Dielectric Properties of Jute Fibers Reinforced Poly(lactic acid)/Poly(butylene succinate) Blend Matrix

Abstract

Dielectric measurements were performed on Poly(lactic acid) (PLA) polymer, Poly(lactic acid)/Poly(butylene succinate) (PLA/PBS) blend matrix and its green composite reinforced with Jute fibers in temperature range from 20 to 140 °C and frequency range from 10−1 Hz to 1 MHz. Thermal analyses based on differential scanning calorimetry technique have evidenced different thermal transitions of the semi-crystalline polymer occurred for PLA one. Addition of PBS into PLA polymer enhanced its crystallinity. However, the presence of Jute fibers in the green composite material lowered such effect and increased the PLA polymer glass transition temperature, Tg. These could be attributed to the PBS contribution into the Jute fibers/blend matrix interactions. Accordingly, dielectric analyses have revealed the presence of three relaxation processes for PLA polymer. These were identified to the α mode relaxation, the dc conductivity effect and the Maxwell–Wagner–Sillars (MWS) interfacial polarization effect. The latter effect was attributed to the accumulation of charges at the crystalline phase/amorphous phase interfaces of PLA polymer. Two additional dielectric relaxations appeared for PLA/PBS blend matrix. These were associated with β relaxation and interfacial polarization effect originating from PLA polymer and the semi-crystalline character of PBS polymer, respectively. The incorporation of Jute fibers into the PLA/PBS blend matrix gave rise to other dielectric relaxations associated with the water dipoles and interfacial (Jute fibers/blend matrix) polarization effects. Analysis of dielectric relaxations at high temperature above the glass transition temperature using the Havriliak–Negami model allowed probing Jute fibers/blend matrix interactions. Adhesion mechanism occurred in the studied green composite was determined by vibrational analysis based on FT-IR technique.