Structure development of polymeric liquids under elongational flow

With an intention of studying dynamic structure in polymeric liquids under elongation, we developed Elongational Flow Opto-Rheometry (EFOR) which enabled us to achieve simultaneous measurements of transient tensile stress sigma(epsilon(0); t) and birefringence Delta n(epsilon(0); t) as a function of time t under uniaxial elongation with constant strain rates. The EFOR is essentially Meissner's melt elongational rheometer (RME) combined with a high precision birefringence apparatus. With this EFOR we examined the validity of stress-optical rule (SOR) and the strain-induced hardening in some polymeric liquids under elongation. The EFOR is also powerful especially when combined with other ex situ structure-analysis techniques such as Rayleigh scattering (LS), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and thermal analysis in elucidating the internal structure development under elongation. This study describes its application, combined with LS, SAXS, TEM, and dynamic thermal analysis, to supercooled semicrystalline polymers, polymer blends, and block copolymers. Furthermore, we introduced our viscoplastic material model of polymeric liquids for 3-dimension FEM (finite element method) analysis on the vacuum forming process.