When polymers are crystallized under flows such as elongational and/or
shear flows the so-called shish-kebab structure is formed, which consists
of long central fiber core (shish) surrounded by lamellar crystalline structure
(kebab) periodically attached along the shish. It is believed that
the shish is formed by crystallization of completely stretched polymer
chains and the kebabs are folded chain lamella crystals and grow to the
direction normal to the shish. The shish-kebab structure is very
important from industrial viewpoint because it is structural origin of
ultra-high strength and ultra-high modulus fiber. However, the formation
mechanism is not still clear. In this work we have the formation mechanism
of shish-kebab structure using light scattering, SR small- and wide-angle
X-ray scattering , and neutron scattering to cover a very wide spatial
scale.
Schematic illustration of shish-kebab structure
Polymer, 46, 1878 (2005)
Polymer, 47, 5669 (2006)
Macromolecules, 39, 7617 (2006)
Time evolution of shishi-kebab structure in a wie scale
Effect of high molecular weight component on shish formation
Critical concentration of HMWPE is =0.5 wt %
DPLS(upper)、SAXS(middle)、WAXS(lower)
Shish-kebab structure formation depends on shear rate and strain, showing
relaxation plays an important role in the formation.
SANS and SAXS of d-PE including 2.8% h-UHMWPE, showing UHMWPE forms shish