PREPARATION AND PROPERTIES OF THERMALLY MOLDED AND CAST LIGNOSULFONATES STARCH BLENDS

Films were prepared from wheat starch and crude commercial lignosulfon ates in presence of glycerol, either by thermal moulding or by casting . Moulded films are compared to standard plasticized starch films thro ugh their mechanical properties and their behavior with respect to wat er. Stress-strain mechanical tests show that incorporating 10% lignosu lfonates modifies the tensile resistance of plasticized starchy films (ultimate stress decreases of a factor three and elongation at break i ncreases of a factor two), independently of the composition of the lig nosulfonates. Above 10%, distinct mechanical behaviors are observed be tween calcium and sodium lignosulfonate based films. Dynamic mechanica l thermal analysis reveals a single grass transition temperature rangi ng from 16-40 degrees C as a function of lignin content. (C) 1997 Else vier Science B.V.