Carbon fiber with high strength, high modulus, high temperature and other excellent performance, is a high performance composite materials commonly used enhanced phase. However, AKD Sizing Agent the elongation of carbon fiber is low, the brittleness is large, the surface is chemically inert, and the repeated friction during the process is easy to cause the monofilament fracture and the filament, and the wetting difference with the matrix resin leads to poor mechanical properties of the composites. In order to solve this problem, AKD Sizing Agent it is necessary to carry out sizing the carbon fibers. The sizing treatment can merge the filaments to bundle the carbon fibers while protecting the carbon fibers and introduce a variety of reactive functional groups on the surface to improve the wettability of the carbon fibers and the matrix resin and increase the interlaminar shear strength of the composites.
Different composite materials of the base resin is different, AKD Sizing Agent its performance varies, the sizing agent should also adapt to different resins. Sizing agent corresponding to the main resin can be divided into epoxy, polyurethane, acrylic and bicycles and so on. With the increasing demand for environmental protection, waterborne epoxy sizing agent has been paid more and more attention. AKD Sizing Agent Depending on the preparation method, the epoxy water-based process comprises a physical method, a chemical modification method and a reverse conversion method. Since the epoxy itself is insoluble in water, to prepare a stable aqueous epoxy emulsion, AKD Sizing Agent it is necessary to introduce a strong hydrophilic group in its molecular chain for chemical modification or to add a hydrophilic lipophilic component to the system as an additional emulsifier However, AKD Sizing Agent the addition of emulsifier can lead to the larger particle size and uneven distribution of emulsions, the residual effect of emulsifier on the weatherability and mechanical properties of the composites, and the disperse phase of the aqueous epoxy emulsion prepared by the chemical modification method Small, about tens to hundreds of nanometers, and to avoid the addition of emulsifiers to bring a lot of problems, quite practical value.
In the experiment, because of the environmental protection and low cost of polyethylene glycol, and the molecule contains a large number of hydrophilic groups, the alcoholic hydroxyl groups at both ends of the molecule can be ring-opening addition polymerization reaction with epoxy groups in epoxy, Oxygen, AKD Sizing Agent and the other end is a hydroxyl self-emulsifying epoxy product. In addition, because the alcoholic compound is not very good, it is difficult to under normal conditions and epoxy reaction, AKD Sizing Agent so the experiment using ammonium persulfate as a catalyst, so that different molecular weight polyethylene glycol and epoxy ring-opening addition reaction, Preparation of modified epoxy emulsion sizing agent.
⑴ epoxy value determination using hydrochloric acid - acetone method, AKD Sizing Agent epoxy value EV according to EV = (V 0-V) / m × 10 basis.
(2) product infrared spectroscopy. Fluorescence spectroscopy was performed using a Bruker Tensor 27 type Fourier transform infrared spectrometer.
⑶ storage and centrifugal stability: storage stability test: room temperature for 2 months, observe the demulsification of emulsion emulsion layer. Centrifugal stability test: 3 000 r / min under the conditions of centrifugation 30 min , observe the emulsion demulsification stratification situation.
⑷ emulsion film forming. Take a transparent glass plate and apply the sizing agent evenly to the glass plate. Dried at room temperature for a period of time and then dried in an oven at 120 ℃ for 30 min. The solid content of the solid content was measured after film formation and its film forming performance was evaluated.
⑸ emulsion particle size distribution. AKD Sizing Agent The particle size distribution of the emulsion was tested by American Beckman Coulter laser particle size analyzer.
The thermal stability of sizing agent. Thermal stability analysis of sizing agent using STA449C thermal analyzer.
⑺ surface morphology and roughness analysis (AFM, SEM). The carbon fiber tow was fixed on the sample table with double-sided adhesive, AKD Sizing Agent and the surface roughness and morphology of the carbon fiber were analyzed by the Dimension Iconwith ScanAsyst atomic force microscope and the SU-70 scanning tunneling microscope from Hitachi, Japan.
⑶ composite interlayer shear strength (I L S S). The carbon fiber / epoxy composites were prepared and tested according to ASTM D2344  "Standard Test Method for Determining the Intracellular Interlayer Shear Strength of Parallel Fiber Composites by Short Beam Method". The ILSS was calculated by the following formula: ILSS = 3 P B / 4bh.