Fabrication of Aligned Nanofiber Blends for Packaging

• Snehal Choudhury, Chemical Engineering, Case Western Reserve University

• Dr. LaShanda T.J. Korley, Chemical and Biomolecular Engineering, Materials Science and Engineering, University of Delaware
• Dr. Subhash Kalidindi, Chemical and Biomolecular Engineering , University of Delaware

Packaging for a variety of products, such as food and cosmetics, often utilize multilayer film technologies. These multilayer films are typically comprised of polymers such as polypropylene (PP) and high- and low-density polyethylene (HDPE and LDPE). Despite widespread usage, these polymeric layers are derived from nonrenewable sources and often require extreme conditions and multiple steps to be deconstructed into monomeric form. Additionally, common molding techniques used for layer fabrication restrict morphological changes to micro- and macroscales while utilizing high temperatures, limiting fabrication to thermally stable polymers that are often not naturally derived. While naturally derived polylactic acid (PLA) is an alternative for existing packaging polymers, development of PLA-based packaging with controlled morphology and mechanical properties is not well-explored due to inherent mechanical weakness of PLA. Our proposed solution to address these challenges is to fabricate highly aligned nanofiber mats made of polylactic acid (PLA) and polyurethane (PU), added to mechanically strengthen PLA. Fabrication is done by electrospinning, which allows nanoscale fabrication and greater tunability of morphology and composition at room temperature. The following PLA/PU ratios (wt%) were tested: 100/0, 90/10, 50/50, and 10/90. Electrospinning solutions were prepared at 10% w/v in 80/20 chloroform/DMF. All four ratios demonstrated the successful fabrication of electrospun mats. Scanning electron microscopy (SEM) showed the fabrication of highly porous nanofibers and post-image processing showed high alignment. Differential scanning calorimetry (DSC) confirmed the presence of PU in the blends. Tensile testing indicated that increasing the amount of PU in the blend generally led to increased mechanical strength and stretchiness, the latter of which was evidenced by lower Young’s modulus and higher strain (%) at break.