Optimization of cellulose nanocrystal (CNC) concentration in polycaprolactone bio-composites for bio-plotting: a robust interpretation of the reinforcement mechanisms
Nectarios Vidakis, Markos Petousis, Nikolaos Michailidis, Constantine David, Nikolaos Mountakis, Vassilis Papadakis, Evangelos Sfakiotakis, Dimitrios Sagris, Apostolos Argyros
Abstract
Abstract Bioabsorbable and biodegradable composites have experienced rapid growth, owing to their high demand in the biomedical sector. Polymer-cellulose nanocrystal (CNC) compounds were developed using a medical-grade poly (ε-caprolactone) (PCL) matrix to improve the stiffness and load-bearing capacity of pure PCL. Five PCL/CNCs filament grades were melt-extruded, pelletized, and fed into an industrial bioplotter to fabricate specimens. To assess the effects of CNCs on pure PCL, 14 tests were conducted, including rheological, thermomechanical, and in situ micro-mechanical testing, among others. The porosity and dimensional accuracy of the samples were also documented using micro-computed tomography while scanning electron microscopy was employed for morphological characterization. Overall, the 4.0 wt % CNCs loading accomplished the optimum mechanical response, with an increase in its tensile (19.1%) and flexural strength (12.6%) compared to pure PCL. Concurrently, this grade exhibited the highest MFR, minimum porosity, and highest nominal-to-actual geometric accuracy, thereby convincingly interpreting the reinforcement mechanisms.