Influence of uniaxial orientation of fluorinated polymer/phosphonate-modified needle-like nanofiller composite by drawing

The orientation effect of sepiolite natural clay, a needle-shaped nanoparticle, in a polymer matrix was investigated. Uniaxial drawing was performed on polymer-based nanocomposites containing organo-modified sepiolite, achieving uniform dispersion in the crystalline polymer by modifying the surface with organic molecular chains. Fluorinated polymer was used as the matrix, and sepiolite was modified using fluorinated chains. High-temperature drawing was conducted to increase the density of amorphous chains in the fluoropolymer. Observations confirmed the orientation of the nanofiller in the drawing direction. When the filler content was intentionally increased, it was as if it were a nanosized mille-feuille. As a result of 5× drawing, a 20% improvement in crystallinity was calculated. Small-angle X-ray scattering (SAXS) analysis showed a 32 Å increase in long-period values. When high-drawing was conducted, some amorphous parts transformed into crystals, and the difference in electron densities between the two regions widened, increasing the long-period value while decreasing the SAXS intensity. The crystallization temperature increased by 1.8°C, and the Young's modulus calculated from the strain-stress curve showed a nearly 4× increase. The mechanical strength doubled when the neat fluoropolymer was drawn five times. This provides a clear understanding of the enhancement behavior of the structural and physical properties of a uniform dispersible polymer/needle nanoparticle nanocomposite using uniaxially oriented nanofillers.