19. Liu YM, Zheng Y, Lin HJ, et al. Calculation of contact angle via Young-Dupr´e equation with molecular dynamic simulation: Kaolinite as an example. Colloids Surfaces A: Physicochemical and Engineering Aspects. 2024; 697:134469.
20. Zhang C, Wang XM, Li LX, et al. Surface Wettability Analysis from Adsorption Energy and Surface Electrical Charge. Minerals. 2024; 14:628.
21. Tokihiro JC, McManamen AM, Phan DN, et al. On the Dynamic Contact Angle of Capillary-Driven Microflows in Open Channels. Langmuir. 2024; 40:7215−24p.
22. Dai JY, Pi S, Wu JZ, et al. Research on the influence of dynamic contact angle of mercury meniscus on the interpretation of rock pore throat radius in mercury intrusion experiments. Front. Earth Sci.12:1434211.
23. Kim YB, Sung JY. Transient Phenomena of Dynamic Contact Angle in Micro Capillary Flows. Appl Sci., 2024; 14:3293.
24. Brindt N, Min XY, Yan JZ, et al. Measuring pore water velocities and dynamic contact angles at unstable wetting fronts. Adv Water Resour. 2024; 186:104661.
25. Zhang C, Wang XM, Li LX, et al. Surface Wettability Analysis from Adsorption Energy and

26. Lee YN, Chiao SM. Visualization of Dynamic Contact Angles on Cylinder and Fiber. J Colloid Interface Sci. 1996; 181:378-84p.
27. Zhang LM, Wang J, Fuentes CA, et al. Wettability of carbon nanotube fibers. Carbon. 2017; 122:128e140.
28. Qiu S, Fuentes CA, Zhang DX, et al. Wettability of a Single Carbon Fiber. Langmuir. 2016; 32: 9697-705p.
29. Wang XL,Wang WK, Qu ZG, et al. Surface roughness dominated wettability of carbon fiber in gas diffusion layer materials revealed by molecular dynamics simulations. Int J of Hydrogen Energy.  2021; 46:26489-98p.
30. Liu WB, Zhang S, Hao LF, et al. Effect of Fiber Surface on the Interfacial Properties for Carbon Fiber Reinforced Polymer Composites. Polym Polym Compos. 2014; 22 (3):283-8p.
31. Lee YS, Lee BK, Rho JS. The Physicochemical Characteristics of Modified Carbon Fibers by Fluorination. Korean J. Chem. Eng., 2003; 20(1):151-6p.
32. Zhao F, Huang YD. Improved interfacial properties of carbon fiber/epoxy composites through grafting polyhedral oligomeric silsesquioxane on carbon fiber surface. Materials Letters. 2010; 64: 2742–4p
33. Trana LQN, Fuentes CA, Dupont-Gillain C, et al. Wetting analysis and surface characterisation of coir fibres used as reinforcement for composites. Colloids and Surfaces A: Physicochem. Eng. Aspects. 2011; 377:251-60p.
34. Qiu S, Wang J, Zhang DX, et al. Wetting dynamics and surface energy components of single carbon fibers. J Colloid Interface Sci. 2019; 557:349-356.
35. Zhang RL, Huang YD, Su D, et al. Influence of sizing molecular weight on the properties of carbon fibers and its composites Mater Des. 2012; 34:649-54p.
36. Jiao ZB, Yao ZJ, Zhou JT, et al. Reinforced interface and mechanical properties of high strength carbon fiber composites. High Performance Polymers. 2021; 33(3):255-63.
37. Xiao J, Tian SY, Zhou H, et al. Construction of Polar Functional Groups on the Surface of a High-Modulus Carbon Fiber and Its Effect on the Interfacial Properties of Composites. ACS Omega. 2023, 8, 29262-69p.
38. Yu L, Wang K, Guan YF, et al. Effect of carbon fiber surface properties on carbon fiber/polyphenylene sulfide composite interfacial property. Polymer Composites. 2023; 44:2005-2015.
39. Yang L, Xia H, Xu ZZ, et al. Influence of surface modification of carbon fiber based on magnetron sputtering technology on mechanical properties of carbon fiber composites. Mater. Res. Express. 2020; 7:105602
40. Chen J, Zhao Y, Sun MC, et al. Functionalized carbon fibers with MXene via electrochemistry aryl diazonium salt reaction to improve the interfacial properties of carbon fiber/epoxy composites. Journal of materials research and technology. 2022; 19:3699-712p.
41. An F, Lu CX, Guo J, et al. Preparation of vertically aligned carbon nanotube arrays grown onto carbon fiber fabric and evaluating its wettability on effect of composite. Appl Surf Sci. 2011; 258:1069-76p.

