Advancements in processing techniques have facilitated the development of an expansive set of distinct high-performance DuPont™ Kevlar® fibers.i Characterizing fibers’ interior structures is vital for linking processing conditions with resulting structures and mechanical properties. However, the complex, multiscale structural motifs throughout Kevlar® fibers have introduced significant difficulties in developing direct, comprehensive understanding of these structures. Here we report detailed investigations of processing-internal structure-property relationships among four distinct classes of Kevlar® fibers (K119, K29, KM2+, and K49). We employ a novel focused ion beam (FIB) notch technique to obtain pristine interior fiber planes and measure morphology and transverse stiffness across these surfaces <i>via </i>multifrequency atomic force microscopy (AFM) maps. Combining multiscale AFM observations with tensile tests of single fibers drawn from the same tows, we uncover distinct interior structural phenomena that provided clear footprints of processing effects and corresponding impacts on mechanical behavior. Most notably, we uncover alternating stiffness bands that are especially apparent in low-modulus, non-heat-treated fibers, revealing a unique manifestation of internal structural variations that helps explain the observed trends in material responses.

Structure-property relationships through a novel FIB notch technique

256th National Meeting (2018)

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