Study On Competitive Adsorption Of The Components In Phenolics Solution And Cure Monitoring During The RTM Process

Resin transfer molding (RTM) process has been extensively applied in aircraft, aerospace and communication industries for its outstanding advantages, including relatively short cycle times with good surface quality, the ability to manufacture large complex structures and low investment costs for equipment and tooling. However, impregnation in a RTM process is complicated. The performances of a part produced by RTM process are influenced by the competitive adsorption of resin components onto fiber reinforcement.Solution impregnation route is effective in making use of resin with high viscosity to produce high performance composites through RTM process. Effects of solvent and fiber modification on the impregnation process of RTM silica/phenolics composites were investigated in this study. The results show that the competitive adsorption of the components in the phenolics solution affects the interlaminar shear strength (ILSS) uniformity of a RTM product. Not only the ILSS values but also ILSS uniformity of a RTM product are influenced by the phenolics solution with different solvents.Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, UV-visible absorption spectroscopy were used to investigate the mechanism for the competitive adsorption occurring at silica fiber/phenolics interface. The competive adsorption of phenolics components onto silica fiber is the result of hydrogen-bonding interactions occuring among reinforcement, solvent and polymer. The changes in viscosity and surface tension were measured for the solution systems before and after adsorption. The inhomogeneity of resin distribution a RTM product was demonstrated by thermogravimetric analysis (TGA), which explains the effects of solvent and fiber modification on void and ILSS.Fiber Bragg grating was used to monitor the strain evolution of the silica/phenolic composites during the cure process. Optical fiber sensor is sensitive enough to monitor the consolidation process of composites. Monitoring of the course of strain and temperature in RTM composites has been achieved after the fiber Bragg grating was embedded in the composites. The results...