Reduced Cost Fabrication of Large Composite Aerospace Structures Through Nanoparticle Modification of Thermoplastics (Preprint)

摘要

To achieve superior mechanical properties and environmental durability in semi-crystalline engineering thermoplastic composites an intermediate degree of molecular ordering is required. While many thermoplastics achieve their potential crystallinities with autoclave processing, only a fraction of that which is desired is developed with lower cost manufacturing processes, viz. automated fiber placement and tape laying featuring polymer chilling from the melt in seconds. Implementation of such processes for the manufacture of large composite aerospace structures is therefore rooted in material selection and the minimization of cycle times. Polyetheretherketone (PEEK) has demonstrated utility in composite structures due to its processing behavior. The cost-driven replacement of PEEK with other materials depends whether desired laminate crystallinities may be attained avoiding costly annealing steps. Polyetherketoneketone (PEKK) represents an alternative but suffers from reduced crystallization rates. The use of nucleating agents presents a route towards enhancing the ordering phenomena in polymers. A study has been undertaken to evaluate the effectiveness of utilizing silicon-based nanoparticles in improving the crystallization kinetics of PEKK. Relevant findings including the impact of the addition of such nanoparticles on other properties will be discussed.