P1H-3 Monitoring Bio-Polymer Film Formation with Ultrasonic Spectroscopy Technique

Bio-based polymers have potential to replace plastics in packages. Recently, degradable bags made of potato starch, have become commercially available. One promising starting material for packing films is xylan, which is heteropolysaccharide extracted from oat grain husks. We report on efforts to monitor the mechanical properties of xylan films during layer formation. This characterization should allow recipe optimization and engineering of the layer end-use properties. The aqueous polymer suspension was placed on a quartz glass cylinder that additionally served as an acoustic delay line. The drying sample was probed from below with an ultrasonic pulse-echo set-up. Pulses that reflected from sample-quartz glass boundary were recorded. The phase and the amplitude content of these pulses were used to obtain the temporal development of the shear modulus and the out-of-plane longitudinal modulus of forming layers. In the end stage the longitudinal modulus of sorbitol plasticized xylan layer was (22.3plusmn4.2) GPa. This figure for glycerol plasticized xylan was (6.8plusmn0.7) GPa