Development of Dielectric Biocomposite and Biaxially Oriented Films from Poly(Lactic Acid) and Nano-silver Coated Microcrystalline Cellulose

The objective of this study is to enhance the dielectric properties of biocomposite films through the fabrication of biaxially oriented films (BO) and the incorporation of silver-coated microcrystalline cellulose (Ag/MCC). The silver coating was used in concentrations ranging from 0.2 to 2% using an environmentally friendly method. The dielectric constant and dielectric loss of all sample were measured in the frequency range from 10³ to − 10⁶ Hz. The sample containing 0.6% silver on microcrystalline cellulose (0.6Ag/MCC) demonstrated the highest dielectric constant, measured 64. Subsequently, biocomposite films were produced by utilizing 0.6%Ag/MCC at different ratios (1–5 phr) through a one-step cast film twin-screw extruder. The sample with the highest dielectric constant was PLA-0.6Ag/MCC4, which increased from 3 (PLA) to 37. Furthermore, biaxially oriented films were successfully prepared using a film biaxial stretching machine, achieving a thickness of 70 μm. This technique can significantly improve their dielectric properties, surpassing those of unstretched films. The improvement in dielectric properties can be attributed to the reorganization of molecular chains, promoting a more orderly arrangement and increases crystallinity. Therefore, the resultant biocomposite and biaxially oriented film demonstrate exceptional dielectric properties, rendering them suitable for dielectric applications such as capacitor dielectric films.