One-step strategy for preparing renewable polylactic acid (PLA)/thermoplastic starch (TPS) composite filaments for 3D printing

Renewable, sustainable, and cost-effective polylactic acid (PLA)/thermoplastic starch (TPS) filaments for 3D printing are desirable. Nevertheless, previous methods for fabricating such filaments were based on a two-step extrusion process, which is energy- and time-consuming. In this study, we demonstrate a one-step strategy to prepare PLA/TPS filaments by using a certain amount of glycerol, where the plasticization of starch and compounding between PLA and TPS can be simultaneously achieved through a single melt-extrusion process. Not only did glycerol function as a plasticizer for both starch and PLA, but it also acted as a dispersing agent to realize a homogeneous distribution of TPS. Due to the introduction of the TPS, cold crystallization temperature presented a remarkable reduction from 128 °C for pure PLA filament to 104–110 °C for the composite counterparts. The melt flow index of the filaments heightened with increasing TPS content, which was advantageous in preventing occurrence of voids during 3D printing. Moreover, water contact angle showed a considerable decrease by approximately 20 ° with the incorporation of 10 % TPS. Most importantly, by this proposed one-step strategy, less energy consumption and higher throughput can be readily realized, thus enabling a cost-effective production for renewable PLA/TPS filaments.