Dielectric relaxation and viscoelastic behavior of polyurethane–titania composites: dielectric mixing models to explain experimental results
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- 作者：Suryakanta Nayak ; Tapan Kumar Chaki ; Dipak Khastgir
- 关键词：Polyurethane ; Titania ; Impedance ; Dielectric ; Mechanical ; DMA
- 刊名：Polymer Bulletin
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：74
- 期：2
- 页码：369-392
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Polymer Sciences; Soft and Granular Matter, Complex Fluids and Microfluidics; Characterization and Evaluation of Materials; Physical Chemistry;
- 出版者：Springer Berlin Heidelberg
- ISSN：1436-2449
- 卷排序：74
文摘
Polyurethane–titania nanocomposites with varying composition are prepared through two different mixing methods. The effect of titania on dielectric, mechanical, and thermal properties is investigated for different composites. A variety of electrical tests (like impedance and dielectric constant) are performed on the resultant composites and it was found that the dielectric constant of composites increased significantly, whereas impedance (|Z|) decreased with the increase in titania concentration. The effect of temperature on dielectric properties was also studied and it was found that the dielectric constant increased up to a certain temperature and beyond that it decreased. From mechanical testing, it is observed that the properties depend on both the composition and mixing methods. The glass transition temperature (Tg) of soft and hard segments along with vulcanization temperature (Tv) observed from the differential scanning calorimetry (DSC) are found to shift with the incorporation of titania into the PU matrix. The viscoelastic behavior of the nanocomposites was studied by dynamic mechanical analysis (DMA), and increase in storage modulus (E′) was achieved through addition of titania to the PU matrix, especially in the low strain region, whereas some decrease was observed in the higher strain region. Finally, different dielectric models were compared with the experimental data and the best match was achieved by the Lichtenecker model, especially at 1 kHz, which can be used as a predictive rule for different volume contents of titania filler in the PU matrix.