Dielectric and Viscoelastic Behavior of Polyvinyl Butyral Films

Area of Science:

• Materials Science
• Polymer Physics
• Dielectric Spectroscopy

Background:

• Polyvinyl butyral (PVB) is a versatile polymer with applications requiring specific dielectric and thermal characteristics.
• Understanding relaxation processes is crucial for predicting PVB performance under varying conditions.
• Previous studies have explored PVB's mechanical properties, but a comprehensive dielectric analysis, especially above its glass transition, is needed.

Purpose of the Study:

• To comprehensively investigate the dielectric and thermal properties of polyvinyl butyral (PVB).
• To analyze electrical relaxation processes, specifically glass transition and interfacial polarization.
• To elucidate the conductive behavior of PVB at elevated temperatures using advanced analytical techniques.

Main Methods:

• Dynamic Electrical Analysis (DEA) was employed across a frequency range of 100 Hz to 1 MHz and temperatures from 293 K to 473 K.
• Dynamic Mechanical Analysis (DMA) was used to assess viscoelastic behavior and the mechanical aspect of the glass transition.
• Fractional calculus, utilizing a fractional Debye model, was applied to analyze dielectric measurement results.

Main Results:

• Two primary electrical relaxation processes were identified: glass transition and interfacial polarization.
• Above the glass transition temperature (~343 K), interfacial polarization was found to dominate the conductive behavior of PVB.
• The complex electric modulus framework provided valuable insights into interfacial polarization, showing good correlation with theoretical predictions.
• Fractional order derivative values close to 1 indicated significant conductive behavior above the glass transition temperature.

Conclusions:

• Interfacial polarization plays a dominant role in the electrical conductivity of PVB at temperatures exceeding its glass transition.
• Fractional calculus and the complex electric modulus are effective tools for analyzing dielectric phenomena in polymers like PVB.
• The study provides a deeper understanding of PVB's dielectric response, crucial for optimizing its use in various technological applications.