Study On The Preparation And Properties Of Aluminum-containing Silsesquioxanes Hybrid Film

Quartz fiber-reinforced phosphate matrix composites can meet the needs of a variety of functional materials for its high temperature endurance, antioxidance and good processability. But the phosphate matrix corrosion of the quartz fiber will result in lower overall performance of the composite materials, particularly in the high temperature. Because mechanical properties of these materials will decrease significantly in the high temperature and this restricts its applications. Therefore, how to improve the effects of the reinforcement becomes the main focus. In this paper, Al₂O₃-POSS composite sol was prepared with Al-butanol and three types of double bonds silane coupling agent as the precursor by sol-gel. And then coated it on the surface of the quartz fiber. At last, properties of the corrosion-resistant protective film and mechanical properties of the composite materials were discussed.In this paper, such factors as the precursor type, the amount of solvent, chelating agents and the amount of added water on the transparency and stability of the aluminum sol were discussed. And the optimum conditions were obtained: with Al-butanol: acetyl ethyl acetate: ethanol: deionized water = 1:0.3:30:0.8 by molar ratio, control reaction temperature at 80℃in water bath. Transparent and stable Al₂O₃ sol was obtained after 5h reflux.Then mixed it with POSS sol and got the uniform Al₂O₃-POSS composite sol. First, the composite sol bond conditions were characterized by infrared absorption spectroscopy (FT-IR). Then, the thermal properties of the composite sol were analyzed by differential scanning calorimetry (TG-DTA). Finally, molecular weight distribution of the composite sol were characterized by gel permeation chromatography (GPC). The results show that the composite sol bonded with Al-O-Si has good thermal performance and higher degree of molecular aggregation.Besides, research on the coating process of the hybrid membrane was carried out. By X-ray photoelectron spectroscopy (XPS), we determined that washing the Quartz fibers with sulphuric acid could remove the organic surfactants on the surface. By scanning electron microscopy (SEM), the surface coated with the hybrid membrane was tested.The results showed that at room temperature and high temperature conditions, both Al₂O₃-POSS 30 and Al₂O₃-POSS 70 hybrid membranes are dense, uniform and complete. And they are suitable for quartz fiber surface protective film material.We also did some research on corrosion resistance and flexural strength of composites with different functional groups of the POSS. By scanning electron microscopy (SEM), surface morphology of the fibers coated with the hybrid membrane was tested at room temperature , high temperature and after etching. The results show that the Al₂O₃-POSS 30 and Al₂O₃-POSS 70 played a significant role in the fiber protection. Finally, mechanical properties of these materials were tested by three-point bending method. The results show that the hybrid membrane coating can improve the flexural strength by more than50%.