Utilizing food waste and thermoplastic starch (TPS) in 3D printed PLA formulations for sustainable and customizable controlled delivery systems

• Main Author: Wang, Liwen
• Other Authors: Loo Say Chye Joachim
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; 3D printing; Controlled release; Sustainability
• Online Access: https://hdl.handle.net/10356/180280
• Institution: Nanyang Technological University

In recent years, there has been growing interest in innovative methods for repurposing food waste. One promising approach involves integrating food waste with polylactic acid (PLA) for use in 3-dimension printing (3DP). Despite its extensive utility, PLA suffers from slow degradation rate which can take up to a few years. This study explores a novel approach to prepare PLA 3D printed (3DP) composite filament by blending thermoplastic starch (TPS) and food waste – brewer’s spent grain (BSG), spent coffee grounds (SCG), and sesame cake (SC) to accelerate degradation rates and enable tunable delivery of active compounds. The first part of the work looks at composite filaments preparation, suitable printing parameters and the development of 3DP PLA-TPS filaments incorporated with risperidone (RIS) or metoprolol tartrate (MT) as drug models. Up to 60% of TPS can be blended with 40% PLA without compromising on the integrity of the filament and 3DP capsule structure. With the addition of TPS, the drug release profile can be adjusted from 8 – 120 hours using different TPS ratios and different printed wall thicknesses. The second part of the work explored the blending of food waste to prepare 3DP PLA composite filament and the evaluation of mechanical performance. For all food wastes studied in this work, up to 15% could be blended into PLA-food waste composites. Delivery studies found that MT was fully released within 4 hours and RIS could achieve sustained release profile of about 48 hours. Lastly, the tensile strength of PLA-TPS, PLA- food waste were investigated. 3D printed PLA-TPS and PLA-BSG had tensile strength of 42.6 MPa and 36.8 MPa which were the closest to pure PLA of 49.0 MPa. The preliminary studies showed promising results for adjusting release profile and reducing PLA amount with using TPS and food waste. While the work was modelled with drugs, such a biodegradable system will be valuable in applications such as agricultural, personal care and water treatment. We offer a promising pathway towards sustainable, tunable, and cost-effective delivery systems by harnessing the properties of PLA, TPS, and industrial food waste.