Dielectric properties and thermal stability of cellulose high-density polyethylene bio-based composites

The project aims to develop cellulose in new biocomposites to produce dielectric materials based on thermoplastic matrices. Cellulose fibers bring multiple advantages to thermoplastic matrices in mechanical, physicochemical, thermal, and dielectric properties. Although these biocomposites are known for their advanced mechanical properties, only a few studies investigated their dielectric behavior and the effect of cellulose fibers on these properties. The bio-based composites must have better dielectric properties and excellent ductility to use as insulators in electrical cables. Thus, we investigated the dielectric properties (dielectric constant (ε’), loss factor (ε’’), conductivity (σ) and resistivity (ρ)) of high-density polyethylene (HDPE) and cellulose fibers composites. Results prove that the addition of cellulosic fibers increased the dielectric constant, the loss factor, and the conductivity of the materials compared to the neat polymer. Composites with 50 wt% fiber content showed the highest values. Therefore, the volume resistivity of all the composites studied decreased with frequency and fiber content. In addition, the reinforced polymer exhibited an intermediate thermal behavior between the polymer and the fibers. Thus, they are thermally stable materials up to 320 °C.