Effect of sisal and hydrothermal ageing on the dielectric behaviour of polylactide/sisal biocomposites

Abstract

The dielectric properties of virgin polylactide (PLA) and its reinforced composites with different weight amounts of sisal fibres were assessed at broad temperature (from-130ºC to 130ºC) and frequency ranges (from 10-2 to 10 7 Hz), before and after being subjected to accelerated hydrothermal ageing. The synergetic effects of both the loading of sisal and hydrothermal ageing were analysed by means of dielectric relaxation spectra. The relaxation time functions were evaluated by the Havriliak-Negami model, substracting the ohmic contribution of conductivity. The intramolecular and intermolecular relaxations were respectively analysed by means of Arrhenius and Vogel-Fulcher-Tammann-Hesse thermal activation models. The addition of fibre increased the number of hydrogen bonds, which incremented the dielectric permittivity and mainly hindered the non-cooperative relaxations of the biocomposites by increasing the activation energy. Hydrothermal ageing enhanced the formation of the crystalline phase at the so-called transcrystalline region along sisal. This fact hindered the movement of the amorphous PLA fraction, and consequently decreased the dielectric permittivity and increased the dynamic fragility.

Electrospun Poly(ethylene-co-vinyl alcohol)/Graphene Nanoplatelets Composites of Interest in Intelligent Food Packaging Applications

“…The dielectric analysis of polymer materials and composites permits understanding the macromolecular relaxations [ 33 , 34 , 35 , 36 ] and is also a valuable approach for evaluating their conductivity and electric response. In this sense, Figure 7 , Figure 8 , Figure 9 and Figure 10 show the dielectric spectra of the EVOH and EVOH/GNP fibers in terms of ε′, ε″, tan δ, and M″, respectively, in all the frequency range at 25 °C.…”

Processing and Wear Behaviour of 3D Printed PLA Reinforced with Biogenic Carbon

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Influence of chitin nanocrystals on the dielectric behaviour and conductivity of chitosan-based bionanocomposites

“…Dielectric Thermal Analysis (DETA) is of great importance to test the segmental rearrangements and dynamic fragility of polymers [43]- [47] , which modifications are not perceptible by other macroscopic techniques. A particular experimental methodology was applied to obtain an accurate dielectric spectrum of these samples, without being affected by interfacial polarization effects nor by the conductivity contribution.…”