Structural and Electronic Properties of Defect‐Free and Defect‐Containing Polypropylene: A Computational Study by van der Waals Density‐Functional Method

Abstract

This paper presents a study on structural and electronic properties of bulk polypropylene – one of the fastest growing engineering plastics – based on density‐functional calculations. The use of recently developed non‐local van der Waals functionals to approximate the exchange–correlation energy is crucial for a good description of structural properties. Various types of chemical imperfections, their impacts on electronic properties of polypropylene are also studied.

Practical Notes on the Measurement and Interpretation of Thermally Stimulated Discharge Currents in Biaxially Oriented Polypropylene

“…While TSDC does not provide any direct evidence of the origin of the deep trap states, various complementary methods have indicated that they may be caused by additives (i.e. antioxidants), chemical impurities or melting of less perfect PP crystallites [5]- [7]. Previously, the high temperature TSDC peaks of BOPP have also been associated with ionic conduction [8].…”

Biaxially oriented silica–polypropylene nanocomposites for HVDC film capacitors: morphology-dielectric property relationships, and critical evaluation of the current progress and limitations

“…Fundamentally, the DC electro-thermal properties of BOPP are trap-controlled-that is, the electronic trap states within the energy band gap of semi-crystalline PP arising from physical/morphological disorder 3,21 and chemical defects 22 dictate the temperature-and field-dependent mobility, trapping and scattering of free charge carriers. The nature of these electron/hole trap states, particularly the trap density and depth distribution (both energetic and spatial), has significant effects on the bulk polarization, electrical conductivity, space charge accumulation and dielectric strength of polymer insulation, thus making it very desirable to be able to control their nature and quantity.…”

Ageing: Causes and Effects on the Reliability of Polypropylene Film Used for HVDC Capacitor

“…Distinct occupied and unoccupied levels in the band-gap exist in the case of C = O, vinyl, conjugated double bond and dienone defects while are separated by a 5 -6 eV. These defects are partly responsible for the reduction of breakdown strength by decreasing the band-gap of a dielectric [59].…”