Improved interfacial adhesion in carbon fiber/epoxy composites through a waterborne epoxy resin sizing agent

Abstract

A series of self‐emulsified waterborne epoxy resin (WEP) emulsions were used as surface sizing for carbon fibers (CFs) to improve the interfacial adhesion between the CF and epoxy matrix. In this work, the hydrogenated bisphenol‐A epoxy resin (HBPAE) was modified by polyethylene glycol (PEG) with molecular weights of 400, 800, 1000, 1500, 2000, 4000, and 6000 g/mol. The properties of the WEP emulsion were examined by Fourier transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopy. The surface characteristics of sized CFs were evaluated using scanning electron microscopy, atomic force microscopy, and X‐ray photoelectron spectroscopy. Afterwards, CF/EP composites were prepared and their fracture surface and interlaminar shear strength (ILSS) were examined. The results indicated that PEG2000 modified HBPAE sizing had the optimum emulsion stability and film‐forming ability. Meanwhile, the results also demonstrated that a continuous and uniform sizing layer was formed on the surface of CFs and the surface sizing was excellent in improving the chemical activity of CFs. Compared with unsized CFs, the O1s/C1s composition ratio was observed to increase from 11.51% to 33.17% and the ILSS of CF/EP composites increased from 81.2 to 89.7 MPa, exhibiting better mechanical property than that of commercial Takemoto S64 sized CFs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44757.

Improving the interfacial properties of carbon fiber–epoxy resin composites with a graphene‐modified sizing agent

“…Carbon‐fiber (CF)‐reinforced composites have been widely applied in various fields, including the aerospace, automotive, medical, energy, and sports equipment industries, because of their advantages, including good fatigue and corrosion resistances, high specific strength, and high modulus . However, it is difficult to ignore the fact that these composites have poor interfacial performance because of the smooth and inert characteristics of the CF surface; this affects the ultimate mechanical properties of composites.…”

Nanoscale toughening of carbon fiber‐reinforced epoxy composites through different surface treatments

“…The sulfuric acid (H 2 SO 4 ) and nitric acid (HNO 3 ) were obtained from Shanghai Chemical Reagent Corporation (China), analytical reagent. The self‐made sizing agent (polyethylene glycol modified hydrogenated bisphenol A epoxy resin, mass ratio = 1:1) was produced in our lab, with the mean particle size of 0.26 μm . The silane coupling agent, APTES, was supplied by Aladdin Co., Ltd. (China).…”

“…The sizing treatment was performed by a successive impregnation technology. The virgin CFs were pulled through the obtained sizing emulsion , which was kept in a circulating state achieved by a pump to avoid sedimentation. Then the sized fibers were dried instantly in a rotary hot roller at 120°C.…”

“…The ILSS of CFREs was determined according to ASTM D2344, with a crosshead speed of 2 mm/min. A total of 10 specimens were tested from each kind of unidirectional laminate sample.…”

Effect of polyurethane sizing on carbon fibers surface and interfacial adhesion of fiber/polyamide 6 composites

“… Sizing is a simple and valid method that is used to improve fiber/matrix adhesion . It involves coating CFs with a very thin film of polymer to make them easier handling and improve mechanical performance of composite materials . However, most commercial CF sizing agents contain epoxy‐matrix‐matched organic prepolymers or polymers, which have similar characteristics to those of epoxy.…”