Nano-Silver-Coated Porous Clay Heterostructure Fillers for PLA and Biaxially Oriented Poly(lactic acid) Dielectric Films

In this work, poly(lactic acid) (PLA) and nano-silver-coated porous clay heterostructure (PCH) hybrid films were successfully fabricated by a twin-screw extruder. Because of the low dielectric constant of PLA, nano-silver and PCH were employed to enhance the dielectric properties of PLA, and nano-silver-coated porous clay heterostructures (Ag/PCH) with different concentrations of Ag were synthesized by the green process using ascorbic acid as a reducing agent. The results revealed that 1 wt % of Ag-coated PCH (Ag/PCH1) exhibited the highest dielectric constant of up to 40. The physical, chemical, thermal, mechanical, and dielectric properties of pristine PLA and hybrid films were studied. The results indicated that adding Ag/PCH fillers could enhance the dielectric properties of hybrid films, increasing the dielectric constant almost 10 times higher than that of PLA. In addition, Ag/PCH could reinforce the mechanical properties of PLA. Furthermore, we prepared biaxially oriented poly(lactic acid) (BOPLA) films with 4 μm of thickness. The dissipation factor of BOPLA-Ag/PCH was improved, while the dielectric constant was only slightly decreased. However, the BOPLA-Ag/PCH showed better dielectric properties than those of traditional BOPP films. As a result, PLA-Ag/PCH and BOPLA-Ag/PCH hybrid films derived from poly(lactic acid) as biodegradable polymers with superior properties can be applied as dielectric films in capacitors.