Synthesis and characterization of additively manufactured microcapsule-reinforced polylactic acid composites for autonomous self-healing

Material extrusion-based additive manufacturing (AM) process builds the objects/structures through a precise feedstock deposition in a layer-by-layer manner. Polylactic acid (PLA) is a popular biodegradable feedstock in AM, while octyl methoxycinnamate (OMC) is known for its eco-friendliness and ultraviolet (UV) protection properties. The present study focuses on the novel infusion methodology of OMC-based microcapsules into PLA to develop self-healing composite filaments. Post-composition iterations, the optimum compositions for the filler and plasticizer were determined, and the filaments were extruded. Microcapsule-infused PLA and the neat PLA samples were printed as per the American Society for Testing and Materials (ASTM) standard. The uniaxial tensile test results showed that the failure strain endured by the microcapsule-infused samples was about 10 times more than the neat PLA counterparts. It is attributed to the effective load distribution and the complex polymerization reaction (due to the interaction of OMC with the matrix). Fracture surface morphology of the samples via optical microscopy (OM) and field emission scanning electron microscope (FESEM) affirmed the strong PLA-OMC interface. A depreciation in the Brinell Hardness for the microcapsule-based samples was due to the localized indenter force, causing greater damage in a narrow area than microcapsule ruptures' healing ability.Highlights The optimized composition of PLA: plasticizer:microcapsule is 1:0.04:0.05. Microcapsule-infused PLA has improved Young's modulus and failure strain. Interaction with microcapsules improves elastic behavior and self-healing. FESEM reveals close bonding of microcapsule with the PLA matrix. Synthesis and characterization of Microcapsule-based composites with self-healing properties. image