Development Of High Performance Tackifiers And Tackifacation/Preforming Technologies For Resin Transfer Molding

The shape and geometry accuracy of structural composite components is critical for composite manufacturing in aeronautical industry. As recognized by many applications, Resin Transfer Molding (RTM) technology enables production of high-performance composite component with accurate shape of large size if there is a net/near shaped preform in existance. The preform is generally made with tackified fabrics by so-called tackification technology and by means of sophisticatedly designed tools and processing procedure. Therefore, a RTM production will only be successful if by taking the tackification and preforming technology into consideration. Unfortunately, little attention has been paid on this important research area in China.This thesis focuses primarily on development of tackifiers for RTM application. The properties and interaction of the tackifiers with different RTM resin systems were evaluated and studied. The tackifiers were then be used to bind carbon fiber fabrics. The tackification study included the application technology, the tackifier distribution and the mechanical properties of the tackified fabrice such as the compressibility and spring-back effect.First, based on domestic materials and the urgent demand of application, a new, non-reactive tackifier (ES-T321) without curing agent and accelerant was developed. The application temperature of ES-T321 is about 80℃～125℃. ES-T321 demonstrated good compatibility with an intermedial temperature RTMable epoxy resin 3266, met the requirements of multiple handling and heating, did not affect the drapability and mechanical properties of the final composites. And finally, ES-T321 was successfully used in critical aerocraft and marine applications, namely for manufacturing of composite blades. ES-T321 was also tested for tackification with a high temperature epoxy 5284 and the test results in compatibility, handling and mechnical properties were similar to those of ES-T321 with 3266.Then, other types of tackifiers were also developed to satisfy the demand of different RTMable resin systems. The composition was varied to adopt different resin chemistry and curing conditions. They included epoxy-based intermedial temperature reactive tackifier, epoxy-based high temperature reactive tackifier and bismaleimide-based high temperature reactive tackifier, respectively. All these tackifier were solid in the ambient temperature with long storage life. They were generally soluble in acetone, making them applied as functional solution. They could also be made in form of powders with variable size distribution. It was evident that the tackifiers were compatible with the respective RTM resins. By analyzing reaction kinetics of the takifiers, activation energy and the oder of reaction could be calculated. Furthermore, the rheological and gelation behavior was determined by using FT-IR spectrum, thermoanalytical method and rheometry. The glass transition temperature and thermal decomposition temperature of the composites made of the tackified fabrics were almost the same as those of the origin controls. There were also no significant negative effects on thermal and mechanical properties of the composites observed.The tackified fabrics exhibited certain resistance against wash-out. Process parameters of wet and dry preforming were optimized by selecting different tackfier contents. Spring-back and compressibility were investigated and compared on preforms made by wet and dry process, respectively.