Controlling Crystal Microstructure To Minimize Loss in Polymer Dielectrics

Abstract

A model semicrystalline polymer, poly­(ethylene naphthalate) (PEN), was used to examine how morphological factors inhibit chain segment relaxations that contribute to dielectric loss. This was achieved by manipulating the extent of crystallization and the crystalline microstructure through a combination of annealing and uniaxial drawing and investigating the effects on dielectric performance. Varying crystallization conditions influenced the dynamic T g and extent of rigid amorphous fraction formation but had only a moderate effect on loss magnitude. Film orientation, however, greatly reduced loss through strain-induced crystallization and the development of oriented amorphous mesophasic regions. Postdrawing annealing conditions were capable of further refining the crystal microstructure and, in turn, the dielectric properties. These findings demonstrate that the semicrystalline polymer morphology can have a very significant influence on amorphous chain relaxations that contribute to dielectric loss, and understanding how processing conditions affect morphology is critical to the rational design of polymer dielectrics.

Effects of Rigid Amorphous Fraction and Lamellar Crystal Orientation on Electrical Insulation of Poly(ethylene terephthalate) Films

“…Effects of the RAF and crystal orientation were discussed to understand the primary reason for the unsatisfied dielectric performance of BOPET, especially at elevated temperatures. This knowledge will help us to develop new low-loss BOPEN films for even higher temperature ratings up to 150 °C. , …”

“…This knowledge will help us to develop new low-loss BOPEN films for even higher temperature ratings up to 150 °C. 23,27 ■ EXPERIMENTAL SECTION Materials and Sample Preparation. The BOPET film (6.0 μm) was provided by SBE, Inc. (Barre, VT).…”

Control over microphase separation and dielectric properties via para-fluoro thiol click reaction

“…In general, tan δ is known to be influenced by the crystallinity and uniformity of the microstructure as well as the interaction between the nanostructures and the polymer boundary as reported for polymer composites. 27,43 On the contrary, considering this slight decrease is as expected due to the change in the chemical structure of the polymer, no microphase-related effect was observed on dielectric loss. This morphology independent behaviour is due to a stable continuous PFS phase in all-polymer film samples.…”

Controllable synthesis and structural design of novel all-organic polymers toward high energy storage dielectrics

“…Controlling the aggregated structure of the molecular chain, that is, the crystalline morphology, or regulating the interface between the electrode and the dielectric material is also a commonly used method to improve the energy storage performance of polymer dielectric materials in recent years. Miranda et al (2017) used a model semicrystalline polymer, poly (ethylene naphthalate) (PEN) to examine the effect of crystalline/amorphous lamellar microstructure on amorphous chain relaxations and how this affects dielectric loss through a combination of annealing and uniaxial drawing. By understanding the influence of the lamellar microstructure on amorphous relaxations that contribute to dielectric loss, the morphology can be tuned through appropriate processing conditions to minimize energy dissipation and improve capacitor performance.…”