Development Of Sizing Agent For Continuous Basalt Fibers And Its Effect On The Fiber Porperty

The basal fiber is a new kind of inorganic fiber. It has several advantages, such as high intensity, high temperature stability, and high corrosion resistance. But it also contains lots of problems, for instance brittle and likely to be damaged during ply, when compared with the organic-fiber. This work focuses on designing and preparing sizing agent for the fiber in the light of the structure and property of the basalt fiber. The treatment with sizing agent can improve the mass force and abrasion performance of the fiber, and make the fiber softer, enhancing its mechanical properties and improving the interface condition of its reinforced composites. This research can supply some valuable experimental data for the basalt composite preparation.Epoxy latex,PU latex and polyester latex were used as the film-former along with some promoter to prepare the sizing agent. The surface energy, granularity and stability of the sizing agent were measured. Through the obtained data, the formula was optimized and the properties of sizing agent were evaluated. The results showed that the four types of sizing prepared were all stable. After centrifugal settling treatment, there was no demulsification phenomenon occurring. And sizing agent's surface energy was lower than basalt fibers'surface energy. The lower the surface energy of the sizing agent, the larger the spreading coefficient of sizing agent is, and the corresponding contact angle between the sizing agent and the basalt fibers will become smaller.The introduction of sizing agent can improve the basalt fibers'interface properties, mechanical properties, and its composite properties. In addition, in order to explore better properties of the composite, another kind of sizing agent was obtained through adding some amount of nano-SiO2 particles. The results showed that nano-SiO2 particles had no apparent effect on the sizing agent's surface energy, granularity and stability. Also, the nano-SiO2 particles were uniformly dispersed in the sizing agent.After epoxy-sizing treatment, the basalt fibers'mechanical and its composite properties were evaluated, including the multifilament's breaking force, tensile strength and interlayer shear strength. Because of the existence of high active and polar hydroxyl groups in the epoxy film former, the film on the basalt fiber surface had a high viscosity. Hence, the fibers had higher mass force and larger breaking force. After the waterborne polyurethane sizing treatment, because it was intermolecular force, e.g., Van Der Waals force, to bond two single fibers, the mass force of the basalt fibers was not large. However, on their surfaces, there were several groups with big polarity. So, the resin could infiltrate the fibers better. Nevertheless, polyurethane was easy to hydrolyze in alkali environments, this kind of sizing agent's alkali resistance was not good. Furthermore, when polyester was used as film former, it could make the fiber possess many good properties, such as good friction resistance and alkali resistance. In this work, the polyester was used as an assistant film former with epoxy. Using this sizing agent, the fibers'mechanical properties and its composites'ones were common, but it was suitable for the weaving process.Through adding modified nano-SiO2 particles in the sizing agent, the nano-SiO2 particles were connected onto the surface of the basalt fibers, making the basalt fiber surface become rough and thus enabling the adhesive force between fibers and resin to increase. It was found that the interlayer shear strength of the epoxy matrix composite increased by about 5%.