MICROSTRUCTURE AND MELT FLOW BEHAVIOR OF A STARCH-BASED POLYMER

Results on some physical properties and on melt processing of a starch-based polymer under steady-state shearing are presented. A peculiar microstructure involving a strong pseudoplastic behavior at high shear rates as well as yield stress at lower ones is discussed. A model is proposed to explain the characteristic viscoelastic behavior of this material based on hydrophylic and hydrophobic interactions between starch and vinyl-alcohol copolymers. In spite of the highly structured and composite nature of this class of materials, the full body of results reveals that they can be easily processed by means of common manufacturing techniques involving melt pumping and die forming. A comparison with a low density polyethylene (LDPE) grade for film blowing is also shown.