Effect of Stretching Direction on Dielectric Property of Poly(Lactic acid)/Nano-silver Coated Microcrystalline Cellulose Biocomposite Films

This study investigates the dielectric effects of bidirectional stretching (BO), which involves both machine (MDO) and transverse (TDO) directions, on poly(lactic acid) and nano-silver coated microcrystalline cellulose. The experiments employed stretching ratios of 2 × 2, 3 × 3, and 4 × 4. Results indicate that BOPLA-Ag/MCC4, which underwent the highest biaxial stretching ratio, exhibited the most significant increase in dielectric constant. The BOPLA-MCC4 and BOPLA-Ag/MCC4 demonstrated the highest dielectric constants, measuring 48 and 53, respectively. This increase can be attributed to the reorganization of molecular chains, leading to higher structural order and crystallinity, which promotes dipole and interface polarization. Biaxial stretching also enhances the mobility of polar polymer chains, enabling a stronger response to electric fields. Conversely, unidirectional stretching can reduce polymer chain disruption, limiting the movement of polar polymers and leading to a drop in dielectric properties. Consequently, biocomposite films stretched in biaxial directions demonstrate superior dielectric properties, indicating their potential for dielectric applications and suitability as environmentally friendly, biodegradable films.