Sparking Nanometal Oxides for Modifying Surface Properties of Thermoplastic Starch/Carboxymethyl Cellulose Blends

A thermoplastic starch (TPS) was developed by blending cassava starch in a 70/30% wt/wt ratio. Carboxymethyl cellulose (CMC) 5% wt/wt was added during TPS solution mixing at 80 °C. Sparking technology was applied to deposit nanometal particles onto polymer surfaces. Nanometal oxide particles of Ag, Zn, and Cu were sparked on the surface of TPS and TPS/CMC samples to investigate the effects of the metal type and polymer surface chemistry on the resulting material properties. The surface morphology, element distribution, mechanical properties, color characteristics, wettability, and thermal behavior were evaluated. The tensile strength of TPS/CMC increased from 2.2 MPa to 5.0 MPa with Ag sparking, while the contact angle of TPS/CMC increased from 41.3° to 91.6°, 89.3°, and 95.1° after Ag, Zn, and Cu sparking, respectively. SEM–EDS confirmed the deposition and distribution of the nanometal types on the polymer surfaces. The sparked TPS/CMC samples exhibited higher contact angles than the sparked TPS sample due to the strong interactions between the deposited nanometal particles and –COOH functional groups of CMC. The thermal analysis showed that the deposited metal type influenced the degradation behavior of the TPS and TPS/CMC samples. Sparking technology provided effective surface modification via depositing nanometal particles onto TPS/CMC, resulting in uniform particle distribution and enhanced mechanical and surface wettability properties, with potential applications in the sustainable packaging industry.