Wettability is the property that quantifies the propensity of a solid surface (carbon fiber) to be covered by a liquid (resin). For a wettable solid, the solid-liquid contact is favoured and as a result the liquid spreads on such surface of the solid. Spreading of the liquid on the solid surface is primarily driven by the adhesive forces between the liquid and the solid, while the inter molecular cohesive forces of the liquid molecules prevent spreading and keep the liquid confined.  Wettability of the carbon fibers, namely, NX90, NX100, M55J, T700SC, CCF800H and T800HB, was determined using Wilhelmy balance method with resin test liquids, like, HY, cyanate ester, AG80, E51 and other test liquids, like, glycerol and 1-bromonapthalene.  Among all the CF-resin combinations tested for composite applications, T700SC-HY stood out with the lowest dynamic contact angle (DCA, 22.9°) and correspondingly highest wettability followed by M55J-cyanate ester and M55J-AG80.  PAN based fibers showed higher wettability (lower DCA values) compared to pitch based counter parts.  Among pitch based fibers-resin composites, NX90-HY showed the lowest DCA (55°) and so the highest wettability and this combination is recommended for the production of CFRC’s with strong interface and highest load bearing capability.  For the preparation of single filaments from the carbon fiber tows, in the course of sample preparation for the DCA measurements, it is recommended that the pitch based CFs, namely, NX90 and NX100 be wetted with a few mL of ethanol that facilitates the easy separation of CFs by making the sizing (DGEBA polymer) compound on the surface expand and thereby weakening the binding between adjacent pitch based fibers in the carbon fiber tows.  Such a measure would save time and prevent the testing of patience of the researcher.

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Sarkar S, Roy T, Roy A, et al. Revisiting the supplementary relationship of dynamic contact angles measured by Sessile-droplet and captive-bubble methods: Role of surface roughness. J Colloid Interface Sci. 2021; 581:690-7p.
2. Wang CY, Nair S, Wynne KJ. Wilhelmy balance characterization beyond contact angles: Differentiating leaching from nanosurface reorganization and optimizing surface modification. Polymer. 2017; 116:565-71p.
3. https://www.kibron.com/dynamic-contact-angle
4. Yang CC, Zhu DD, Sun CY, et al. Electrothermal responsive self-healing for carbon fiber/epoxy interphase based on Diels-Alder adducts. Compos Sci Technol. 2021; 208:108767.
5. Pulidindi IN. Chemical composition of oil finishing agent used in the production of carbon fibers for imparting unusual strength. IJCM. 2024; (Ahead of print).
6. Pulidindi IN. Crystallinity of Commercial Carbon Fibers from X-ray Diffraction (XRD) Studies. IJPPR. 2023; 1(1):17–27p.
7. Pulidindi IN. Raman spectroscopy for the determination of relative crystallinity of carbon fibers. IJCM. 2024; 1(1):30-7p.
8. Pulidindi IN. Three dimensional (3D) structure and morphology of carbon fibers from X-ray microscopy (XRM) analysis. IJCMM. 2024; 10 (2):23-32p.
9. Pulidindi IP. Diglycidyl ether of bisphenol A (DGEBA) based epoxy sizing agent induces surface polarity in carbon fibers. IJCM. 2024; 1 (2):24-34p.
10. Pulidindi IN. New insight into the composition and structure of sizing agent from NMR spectroscopy. IJPPR. 2024; 2 (2):6-23p.
11. Patel D, Joshi MK, Joshi YR, et al. Direct synthetic routes of MXenes and their application in carbon fiber reinforced plastics (CFRPs) as supplementary sizing layer. IJCM. 2024; 1(1):7-13p.
12. Pulidindi IN, Morphology and elemental composition of carbon fibers. IJCMM. 2024; (in press).
13. Pulidindi IN, Gedanken A. Surface Modification of Carbon Fibers. Preprints 2023; 2023082053. https://doi.org/10.20944/preprints202308.2053.v1.
14. Zhang YY, Zhang YZ, Liu Y, et al. A novel surface modification of carbon fiber for high-performance thermoplastic polyurethane composites. Appl Surf Sci. 2016; 382:144–54p.
15. Liu Y, Fang YC, Qian JH, et al.. Bio-inspired polydopamine functionalization of carbon fiber for improving the interfacial adhesion of polypropylene composite. RSC Adv., 2015; 5:107652–61p.
16. Liu Y, Zhang X, Song CC, et al. An effective surface modification of carbon fiber for improving the interfacial adhesion of polypropylene composites. Mater Design. 2015; 88:810-9p.
17. Liu Y, Fang YC, Liu XL, et al. Mussel-inspired modification of carbon fiber via polyethyleneimine/ polydopamine co-deposition for the improved interfacial adhesion, Compos Sci Technol. 2017; 151:164-73p.
