Nanofibrils from Nylon 6/Polypropylene-g-maleic anhydride/Polypropylene Blended Filaments

A descriptive and historical account with experimental evidence is provided for the production feasibility of micro- and nanofibrils from structured-fibres using existing technologies. Blends of 6.25% polypropylene, 87.5% nylon 6 and 6.25% polypropylene grafted with maleic anhydride as compatibilizer (N6/PP-g-MAH/PP) were spun into continuous filaments yarns using a melt spinning unit (pilot plant) at the speed of 2000 m/min. The yarn samples were drawn in a drawing unit with draw ratios of 1.3 and 2.6. Samples were treated with formic acid (98%) to dissolve the nylon component that forms the matrix of the bi-constituent filaments. Different analytical techniques including polarizing microscopy, scanning electron microscopy, FTIR spectroscopy, differential scanning calorimetry and wide angle X-ray diffraction were used to examine the filaments and fibrils. It is shown that by existing technology it is possible to produce polyblend filaments from two rather incompatible polymers, while the extraction of polypropylene micro and nanofibrils is possible either by decantation or Soxhlet using formic acid as solvent for nylon 6. The extracted fibrils were partially crystalline having melting temperature close to neat polypropylene. The fibrils have diameters less than one micrometer, down to less than 100 nm. By examining the fibrils, it was found that fibrils are partially crystalline with considerable molecular orientation.