Dielectric study on size effects in polymer laminates and blends

✍ Scribed by A. Boersma; J. van Turnhout

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 327 KB
• Volume: 36
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19981115)36:15<2835::aid-polb18>3.0.co;2-6

✦ Synopsis

In this article we will focus on the dielectric properties of laminates and blends of a partially conducting (the liquid crystalline copolyesteramide Vectra B950) and an insulating (polypropylene or mica) phase. Dielectric spectroscopy was used as a tool to obtain information about the influence of the dimensions of the conducting phase in these laminates and blends. With decreasing thickness of the conducting layer in the laminates, the measured permittivities deviate more and more from the values predicted using conventional dielectric mixture models. From this discrepancy it is possible to calculate the thickness of the charge layer (ϭDebye length) in the conducting phase and the thickness of this phase itself, using a model derived by Trukhan. This model incorporates not only conduction, but also diffusion of the charges. Similar experiments were performed on a system of Vectra B950 particles in a polypropylene matrix. After the derivation of a new model, which combines the Trukhan model for space charges with the Bo ¨ttcher equation for dielectric mixtures, we could make a distinction between samples containing large and small particles. For samples containing small particles, it is even possible to determine the variation in particle sizes. However, the use of a Debye length of 1.1 m obtained from the laminates resulted in particle sizes that were two times higher than the actual values.