Optimizing biodegradable starch composite films reinforced with oil palm cellulose: A structure–property–degradability approach for sustainable packaging

This study is an investigation of cellulose fibers from oil palm empty fruit bunches (EFB) and their effect on the properties of cassava starch biocomposite films at concentrations ranging from 0 % to 8 % by weight. At low cellulose concentration levels, SEM analysis uncovered smooth surfaces with precipitation occurring at 6–8 %. Utilizing XRD, the significant increase in the crystallinity index was confirmed, peaking at the 6 % concentration. This maximum crystallinity level is the structural basis for the optimal mechanical and barrier properties observed. Mechanical testing corroborates that optimal tensile strength occurs at 6 % cellulose (7.21 MPa, 124 % improvement), accompanied by a maximum Young's Modulus (E) of 5.60 MPa, which confirms the highest stiffness elongation will decrease as the cellulose content increases. Barrier properties were optimal at 6 % cellulose, reducing water vapor and oxygen permeability by 44 % and 38 % respectively, but deteriorated at higher concentrations due to agglomeration. The optimal film, StEFB06 %, exhibited superior performance, showing a significant increase in contact angle to 85.68°, corresponding to the lowest Work of Adhesion (WA) of 78.29 mJ/m 2 , confirming the highest hydrophobicity. This optimal formulation also displayed the lowest WVP value, thereby validating EFB cellulose as a promising sustainable reinforcement for food packaging. Optical properties showed increased opacity and decreased transparency with an increasing cellulose content. Biodegradability testing demonstrated reduced weight loss and degradation rates with an increasing cellulose concentration. The 6 % cellulose concentration (StEFB06 %) provided the best balance of enhanced mechanical and barrier properties while maintaining acceptable biodegradability, thus making these films suitable for sustainable food packaging applications.