Abstract A series of bionanocomposite films based on chitosan, reinforced with chitin nanocrystals, were developed, and assessed in terms of dielectric behaviour and conductivity by using an experimental methodology that allows avoiding the conductivity contribution and the exclusion of contact and interfacial polarization effects. The dielectric relaxations at low and high frequency and temperatures were modeled by Havriliak-Negami functions. Below the glass transition temperature (Tg), the γ and β relaxations were observed, which were related to intramolecular and non-cooperative segmental movements. At higher temperatures, an intermolecular and cooperative macromolecular movement, related to the glass transition, gave rise to α-relaxation. In addition, two over-Tg ρI and ρII relaxations were found, which were related to the displacement of dipoles in the disordered structure of bionanocomposites. The addition of chitin nanocrystals did not affect the apparent activation energy Ea of the γ-relaxation. However, it decreased the Ea of the β-relaxation and increased the free volume at temperatures in the vicinities of the α-relaxation. Finally, the electric conductivity of the bionanocomposites was lower than that of neat chitosan and chitin due to the interaction between the OH and NH2 groups that reduced the ionic mobility, along with the increase of free volume, with the subsequent separation of phases.

中文翻译：

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甲壳素纳米晶对壳聚糖基生物纳米复合材料介电行为和电导率的影响

摘要 开发了一系列基于壳聚糖并用几丁质纳米晶体增强的生物纳米复合薄膜，并通过使用允许避免电导率贡献和排除接触和界面极化效应的实验方法评估介电行为和电导率。低频和高频以及温度下的介电弛豫由 Havriliak-Negami 函数建模。在玻璃化转变温度 (Tg) 以下，观察到 γ 和 β 弛豫，这与分子内和非合作的节段运动有关。在较高温度下，与玻璃化转变相关的分子间和协同大分子运动引起 α-弛豫。此外，还发现了两个过 Tg ρI 和 ρII 弛豫，这与生物纳米复合材料无序结构中偶极子的位移有关。添加几丁质纳米晶体不影响 γ-弛豫的表观活化能 Ea。然而，它降低了 β-弛豫的 Ea 并增加了 α-弛豫附近温度下的自由体积。最后，由于 OH 和 NH2 基团之间的相互作用降低了离子迁移率，随着自由体积的增加以及随后的相分离，生物纳米复合材料的电导率低于纯壳聚糖和几丁质的电导率。它降低了 β-弛豫的 Ea 并增加了 α-弛豫附近温度下的自由体积。最后，由于 OH 和 NH2 基团之间的相互作用降低了离子迁移率，随着自由体积的增加以及随后的相分离，生物纳米复合材料的电导率低于纯壳聚糖和几丁质的电导率。它降低了 β-弛豫的 Ea 并增加了 α-弛豫附近温度下的自由体积。最后，由于 OH 和 NH2 基团之间的相互作用降低了离子迁移率，随着自由体积的增加以及随后的相分离，生物纳米复合材料的电导率低于纯壳聚糖和几丁质的电导率。