Development of biofilms using polylactic acid (PLA) and chitosan: Effect of incorporating cellulose microfibers

<h2>Abstract</h2> The use of biopolymers as alternatives to petroleum-based materials, especially for sustainable packaging, is promising because of their biodegradability, strong mechanical properties, and ability to deliver active substances. This study investigates the incorporation of cellulose microfibers from cocoa pod husks (CPHs) into two biopolymers: polylactic acid (PLA) and chitosan. First, chitosan film formulations were designed using a Taguchi L4 experimental design to identify the optimal fiber content, which was determined to be 5% <i>w/w</i> tCPH. Then, the incorporation of fiber into PLA and chitosan films was evaluated using a 2² Factorial Design. The analysis included mechanical testing, morphological analysis via Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), thermal analysis (DSC and TGA), and water absorption testing for the chitosan films. Results showed that PLA/tCPH films with 5% fiber had a tensile strength of 53.37 MPa, exceeding that of PLA/CPH films (51.47 MPa) and nearly matching that of the control PLA film (55.91 MPa). Chitosan/tCPH films increased tensile strength from 9.55 MPa to 19.04 MPa, although stiffness remained low. PLA/tCPH films displayed higher crystallinity, which could potentially be related to improved barrier properties. Chitosan/tCPH films absorbed 8.67% less water than those with untreated fibers, but chitosan remained highly hydrophilic. These findings offer valuable insights for developing sustainable packaging using cocoa waste, enabling the creation of packaging systems that combine the mechanical strength of reinforced PLA with the functional properties of chitosan, including the delivery of active substances through film manufacturing.