Paper Title
Development Of Bio-Nanocomposite Fibers From Cellulose Nanocrystal And Renewable Biopolymers: Spinnability And Mechanical Properties

Abstract
As utilization of renewable materials become central to future sustainability, polybutylene succinate adipate (PBSA) emerge as a promising, degradable and biocompatible alternative to petrochemical commodity products. Excellent in elongation at break and ductility, the polymers suffer from low melt flow index and poor Young’s modulus. As such, practical applications of the soft bioplastic require special processing conditions and additives that improve the mechanic strength at the cost of undesired contamination and loss of the distinctive biodegradability. In the present contribution, cellulose nanocrystals (CNCs) are investigated as a strength enhancer bio-nanoadditive in the fabrication of PBSA into bio-nanocomposite microfibers. First, CNCs are extracted from Natta de coco (100% bacterial cellulose) by strong alkaline treatment in sodium hydroxide, followed by acid hydrolysis in sulfuric acid solution. Under transmission electron microscopy, (TEM), the obtained bio-additives appear rod-like with 400-450 nm in length, 10-20 nm in diameter and aspect ratio (Length/Diameter) of approximately 30. The nanostructures are then mixed with the PBS chips under melt processing in order to disperse the bio-additive in the biopolymer matrix. The bio-nanocomposites are then diluted with pristine PBS chips at 0.1-1 wt. % for a subsequent melt fiber spinning. Under scanning electron microscopy (SEM), the obtained microfibers, 10 micron in diameter, appear round and continuous with smooth surface, which confirms both compatibility and spinnability of the nanacomposites. The effects of the nanocrystals on the physical, thermal and mechanical properties of the biopolymers are studied by SEM, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The changes or lack there of in the melting and crystallization profiles upon the addition of CNC could reveal the extent to which the bio-nanoadditives and their spatial distribution affect the melt spinning process. Finally, high speed melt spinning is applied to the nanocomposite to investigate how the nanocrystals may influence the melt spinnability and continuity process at pilot and industrial scale, the level at which the drawing speed and drawing ratio are set at high values for high throughput and small denier fiber outputs. Even though the CNC incorporation may not drastically modify the diameter and crystallization profile at high speed, the additives could improve the mechanical strength of the obtained fine melt spun fibers. Keywords - Bio-nanocomposite Fibers, Bacterial Cellulose Nanocrystal, Melt Spinning, Mechanical Strength