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Micro-Scale Chemical, Morphological and Mechanical Characterization of Polymer-Matrix Textile Composites
Abstract
Polymer matrix composites (PMC) with textile fiber architectures are of significant interest in advanced aerospace applications. Despite the great promise, there are significant challenges associated with the uncertainties in material response caused by the complexity and variability of the geometry and the characteristic materials properties. These variabilities include local dissimilarities in fiber alignment, fiber volume fraction, resin rich pockets and variations in matrix dimension (interphases, local area covered by matrix, voids between the fibers or in resin pockets). Understanding of these variations is critical, and it must be taken into account for stiffness and strength calculations. This study illustrates our initial efforts on understanding the variability and its corresponding effect on the properties of textile PMC using nanoscale characterization techniques combining spectroscopy, microscopy, and mechanical testing. We have chosen first to examine micro-scale variations in laminated tape prepreg composites as a simpler beginning. Using atomic forced microscopy coupled with infrared spectroscopy (AFM-IR), we were able to evaluate thickness, chemistry and relative modulus of the interphase. This has also allowed us to distinguish resin rich pockets and variation of fibers distribution. Similarly, combining it with electron microscopic techniques (SEM) and mechanical (Nanoindentation) characterization techniques, this study illustrates deeper understanding of the composite laminate in terms of the chemical mapping, morphology and the mechanical properties. This will provide guidance for future advancement of composites in terms of composite processing as well as toward developing advanced modelling methodologies.