18. Zou YQ, Ross N, Nawaj W, et al. A Simplified Approach for Dynamic Contact Angle Measurements. J. Chem. Educ. 2024; 101:3883-90p.
19. Liu YM, Zheng Y, Lin HJ, et al. Calculation of contact angle via Young-Dupr´e equation with molecular dynamic simulation: Kaolinite as an example. Colloids Surfaces A: Physicochemical and Engineering Aspects. 2024; 697:134469.
20. Zhang C, Wang XM, Li LX, et al. Surface Wettability Analysis from Adsorption Energy and Surface Electrical Charge. Minerals. 2024; 14:628.
21. Tokihiro JC, McManamen AM, Phan DN, et al. On the Dynamic Contact Angle of Capillary-Driven Microflows in Open Channels. Langmuir. 2024; 40:7215−24p.
22. Dai JY, Pi S, Wu JZ, et al. Research on the influence of dynamic contact angle of mercury meniscus on the interpretation of rock pore throat radius in mercury intrusion experiments. Front. Earth Sci.12:1434211.
23. Kim YB, Sung JY. Transient Phenomena of Dynamic Contact Angle in Micro Capillary Flows. Appl Sci., 2024; 14:3293.
24. Brindt N, Min XY, Yan JZ, et al. Measuring pore water velocities and dynamic contact angles at unstable wetting fronts. Adv Water Resour. 2024; 186:104661.
25. Zhang C, Wang XM, Li LX, et al. Surface Wettability Analysis from Adsorption Energy and

26. Lee YN, Chiao SM. Visualization of Dynamic Contact Angles on Cylinder and Fiber. J Colloid Interface Sci. 1996; 181:378-84p.
27. Zhang LM, Wang J, Fuentes CA, et al. Wettability of carbon nanotube fibers. Carbon. 2017; 122:128e140.
28. Qiu S, Fuentes CA, Zhang DX, et al. Wettability of a Single Carbon Fiber. Langmuir. 2016; 32: 9697-705p.
29. Wang XL,Wang WK, Qu ZG, et al. Surface roughness dominated wettability of carbon fiber in gas diffusion layer materials revealed by molecular dynamics simulations. Int J of Hydrogen Energy.  2021; 46:26489-98p.
30. Liu WB, Zhang S, Hao LF, et al. Effect of Fiber Surface on the Interfacial Properties for Carbon Fiber Reinforced Polymer Composites. Polym Polym Compos. 2014; 22 (3):283-8p.
31. Lee YS, Lee BK, Rho JS. The Physicochemical Characteristics of Modified Carbon Fibers by Fluorination. Korean J. Chem. Eng., 2003; 20(1):151-6p.
32. Zhao F, Huang YD. Improved interfacial properties of carbon fiber/epoxy composites through grafting polyhedral oligomeric silsesquioxane on carbon fiber surface. Materials Letters. 2010; 64: 2742–4p
33. Trana LQN, Fuentes CA, Dupont-Gillain C, et al. Wetting analysis and surface characterisation of coir fibres used as reinforcement for composites. Colloids and Surfaces A: Physicochem. Eng. Aspects. 2011; 377:251-60p.
34. Qiu S, Wang J, Zhang DX, et al. Wetting dynamics and surface energy components of single carbon fibers. J Colloid Interface Sci. 2019; 557:349-356.
35. Zhang RL, Huang YD, Su D, et al. Influence of sizing molecular weight on the properties of carbon fibers and its composites Mater Des. 2012; 34:649-54p.
36. Jiao ZB, Yao ZJ, Zhou JT, et al. Reinforced interface and mechanical properties of high strength carbon fiber composites. High Performance Polymers. 2021; 33(3):255-63.
37. Xiao J, Tian SY, Zhou H, et al. Construction of Polar Functional Groups on the Surface of a High-Modulus Carbon Fiber and Its Effect on the Interfacial Properties of Composites. ACS Omega. 2023, 8, 29262-69p.
38. Yu L, Wang K, Guan YF, et al. Effect of carbon fiber surface properties on carbon fiber/polyphenylene sulfide composite interfacial property. Polymer Composites. 2023; 44:2005-2015.
39. Yang L, Xia H, Xu ZZ, et al. Influence of surface modification of carbon fiber based on magnetron sputtering technology on mechanical properties of carbon fiber composites. Mater. Res. Express. 2020; 7:105602
40. Chen J, Zhao Y, Sun MC, et al. Functionalized carbon fibers with MXene via electrochemistry aryl diazonium salt reaction to improve the interfacial properties of carbon fiber/epoxy composites. Journal of materials research and technology. 2022; 19:3699-712p.
41. An F, Lu CX, Guo J, et al. Preparation of vertically aligned carbon nanotube arrays grown onto carbon fiber fabric and evaluating its wettability on effect of composite. Appl Surf Sci. 2011; 258:1069-76p.