Fused Deposition Modeling (FDM) and Nano-Fillers Impact on Shape Memory Properties of 3D Printed Thermoplastic Polyurethane (TPU) Filament

Abstract

Nature's diversification has been inspiring the world's creative minds to replicate its convoluted structure. However, since the 1980s, 3D printing has challenged conventional processing with material, design, and cost efficiencies. 3D printing incorporation with stimuli-responsive materials generates a window to fabricate dynamic structure to alter its printed shape when actuated. The present work has employed nano additives' effect on shape memory performance of 3D printing shape memory polyurethane (SMPU) filament and printing process impact on SMPU filament. Reinforcement materials such as MWCNT, nanoclay, activated charcoal, and polypyrrole were compounded and extruded in 2 wt.% with SMPU, and the output of which was utilized for characterization like FTIR and TGA, and shape memory testing was performed. Extrudate filament fed to spring-force assembly, specially designed and fabricated, and shape transition values were determined using the involute curve profile. The results testified shape recovery > 90% for neat SMPU, as well as SMPU composites 3D printed filaments. Considering to shape fixity, only pure polyurethane and nano clay composite stood > 80%, whereas another composite deteriorated to 70% because of soft segment interaction. The experiment was carried forward to analyze the additive manufacturing impact on shape memory performance of SMPU. 3D printed filaments and printed structure both serve a vital range of application in biomedical, soft robotics, aeronautical industries, electronics, and numerous others.