Improving the Processability & Functional Properties of Thermoplastic Polymers for Fused Filament Fabrication

Additive Manufacturing (AM), often referred to as 3D printing, is recognized as a transformative technology for its capacity to efficiently fabricate complex parts using multiple materials while minimizing material wastage. However, despite its versatility, challenges such as limited portfolio of available polymeric materials, lack of functional materials, and absence of standardization & certifications of testing processes remain significant challenges to its widespread adoption. Overcoming these challenges is crucial for unlocking the full potential of AM in improving manufacturing efficiency and sustainability. This thesis investigates methods to enhance the processability and functional properties of thermoplastic polymers, with a specific focus on Poly(lactic acid) (PLA) and thermoplastic polyimides (TPIs) within the realm of Fused Filament Fabrication (FFF). Initial investigation offers a comprehensive overview of recent advancements in AM, specifically concentrating on FFF 3D printing, its principles, advantages, and limitations. It also provides an in-depth analysis of various thermoplastic polymer materials, particularly PLA, TPI, as well as their blends and composites in the context of FFF. Further investigation concentrates on developing functional PLA composite filaments for FFF, emphasizing the preparation of a PLA ternary biocomposite with well-balanced mechanical properties. This involves the synthesis and modification of cellulose nanofibers (CNFs) with 1-Pyrenebutyric acid (PBA). The study thoroughly investigates the enhanced mechanical properties of the printed ternary biocomposite through various characterization techniques. Additionally, this study explores the solid-state fluorescence emission of the PLA biocomposite, suggesting potential applications in the 3D printing of fluorescence-based sensors and optical devices. Furthermore, the synthesis of PLA-PEG-PLA triblock copolymer and its blending with PLA are discussed as a strategy to address the inherent brittleness commonly observed in 3D printed PLA. The research demonstrates the blend's miscibility, resulting in improved toughness without phase separation, distinguishing it from other PLA blends with soft polymers and plasticizers. A detailed investigation into the crystallization behavior of the printed PLA blend is conducted, including studies on nucleation efficiency and sph erulite morphology. Subsequent studies highlight the successful production of 3D printable TPI filaments and studied change in viscosity with processing temperature over a consistent time period. Mechanical and thermal properties of 3D printed TPI filaments in different build orientations are assessed, along with an examination of their solid-state quantum yield to analyze fluorescence properties. This research reveals the potential of TPI as a high-performance polymer for advanced FFF applications requiring high-temperature stability, intricate shapes, and fluorescence properties. Finally, subsequent investigation summarizes the overall findings and outlines potential directions for future research. This investigation lays the groundwork for developing functionalized filaments capable of meeting diverse industrial requirements while promoting sustainability and efficiency in manufacturing processes.