Extruded composite films based on polylactic acid and sodium alginate

Sodium alginate (SA) and polylactic acid (PLA) are two biopolymers obtained from renewable resources that recently gained attention in the scientific community. Despite the promising properties of both polymers, their blends are seldom investigated. Herein we report the preparation of PLA/SA blends with SA content up to 30% by the melt mixing extrusion method, a scalable well-established and environmentally friendly technology. XRD and FTIR analysis confirmed the successful incorporation of SA in the PLA matrix. DSC revealed a different thermal response of the PLA/SA films with respect to bare PLA, especially in samples with high SA content, and the calculated crystallization degree was higher in blends. The wettability of PLA/SA blends was found to be similar to pure PLA, while mechanical properties and surface morphology were found to be lower. Discussion on possible reasons for this features and possible applicable solutions to overcome the problem are also presented.