Desiccant effect of starch in polylactic acid composites

• Main Authors: J. Moczo, D. Kun, E. Fekete
• Format: Article
• Language: English
• Published: Budapest University of Technology 2018-11-01
• Series: eXPRESS Polymer Letters
• Subjects: Biopolymers, biocomposites; thermoplastic starch; polylactic acid; biodegradable packaging; water uptake
• Online Access: http://www.expresspolymlett.com/letolt.php?file=EPL-0009205&mi=cd

Polylactic acid (PLA)/starch and PLA/starch-glycerol composites with different glycerol contents were prepared in a wide composition range, in order to study their applicability as packaging materials for dry products. Water uptake was determined at a temperature of 23 °C and different relative humidities. Structure and mechanical properties were also investigated. PLA/ unplasticized starch composites could absorb a considerable amount of water. As a result, they may be adequate as a biodegradable inner container in dry packaging. The absorption capacity of the composites increased significantly with increasing starch content and relative humidity, respectively. Unplasticized starch exhibited not only a desiccant but also a reinforcing effect in PLA, thus both stiffness and strength increased with increasing starch loading. The nfluence of glycerol content on the water uptake was difficult to reveal due to the migration of glycerol from the bulk to the surface. Furthermore, glycerol weakened the PLA/starch adhesion and softened starch particles.